Systems and methods for determining compression depth and providing feedback during active compression decompression

Abstract

A system for assisting in cardiopulmonary resuscitation (CPR) includes an active compression-decompression (ACD) device configured to cause a user to push down on and pull up on a patient's chest, a sensor to measure force applied to the patient's chest, a sensor configured to measure displacement of the patient's chest, one or more processors, and a user interface. The processors are configured to execute computer-executable instructions to determine a maximum compression force applied to the patient's chest during a compression cycle and a maximum decompression force applied to the patient's chest during the compression cycle, estimate a displacement value of a total displacement of the patient's chest during the compression cycle for compressing and decompressing the patient's chest, and estimate at least one of a compression depth and a decompression displacement of the compression cycle.

Description

[0001] Priority Statement

[0002] This application claims priority to U.S. Provisional Patent Application No. 62 / 799,267, filed January 31, 2019; U.S. Provisional Patent Application No. 62 / 888,216, filed August 16, 2019; and U.S. Provisional Patent Application No. 62 / 928,083, filed October 30, 2019, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This invention relates to the field of cardiac resuscitation, and particularly to a device for assisting rescuers in performing active chest compressions and decompressions during cardiopulmonary resuscitation (CPR). Background Technology

[0004] Cardiac arrest is a leading cause of death worldwide and is the result of a variety of conditions, including heart disease and severe trauma. In cases of cardiac arrest, several measures are considered necessary to improve a patient's chances of survival. These measures, known as cardiopulmonary resuscitation (CPR), must be initiated as quickly as possible to at least partially restore the patient's breathing and blood circulation. CPR is a set of therapeutic interventions designed to provide blood flow through external manipulation of the patient's external surfaces (e.g., chest, abdomen, legs) and typically oxygenates the patient's blood by delivering external oxygen and other gases to the lungs. One commonly used technique developed approximately 30 years ago is chest compressions.

[0005] Chest compressions during CPR are used to mechanically support circulation in cases of cardiac arrest by maintaining blood flow and oxygen delivery until the heart resumes beating. Rescuers ideally compress the victim's chest at a rate and depth according to medical guidelines, such as the American Heart Association (AHA) guidelines. Other key chest compression parameters are the decompression or release rate and the duty cycle between the compression and decompression phases.

[0006] Traditional chest compressions are performed by the rescuer placing the patient supine on their sternum, applying downward pressure towards the spine in an anterior-posterior direction. The rescuer then lifts their hands off the sternum, allowing the chest to expand naturally, thus expanding the chest wall. The rescuer then repeats this downward-upward motion in a cyclical manner, maintaining sufficient blood flow. The downward phase of the compression is typically referred to as the compression phase. The upward portion of the compression cycle is typically referred to as the release or decompression phase.

[0007] A key step in creating blood flow through the heart is to fully release the chest after each chest compression. Full chest release increases negative pressure within the chest cavity, promoting venous filling of the heart's ventricles and increasing the amount of blood available for distribution during the next chest compression. If the chest is not fully released, venous return and right atrial filling will be impaired.

[0008] To enable rescuers to deliver chest compressions correctly, it is beneficial to provide them with real-time feedback that allows them to adjust various aspects of their compressions to deliver optimal care to the patient. Systems such as ZOLL MedicalRealCPRHelp (Chelmsford, Massachusetts) use accelerometers or other motion sensors to measure the movement of the patient's sternum and provide real-time feedback related to chest compression parameters such as those described above. The sternal movement is also stored in a monitoring device (i.e., a defibrillator or even a smartphone, smartwatch, etc.) for review by rescuers or other medical personnel. Some systems use only force sensors to estimate chest compression motion parameters by assuming some nominal value of the patient's chest compliance and calculating estimated displacements based on the measured forces. Summary of the Invention

[0009] A system for assisting in cardiopulmonary resuscitation (CPR) is described. The system includes at least one sensor (e.g., a force sensor and a sensor for measuring displacement); and one or more processors configured to calculate a relationship between force and displacement based on data received from said at least one sensor, and to determine an estimated neutral position for chest compressions based at least in part on the relationship between force and displacement. The system may take the form of an active compression-decompression device.

[0010] This system offers several advantages. For example, it can provide feedback (e.g., on a user interface) that allows rescuers to understand the effectiveness of the CPR they are applying. Rescuers can then adjust the force they are applying during CPR and receive feedback confirming whether that adjustment is improving the effectiveness of the treatment. Depending on the implementation, this feedback can be provided by the CPR device or sent to a second device external to the CPR device. This makes CPR more likely to effectively resuscitate the victim and less likely to cause injury.

[0011] In one aspect, an active chest compression and decompression (ACD) system includes: a device configured to push down and pull up on a patient's chest; a force sensor configured to measure the force applied to the patient's chest by the ACD device; a motion sensor configured to measure the displacement of the patient's chest; one or more computer-readable media for storing computer-executable instructions; and one or more processors configured to execute the computer-executable instructions, the execution of which performs the following operations: identifying a compression cycle based on one or more signals received from at least one of the force sensor and the motion sensor, the compression cycle including a compression phase and a decompression phase; determining a first depth of chest compression corresponding to a force-displacement relationship of the compression phase of the compression cycle; determining a second depth of chest compression corresponding to a force-displacement relationship of the decompression phase of the compression cycle; and estimating a neutral position of the patient's chest based on the first depth and the second depth.

[0012] In some implementations, estimating the neutral position of the patient's chest based on the first depth and the second depth includes determining an external chest compression depth representing the neutral position of the chest within a range defined by the first depth and the second depth.

[0013] In some implementations, estimating the neutral position of the patient's chest based on the first depth and the second depth includes: determining a chest compression depth representing the neutral position of the chest outside the range defined by the first depth and the second depth. In some implementations, estimating the neutral position of the patient's chest based on the first depth and the second depth includes: determining a chest compression depth representing the neutral position of the chest as a function of the average of the first depth and the second depth. In some implementations, the function of the average of the first depth and the second depth includes a moving average of the first depth and the second depth over a plurality of compression cycles, the plurality of compression cycles including the compression cycle and one or more compression cycles immediately preceding the compression cycle.

[0014] In some implementations, estimating the neutral position of the patient's chest based on the first depth and the second depth includes: determining a chest compression depth representing the neutral position of the chest as a function of the first depth and the second depth, wherein the first depth is weighted by a first weight value, and wherein the second depth is weighted by a second weight value different from the first weight value. In some implementations, the compression phase includes at least one of a compression-lift portion and a compression-non-lift portion. In some implementations, the decompression phase includes at least one of a decompression-lift portion and a decompression-non-lift portion. In some implementations, the force-displacement relationship of the compression phase differs from the force-displacement relationship of the decompression phase due to hysteresis in the compression cycle.

[0015] In some implementations, the ACD device includes: a first element configured to be coupled to a patient's chest; and a second element configured to be grasped by a rescuer, the second element being coupled to the first element. In some implementations, the ACD device includes at least one of the force sensor and the motion sensor. In some implementations, the motion sensor includes an accelerometer.

[0016] In some implementations, the ACD system includes a user interface configured to display data representing one or more of the first depth and the second depth. In some implementations, the user interface is configured to display data indicating one or more of the force and the displacement. In some implementations, the user interface is configured to display the non-lift depth of the compression phase. In some implementations, the user interface is configured to display the decompression lift height of the decompression phase. In some implementations, the user interface is configured to display a trend graph representing chest reshaping. In some implementations, the user interface is configured for display on a device external to the ACD device. In some implementations, the device is located remotely from the ACD device.

[0017] In some implementations, the device includes at least one of a smartphone, smartwatch, and tablet device. In some implementations, the ACD system includes a communication device configured to communicate data to and receive data from an external device.

[0018] In some implementations, the execution involves: determining a third depth of chest compression corresponding to when approximately zero force is applied to the patient's chest during the compression phase of the compression cycle; determining a fourth depth of chest compression corresponding to when approximately zero force is applied to the patient's chest during the decompression phase of the compression cycle; and estimating a neutral position of the patient's chest based on the first, second, third, and fourth depths. In some implementations, the execution involves: determining a fifth depth of chest compression corresponding to a first product of force and displacement during the compression phase of the compression cycle; determining a sixth depth of chest compression corresponding to a second product of force and displacement during the decompression phase of the compression cycle; and estimating a neutral position of the patient's chest based on the first, second, third, fourth, fifth, and sixth depths.

[0019] In some implementations, estimating the neutral position of a patient's chest based on the first depth, the second depth, the third depth, the fourth depth, the fifth depth, and the sixth depth includes: a function of the average of the first depth, the second depth, the third depth, the fourth depth, the fifth depth, and the sixth depth.

[0020] In one aspect, a system includes: an active compression-decompression device, i.e., an ACD device, configured to push down and pull up on a patient's chest; a force sensor configured to measure the force applied to the patient's chest by the ACD device; a motion sensor configured to measure the displacement of the patient's chest; one or more computer-readable media for storing computer-executable instructions; and one or more processors configured to execute the computer-executable instructions, the execution of which performs the following operations: identifying a compression cycle based on one or more signals received from at least one of the force sensor and the motion sensor, the compression cycle including a compression phase and a decompression phase; determining a first depth of chest compression corresponding to when approximately zero force is applied to the patient's chest during the compression phase of the compression cycle; determining a second depth of chest compression corresponding to when approximately zero force is applied to the patient's chest during the decompression phase of the compression cycle; and estimating a neutral position of the patient's chest based on the first depth and the second depth.

[0021] In some implementations, estimating the neutral position of the patient's chest based on the first depth and the second depth includes: determining a chest compression depth representing the neutral position of the chest within a range defined by the first depth and the second depth. In some implementations, estimating the neutral position of the patient's chest based on the first depth and the second depth includes: determining a chest compression depth representing the neutral position of the chest outside a range defined by the first depth and the second depth. In some implementations, estimating the neutral position of the patient's chest based on the first depth and the second depth includes: determining a chest compression depth representing the neutral position of the chest as a function of the average of the first depth and the second depth. In some implementations, the function of the average of the first depth and the second depth includes a moving average of the first depth and the second depth over a plurality of compression cycles, the plurality of compression cycles including the compression cycle and one or more compression cycles immediately preceding the compression cycle.

[0022] In some implementations, estimating the neutral position of the patient's chest based on the first depth and the second depth includes: determining a chest compression depth representing the neutral position of the chest as a function of the first depth and the second depth, wherein the first depth is weighted by a first weight value, and wherein the second depth is weighted by a second weight value different from the first weight value. In some implementations, the compression phase includes at least one of a compression-lift portion and a compression-non-lift portion. In some implementations, the decompression phase includes at least one of a decompression-lift portion and a decompression-non-lift portion. In some implementations, the difference between the first depth and the second depth is based on a hysteresis of the compression cycle. In some implementations, the ACD device includes: a first element configured to be coupled to the patient's chest; and a second element configured to be grasped by a rescuer, the second element being coupled to the first element. In some implementations, the ACD device includes at least one of the force sensor and the motion sensor. In some implementations, the motion sensor includes an accelerometer.

[0023] In some implementations, the system includes a user interface configured to display data representing one or more of the first depth and the second depth. In some implementations, the user interface is configured to display data indicating one or more of the force and the displacement. In some implementations, the user interface is configured to display the non-lift depth of the compression phase. In some implementations, the user interface is configured to display the decompression lift height of the decompression phase. In some implementations, the user interface is configured to display a trend graph representing chest reshaping. In some implementations, the user interface is configured for display on a device external to the ACD device. In some implementations, the device is remote from the ACD device. In some implementations, the device includes at least one of a smartphone, smartwatch, and tablet device.

[0024] In some implementations, the system includes a communication device configured to communicate data to and receive data from an external device.

[0025] In some implementations, the execution involves: determining a third depth of chest compression corresponding to the force-displacement relationship of the compression phase of the compression cycle; determining a fourth depth of chest compression corresponding to the force-displacement relationship of the decompression phase of the compression cycle; and estimating the neutral position of the patient's chest based on the first, second, third, and fourth depths. In some implementations, the execution involves: determining a fifth depth of chest compression corresponding to a first product of force and displacement of the compression phase of the compression cycle; determining a sixth depth of chest compression corresponding to a second product of force and displacement of the decompression phase of the compression cycle; and estimating the neutral position of the patient's chest based on the first, second, third, fourth, fifth, and sixth depths. In some implementations, estimating the neutral position of the patient's chest based on the first, second, third, fourth, fifth, and sixth depths includes: a function of the average values ​​of the first, second, third, fourth, fifth, and sixth depths.

[0026] In one aspect, a system includes: an active compression-decompression device, i.e., an ACD device, configured to push down and pull up on a patient's chest; a force sensor configured to measure the force applied to the patient's chest by the ACD device; a motion sensor configured to measure the displacement of the patient's chest; one or more computer-readable media for storing computer-executable instructions; and one or more processors configured to execute the computer-executable instructions, the execution of which performs the following operations: identifying a compression cycle based on one or more signals received from at least one of the force sensor and the motion sensor, the compression cycle including a compression phase and a decompression phase; determining a first depth of chest compression corresponding to a first product of force and displacement during the compression phase of the compression cycle; determining a second depth of chest compression corresponding to a second product of force and displacement during the decompression phase of the compression cycle; and estimating a neutral position of the patient's chest based on the first depth and the second depth.

[0027] In some implementations, estimating the neutral position of the patient's chest based on the first depth and the second depth includes: determining a chest compression depth representing the neutral position of the chest within a range defined by the first depth and the second depth. In some implementations, estimating the neutral position of the patient's chest based on the first depth and the second depth includes: determining a chest compression depth representing the neutral position of the chest outside a range defined by the first depth and the second depth. In some implementations, estimating the neutral position of the patient's chest based on the first depth and the second depth includes: determining a chest compression depth representing the neutral position of the chest as a function of the average of the first depth and the second depth.

[0028] In some implementations, the function of the average of the first depth and the second depth includes a moving average of the first depth and the second depth over a plurality of compression cycles, the plurality of compression cycles including the compression cycle and one or more compression cycles immediately preceding the compression cycle. In some implementations, estimating the neutral position of the patient's chest based on the first depth and the second depth includes: determining an external chest compression depth representing the neutral position of the chest as a function of the first depth and the second depth, wherein the first depth is weighted by a first weight value, and wherein the second depth is weighted by a second weight value different from the first weight value. In some implementations, the compression phase includes at least one of a compression-lift portion and a compression-non-lift portion. In some implementations, the decompression phase includes at least one of a decompression-lift portion and a decompression-non-lift portion. In some implementations, the difference between the first depth and the second depth is based on the hysteresis of the compression cycle.

[0029] In some implementations, the ACD device includes: a first element configured to be coupled to a patient's chest; and a second element configured to be grasped by a rescuer, the second element being coupled to the first element. In some implementations, the ACD device includes at least one of the force sensor and the motion sensor. In some implementations, the motion sensor includes an accelerometer.

[0030] In some implementations, the system includes a user interface configured to display data representing one or more of the first depth and the second depth. In some implementations, the user interface is configured to display data indicating one or more of the force and the displacement. In some implementations, the user interface is configured to display the non-lift depth of the compression phase. In some implementations, the user interface is configured to display the decompression lift height of the decompression phase. In some implementations, the user interface is configured to display a trend graph representing chest reshaping. In some implementations, the user interface is configured for display on a device external to the ACD device. In some implementations, the device is located remotely from the ACD device.

[0031] In some implementations, the device includes at least one of a smartphone, smartwatch, and tablet device. In some implementations, the system includes a communication device configured to communicate data to and receive data from an external device.

[0032] In some implementations, the one or more processors are configured to generate a press cycle representation comprising a product of force and displacement for a plurality of displacement values ​​during the press phase and the depressurization phase. In some implementations, a first product of force and displacement comprises a local minimum of the product of force and displacement for the press phase portion of the press cycle representation. In some implementations, a second product of force and displacement comprises a local minimum of the product of force and displacement for the depressurization phase portion of the press cycle representation. In some implementations, the first depth and the second depth each correspond to a press depth where the first product of force and displacement is equal to the second product of force and displacement. In some implementations, the press cycle representation comprises a first press cycle representation, wherein the one or more processors are configured to generate a second press cycle representation comprising derivatives of the first press cycle representation for a plurality of displacement values ​​during the press phase and the depressurization phase. In some implementations, the first depth is approximately equal to the second depth, wherein the first product of force and displacement is approximately equal to the second product of force and displacement. In some implementations, the execution involves: determining a third depth of chest compression corresponding to the force-displacement relationship of the compression phase of the compression cycle; determining a fourth depth of chest compression corresponding to the force-displacement relationship of the decompression phase of the compression cycle; and estimating the neutral position of the patient's chest based on the first, second, third, and fourth depths. In some implementations, the execution involves: determining a fifth depth of chest compression corresponding to when approximately zero force is applied to the patient's chest during the compression phase of the compression cycle; determining a sixth depth of chest compression corresponding to when approximately zero force is applied to the patient's chest during the decompression phase of the compression cycle; and estimating the neutral position of the patient's chest based on the first, second, third, fourth, fifth, and sixth depths. In some implementations, estimating the neutral position of the patient's chest based on the first, second, third, fourth, fifth, and sixth depths includes: a function of the average of the first, second, third, fourth, fifth, and sixth depths.

[0033] As further described herein, when active compression decompression therapy is being applied to a victim, the compression ratio method can be used to estimate the depth of compression. The compression ratio method can reduce or eliminate estimation errors introduced by mechanical aspects of the CPR device, such as the elastic plunger. Since the force measurements used in Equation (3) are peak forces, the forces are static measurements unaffected by the elastodynamics of the plunger (or other mechanical coupling systems of the CPR device). In addition, there is a large tolerance for data time synchronization between force measurements and acceleration. The CPR device correlates the individual force measurements with the compression cycles during which these force measurements are measured. Synchronized measurements of motion and force are not required; instead, forces can be measured independently of measuring the patient's motion. As a result, the presentation of feedback generated on the user interface, the communication of data to another device, and the calculation of the compression depth estimate are all simpler than when synchronized data is required. The various mechanical configurations of the CPR device can be correlated with training data.

[0034] In one aspect, a system for assisting cardiopulmonary resuscitation (CPR) includes: an active compression-decompression device (ACD) configured to allow a user to push down and pull up on a patient's chest. The system may include: a force sensor configured to measure the force applied to the patient's chest by the user using the ACD. The system may include: a motion sensor configured to measure displacement of the patient's chest. The system may include: one or more processors configured to execute computer-executable instructions stored in a memory to perform operations. The operations may include: determining, based on at least one signal from the force sensor, a maximum compression force and a maximum decompression force applied to the patient's chest during a compression cycle. The operations may include: estimating, based on at least one signal from the motion sensor, a displacement value of the total displacement of the patient's chest during a compression cycle for pressing and decompressing the patient's chest. The operations may include: estimating at least one of the compression depth and decompression displacement for the compression cycle, the estimation being based on the determined compression force, the determined decompression force, and the estimated displacement. The system may include a user interface configured to provide indications of one or more of the compression depth and neutral position of the patient's chest.

[0035] In some implementations, the operation includes estimating the compression depth during the compression cycle by determining a proportion of the estimated displacement value. In some implementations, the proportion includes i) a first function of the determined compression force and ii) a ratio between the determined compression force and a second function of the determined decompression force, the second function being different from the first function.

[0036] In some implementations, the operation includes estimating a neutral position value of the patient's chest for the compression cycle, the estimation being based on the estimated compression depth. In some implementations, the operation includes applying a first weight value to the determined compression force; and applying a second weight value to the determined decompression force. The first weight value and the second weight value may be based on training data used to specify a first relationship between the determined compression force and the compression depth, and a second relationship between the determined decompression force and the decompression displacement.

[0037] In some implementations, the operation includes applying a third weight value to the square of the determined compression force, the third weight value being based on the training data. The training data may be generated using known compression depth values ​​and known decompression depth values. In some implementations, the first relationship and the second relationship each include one of a linear relationship, a quadratic relationship, and a higher-order relationship.

[0038] In some implementations, the determined pressing force value may be determined based on a first range of pressing force measurements, and the determined depressurization force may be determined based on a second range of depressurization force measurements.

[0039] In some implementations, the determined pressing force and the determined depressing force each comprise moving averages of pressing force and depressing force values ​​for a plurality of pressing cycles, the plurality of pressing cycles including the pressing cycle and one or more pressing cycles immediately preceding the pressing cycle.

[0040] In some implementations, the ACD device includes: a first element configured to be coupled to a patient's chest; and a second element configured to be grasped by a rescuer, the second element being coupled to the first element. In some implementations, the ACD device includes a plunger. The plunger may include an elastic element. In some implementations, the ACD device includes at least one of the force sensor and the motion sensor. The motion sensor may include an accelerometer.

[0041] In some implementations, the user interface is configured to display data indicating one or more of the determined pressing force, the determined depressurization force, and the estimated displacement value. In some implementations, the user interface is configured for display on a device external to the ACD device. In some implementations, the device can be remote from the ACD device. In some implementations, the device includes at least one of a smartphone, smartwatch, and tablet device. In some implementations, the system includes a communication device configured to communicate data to and receive data from the external device. In some implementations, the force sensor includes a force-measuring sensor.

[0042] In one aspect, a process for determining compression depth during active chest compression therapy (ACD) includes: receiving training data for training a function that correlates compression depth estimation with compression force and decompression force. The process includes: training the function using the training data. The process includes: determining a maximum compression force applied to the patient's chest during a compression cycle and a maximum decompression force applied to the patient's chest during the compression cycle, based on signals from at least one force sensor configured to measure force applied to the patient's chest by a user using an ACD device. The process includes: estimating a displacement value of the total displacement of the patient's chest during a compression cycle for compression and decompression of the patient's chest, based on signals from at least one motion sensor configured to measure displacement of the patient's chest. The process includes: estimating at least one of the compression depths using the trained function, the estimation being based on the determined compression force, the determined decompression force, and the estimated displacement. The process includes: providing an indication of one or more of the compression depth and neutral position of the patient's chest via a user interface.

[0043] In some implementations, training the function may include: receiving baseline data generated through neutral point estimation processing; and using the baseline data to train the function.

[0044] In some implementations, the neutral point estimation process includes: identifying a compression cycle, comprising a compression phase and a decompression phase, based on one or more signals received from at least one of the force sensor and the motion sensor. The neutral point estimation process includes: determining a first depth of chest compression corresponding to a force-displacement relationship of the compression phase of the compression cycle. The neutral point estimation process includes: determining a second depth of chest compression corresponding to a force-displacement relationship of the decompression phase of the compression cycle. The neutral point estimation process includes: estimating a neutral position of the patient's chest based on the first depth and the second depth.

[0045] In some implementations, the neutral point estimation process includes: identifying a compression cycle based on one or more signals received from at least one of the force sensor and the motion sensor, the compression cycle including a compression phase and a decompression phase. In some implementations, the neutral point estimation process includes: determining a first depth of chest compression corresponding to when approximately zero force is applied to the patient's chest during the compression phase of the compression cycle. In some implementations, the neutral point estimation process includes: determining a second depth of chest compression corresponding to when approximately zero force is applied to the patient's chest during the decompression phase of the compression cycle. In some implementations, the neutral point estimation process includes: estimating a neutral position of the patient's chest based on the first depth and the second depth.

[0046] In some implementations, the neutral point estimation process includes: identifying a compression cycle based on one or more signals received from at least one of the force sensor and the motion sensor, the compression cycle including a compression phase and a decompression phase. In some implementations, the neutral point estimation process includes: determining a first depth of chest compression corresponding to a first product of force and displacement during the compression phase of the compression cycle; and determining a second depth of chest compression corresponding to a second product of force and displacement during the decompression phase of the compression cycle. In some implementations, the neutral point estimation process includes: estimating a neutral position of the patient's chest based on the first depth and the second depth.

[0047] In some implementations, the process includes training a neutral point function using a set of neutral point training data that includes neutral point baseline data.

[0048] By displaying feedback based on an estimated neutral position of the patient's chest, the ACD device described herein can update the feedback provided to rescuers during CPR in response to changes in the patient's chest compliance. For example, the range of compressions and / or decompressions can be varied over time to respond to changes in the patient's chest compliance. Updated feedback can assist rescuers in providing more effective CPR compressions compared to a static target range for compression depth (e.g., downstroke displacement) provided to rescuers via the ACD device. Similarly, updated feedback can assist rescuers in providing more effective CPR decompressions compared to a static target range for decompression depth (e.g., upstroke displacement) provided to rescuers via the ACD device.

[0049] Furthermore, feedback can be provided intuitively via an ACD device to assist rescuers in adjusting the compression and / or decompression forces they are applying to the patient. For example, feedback can show predictions of the compression and / or decompression forces the user should apply in subsequent compression cycles. Rescuers can anticipate changes in the recommended compression and / or decompression forces to be applied to the patient (e.g., increasing or decreasing). Rescuers can then respond to these changes without pausing during the application of the compression cycle.

[0050] Alternatively or additionally, the ACD device may provide feedback including a history of the pressure applied to the patient during compression and decompression. This history may include trends in compression and decompression (e.g., the application of increasing or decreasing force within a compression cycle sequence).

[0051] An ACD device can be configured to provide feedback to rescuers in the form of an interactive application. This application can include a plotted trajectory as compression pressure, depth, etc., relative to time. For example, the trajectory can include a sine wave showing the depth vs. time of a compression cycle that continues on the screen at a frequency corresponding to the recommended compression cycle time. The rescuer can change his or her compression movements to follow the sine wave. Deviation from the trajectory can cause the ACD device to alert the user to change the treatment (e.g., audible prompts, warnings, verbal instructions, etc.). Interactive feedback can help rescuers understand how treatment should be performed during CPR, thereby improving the accuracy of the applied treatment relative to the recommended treatment and reducing rescuer errors, delays, or pauses during CPR.

[0052] In one aspect, a system for managing active compression-decompression cardiopulmonary resuscitation (ACD CPR) on a patient includes: an applicator configured to enable a rescuer to apply the ACD CPR to the patient's chest; a motion sensor configured to be coupled to the patient's chest and generate a displacement signal associated with the ACD CPR; a force sensor configured to be coupled to the patient's chest and generate a force signal associated with the ACD CPR; and a feedback device for providing feedback to the rescuer to adjust the ACD CPR. The system may include: at least one processor configured to: process both displacement and force signals associated with the ACD CPR treatment; estimate a neutral position of the chest based on the displacement and force signals; determine a lower stroke displacement and an upper stroke displacement based on the estimated neutral position and the displacement signals; adjust at least one of a target lower stroke displacement range and a target upper stroke displacement range based on the estimated neutral position; determine whether the lower stroke displacement falls within the target lower stroke displacement range and whether the upper stroke displacement falls within the target upper stroke displacement range; and generate at least one feedback signal for the feedback device to provide guidance on how to modify the ACD CPR treatment based on whether the lower stroke displacement falls within the target lower stroke displacement range and whether the upper stroke displacement falls within the target upper stroke displacement range.

[0053] In some implementations, the at least one processor is configured to determine an updated estimate of the neutral position, an updated lower travel displacement, and an updated upper travel displacement. In some implementations, the at least one processor is configured to adjust at least one of the target lower travel displacement range and the target upper travel displacement range based on the updated estimate of the neutral position. In some implementations, the target lower travel displacement range is adjusted from an initial target lower travel displacement range to an updated target lower travel displacement range. In some implementations, the target lower travel displacement range is adjusted from an initial target lower travel displacement range to an updated target lower travel displacement range after a predetermined interval. In some implementations, the target lower travel displacement range is adjusted from an initial target lower travel displacement range to an updated target lower travel displacement range based on whether the lower travel displacement falls within the target lower travel displacement range. In some implementations, the updated target lower travel displacement range is larger than the initial target lower travel displacement range. In some implementations, the updated target lower travel displacement range is smaller than the initial target lower travel displacement range. In some implementations, the target upper travel displacement range is adjusted from an initial target upper travel displacement range to an updated target upper travel displacement range. In some implementations, the target upper travel displacement range is adjusted from the initial target upper travel displacement range to the updated target upper travel displacement range after a predetermined interval. In some implementations, the target upper travel displacement range is adjusted from the initial target upper travel displacement range to the updated target upper travel displacement range based on whether the upper travel displacement falls within the target upper travel displacement range. In some implementations, the updated target upper travel displacement range is larger than the initial target upper travel displacement range. In some implementations, the updated target upper travel displacement range is smaller than the initial target upper travel displacement range. In some implementations, the target lower travel displacement range and the target upper travel displacement range are approximately equal in magnitude.

[0054] In some implementations, the at least one feedback signal provides guidance on how to modify the ACD CPR treatment such that future downstroke displacement falls within the target downstroke displacement range. In some implementations, the at least one feedback signal provides guidance on how to modify the ACD CPR treatment such that future upstroke displacement falls within the target upstroke displacement range. In some implementations, the at least one feedback signal provides guidance on how to modify the ACD CPR treatment such that the downstroke displacement falls within the target downstroke displacement range before the upstroke displacement falls within the target upstroke displacement range. In some implementations, at least one of the target downstroke displacement range and the target upstroke displacement range is based on clinically accepted guidelines. In some implementations, the target downstroke displacement range is greater than or less than clinically accepted guidelines. In some implementations, the target upstroke displacement range is greater than or less than clinically accepted guidelines. In some implementations, the at least one processor is configured to determine how to reshape the patient's chest based on an estimated neutral position. In some implementations, the at least one feedback signal causes a display to provide indications of patient chest reshaping. In some implementations, the at least one feedback signal causes the display to provide visual indications of the lower travel displacement, the upper travel displacement, and the estimated neutral position relative to each other. In some implementations, the at least one processor is configured to estimate the past neutral position of the chest, past lower travel displacement, and past upper travel displacement. In some implementations, the lower travel displacement includes the current lower travel displacement, and the upper travel displacement includes the current upper travel displacement. In some implementations, the at least one feedback signal causes the display to provide visual indications of the current lower travel displacement, the current upper travel displacement, the past lower travel displacement, and the past upper travel displacement. In some implementations, the guidance includes visual indications of whether the lower travel displacement falls within the target lower travel displacement range and whether the upper travel displacement falls within the target upper travel displacement range.

[0055] In some implementations, the visual indication includes a color or highlighting change of at least a portion of the display based on whether the lower travel displacement falls within the target lower travel displacement range or whether the upper travel displacement falls within the target upper travel displacement range. In some implementations, the visual indication includes a color or highlighting change of at least a portion of the display based on whether the lower travel displacement falls outside the target lower travel displacement range or whether the upper travel displacement falls outside the target upper travel displacement range. In some implementations, the visual indication includes at least one of the following: bars indicating the lower and upper travel displacements, a target lower travel area indicating the target lower travel displacement range, and a target upper travel area indicating the target upper travel displacement range. In some implementations, the visual indication includes a color or highlighting change of at least one of the following: bars indicating the lower and upper travel displacements, a target lower travel area indicating the target lower travel displacement range, and a target upper travel area indicating the target upper travel displacement range.

[0056] In some implementations, the at least one processor is configured to determine a current displacement based on the displacement signal and a current force based on the force signal, and the at least one feedback signal for the display provides at least one graph of force and displacement illustrating the current displacement and the current force. In some implementations, the at least one graph of force and displacement includes a force-displacement graph. In some implementations, the at least one graph of force and displacement includes a force-time graph and a displacement-time graph. In some implementations, at least one of the target lower stroke displacement range and the target upper stroke displacement range is between 0.5 inches and 3.0 inches. In some implementations, at least one of the target lower stroke displacement range and the target upper stroke displacement range is between 0.5 inches and 1.5 inches. In some implementations, at least one of the target lower stroke displacement range and the target upper stroke displacement range is between 1.5 inches and 2.5 inches. In some implementations, at least one of the target lower stroke displacement range and the target upper stroke displacement range is between 2.0 inches and 2.4 inches.

[0057] In some implementations, the at least one feedback signal causes the display to provide a visual indication of how at least one of the target lower travel displacement range and the target upper travel displacement range is updated. In some implementations, the at least one feedback signal causes the display not to provide a visual indication of how at least one of the updated neutral position estimate, the updated target lower travel displacement range, and the updated target upper travel displacement range is updated. In some implementations, the at least one feedback signal causes the display to provide a visual indication of how at least one of the updated neutral position estimate, the updated target lower travel displacement range, and the updated target upper travel displacement range is updated.

[0058] In some implementations, the applicator device includes a handle for rescuers to push and pull on the patient's chest to apply the ACD CPR treatment. In some implementations, the handle includes a display. In some implementations, the handle is configured to provide tactile feedback to provide guidance on how to modify the ACD CPR treatment.

[0059] In some implementations, the system includes a patient monitor comprising at least one sensor for obtaining physiological data from the patient. In some implementations, the patient monitor includes a display. In some implementations, the at least one feedback signal provides an indication to rescuers of a hold period following a downstroke or upstroke. In some implementations, the at least one feedback signal causes the display to provide a visual indication of the hold period following a downstroke or upstroke. In some implementations, the system includes a speaker for providing audio feedback to provide guidance on how to modify the ACD CPR treatment. The at least one feedback signal provides an indication to rescuers to exchange positions with another person while providing the ACD CPR treatment. The indication for exchanging positions is based on whether the downstroke displacement falls within a target downstroke displacement range or whether the upstroke displacement falls within a target upstroke displacement range. The at least one feedback signal provides an indication to rescuers to adjust the speed of the downstroke or the speed of the upstroke.

[0060] In one aspect, a system includes: an applicator configured to enable a rescuer to apply the ACD CPR treatment to a patient's chest; a motion sensor configured to be coupled to the patient's chest and generate a displacement signal associated with the ACD CPR treatment; a force sensor configured to be coupled to the patient's chest and generate a force signal associated with the ACD CPR treatment; a display for providing feedback to the rescuer to adjust the ACD CPR treatment; and at least one processor configured to: process both the displacement signal and the force signal associated with the ACD CPR treatment; estimate a past neutral position and a current neutral position of the chest based on the displacement signal and the force signal; determine a past downstroke displacement and a past upstroke displacement based on the past estimate of the neutral position; determine a current downstroke displacement and a current upstroke displacement based on the current estimate of the neutral position; and generate at least one feedback signal for the display to provide visual indications of the current downstroke displacement, the current upstroke displacement, the past downstroke displacement, and the past upstroke displacement.

[0061] In some implementations, the visual indicators of the current downstroke displacement and the current upstroke displacement include a first bar chart, and the visual indicators of the past downstroke displacement and the past upstroke displacement include a second bar chart. In some implementations, the first bar chart and the second bar chart are displayed adjacent to each other. In some implementations, the first bar chart is represented by a different color compared to the second bar chart. In some implementations, the second bar chart is represented by a lighter shade compared to the first bar chart. In some implementations, the first bar chart includes a solid line, and the second bar chart includes a dashed line.

[0062] In some implementations, the at least one processor is configured to determine whether the current downstroke displacement falls within a target downstroke displacement range and whether the current upstroke displacement falls within a target upstroke displacement range. In some implementations, the at least one feedback signal provides guidance on how to modify the ACD CPR treatment based on determining whether the current downstroke displacement falls within the target downstroke displacement range and whether the current upstroke displacement falls within the target upstroke displacement range. In some implementations, the guidance includes visual indications of whether the current downstroke displacement falls within the target downstroke displacement range and whether the current upstroke displacement falls within the target upstroke displacement range. In some implementations, the visual indications include color or highlighting changes on at least a portion of the display based on whether the current downstroke displacement falls outside the target downstroke displacement range or whether the current upstroke displacement falls outside the target upstroke displacement range. In some implementations, the visual indications include color or highlighting changes on at least a portion of the display based on whether the current downstroke displacement falls outside the target downstroke displacement range or whether the current upstroke displacement falls outside the target upstroke displacement range.

[0063] In some implementations, the at least one processor is configured to adjust at least one of the target lower travel displacement range and the target upper travel displacement range based on a current estimate of the neutral position. In some implementations, the at least one processor is configured to adjust at least one of the target lower travel displacement range and the target upper travel displacement range based on determining whether the current lower travel displacement falls within the adjusted target lower travel displacement range and whether the current upper travel displacement falls within the adjusted target upper travel displacement range.

[0064] In some implementations, the at least one feedback signal provides guidance on how to modify the ACD CPR treatment based on determining whether the current downstroke displacement falls within the adjusted target downstroke displacement range and whether the current upstroke displacement falls within the adjusted target upstroke displacement range. In some implementations, the guidance includes visual indications of whether the current downstroke displacement falls within the adjusted target downstroke displacement range and whether the current upstroke displacement falls within the adjusted target upstroke displacement range. In some implementations, the visual indications include color or highlighting changes on at least a portion of the display based on whether the current downstroke displacement falls within the target downstroke displacement range or whether the current upstroke displacement falls within the target upstroke displacement range. The visual indications also include color or highlighting changes on at least a portion of the display based on whether the current downstroke displacement falls outside the target downstroke displacement range or whether the current upstroke displacement falls outside the target upstroke displacement range. In some implementations, the at least one feedback signal provides guidance on how to modify the ACD CPR treatment such that future downstroke displacements fall within the target downstroke displacement range. In some implementations, the at least one feedback signal provides guidance on how to modify the ACD CPR treatment so that future upper stroke displacement falls within the target upper stroke displacement range.

[0065] In some implementations, the at least one processor is configured to determine how to reshape the patient's chest based on a past estimate of the neutral position and a current estimate of the neutral position. In some implementations, the at least one feedback signal causes a display to provide an indication of the patient's chest reshaping. The at least one processor is configured to determine a current displacement based on the displacement signal and a current force based on the force signal, and the at least one feedback signal for the display provides at least one graph of force and displacement illustrating the current displacement and the current force. In some implementations, the at least one graph of force and displacement includes a force-displacement graph. In some implementations, the at least one graph of force and displacement includes a force-time graph and a displacement-time graph.

[0066] In some implementations, the applicator device includes a handle for rescuers to push and pull on the patient's chest to apply the ACD CPR treatment. In some implementations, the handle includes a display. In some implementations, the handle is configured to provide tactile feedback to provide guidance on how to modify the ACD CPR treatment.

[0067] In some implementations, the system includes a patient monitor comprising at least one sensor for obtaining physiological data from the patient. In some implementations, the patient monitor includes a display. In some implementations, the at least one feedback signal provides an indication to rescue personnel of a hold period following the next or previous travel. In some implementations, the at least one feedback signal causes the display to provide a visual indication of the hold period following the next or previous travel.

[0068] In some implementations, the system includes a speaker for providing audio feedback to guide how to modify the ACD CPR treatment. The at least one feedback signal provides instructions for rescuers to exchange positions with another person while providing the ACD CPR treatment. The instructions for exchange are based on whether the current downstroke displacement falls within a target downstroke displacement range or whether the current upstroke displacement falls within a target upstroke displacement range. The at least one feedback signal provides instructions for rescuers to adjust the downstroke speed or the upstroke speed.

[0069] In one aspect, a system includes: an applicator configured to enable a rescuer to apply the ACD CPR treatment to a patient's chest; a motion sensor configured to be coupled to the patient's chest and generate a displacement signal associated with the ACD CPR treatment; a force sensor configured to be coupled to the patient's chest and generate a force signal associated with the ACD CPR treatment; a display for providing feedback to the rescuer to adjust the ACD CPR treatment; and at least one processor configured to: process both the displacement signal and the force signal associated with the ACD CPR treatment, determine a current displacement based on the displacement signal, determine a current force based on the force signal, and generate at least one feedback signal for the display to provide at least one graph of force and displacement showing the current displacement and the current force.

[0070] In some implementations, at least one graph of force and displacement includes a force-displacement graph. In some implementations, at least one graph of force and displacement includes a force-time graph and a displacement-time graph.

[0071] In some implementations, the at least one processor is configured to determine whether the current displacement falls within a target displacement range. In some implementations, the at least one processor is configured to determine whether the current force falls within a target force range. In some implementations, the at least one feedback signal provides guidance on how to modify the ACD CPR treatment based on determining whether the current displacement falls within the target displacement range and whether the current force falls within the target force range.

[0072] In some implementations, the guidance includes visual indications of whether the current displacement falls within the target displacement range and whether the current force falls within the target force range. In some implementations, the visual indications include color or highlighting changes of at least a portion of the display based on whether the current displacement falls within the target displacement range or whether the current force falls within the target force range. In some implementations, the visual indications include color or highlighting changes of at least a portion of the display based on whether the current displacement falls outside the target displacement range or whether the current force falls outside the target force range.

[0073] In some implementations, the visual indication includes at least one graphical target showing at least one of the target displacement range and the target force range. In some implementations, the at least one graphical target is displayed on at least one force-displacement graph, and a comparison is shown between the at least one graphical target and the at least one force-displacement graph. In some implementations, the at least one graphical target includes a target boundary displayed on a force-displacement graph, which shows a comparison between the current displacement, the current force, and the target boundary. In some implementations, the at least one graphical target includes a target displacement boundary displayed on a displacement-time graph, which shows a comparison between the current displacement and the target displacement boundary. In some implementations, the at least one graphical target includes a target force boundary displayed on a force-time graph, which shows a comparison between the current force and the target force boundary. In some implementations, the current displacement includes a current downstroke displacement or a current upstroke displacement. In some implementations, the current force includes a current pressing force or a current depressing force.

[0074] In some implementations, the at least one processor is configured to determine a current estimate of the neutral position of the chest based on the displacement signal and the force signal. In some implementations, the current lower stroke displacement or the current upper stroke displacement is based on the current estimate of the neutral position.

[0075] In some implementations, the at least one processor is configured to determine whether the current downstroke displacement falls within a target downstroke displacement range and whether the current upstroke displacement falls within a target upstroke displacement range. In some implementations, the at least one feedback signal provides guidance on how to modify the ACD CPR treatment based on determining whether the current downstroke displacement falls within the target downstroke displacement range and whether the current upstroke displacement falls within the target upstroke displacement range. In some implementations, the guidance includes visual indications of whether the current downstroke displacement falls within the target downstroke displacement range and whether the current upstroke displacement falls within the target upstroke displacement range. In some implementations, the visual indications include color or highlighting changes on at least a portion of the display based on whether the current downstroke displacement falls outside the target downstroke displacement range or whether the current upstroke displacement falls outside the target upstroke displacement range. In some implementations, the visual indications include color or highlighting changes on at least a portion of the display based on whether the current downstroke displacement falls outside the target downstroke displacement range or whether the current upstroke displacement falls outside the target upstroke displacement range.

[0076] In some implementations, the at least one feedback signal provides guidance on how to modify the ACD CPR treatment such that future downstroke displacement falls within the target downstroke displacement range. In some implementations, the at least one feedback signal provides guidance on how to modify the ACD CPR treatment such that future upstroke displacement falls within the target upstroke displacement range. In some implementations, the at least one processor is configured to determine how to reshape the patient's chest based on an estimate of the neutral position of the patient's chest. In some implementations, the at least one feedback signal causes a display to provide indications of patient chest reshaping.

[0077] In some implementations, the applicator device includes a handle for a rescuer to push and pull on the patient's chest to apply the ACD CPR treatment. In some implementations, the handle includes a display. In some implementations, the handle is configured to provide tactile feedback to provide guidance on how to modify the ACD CPR treatment. In some implementations, the system includes a patient monitor including at least one sensor for obtaining physiological data from the patient. In some implementations, the patient monitor includes a display. In some implementations, the system includes a speaker for providing audio feedback to provide guidance on how to modify the ACD CPR treatment. In some implementations, the at least one feedback signal provides instructions for instructing a rescuer to exchange information with another person while providing the ACD CPR treatment.

[0078] In one aspect, a system includes: an applicator configured to provide the ACD CPR treatment to a patient's chest; a motion sensor configured to be coupled to the patient's chest and generate a displacement signal associated with the ACD CPR treatment; a force sensor configured to be coupled to the patient's chest and generate a force signal associated with the ACD CPR treatment; a feedback device for providing information associated with the ACD CPR treatment; and at least one processor configured to: process both the displacement signal and the force signal associated with the ACD CPR treatment; estimate a neutral position of the chest based on the displacement signal and the force signal; estimate an initial zero point of the chest before the application of the ACD CPR treatment; determine an amplitude difference between the estimated initial zero point of the chest and the estimated neutral position of the chest; and generate at least one feedback signal for modifying the ACD CPR treatment to reduce the amplitude difference between the estimated initial zero point of the chest and the estimated neutral position of the chest.

[0079] In some implementations, the dressing device is an automatic chest compression device. In some implementations, the at least one feedback signal controls the automatic chest compression device to modify the ACD CPR treatment. In some implementations, modifying the ACD CPR treatment includes the automatic chest compression device increasing the amplitude of the decompression force applied to the chest. In some implementations, modifying the ACD CPR treatment includes the automatic chest compression device decreasing the amplitude of the decompression force applied to the chest.

[0080] In some implementations, the at least one processor is configured to determine a current displacement based on the displacement signal and a current force based on the force signal. In some implementations, the current displacement includes a current downstroke displacement or a current upstroke displacement. In some implementations, the current force includes a current pressing force or a current depressing force.

[0081] In some implementations, the at least one processor is configured to determine how to reshape the patient's chest based on the estimated neutral position. In some implementations, the at least one feedback signal causes the display to provide indications of the patient's chest reshaping.

[0082] In some implementations, the system includes a patient monitor that includes at least one sensor for obtaining physiological data from the patient. In some implementations, the patient monitor includes a display.

[0083] In some implementations, modifications to the ACD CPR treatment include increasing the amplitude of the compression force applied to the chest using the automated chest compression device. In some implementations, modifications to the ACD CPR treatment include decreasing the amplitude of the compression force applied to the chest using the automated chest compression device. In some implementations, the physiological data includes end-tidal CO2. 2 Data, arterial pressure data, volumetric CO2, pulse oxygen saturation data, or carotid artery blood flow data.

[0084] Details of one or more implementations are set forth in the accompanying drawings and the following description. Other features, objects, and advantages will become clear from the description and drawings, and from the claims. Attached Figure Description

[0085] Figure 1 A device is shown for assisting a user in performing active compression-decompression (ACD) CPR on a patient.

[0086] Figure 2 This indicates changes in the shape of the patient's chest.

[0087] Figure 3 This indicates the signals recorded during CPR.

[0088] Figure 4 yes Figure 1 The diagram shows the components of the ACD device.

[0089] Figure 5 An example graph including the chest compliance curve is shown.

[0090] Figure 6A and 6B A graph showing the stiffness curve is provided.

[0091] Figure 7 An example graph showing the chest compliance curve, which includes the hysteresis loop, is shown.

[0092] Figure 8 An example of a user interface is shown.

[0093] Figure 9 This diagram illustrates the state transitions of the chest compression cycle.

[0094] Figure 10 The graph shows the trend of breast reshaping.

[0095] Figure 11 This is a block diagram of an example computer system.

[0096] Figure 12 Such as Figure 1 A block diagram of the components of an example ACD device, such as an ACD device.

[0097] Figure 13 An example of a research protocol using big data related to force and displacement during a compression cycle in ACD treatment is shown.

[0098] Figure 14 Example data on force and displacement during a compression cycle in ACD therapy are shown.

[0099] Figure 15 Example data on force and displacement during a compression cycle used to estimate the patient’s neutral position are shown.

[0100] Figures 16A to 16B Example data on force and displacement during multiple compression cycles used to estimate the patient’s neutral position are shown.

[0101] Figures 17A to 17B Example graphs are shown depicting the relationship between work and displacement during multiple compression cycles used to estimate the patient's neutral position.

[0102] Figures 18A to 18B Example graphs are shown depicting the relationship between work and displacement during multiple compression cycles used to estimate the patient's neutral position.

[0103] Figures 19A to 19B An example graph is shown depicting the relationship between instantaneous work and displacement during multiple compression cycles used to estimate the patient's neutral position.

[0104] Figures 20 to 23 A flowchart is shown for an example process for estimating the neutral position using an ACD device.

[0105] Figures 24A to 24B The diagram illustrates peak compression and lift associated with the patient's ACD chest compressions.

[0106] Figures 25-26 An example of a user interface is shown.

[0107] Figures 27A to 27B The example training data is shown.

[0108] Figure 28 Includes the following graph, which shows the results based on... Figures 24A to 27B The pressure depth calculation results obtained by the pressure ratio method discussed herein are consistent with those based on the following... Figures 13 to 23 A comparison of the pressing depth calculation results obtained by the neutral point estimation method discussed.

[0109] Figure 29 An example is shown where a press ratio method is trained using a research protocol related to big data as a baseline, compared to using the results obtained from a neutral point method as a baseline.

[0110] Figure 30 Includes a graph showing the results compared to an alternative pressing ratio method.

[0111] Figure 31 Includes a flowchart illustrating an example procedure for determining compression depth during ACD treatment.

[0112] Figures 32 to 33 This shows a sample user interface configured to provide ACD CPR treatment feedback.

[0113] Figures 34 to 36 Example screenshots show the range of pressure and decompression provided by an ACD device during ACD CPR therapy, as well as the feedback.

[0114] Figures 37 to 38 This is an example screenshot showing the compression frequency feedback provided by the ACD device during ACD CPR treatment.

[0115] Figure 39 An example of a normalized force-displacement graph is shown for use in providing feedback from an ACD device during ACD CPR therapy.

[0116] Figures 40 to 41 Examples are shown as feedback during ACD CPR treatment, including the upper and lower ranges of the previous compression cycle, the upper and lower ranges of the current compression cycle, and the upper and lower ranges of the target compression cycle.

[0117] Figures 42 to 45 A flowchart is shown for an example process used to provide feedback during ACD CPR therapy.

[0118] Similar reference numerals in the figures indicate similar elements. Detailed Implementation

[0119] To increase cardiopulmonary circulation induced by chest compressions, a technique known as Active Compression-Decompression (ACD) has been developed. According to ACD, an applicator body is inserted between the rescuer's hand and the patient's sternum, wherein the applicator body is further attached via one or more suction cups or self-adhesive pads. During the compression phase, as with standard chest compressions, the rescuer presses the applicator pad against the patient's sternum. Unlike standard chest compressions, which passively return the chest to a neutral position during the release phase, the rescuer actively pulls upward during the release or decompression phase using ACD. This active upward pull or active decompression increases the release rate and results in increased intrathoracic negative pressure compared to standard chest compressions, and induces enhanced venous blood flow from the patient's peripheral venous system into the heart and lungs. Apparatus and methods for performing ACD on a patient are described in U.S. Patents 5,454,779 and 5,645,552 (the contents of which are incorporated herein by reference in their entirety).

[0120] During ACD chest compressions, the patient's sternum is typically pulled upwards beyond its neutral position during the decompression phase. "Neutral" is defined as the stable position of the sternum when no upward or downward force is applied by the rescuer. The following will address... Figure 3 Both the compression and decompression phases will have a portion of movement during which the sternum is pulled upwards beyond the neutral position; this is called the "elevated" phase. Thus, there are four phases: Compression: Elevation (CE); Compression: Non-Elevation (CN); Decompression: Elevation (DE); Decompression: Non-Elevation (DN). Providing rescuers with real-time feedback related to these different phases of the active compression-decompression cycle is beneficial.

[0121] During the course of resuscitation, the patient's chest wall will be "remodeled" due to the repetitive forces applied to the chest wall (sometimes exceeding 100 lbs) required to fully displace the sternum to generate adequate blood flow) and the resulting repetitive movements. Chest compliance will typically increase significantly as the sternal / cartilage / rib biomechanical system is subjected to substantial bending and compression. Consequently, the amount of force required to displace the sternum to the appropriate depth of compression and decompression will also change significantly. During this chest wall remodeling process, the anteroposterior diameter (the distance between the sternum and spine) will also change frequently and significantly, meaning that the neutral position will change during resuscitation. Accurate measurement of the neutral position is always required during resuscitation; therefore, taking initial position measurements at the start of resuscitation and assuming a constant neutral position during resuscitation will not be sufficient to generate accurate estimates of the motion parameters for the CE, CN, DE, and DN phases of the compression cycle. For example, it is particularly valuable to be able to measure the motion parameters and forces provided during the DE and CN phases independently of each other and excluding the CE and DN phases.

[0122] Some ACD systems use force sensors inserted between the rescuer's hand and the patient's sternum (where compressions are being delivered) to monitor the relaxation phase of chest compressions. However, the sternal force used in chest compressions may not be perfectly correlated with blood flow, nor with sternal motion or chest wall dynamics. Because chest compliance varies greatly among individual patients, each patient requires a unique amount of force to achieve the same compressions on the sternum and cardiopulmonary system. Furthermore, force sensors are generally not suitable for measuring sternal motion (a key parameter for assessing the quality of chest compressions delivered and venous return).

[0123] Other chest compression monitoring systems that utilize motion sensing systems such as accelerometers (e.g., ZOLLMedical RealCPRHelp (Chelmsford, Massachusetts)) are able to measure motion parameters such as velocity and displacement. However, due to the way ACD compressions are delivered, existing systems have limitations in their ability to distinguish between motion during the lifting phase and motion during the non-lifting phase.

[0124] Figure 1 A device 100 is shown that assists user 102 in performing active compression-decompression (ACD) CPR on patient 104 who is being resuscitated due to a cardiac event. Device 100 includes a user interface 106 for providing feedback to user 102 (sometimes referred to as a rescuer) regarding the effectiveness of the CPR being performed by user 102. This feedback is determined in part based on information relating to chest compliance of patient 104 (sometimes referred to as a victim) as measured by device 100 (sometimes referred to as an ACD device).

[0125] Chest compliance is a measure of the chest's ability to absorb applied forces and change shape in response to those forces. In the context of CPR, information related to chest compliance can be used to determine how forces can be applied to a patient's chest in a manner that will be effective in resuscitation. Ideally, the force applied to the patient will be sufficient to create a vacuum within the heart to induce blood flow. However, if the force is insufficient to create this vacuum, CPR will not be effective, and the patient will die or otherwise deteriorate. Furthermore, if forces are not applied correctly or are excessive, the patient may be injured. Guidance can be provided to user 102 to increase the chances of successful CPR by determining the neutral position for chest compressions and using information related to the application of CPR.

[0126] The neutral position or other phase transition points can be determined using the methods described in this article. The neutral position can also be considered as the location where the force or pressure applied by the rescuer during ACD compressions is zero. This zero-force neutral position may change during resuscitation effort due to so-called chest remodeling that occurs during chest compressions, as the patient's anterior / posterior diameter decreases after multiple compression cycles. Alternatively, the neutral position can simply be the initial position of the sternum before chest compressions are initiated.

[0127] In some implementations, device 100 determines (e.g., calculates) a chest compliance relationship, which is then used to determine what kind of feedback to provide to the user. For example, device 100 may calculate a mathematical relationship between two variables related to chest compliance, such as displacement and force. Device 100 may then identify one or more features of this relationship that can be used to determine information related to CPR treatment. Once the information related to CPR treatment is determined, device 100 can determine what kind of feedback to provide to the user, such as feedback related to the progress of CPR treatment, feedback related to the depth of chest compressions during the non-lift portion of a chest compression cycle, or feedback related to the force during the lift portion of a chest compression cycle.

[0128] In some examples, information related to CPR treatment may include patient-related information, such as the neutral position of chest compressions. In some implementations, chest compliance may be viewed or represented as a curve, such as a curve representing the relationship in a graph. In some implementations, chest compliance may be stored as data, such as a table of measurements (e.g., values ​​of displacement and force at multiple time indices).

[0129] like Figure 1As shown, the device 100 has handles 108, 110 for a user 102 to hold and apply force. The device 100 also has a suction cup 112 that tends to keep the device 100 in contact with the chest 114 of the patient 104. When the user applies an upward force using the device 100, in response, the patient's chest 114 is pulled upward due to the suction of the suction cup 112. This upward force creates negative pressure within the patient's chest cavity during the release phase of CPR treatment. Devices used to create negative pressure in this manner are sometimes referred to as impedance threshold devices (ITD).

[0130] In some examples, (e.g., on user interface 106) the feedback given to user 102 guides the user 102 in how they press the chest using device 100. For example, user interface 106 may include visual indications of the effectiveness of the upward and downward portions of the pressing cycle. Parameters that the feedback can provide include pressing depth and pressing-release speed. In this way, user 102 can adjust various elements of their pressing activity in response to the feedback.

[0131] As a real-world example, user interface 106 could display a graph indicating whether the upward or downward force is too strong or insufficient, allowing user 102 to make adjustments accordingly. For instance, if device 100 determines that the depth of the compression phase is insufficient for effective CPR, device 100 could display feedback indicating that the depth of the downward movement does not meet an effectiveness threshold. In some implementations, device 100 could determine whether the upward or downward force is too strong or insufficient based on an estimate of the neutral position of chest compressions on patient 104. The neutral position of chest compressions on patient 104 serves as an inflection point that can be used to distinguish between upward and downward chest movements and generate specific measurements for the CE, CN, DN, and DE phases of the compression cycle.

[0132] Since user 102 provides manual compressions, the ACD device 100 shown herein is an example of a manual ACD device. Other types of mechanical ACD devices can be used for the techniques described below, such as techniques for determining a neutral position for chest compressions. Although the ACD device 100 shown herein includes a handle and a suction cup, other types of ACD devices used for the techniques described below do not necessarily include these elements. For example, other types of ACD devices may include a first element configured to adhere to a surface of the patient's body and a second element configured to couple to the rescuer's hand. In these examples, the first element allows for upward pulling on the patient's body surface while maintaining contact with it. Furthermore, in these examples, the second element enables the rescuer to push and pull the chest.

[0133] Suction cups and handles are examples of the first and second elements, respectively, but are not the only types of elements that can be used. For example, the first element may include one or more multi-suction cup assemblies, or the first element may be a surface partially or completely covered by an adhesive (e.g., a viscous gel) attached to the patient's chest, or the first element may be any combination of these items. Examples of multi-suction cup assemblies are described in U.S. Patent 8,920,348, entitled "Method and Device for Performing Alternating Chest Compression and Decompression," the entire contents of which are included by reference. Instead of the handles described above, or in addition to the handles described above, the second element may include one or more straps or supports for firmly holding the rescuer's hand on the ACD device.

[0134] Figure 2 This illustrates the shape changes of the chest 200 of patient 104 during ACD CPR using an ACD device. Since the human chest 200 is not rigid, its shape will change in response to the applied force. During the CN phase, with the sternum compressed downwards 202, the chest 200 tends to exhibit a shape 204 that is compressed in the anterior-posterior (AP) dimension 206 and extends in the lateral dimension 208. This shape 204 is sometimes referred to as the compression shape. During the DE phase 210, the chest 200 tends to exhibit a shape 212 that extends in the AP dimension 206 and narrows in the lateral dimension 208. This shape 212 is sometimes referred to as the decompression shape. In the absence of upward or downward force, the chest 200 exhibits a shape 214 corresponding to the neutral position of chest compressions. In other words, shape 214 corresponds to the neutral position of the chest when its shape is substantially unaffected by the applied force (e.g., during CPR chest compressions).

[0135] Chest compliance is a mathematical description of the tendency of the chest to change shape due to applied forces. Chest compliance is the reciprocal of stiffness. Chest compliance is the incremental change in depth at a specific moment divided by the incremental change in force. In the case of chest compression cycles, such as... Figure 3 As shown, compliance can be plotted over time on the horizontal axis, or alternatively, such as... Figure 5As shown in Figure 6, compliance can be plotted as a hysteresis loop with depth as an independent variable and time as implied in the hysteresis loop trajectory. If a patient's chest exhibits relatively small shape changes in response to a specific change in force, the patient has relatively low chest compliance. Conversely, if a patient's chest exhibits relatively large shape changes in response to a specific change in force, the patient has relatively high chest compliance. Furthermore, chest compliance changes during chest compression due to structural changes in the pleural cavity caused by positional / conformal changes during downward chest compressions and upward chest compressions. The following addresses... Figure 5 and Figure 7 To describe it. For example, when pressing down on the chest, the chest's compliance increases as the chest approaches its limit of flexibility (e.g., area 508 or...). Figure 7 The curve descends from the flat area to the right of the curve.

[0136] For each time point n when the system performs displacement measurements, force measurements are also performed to obtain the displacement / force vector pair [d] for each sample time n. n ,f n Typically, compared to a reference time point, compliance c equals the change in displacement divided by the change in pressure: c = Δd / Δp.

[0137] "Instantaneous compliance" (IC) may include a reference time point t0, which is adjacent to or nearly adjacent to a time point t n And therefore, to a greater extent, it is a measure of the slope of the displacement-force curve at a specific point in time. For example, the reference time point t0 could be immediately adjacent to time t n Previous sampling time points. For example, using moving averages, weighted moving averages, or low-pass filters known to those skilled in the art, it is possible to obtain the data immediately following time t. n The reference time point is formed from multiple previous sample points. At the reference time point and time t... n There may be small time gaps (e.g., 1 second or less) between them. In some versions, a reference time point can be selected as the start of the segment, for example, for... Figure 6B The start of a press with slope 1 in the graph (the first segment of the press, and therefore the start of that segment is also the start of the press), or the start of a press with respect to the dashed line at reference time t0 for slope 2 in the same graph. For example, in some implementations, instantaneous compliance InC is calculated as follows. n :

[0138] InC n =|(d n -d r ) / (p n -p r )|

[0139] Among them, InC n It is about time point t n Estimation of the slope of the distance / pressure curve at a given location; d n It is time t n Displacement at p; p It is time t n The pressure at the point; and d r and p r These are the reference times t r Distance and pressure at the location.

[0140] On the other hand, "absolute compliance" (AC) can include a reference point t0, which uses an absolute reference (such as pressure and displacement) at the very beginning of a set of chest compressions. During CPR, there may be so-called "rounds" of chest compressions, which are time intervals of approximately 1 to 3 minutes for providing chest compressions, after which compressions are stopped and various other therapeutic actions can be performed, such as analyzing the patient's ECG, delivering a defibrillation shock, or administering medications such as adrenaline or amiodarone. Therefore, to determine AC, the reference point t0 is before the start of any round of chest compressions (including before the first round of compressions), i.e., at the start of CPR. In most cases, the pressure will be zero at this time point, and displacement will be effectively calibrated to zero using displacement estimation software. Absolute chest compliance can be estimated based on compression displacement and associated compression pressure. The reference pressure "p0" is the pressure at time t0, and the chest displacement "d0" is the displacement at time t0. n "is to achieve displacement "d n "Required pressure. Estimate chest compliance using the following formula:"

[0141] Absolute compliance = |(d p -d0) / (p p -p0)|

[0142] Where, d p It is the displacement at the peak of the pressure, and p p It is the pressure at the peak of the press.

[0143] The compliance and compression depth of the chest 200 can be measured using sensors 216a-216c in device 100. For example, force sensor 216a and motion sensors such as accelerometer 216b can be used. In some implementations, force sensor 216a and accelerometer 216b are disposed within housing 218 of device 100. The accelerometer senses chest movement during CPR, and the force sensor measures the applied force or pressure. The accelerometer signal is integrated (e.g., double integral) to determine the displacement of housing 218, and the output of the force sensor is converted into standard pressure or force units.

[0144] In some implementations, the accelerometer is in a separate housing (e.g., a housing placed on the patient's sternum), and the force sensor is within the housing 218 of device 100. In such implementations, the housing housing the accelerometer and the device with the force sensor can be configured to be attached or connected during CPR.

[0145] In some implementations, multiple accelerometers 216b, 216c can be used. For example, a second accelerometer 216c can be placed on or near the patient's sternum within the suction cup 112. The second accelerometer can be housed in a separate assembly of self-adhesive foam, such as ZOLL CPRStat-Padz (Chelmsford, Massachusetts). In this way, the first accelerometer 216b tends to measure the hand of the rescuer 102 (…). Figure 1 The first accelerometer 216a measures the acceleration experienced by the patient 104, and the second accelerometer 216c tends to measure the acceleration of the patient 104's sternum. In other words, the first accelerometer 216a can be configured to measure movement caused by an applied upward force, for example, since the first accelerometer 216a is proximal to or otherwise mechanically coupled to the suction cup 112, thus providing an appropriate indication of the force applied by the suction cup 112 when it is pulled up on the patient's sternum. Furthermore, the second accelerometer 216b can measure movement caused by an applied downward force, for example, since the second accelerometer 216b is proximal to or otherwise mechanically coupled to the handle of the device 100, thus providing an appropriate indication of the downward force applied by the rescuer's hand. In this way, the system can detect whether the attachment between the ACD device and the patient's sternum is insufficient and warn the rescuer to reapply the ACD device to the patient's chest.

[0146] Figure 3 This indicates, for example, the use of during CPR. Figure 2 The signals recorded by sensors 214a-214c are shown. Although absolute compliance can be used to determine the neutral position, the IC will provide a more accurate measurement of the neutral position.

[0147] The pressure (C1-C5) can be detected based on the displacement signal. The pressure rate is calculated based on the interval between pressures (e.g., (time of C2 - time of C1)), and the pressure depth from the start of the pressure to the peak displacement (e.g., (d1-d0)) is measured. For each pressure, the start pressure value and the peak pressure value are saved. The force used to achieve a given pressure depth is determined using the pressure at the start and end of the pressure.

[0148] Chest compliance is further described in U.S. Patent 7,220,235, entitled "Method and Apparatus for Enhancement of Chest Compressions During CPR," published May 22, 2007, the entire contents of which are incorporated herein by reference. Compression velocity and displacement can be estimated via methods described in U.S. Patents 8,862,228, 6,827,695, and 6,390,996 (the entire contents of each of which are incorporated herein by reference).

[0149] Figure 4 yes Figure 1 The diagram shows a block diagram of the components of an ACD device 100. The device includes a processor 400, such as an electronic component like a microprocessor, which executes instructions (e.g., processing input data to generate output data, and communicating data relative to other components of the device 100). For example, the processor 400 receives signals from sensors such as a force sensor 402 and motion sensors such as accelerometers 404a, 404b (or, in some implementations, a single accelerometer). Other types of motion sensors may include magnetically inductive systems such as those described in U.S. Patent 7,220,235 mentioned above.

[0150] The processor 400 also communicates output information 406 to the user interface module 408. The output information 406 indicates the effectiveness of CPR treatment and is determined by the processor 400 in part based on signals received from sensors (e.g., force sensor 402 and accelerometers 404a, 404b).

[0151] The user interface module 408 can take one of several forms. In some implementations, the user interface module 408 is a combination of software and hardware and includes a display for presenting information to a user of device 100. For example, the presented information may include text information as well as graphical information such as graphs and charts. The user interface module may also include other components such as input devices (e.g., buttons, keys, etc.). In some implementations, the user interface module includes audio input / output elements (e.g., microphone, speaker) and audio processing software.

[0152] In some implementations, the user interface module 408 enables the user interface to appear on an external device 412 (e.g., a device capable of operating independently of the ACD device 100). For example, the external device could be a smartphone, tablet, or another mobile device. The external device could also be a defibrillator with an accelerometer built into the defibrillator pad (CPR Stat-Padz) (such as the ZOLL Medical Corp X-Series defibrillator (Chelmsford, Massachusetts)); or it could be another self-adhesive accessory containing a motion sensor attached to the patient's sternum and primarily used to measure the movement of the patient's sternum. This accessory may or may not be integrated with defibrillation electrodes. The defibrillator can receive acceleration or motion data from the ACD device and compare the motion of the ACD sensor with accelerometer information or motion information from the accelerometer in the defibrillator pad or other attached sternal motion sensing accessory. For example, if (particularly during the decompression phase of a compression cycle) a difference of more than 0.25 inches is found between the two movements, rescuers can be prompted to reapply the ACD device.

[0153] In some implementations, external device 412 communicates with ACD device 100 using a wireless communication technology such as Bluetooth. In this example, ACD device 100 has a wireless communication module 410. For example, user interface module 408 can use wireless communication module 410 to communicate signals with external device 412. Although Bluetooth is used as an example herein, other wireless communication technologies such as WiFi, Zigbee, 802.11, etc., can also be used.

[0154] In some implementations, processor 400 can, for example, use the above-mentioned... Figure 2 The formula is used to calculate and determine an estimate of chest compliance 414.

[0155] In some implementations, the processor 400 can perform calculations to determine whether the patient's chest is substantially released between two compressions (i.e., sufficiently released to create pressure in the chest to promote venous filling and stimulate the heart). The user interface module 408 can provide the user interface 106 of the device 100. Figure 1 ) Display used to send to user 102 ( Figure 1 Provide guidance or other feedback messages, such as releasing the chest more completely between presses and / or pressing the chest more forcefully during presses.

[0156] The processor 400 can also calculate the estimated neutral position 416 of chest compressions, for example, based on data such as the estimated depth of chest compressions and the estimate of chest compliance 414. This calculation can be at least partially based on the following... Figure 5 The characteristics of the compliance relationship are described in more detail in Figure 6.

[0157] Output information 406 may include information determined based on an estimate 414 of chest compliance and a neutral position 416 of chest compressions. For example, output information 406 may include information such as non-lift (CN) depth or decompression-lift (DE) height. Output information 406 may also include feedback to the user regarding adjusting the user's movements in a manner that increases the effectiveness of CPR treatment. The following is for... Figure 8 To describe the example.

[0158] In some implementations, the processor 400 compares the signal received by the first accelerometer 404a with the signal received by the second accelerometer 404b. (As mentioned above regarding...) Figure 2 The first accelerometer 404a can be placed in or near the housing of the ACD device 100, and the second accelerometer 404b can be placed in or near the suction cup 112 of the ACD device 100. In this way, the first accelerometer 216b tends to measure the user 102 (…). Figure 1 The first accelerometer 216b measures the acceleration experienced by the patient 104, and the second accelerometer tends to measure the acceleration experienced by the patient 104. In some implementations, multiple accelerometers 216b, 216c may be used. For example, the second accelerometer 216c may be placed on or near the patient's sternum within the suction cup 112. The second accelerometer may be housed in a separate assembly of self-adhesive foam, such as ZOLL CPR Stat-Padz (Chelmsford, Massachusetts). In this way, the first accelerometer 216b tends to measure the acceleration experienced by the rescuer 102's hand (…). Figure 1 The system measures the acceleration experienced by the ACD device, and the second accelerometer 216c tends to measure the acceleration of the patient's sternum. In this way, the system can detect whether the attachment between the ACD device and the patient's sternum is insufficient and alert rescuers to reapply the ACD device to the patient's sternum.

[0159] In some implementations, processor 400 includes a memory 418 that can store data, or has access to that memory 418. The memory 418 can take any of several forms and can be integrated with processor 400 (e.g., it can be part of the same integrated circuit), or it can be a separate component that communicates with processor 400, or it can be a combination of both. In some implementations, memory 418 stores data such as values ​​for chest compliance estimates 414 and values ​​for the neutral position 416 of chest compressions while processor 400 calculates such data. In some implementations, processor 400 uses memory 418 to store data for later retrieval, for example, storing data during the administration of CPR for later retrieval during the same administration of CPR, or for later retrieval during different administration of CPR.

[0160] Figure 5 An example graph 500 is shown, including a chest compliance curve 502. In some implementations, the compliance curve 502 is generated by a processor 400 ( Figure 4 A representation of data calculated based on inputs received from sensors (e.g., force sensors and / or one or more accelerometers). Figure 5 The graph 500 shown includes an x-axis representing time (e.g., in seconds) and a y-axis representing chest compliance. Curve 502 exhibits a sinusoidal shape. This compliance curve 502 is sometimes referred to as a non-hysteresis compliance curve.

[0161] In fact, when rescuers are using ACD devices (e.g., Figure 1 When performing CPR on a victim using the device 100 shown, the rescuer applies downward and upward forces to the victim's chest. The victim's chest compliance is at its lowest when these forces bring the chest shape close to its natural limits. In other words, the victim's chest compliance is close to its lower limit when the chest is pulled up or pressed down. In some scenarios, when chest compliance approaches this lower limit, it indicates that the tensile strength of the ribs has been reached, and the risk of crushing one or more ribs increases if additional force is applied. In some versions of the system, a warning may be provided in the form of an audio, visual, or tactile / haptic cue indicating that compliance has fallen below a certain threshold level.

[0162] Figure 6A The representative stiffness curves showing the effect of the sternum are shown, and Figure 6B These curves represent the stiffness regions. Referring to these figures, the slope of the curve represents stiffness (e.g., the inverse of compliance). Each of these hysteresis loops is a curve for a different object. Figure 6BSlope 1 in the figure represents the stiffness of the CN phase of the press; this is a lower slope value and less stiffness (and therefore higher compliance). Although the slope of the CN phase of the press varies for each object, as can be seen in the multiple laps in the figure, in most (but not all) cases, at some inflection point during the press, there will be a slope change to a second steeper slope (less compliance and more stiffness), as indicated by the shift to slope 2.

[0163] At the inflection point, represented by the intersection of two lines (slope 1 and slope 2 in the figure), the risk of fracture remains relatively low. Once this inflection point is detected, the system can prompt rescuers to maintain the compression depth, as it remains within safe limits. Patient-specific compression depths may differ from those recommended by the AHA / ILCOR guidelines (e.g., greater than 2 inches). For example, initially at the start of resuscitation efforts, especially in older patients (whose sternal cartilage attaching the sternum to the ribs may be calcified and hardened), the patient's chest may be much stiffer. If rescuers attempt to provide compressions at the depth recommended by the AHA / ILCOR guidelines, they may inflict rib fractures. In fact, the guidelines themselves acknowledge that rib fractures are a common occurrence when using existing chest compression methods. "Rib fractures and other injuries are common but acceptable CPR outcomes compared to death from cardiac arrest." (Source: 2005 International Consensus Conference on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science with Treatment Recommendations, hosted by the American Heart Association, January 23-30, 2005, in Dallas, Texas). Besides the discomfort of in-hospital rib fractures, adverse side effects include reduced chest wall recoil, leading to decreased natural chest recoil during decompression, resulting in reduced venous return and diminished effectiveness of chest compressions. For these reasons, it is desirable to minimize or eliminate rib fractures. Changes in chest wall compliance are monitored, and these findings serve as indicators for rescuers that chest compression depth will not exceed the injury threshold of the ribs and sternum.

[0164] Because the neutral position and overall compliance of the chest change during resuscitation efforts, the system's real-time prompts guiding the depth of chest compressions will also change using this method. During the initial minutes after chest compressions are initiated, a phenomenon known as chest wall remodeling occurs. The AP diameter can decrease by as much as 0.5 to 1 inch, and chest wall compliance increases as the sternal cartilage gradually softens. By maintaining within safe limits in each compression cycle in a patient-specific manner while the sternum gradually softens, injury is reduced, but more importantly, the natural resilience of the chest wall is preserved, and more effective chest compressions are delivered to the patient.

[0165] Generally, methods for detecting changes in slope can include determining the initial statistical characteristics of the slope during the CE phase, and then analyzing the slope for any significant, sustained increase. For example, techniques such as change-point analysis described by Basseville (Basseville M, Nikiforov IV. Detection of Abrupt Changes: Theory and Application. Engelwood, NJ: Prentice-Hall 1993) or Pettitt (Pettitt AN, A simplecumulative sum type statistic for the change point problem with zero-one observations, Biometrika 1980; 67:79-84.) can be used. Other methods, such as Shewhart control charts, can be employed to first detect changes in slope, and then assess whether the detected changes are increasing and have sufficient magnitude to generate prompts for rescuers indicating that compression depth is too deep and that future compressions should be performed in a way that suggests less pressure. In a simpler version, a prompt can be activated if compliance drops below a certain percentage threshold below the initial compliance value at the start of a specific press (e.g., compliance decreases by 15%). The initial compliance value can be averaged over more than one press phase; this average can be used as a comparison value across multiple press cycles.

[0166] In some embodiments, compliance may be tested separately to determine the risk of damage during both the DE phase and the CN phase (i.e., the top of the decompression portion [DN phase and DE phase] of the pressing cycle and the bottom of the pressing portion [CE phase and CN phase] of the pressing cycle).

[0167] Conversely, when the victim's chest is in the neutral position during chest compressions (which typically corresponds to the chest's natural resting position), chest compliance tends to be at its highest point. Therefore, in Figure 5 In the curve 502 shown, points 504 and 506 (e.g., peaks of the sine curve) corresponding to the highest chest compliance tend to correspond to the neutral position of chest compressions. Conversely, point 508 (e.g., troughs of the sine curve) corresponding to the lowest chest compliance tends to correspond to the limits of the chest compression or decompression shape.

[0168] In some implementations, processor 400 ( Figure 4 The characteristics of the nonhysteresis compliance curve 502 can be used to calculate an estimate of the neutral position for chest compressions 416. Figure 4 For example, processor 400 can use the peaks 504 and 506 of curve 502 to calculate an estimate of the neutral position for chest compressions.

[0169] Figure 7 An example curve 600 is shown, including a chest compliance curve 602 that forms a hysteresis loop. This compliance curve 602 is sometimes referred to as a hysteresis compliance curve. In some implementations, the compliance curve 502 is generated by the processor 400 ( Figure 4 A representation of data calculated based on inputs received from sensors (e.g., force sensors and / or one or more motion sensors (e.g., one or more accelerometers)). Figure 7 The graph 600 shown includes an x-axis representing depth (e.g., in centimeters) and a y-axis representing chest compliance. The arrows on the curve indicate the time progress during one compression cycle and represent the ACD device 100 ( Figure 1 The movement of the chest, for example, is illustrated by the portion of the curve with the right-pointing arrow showing the instantaneous compliance (IC) of the pressing portion (CE and CN) of the pressing cycle, and the portion of the curve with the left-pointing arrow showing the instantaneous compliance (IC) of the decompression portion (DE and DN) of the pressing cycle. For example, when the ACD device 100 moves from a high depth to a low depth, chest compliance increases (as the chest approaches the neutral position of the pressing) and then decreases (as the chest becomes more compressed). Then, when the ACD device 100 moves from its lowest depth to a high depth, chest compliance increases again (as the chest approaches the neutral position of the pressing) and then decreases again (as the chest becomes more decompressed).

[0170] In some implementations, processor 400 ( Figure 4 The characteristics of the hysteresis compliance curve 602 can be used to calculate an estimate of the neutral position for chest compressions 416. Figure 4Several features can be used.

[0171] For example, the intersection point 604 of the hysteresis compliance curve 602 can be used to estimate the neutral position 416 of chest compressions. This point 604 represents the depth that can correspond to the neutral position of chest compressions (e.g., as a coordinate on the x-axis).

[0172] As another example, the neutral position 416 of chest compressions can be estimated using a point 612 located approximately halfway between the two peaks 614, 616 of the hysteresis compliance curve 602. For instance, point 612 can be determined by measuring the distance 610 between peaks 614, 616 and identifying a point corresponding to the center of distance 610. Alternatively, the neutral position can be a point corresponding to a predefined percentage of distance 610.

[0173] As another example, the neutral position 416 of chest compressions can be estimated using a point 606 located approximately halfway between other features of the hysteresis compliance curve 602. For instance, the processor can identify the distance 608 between two points on the hysteresis compliance curve 602 that have the same value for compliance, and then calculate point 606 by determining the point corresponding to the center of distance 608.

[0174] Figure 8 An example of a user interface 700 is shown. For example, the user interface 700 could be... Figure 1 An example of the user interface 106 of the ACD device is shown. Furthermore, the user interface 700 can be provided by... Figure 4 The user interface module 408 shown is used for control.

[0175] The user interface 700 displays information 702 indicating the effectiveness of CPR treatment, so that the ACD device 100 ( Figure 1 The user interface 700 can display information 702 in a way that allows the user 102 to effectively administer CPR. The user interface 700 may be part of an ACD device or another device used to process ACD-related information (e.g., a patient monitor, defibrillator, portable computing device, or other computing device).

[0176] Information 702 includes a figure 704 representing the DE height 706 and CN depth 708 of a CPR treatment. This depth and height are separated by a boundary 710. In some implementations, the DE height 706 and CN depth 708 are determined by a processor 400. Figure 4The DE height 706 and CN depth 708 can be determined using information from one or more accelerometers 404a-404b, and by knowing the peak height and peak depth along with the time of occurrence of the neutral position. Alternatively, the DE height and CN depth can be estimated based on force sensor 402, including calculated information such as an estimate 414 of chest compliance and a neutral position 416 of chest compressions determined by processor 400. Alternatively, the DE portion 706 or CN portion 708 displaying feedback can display a measurement of pressure instead of a measurement of displacement. For example, in one embodiment, the DE portion 706 can display a measure of pressure or force (DE force), while the CN portion 708 can display a measure of displacement (CN depth).

[0177] refer to Figure 9 In some examples, a state transition diagram can be used to determine the stages of a pressing cycle (e.g., CN stage, DN stage, DE stage, and CE stage) based on the input of the pressing direction (i.e., DE or CN) and whether a neutral position 416 has been reached. Upon detection of a neutral position (NP), the transition occurs from CE stage 904 to CN stage 902 and from DN stage 906 to DE stage 908. Upon transitioning to CN 902 or DE 908, NP is reset to 0, indicating that the transition is edge-sensitive. Direction-related transitions are level-sensitive. Transitions from CN 902 to DN 906 and from DE 908 to CE 904 occur during a change in direction. Knowing the timing of transitions between pressing stage states, parameters describing the motion, such as velocity, distance, average velocity, peak velocity, etc., can be calculated. In some versions, information 702 may also include other motion information that can be displayed, such as the velocity occurring during the decompression phase. More specifically, the velocity at the point of neutralization can be displayed, or the velocity can be communicated to rescuers in other ways (e.g., tone of voice, speech, etc.). Alternatively, the velocity communicated to rescuers can be an average or other statistical representation of the motion during significant portions of the decompression phase (e.g., both the elevation and non-elevation portions).

[0178] refer to Figure 8Figure 704 also includes a DE height threshold indicator 712 and a CN depth threshold indicator 714. These indicators provide the user of the device with information regarding whether either or both of the DE height and CN depth are too shallow or too deep. For example, if the user sees that the DE height 706 does not meet the threshold indicator 712, the user can adjust his or her movement to increase the DE height (e.g., by pulling the ACD device with greater force during DE movement). Similarly, if the user sees that the DE height indicator 706 exceeds the threshold indicator 712, the user can adjust his or her movement to decrease the DE height (e.g., by pulling the ACD device with less force during DE movement). If the user sees that the CN depth 708 does not meet the threshold indicator 714, the user can also adjust the force during CN movement.

[0179] Furthermore, information 702 may include guidance displayed to the user based on thresholds represented by metrics 712 and 714. For example, if the DE depth or CN depth is not within a specific range of the threshold (e.g., more than 10% larger or less than the threshold), the user interface 700 may display a message to guide the user. Figure 8 In the example shown, CN depth indicator 708 indicates that the CN depth is significantly lower than the CN threshold indicator 714. In response, user interface 700 displays a message 718 to the user instructing him or her to apply more pressure to achieve optimal pressure. If DE height indicator 706 is significantly lower than its corresponding threshold, a similar message can be displayed (for optimal decompression). Similarly, if DE height 706 or CN depth 708 exceeds its corresponding threshold by a large margin (e.g., more than 10% above the threshold indicator), user interface 700 can display a warning message (e.g., “Reduce CN force to avoid injuring the patient”).

[0180] Alternatively, the device that makes physical contact with the rescuer's hand could include a miniature vibrator, such as those used in all cellular phones, and could communicate tactile feedback related to the correct CN and DE depths, for example, by vibrating it when a threshold is reached.

[0181] exist Figure 8 In the example shown, the DE height indicator 706 is close to the DE threshold indicator 712. Therefore, the user interface 700 displays a message 718 indicating that the user is applying an appropriate amount of force to the DE movement.

[0182] In some implementations, threshold indices 712 and 714 are displayed based on thresholds that are static values. For example, the memory 418 of processor 400 ( Figure 4It can store static values, for example, based on experimental data relating to a patient's DE height and CN depth. These static values ​​can be used directly, or they can be modified using variables measured for patients receiving CPR.

[0183] In some implementations, it is based on the processor (e.g., Figure 4 The processor 400 shown calculates thresholds to display threshold indices 712 and 714. In some examples, the calculated thresholds are based on calculations of chest compliance (e.g., Figure 4 The estimated value of chest compliance shown is 414). For example, refer to... Figure 7 The compliance curve 602 shown corresponds to the depth value of the lowest chest compliance, which can correspond to the maximum DE height and the maximum CN depth.

[0184] In some implementations, the user interface 700 displays a trend graph representing chest remodeling. For example, this trend graph could show what happens to a patient's chest during CPR treatment. Figure 10 An example of a trend graph 1000 that can be displayed on a user interface 700 is shown. The x-axis 1002 of the trend graph 1000 represents time, and the y-axis 1004 represents compliance. As shown in the example graph, the trend graph 1000 may include a zero-point trend line 1006 (e.g., a trend line representing the initial depth of the patient's chest) and a compliance trend line 1008. Over time, as shown in the trend graph, neutral position and compliance change with the provision of CPR treatment.

[0185] Figure 11 This is a block diagram of example computer system 1100. For example, refer to... Figure 1 ACD device 100 may be an example of system 1100 described herein, external device 412 ( Figure 4 This could also be an example of the system 1100 described herein. System 1100 includes a processor 1110, a memory 1120, a storage device 1130, and one or more input / output interface devices 1140. Components 1110, 1120, 1130, and 1140 may each be interconnected, for example, using a system bus 1150.

[0186] Processor 1110 can be Figure 4The processor 400 shown is an example and is capable of processing instructions executed within system 1100. As used herein, the term "execution" refers to the technique by which program code causes the processor to execute one or more processor instructions. In some implementations, processor 1110 is a single-threaded processor. In some implementations, processor 1110 is a multi-threaded processor. In some implementations, processor 1110 is a quantum computer. Processor 1110 is capable of processing instructions stored in memory 120 or on storage device 1130. Processor 1110 can perform operations such as determining the neutral position for chest compressions based at least in part on characteristics of the compliance curve.

[0187] Memory 1120 stores information within system 1000. In some implementations, memory 1120 is a computer-readable medium. In some implementations, memory 1120 is a volatile memory cell. In some implementations, memory 1120 is a non-volatile memory cell.

[0188] Storage device 1130 provides mass storage to system 1100. In some implementations, storage device 1130 is a non-transitory computer-readable medium. In various implementations, storage device 1130 may include, for example, a hard disk drive, an optical disk drive, a solid-state drive, a flash drive, magnetic tape, or some other mass storage device. In some implementations, storage device 1130 may be a cloud storage device, such as a logical storage device comprising one or more physical storage devices distributed across a network and accessed via a network. In some examples, the storage device may store long-term data. Input / output interface device 1140 provides input / output operations for system 1100. In some implementations, input / output interface device 1140 may include one or more of the following: a network interface device (e.g., Figure 4 The system 1100 may include a wireless communication module 410 or an Ethernet interface, a serial communication device (e.g., an RS-232 interface), and / or a wireless interface device (e.g., an 802.11 interface, a 3G wireless modem, a 4G wireless modem, etc.). The network interface device enables the system 1100 to communicate (e.g., send and receive) data. In some implementations, the input / output devices may include driver devices configured to receive input data and send output data to other input / output devices (e.g., a keyboard, printer, and display device 1160). In some implementations, mobile computing devices, mobile communication devices, and other devices may be used.

[0189] refer to Figure 4The steps performed by processor 400 can be implemented through instructions, which, when executed, cause one or more processing devices to perform the processes and functions described above, such as determining information related to CPR treatment. These instructions may include, for example, interpreted instructions such as script instructions, executable code, or other instructions stored in a computer-readable medium.

[0190] Computer system 1100 can be implemented in a distributed manner via a network (such as a server cluster) or a widely distributed group of servers, or it can be implemented in a single virtual device comprising multiple distributed devices operating cooperatively with each other. For example, one of these devices can control other devices, or these devices can operate according to a set of cooperative rules or protocols, or these devices can cooperate in other ways. The cooperative operation of multiple distributed devices presents the behavior of operating as a single device.

[0191] In some examples, system 1100 is housed within a single integrated circuit package. This system 1100 is sometimes referred to as a microcontroller, in which processor 1110 and one or more other components are both housed within a single integrated circuit package and / or manufactured as a single integrated circuit. In some implementations, the integrated circuit package includes pins corresponding to input / output ports, which can be used, for example, to communicate signals with one or more input / output interface devices in input / output interface device 1140.

[0192] Despite Figure 11 The example processing system is described herein, but the subjects and functional operations described above can also be implemented in other types of digital electronic circuits, or in computer software, firmware, or hardware (including the structures disclosed herein and their equivalents), or in a combination of one or more of these. Implementations of the subjects described herein (such as storing, maintaining, or displaying artifacts) can be implemented as one or more computer program products, i.e., one or more modules of computer program instructions encoded on a tangible program carrier (e.g., a computer-readable medium) for execution by the processing system or for controlling the operation of the processing system. The computer-readable medium can be a machine-readable storage device, a machine-readable storage substrate, a memory device, or a combination of one or more of these.

[0193] The term "system" can encompass all devices, apparatuses, and machines used for processing data, including, for example, programmable processors, computers, or multiple processors or computers. In addition to hardware, a processing system can include code for creating an execution environment for the computer program in question, such as code constituting processor firmware, protocol stacks, database management systems, operating systems, or combinations thereof.

[0194] Computer programs (also known as programs, software, software applications, scripts, executable logic, or code) can be written in any form of programming language, including compiled or interpreted languages, or declarative or procedural languages, and can be deployed in any form, including as standalone programs or as modules, components, subroutines, or other units suitable for use in a computing environment. A computer program does not necessarily correspond to a file in a file system. A program can be stored as a portion of a file used to hold other programs or data (e.g., one or more scripts stored in a markup language document), as a single file dedicated to the program in question, or as a collection of related files (e.g., files used to store portions of one or more modules, subroutines, or code). A computer program can be deployed to execute on a computing device or on multiple computers located at one site or distributed across multiple sites and interconnected via a communication network.

[0195] Computer-readable media suitable for storing computer program instructions and data include all forms of non-volatile or volatile memory, media, and storage devices, including, for example: semiconductor memory devices (e.g., EPROM, EEPROM, and flash memory devices); magnetic disks (e.g., internal hard disks or removable disks or magnetic tapes); magneto-optical disks; and CD-ROMs, DVD-ROMs, and Blu-ray discs. Processors and memory may be supplemented by or incorporated into dedicated logic circuitry. Servers are, for example, sometimes general-purpose computers, sometimes custom-designed dedicated electronic devices, and sometimes a combination of both. Implementations may include back-end components (e.g., data servers), or middleware components (e.g., application servers), or front-end components (e.g., client computers having a graphical user interface or web browser via which a user can interact with an implementation of the subject matter described in this specification), or any combination of one or more such front-end, middleware, or back-end components. Components of the system may be interconnected via digital data communication (e.g., data networks) of any form or medium. Examples of communication networks include local area networks (“LANs”) and wide area networks (“WANs”), such as the Internet.

[0196] The following system and method will now be described: one or more force-displacement relationships are established using measures of the force applied to the chest and the displacement of the chest while the patient is undergoing active chest compression decompression therapy. Based on these force-displacement relationships, the neutral position of the patient's chest is estimated using multiple compression depths corresponding to the force-displacement relationships(one or more). As discussed above, the force-displacement relationships(one or more) may be based on estimated instantaneous compliance of the chest. As further discussed below, the force-displacement relationships(one or more) may be based on a first depth of chest compression and a second depth of chest compression, the first depth corresponding to a point where approximately zero force is applied to the patient's chest during the compression phase of an ACD compression cycle, and the second depth corresponding to a point where approximately zero force is applied to the patient's chest during the decompression phase of an ACD compression cycle. As discussed below, one or more force-displacement relationships can also be based on a first depth of chest compression corresponding to a first product of force and displacement during the compression phase of an ACD compression cycle, and a second depth of chest compression corresponding to a second product of force and displacement during the decompression phase of an ACD compression cycle. The neutral position of the chest can then be estimated based on the first and second depths as determined by the appropriate force-displacement relationships.

[0197] As described in this article, compression cycles can generally refer to various types of CPR compression therapy. For example, a compression cycle can refer to conventional compressions, in which the patient's chest is pushed down and released to allow for natural recoil of the chest wall. Compression cycles can also generally refer to ACD compression cycles, in which (e.g., using a device for administering ACD therapy) the chest is pushed down during the compression or down stroke and actively pulled up during the decompression or up stroke to enhance circulation.

[0198] The system and method described herein can be applied to both manual and automated active chest compression therapy. That is, when ACD therapy is manually administered to a patient, the neutral position of the chest can be estimated at any given time. Similarly, when ACD therapy is administered to a patient via an automated chest compression device, the neutral position of the chest can also be estimated at any given time. This can be particularly useful in providing indications, manually or via an automated system, of how the neutral position of the chest may change during ACD therapy.

[0199] Figure 12 This is a block diagram of the components of an ACD device 1200, which includes as... Figure 4 Replacement or additional components for the components shown. ACD device 1200 and Figure 1 Similar to the ACD device 100, it has one or more of the differences described below.

[0200] ACD device 1200 includes processor 1202, which can substantially correspond to the above-mentioned... Figure 4 The processor 400 is similar. In some implementations, the processor 1202 of the ACD device 1200 can perform calculations to determine an estimate of the neutral position of the patient's chest during ACD treatment. This processor can use methods such as those described below... Figures 15 to 2 The various techniques described in 4 are used to calculate one or more neutral position estimates 1214. The calculation of one or more neutral position estimates 1214 may be based on the relationship between the force applied to the patient's chest by the ACD device 1200 and the compression distance of the chest during an ACD compression cycle. In various embodiments, although the processor(s) used to perform the calculations described herein may be the processor 1202 of the ACD device 1200, alternatively or additionally, other processors may be involved. For example, information collected from one or more sensors, such as force sensors, accelerometers, and / or position sensors, may be analyzed by another processor (such as the processor of a patient monitor, defibrillator, portable computing device (e.g., tablet computer), or other computing device) and subsequently output on the same device or to another device.

[0201] As described above, the ACD compression cycle includes a compression phase and a decompression phase. The compression phase involves applying compression force to the patient's chest, starting from a starting point (e.g., zero point), moving downwards to the maximum compression depth, and returning to that starting point. The decompression phase typically follows the compression phase and includes decompressing the patient's chest (e.g., raising) to the maximum decompression height, and then lowering the patient's chest back to the starting point. Zero point refers to the initial position of the patient's chest (e.g., compression / decompression volume) before ACD treatment begins.

[0202] Processor 1202, or one or more other processors communicating with the ACD device, is configured to receive data from one or more sensors to estimate one or more neutral position estimates 1214. For example, processor 1202 may communicate with force sensor 1208 (e.g., a force sensor) (which is substantially similar to the above regarding...). Figure 4 The force sensor 402 and accelerometer 1204 (which are essentially similar to those mentioned above) Figure 4 The accelerometers 404a and 404b communicate with the position sensor 1206.

[0203] In some implementations, the ACD device 1200 can be configured to automatically apply ACD therapy to a patient. For example, the ACD device 1200 may include a force actuator (not shown) for automatically applying compression and decompression forces to the patient's chest. This mechanism may include one or more of the following: a compression band, a piston, an elastic element such as a spring, one or more flexible rods, and a rope and pulley mechanism, etc. The force actuator is configured to press on the patient's chest during the compression portion of an ACD compression cycle and to decompress the patient's chest during the decompression portion of an ACD compression cycle (e.g., lifting the patient's chest).

[0204] Position sensor 1206 provides position data for the force actuator of ACD device 1200. In some implementations, position sensor 1206 includes one or more of an encoder, a capacitive transducer, a Hall effect sensor, a potentiometer, and a ranging sensor. The exact hardware of position sensor 1206 may depend on the hardware used by the force actuator. For example, if a piston is used in the force actuator, position sensor 1206 may include an encoder for measuring the relative position of the piston.

[0205] Processor 1202 can receive position data of the force actuator, such as that measured by position sensor 1206. Processor 1202 can determine the compression depth and / or decompression depth (collectively referred to below as “chest displacement”) relative to an initial zero point. The position data can be proportional to the patient’s chest displacement caused by the force actuator of ACD device 1200.

[0206] The processor 1202 is configured to receive data from the force sensor 1200, the position sensor 1206, and the accelerometer 1204, such that the processor can correlate the force applied by the force sensor with the position of the position sensor 1206 and thus with the patient's chest displacement for one or more time points in an ACD compression cycle.

[0207] Go to Figure 13Example treatment data 1300 is shown in the test of a research protocol for the chest of a large object. It is understood that treatment information collected from the large object shown herein can be applied to the treatment of patients in emergency settings. For example, the methods described herein for identifying or otherwise estimating the neutral position of the chest for any given ACD compression cycle can be used for patients undergoing ACD CPR manually or via an automated ACD system. Treatment data 1300 includes data measured by sensors (e.g., position sensor 1206, accelerometer 1204, and force sensor 1208) during operation of an ACD device 1200 attached to the object via an attachment pad. Example displacement data 1302 and force data 1304 are shown for a series of ACD compression cycles. For example, chest displacement can be determined by processor 1202 using one or both of the position data and accelerometer data received from position sensor 1206 and accelerometer 1204, respectively. The position data and accelerometer data are converted into a calculated chest displacement position, such as as described above.

[0208] U.S. Patent 9,125,79, entitled "System for determining depth of chest compressions during CPR" (the entire contents of which are incorporated herein by reference), describes a system and method for estimating displacement or depth from accelerometer data. Typically, the acceleration data can be double-integrated to obtain displacement. Alternatively, the raw data can be appropriately filtered to obtain a clean result. For example, the raw acceleration can be filtered using filters (e.g., high-pass filters, band-pass filters, moving average filters, infinite impulse response filters, autoregressive filters, autoregressive moving average filters) to produce filtered acceleration with significantly reduced signal noise in most forms. However, integration may still result in a velocity waveform that is relatively noisy compared to the acceleration waveform. The filtered acceleration can be integrated to obtain velocity. The velocity can then be filtered (e.g., using high-pass filters, band-pass filters, moving average filters, infinite impulse response filters, autoregressive filters, autoregressive moving average filters) to produce filtered velocity. The filtered velocity can then be integrated to obtain displacement. Integration may still result in a displacement waveform that is slightly noisy compared to the acceleration and velocity waveforms. Therefore, displacement waveforms can be filtered (e.g., using high-pass filters, band-pass filters, moving average filters, infinite impulse response filters, autoregressive filters, and autoregressive moving average filters) to produce filtered displacement waveforms. Typically, chest displacement is expressed in centimeters (cm) or inches (in), while force data can be expressed in Newtons (N) or another measure of force. However, any unit of distance and force is applicable.

[0209] Additionally, graph 1306 shows displacement data, and graph 1308 shows force data. Graphs 1306 and 1308 each show the data covered for the example compression cycle at different percentage decompression values. A percentage decompression value refers to the percentage of the subject's chest that is decompressed (e.g., lifted) to the anteroposterior distance of the thorax above zero during ACD treatment. As mentioned above, zero refers to the patient's initial chest position when ACD treatment begins. A percentage compression value refers to the percentage of the subject's chest that is compressed to the anteroposterior distance of the thorax below zero. In the example data shown, 20% compression refers to a compression approximately 2.0 inches below zero, 15% compression refers to a compression approximately 1.5 inches below zero, 10% compression refers to a compression approximately 1.0 inch below zero, and 5% compression refers to a compression approximately 0.5 inches below zero. Similarly, 20% decompression refers to a decompression of approximately 2.0 inches above zero, 15% decompression refers to a decompression of approximately 1.5 inches above zero, 10% decompression refers to a decompression of approximately 1.0 inch above zero, and 5% decompression refers to a decompression of approximately 0.5 inches above zero.

[0210] Graph 1306 shows displacement data for five ACD compression cycle depths 1310a-1310e. For clarity, graph 1306 illustrates the ACD compression cycle as follows: it begins with a downward stroke initiated at the maximum chest height, followed by an upward stroke involving pressing down to the maximum compression depth, and the upward stroke involving decompression from the maximum compression depth back to the maximum chest height during the cycle. Compression cycles 1310a, 1310b, 1310c, 1310d, and 1310e each represent the displacement of the target's chest when 20% compression (approximately 2.0 inches below zero) is applied; however, the decompression amounts for each compression cycle are different. Compression cycle depth 1310a represents the displacement of the subject's chest within a compression cycle applying 20% ​​compression (approximately 2.0 inches below zero) and 20% decompression (approximately 2.0 inches above zero). Compression cycle depth 1310b represents the displacement of the subject's chest within a compression cycle applying 20% ​​compression and 15% decompression (approximately 1.5 inches above zero). Compression cycle depth 1310c represents the displacement of the subject's chest within a compression cycle applying 20% ​​compression and 10% decompression (approximately 1.0 inch above zero). Compression cycle depth 1310d represents the displacement of the subject's chest within a compression cycle applying 20% ​​compression and 5% decompression (approximately 0.5 inches above zero). Compression cycle depth 1310e represents the displacement of the subject's chest within a compression cycle applying 20% ​​compression and 0% decompression (e.g., decompression that returns the chest to its initial zero point).

[0211] Graph 1308 shows force data for five compression cycles 1312a-1312e. For clarity, graph 1308 illustrates the compression cycle as follows: it begins with a downward stroke initiated at maximum chest height, followed by an upward stroke involving pressing down to maximum compression depth, and the upward stroke involving decompression from maximum compression depth back to maximum chest height during the compression cycle. Compression cycles 1312a, 1312b, 1312c, 1312d, and 1312e each represent the force measured at the subject's chest when 20% compression (approximately 2.0 inches below zero) is applied; however, the decompression amounts for each of the compression cycles 1312a, 1312b, 1312c, 1312d, and 1312e are different. Compression cycle force 1312a represents the force applied to the subject's chest within a compression cycle applying 20% ​​compression (approximately 2.0 inches below zero) and 20% decompression (approximately 2.0 inches above zero). Compression cycle force 1312b represents the force applied to the subject's chest within a compression cycle applying 20% ​​compression and 15% decompression (approximately 1.5 inches above zero). Compression cycle force 1312c represents the force applied to the subject's chest within a compression cycle applying 20% ​​compression and 10% decompression (approximately 1.0 inch above zero). Compression cycle force 1312d represents the force applied to the subject's chest within a compression cycle applying 20% ​​compression and 5% decompression (approximately 0.5 inches above zero). Compression cycle force 1312e represents the force applied to the subject's chest within a compression cycle applying 20% ​​compression and 0% decompression (e.g., decompression that returns the chest to its initial zero position). The pressing cycle forces 1312a-1312e correspond to the pressing cycle displacements 1310a-1310e, respectively.

[0212] Line 1314 is a reference showing a comparison of the applied forces in the corresponding compression cycle forces 1312a-1312e at the time point of maximum depth among the compression cycle depths 1310a-1310e. Typically, forces 1312a-1312e are at their lowest values ​​(e.g., most negative) at the maximum compression displacement. Forces 1312a-1312e are typically at their maximum values ​​(e.g., most positive) during the maximum decompression displacement. Typically, for each compression cycle force 1312a-1312e, the force value is zero at two points during the compression cycle. These points can represent the transition from the compression phase to the decompression phase, and from the decompression phase back to the compression phase. As further described below, these points can also be used to estimate the neutral position of the subject's chest.

[0213] The displacement data graph 1302 and the force data graph 1304 are approximately aligned to show a comparison between force and distance values ​​during a pressing cycle. An example pressing cycle is marked by line 1314.

[0214] As mentioned above, the subject's chest becomes more compliant during compression cycles, meaning that relatively less force is needed to apply pressure and / or decompression to the subject's chest over time. This is in Figure 14 As shown in the figure, Figure 14 Data 1400 shows a series of several pressing cycles over time (on the order of approximately half an hour). Displacement data 1402 shows the displacement of the object's chest over time. Force data 1404 shows the force applied to the object's chest over time. Point 1410 shows the zero point as the initial rest displacement (set to zero displacement) of the object's chest.

[0215] During the initial time period marked 1406, a relatively larger force was applied to the subject's chest compared to the time period 1408. This is because organic structures in the subject's chest, such as ribs, may bend, crack, or even fracture during compression, resulting in significant chest remodeling in the initial time period. Examining time period 1406 reveals that, shortly afterward, an upward force was still applied when the ACD device was returned to zero, indicating that the chest's neutral position had shifted downward from zero. In time period 1408, a relatively smaller force was applied to achieve the same compression displacement as the chest became more compliant.

[0216] As a subject's chest becomes more compliant over time, the neutral position of the chest may change depending on how compressions and decompressions are applied. The neutral position of the chest refers to its natural, resting displacement when no force is applied. Estimating the neutral position allows for more accurate determination of compression depth and decompression lift during ACD CPR, and thus allows for better feedback related to the quality of CPR performed. Initially, the neutral position is zero. However, as the chest becomes more compliant, and with rib cracks and / or fractures, the neutral position of the chest may change. Typically, after chest compressions, the chest wall rests in a position lower than zero. For example, initially, when the chest is compressed, the neutral position of the chest will naturally shift downwards. However, when decompressions are applied, the neutral position of the chest may rise upwards. The combination of downward compressions and upward decompressions can change the position of the neutral position in real time. Figure 12 The processor 1202 is configured to estimate the neutral position of the chest to which ACD therapy has been applied. The neutral position of the chest is estimated, and the neutral position estimates can be used to fine-tune, or otherwise adjust, the compression and decompression forces applied to the user and the compression and decompression displacements of the chest.

[0217] As follows about Figures 15 to 2 As described in 4, the processor 1202 is configured to estimate the neutral position of the chest to which ACD treatment has been applied in several different ways.

[0218] Figure 15 Example graph 1500 shows the relationship 1502 between displacement 1522 and force 1520 during a compression cycle. As indicated by arrows 1524 and 1526, the upper part of the curve shows the compression stroke represented by arrow 1524, and the lower part of the curve shows the decompression stroke represented by arrow 1526. The force-displacement relationship curve 1502 shows that, generally, the force value increases with the displacement value. During a compression cycle, the amount of force being applied at a given displacement in the chest is different from compression to decompression, and therefore, mathematically speaking, force 1520 is not strictly a function of displacement 1522. This is due to mechanical hysteresis in the compression cycle. For a given displacement value, the magnitude of the force value during compression may be lower than the force value during decompression. In some implementations, the force value 1520 of the force-displacement relationship curve 1502 is determined by a force sensor (e.g., Figure 12 The force is measured by a force sensor 1208. In some implementations, the displacement value 1522 of the force-displacement relationship curve 1502 is based on a position sensor (e.g., Figure 12 Position sensor 1206) and / or accelerometer (e.g., Figure 12 The force-displacement relationship is determined by measurements from the accelerometer 1204. It is understood that a similar force-displacement relationship can be obtained during the use of an ACD device employing manual ACD therapy. In this case, the force value of the force-displacement relationship curve is measured by a force sensor located on the ACD device, and the displacement value of the force-displacement relationship curve is determined based on measurements from the position sensor and / or the accelerometer. For example, a manual ACD device may include the above-mentioned... Figures 1 to 10 The aforementioned device 100.

[0219] Referring to graph 1500, the force-displacement curve 1502 intersects the measured point of zero force at two locations marked by points 1504 and 1506 where the force applied to the chest is zero. As shown in graph 1500, the zero-force intersection points 1504 and 1506 are 1508 apart. In some implementations, processor 1202 estimates the neutral position of the object's chest (e.g., the displacement value corresponding to the neutral position) based on the zero-force intersection points 1504 and 1506. In some implementations, the zero-force intersection points 1504 and 1506 are not equal to zero displacement (e.g., zero point), but are slightly less than or greater than the zero displacement value. As mentioned above... Figure 14 This is due to the increased biomechanical chest compliance or remodeling of the sternum / thoracic structures during chest compressions.

[0220] Processor 1202 can be configured to estimate the neutral position of the object's chest based on the two zero-force intersection points 1504 and 1506. For example, the estimation of the neutral position of the object's chest may include the average of the displacement values ​​corresponding to the zero-force intersection points 1504 and 1506. The average of the displacement values ​​corresponding to the zero-force intersection points 1504 and 1506 is approximately at point 1514 in the curve 1500, or at -0.005 m above the zero point.

[0221] In some implementations, the estimate of the neutral position is a weighted function (e.g., a weighted average) of the displacement values ​​corresponding to the zero-force intersection points 1504 and 1506. The weighting function can include linear functions, exponential functions, etc. For example, the weighting function can include an expression where the weights are coefficients in a polynomial expression. In one example, the weighting function could be NP = a u *x u +a d *x d In the form of: weight a u and a d Used to adjust the displacement values ​​corresponding to points 1504 and 1506, and x u Corresponding to the intersection points during the previous journey, and x d Corresponding to the intersection points during the next travel period, and the weights are normalized so that the sum of all weights equals 1.

[0222] In the example, weights can be applied to a function that correlates the zero-force crosspoints 1504 and 1506 with the estimated neutral position. The values ​​of the weights can be based on historical data (e.g., collected over time from many patients and / or subjects), can be dynamically fine-tuned based on the current patient's previous compression cycles, or can be manually adjusted (e.g., calibrated), such as based on the hardware being used. Predetermined weights can be determined based on prior experimental and empirical data, which yield the best estimate of the neutral position across the widest possible population of subjects. Alternatively, the predetermined weights can be based on estimates of one or more sternal / thoracic biomechanical parameters (such as chest compliance, damping, mass, stiffness, viscosity, etc.) for a particular subject. Separate models can be estimated for the upper and lower strokes of the compression cycle. Separate models can be generated for compression or decompression at different depths. For example, weights can be proportional to the relative stiffness, viscosity, and damping over the upper and lower strokes. Weights can be based on damping at the midpoint of the compression / decompression cycle. The predetermined weights can be further modified by estimating one or more sternal / thoracic biomechanical parameters of a specific object.

[0223] In some implementations, the estimated neutral position is a displacement value between or within the range 1508 of the zero-force intersection points 1504 and 1506. In some implementations, the estimate of the neutral position can be outside the range 1508, such as always being below the zero-force intersection points 1504 and 1506 (e.g., approximately point 1510). In some implementations, the estimate of the neutral position can always be greater than the zero-force intersection points 1504 and 1506 (e.g., approximately point 1518). In some implementations, processor 1202 can output the probability that the neutral position is within the range 1518 (e.g., a 90% probability, a 100% probability, or any percentage value). In some implementations, processor 1202 can provide the probability that the neutral position of the object's chest is greater than the displacement value at point 1506, less than the displacement value at point 1504, or both. This situation may occur if there is already in-hospital injury caused by chest compressions (such as rib fractures or sternal cartilage separation); it may also occur if ventilation is delivered during chest compressions that causes a transient change in mechanical nature.

[0224] Go to Figure 16A The curve 1600 includes... Figure 15 The force-displacement relationship curve 1502 is similar to the force-displacement relationship curves 1602a-1602e. The force-displacement relationship curves 1602a-1602e show the relationship between the displacement value 1606 of the subject's chest and the corresponding force value 1604 of the force applied to the subject's chest during the ACD compression cycle.

[0225] Force-displacement curves 1602a-1602e each represent the force-displacement relationship for a press cycle at different decompression percentages while maintaining approximately the same 20% press (approximately 2.0 inches of depth). Force-displacement curve 1602a represents the force-displacement relationship at 20% press and 0% decompression above zero. Force-displacement curve 1602b represents the force-displacement relationship at 20% press and 5% decompression above zero. Force-displacement curve 1602c represents the force-displacement relationship at 20% press and 10% decompression above zero. Force-displacement curve 1602d represents the force-displacement relationship at 20% press and 15% decompression above zero. Force-displacement curve 1602e represents the force-displacement relationship at 20% press and 20% decompression above zero.

[0226] In some implementations, the force value 1604 of the force-displacement relationship curves 1602a-1602e is determined by a force sensor (e.g., Figure 12 The force is measured by a force sensor 1208. In some implementations, the displacement value 1606 of the force-displacement relationship curves 1602a-1602e is based on a position sensor (e.g., Figure 12Position sensor 1206) and / or accelerometer (e.g., Figure 12 It is determined by the measurement value of the accelerometer 1204.

[0227] In graph 1600, the zero-force cross points 1608 and 1610 are shown. Figure 12 Processor 1202 can use zero-force cross points 1608 and 1610 to work with the processors mentioned above. Figure 15 The neutral position of the subject's chest is estimated in a similar manner to the zero-force crossover points 1504 and 1506. Here, point 1610 represents the zero-force crossover point during the compression phase, and point 1608 represents the zero-force crossover point during the decompression phase.

[0228] Figure 16B This is a magnified portion (1650) of graph 1600. Zero-force crossover points (1612a-1612e) are marked in pairs for each force-displacement curve (1602a-1602e). Zero-force crossover point 1612a corresponds to force-displacement curve 1602a. Zero-force crossover point 1612b corresponds to force-displacement curve 1602b. Zero-force crossover point 1612c corresponds to force-displacement curve 1602c. Zero-force crossover point 1612d corresponds to force-displacement curve 1602d. Zero-force crossover point 1612e corresponds to force-displacement curve 1602e.

[0229] In this example, for the force-displacement relationship curves 1602a-1602e, as the percentage decompression increases, the corresponding zero-force crossover points 1612a-1612e are relatively further apart in terms of the corresponding chest displacement. Furthermore, since the zero-force crossover point 1610 changes more with increasing percentage decompression compared to its relative position at the zero-force crossover point 1608 as the percentage decompression increases, the zero-force crossover points 1608 and 1610 change more asymmetrically. In some implementations, this trend can be taken into account when the processor 1202 estimates the neutral position of the object's chest. For example, the processor 1202 can be configured to estimate the neutral position of the object's chest using different weight values ​​based on the percentage decompression associated with the measured zero-force crossover points 1608 and 1610. (This is related to the above...) Figure 15 Similarly, various weighting factors and / or other calculations can be applied to the zero-force crossover point to estimate the neutral position of the chest.

[0230] Go to Figure 17AGraph 1700 includes curves 1702a-1702e showing the relationship between displacement on the x-axis and the product of force and displacement on the y-axis. Curves 1702a-1702e show the relationship between the displacement value 1706 of the object's chest and the corresponding force-displacement product value 1704 of the force applied to the object's chest during an ACD compression cycle. For clarity, the force-displacement product value 1704 may be referred to as the product value, or simply as product value 1704. In some implementations, the force-displacement product may be referred to as the force or force value. The force value can represent the physical force used (e.g., by a rescuer, device, etc.) to hold the object's chest in a specific displacement position. The force is minimal when the object's chest is in a neutral position. In some implementations, the force increases approximately parabolically as the compression or decompression displacement value increases from the neutral position.

[0231] Product-displacement curves 1702a-1702e each represent the product-displacement relationship for a compression cycle at different decompression percentages. Curve 1702a represents the product-displacement relationship at 20% compression and 0% decompression above zero. Curve 1702b represents the product-displacement relationship at 20% compression and 5% decompression above zero. Curve 1702c represents the product-displacement relationship at 20% compression and 10% decompression above zero. Curve 1702d represents the product-displacement relationship at 20% compression and 15% decompression above zero. Curve 1702e represents the product-displacement relationship at 20% compression and 20% decompression above zero.

[0232] In some implementations, the product value 1704 of the product-displacement relationship curves 1702a-1702e is based on data from a force sensor (e.g., Figure 12 The displacement value 1706 is determined by the measurement value of the force sensor 1208. In some implementations, the displacement value 1706 of the product-displacement relationship curve 1702a-1702e is based on the position sensor (e.g., Figure 12 Position sensor 1206) and / or accelerometer (e.g., Figure 12 It is determined by the measurement value of the accelerometer 1204.

[0233] In some implementations, Figure 12 The processor 1202 is configured to estimate the neutral position of the object's chest based on a local minimum of the product value 1704 measured for displacement value 1706, as shown in graph 1700. In some implementations, the local product minimum is referred to as the point of minimum force.

[0234] The local minimum product value 1708 represents the minimum product value for each product-displacement relationship curve 1702a-1702e during the pressing phase. The local minimum product value 1710 represents the minimum product value for each product-displacement relationship curve 1702a-1702e during the decompression phase.

[0235] Figure 17B This is a magnified portion (1750) of curve 1700. For each product-displacement relationship curve 1702a-1702e, the local minimum values ​​of the product-displacement relationship 1712a-1712e are marked in pairs. The local minimum value of the product-displacement relationship 1712a corresponds to curve 1702a. The local minimum value of the product-displacement relationship 1712b corresponds to curve 1702b. The local minimum value of the product-displacement relationship 1712c corresponds to curve 1702c. The local minimum value of the product-displacement relationship 1712d corresponds to curve 1702d. The local minimum value of the product-displacement relationship 1712e corresponds to curve 1702e.

[0236] In some implementations, processor 1202 can be configured to estimate the neutral position of the object's chest based on a pair of local minima 1708 and 1710 for each product-displacement relationship curve 1702a-1702e. For example, the estimation of the neutral position of the object's chest for each product-displacement relationship curve 1702a-1702e may include average displacement values ​​corresponding to the local product minima 1712a-1712e, respectively. In graph 1750, the average values ​​of the displacement values ​​corresponding to the local product minima 1712a-1712e are different for each. For example, the average value of the displacement values ​​corresponding to the local product minima 1712a is slightly less than 0 m displacement. The average value of the displacement values ​​corresponding to the local product minima 1712b is approximately 0 m displacement. The average value of the displacement values ​​corresponding to the local product minima 1712c-1712e is slightly greater than 0 m displacement.

[0237] In some implementations, the estimate of the neutral position is a weighted function (e.g., a weighted average) of the average of the displacement values ​​corresponding to the local product minima 1712a-1712e. The weighting function can include linear functions, exponential functions, etc. For example, the weighting function can include an expression where the weights are coefficients in a polynomial expression. In one example, the weighting function could be NP = a u *x u +a d *x d In the form of: weight a u and a d Used to adjust the displacement values ​​corresponding to intersections 1712a-1712e, and x u Corresponding to the intersection points during the previous journey, and xd Corresponding to the intersection points during the next travel period, and the weights are normalized so that the sum of all weights equals 1.

[0238] For example, weights can be applied to a function that correlates the local multiplicative minimum value 1712b with the estimated neutral position. The values ​​of the weights can be based on historical data (e.g., collected from many patients over time), can be dynamically fine-tuned based on the current patient's previous compression cycles, can be manually adjusted (e.g., calibrated), and can be adjusted based on the hardware being used, etc.

[0239] Weights can be determined based on prior experimental and empirical data, yielding optimal estimates of neutral positions across the widest possible group of objects. Alternatively, predetermined weights can be based on estimates of one or more sternal / thoracic biomechanical parameters for a specific object, such as chest compliance, damping, mass, stiffness, viscosity, etc. Separate models can be estimated for the upper and lower strokes of the compression cycle. Separate models can be generated for compression or decompression at different depths. For example, weights can be proportional to relative stiffness, viscosity, and damping over the upper and lower strokes. Weights can be based on damping at the midpoint of the compression / decompression cycle. Predetermined weights can be further modified by estimates of one or more sternal / thoracic biomechanical parameters for a specific object.

[0240] In some implementations, the estimated neutral position is a displacement value between a pair of local minima 1708 and 1710. In some implementations, the estimate of the neutral position may always be lower than the local minimum 1708. In some implementations, the estimate of the neutral position may always be greater than the local minimum 1710. In some implementations, processor 1202 may output the probability that the neutral position is between the local minimums 1708 and 1710 (e.g., 90%, 100%, or any percentage value). In some implementations, processor 1202 may provide the probability that the neutral position of the object's chest is greater than the displacement value near the local minimum 1708, less than the displacement value at the local minimum 1710, or both.

[0241] This situation may occur if there is pre-existing in-hospital injury caused by chest compressions (such as rib fractures or sternal cartilage separation); it may also occur if the delivery of gas during chest compressions causes brief periods of ventilation. The variability in the neutral position caused by ventilation can be measured and characterized statistically (e.g., through measures such as mean and standard deviation), and the probability of the neutral position being between local minima can be calculated.

[0242] The estimated neutral position value 1214 obtained using the product-displacement local minima 1712a-1712e can differ from the estimated neutral position value obtained using the force-displacement zero-force crossover point 1612a-1612e. In some implementations, the neutral position estimate 1214 generated using the product-displacement local minima 1708, 1710 and the force-displacement zero-force crossover point 1612a-1612e can be combined into another function to improve the accuracy of the estimate 1214. For example, the product-displacement local minima 1708, 1710 can be associated with a first weight, and the force-displacement zero-force crossover point 1612a-1612e can be associated with a second weight, and the neutral position can be a function of both the first and second weights.

[0243] Go to Figure 18A Graph 1800 includes product-displacement curves 1802a-1802e. These curves show the relationship between the displacement value 1806 of the subject's chest and the corresponding product value 1804 of the force applied to the subject's chest during an ACD compression cycle. In other words, each of the product-displacement curves 1802a-1802e shows the amount of force applied at each displacement value of the subject's chest. At a specific displacement value for each decompression percentage, the force applied for both decompression and compression is equal. This is... Figure 18A The intersection point 1808 is shown and can be referred to as the equal force value.

[0244] Product-displacement curves 1802a-1802e each represent the product-displacement relationship for a compression cycle at different decompression percentages. Curve 1802a represents the product-displacement relationship at 20% compression and 0% decompression above zero. Curve 1802b represents the product-displacement relationship at 20% compression and 5% decompression above zero. Curve 1802c represents the product-displacement relationship at 20% compression and 10% decompression above zero. Curve 1802d represents the product-displacement relationship at 20% compression and 15% decompression above zero. Curve 1802e represents the product-displacement relationship at 20% compression and 20% decompression above zero.

[0245] In some implementations, the product value 1804 of the product-displacement relationship curves 1802a-1802e is based on data from a force sensor (e.g., Figure 12 The displacement value 1806 is determined by the measurement value of the force sensor 1208. In some implementations, the displacement value 1806 of the product-displacement relationship curve 1802a-1802e is based on the position sensor (e.g., Figure 12 Position sensor 1206) and / or accelerometer (e.g., Figure 12It is determined by the measurement value of the accelerometer 1204.

[0246] In some implementations, Figure 12 The processor 1202 is configured to estimate the neutral position of the object's chest based on the displacement value corresponding to the intersection point 1808 of the product-displacement relationship curves 1802a-1802e, as shown in graph 1800. The intersection point 1808 represents a displacement value in which the force applied to the object's chest during both the pressing and depressurization phases is the same for a given displacement value.

[0247] Figure 18B This is a magnified portion (1850) of graph 1800. Crosspoints 1812a-1812e are marked for each product-displacement curve 1802a-1802e. Crosspoint 1812a corresponds to product-displacement curve 1802a. Crosspoint 1812b corresponds to product-displacement curve 1802b. Crosspoint 1812c corresponds to product-displacement curve 1802c. Crosspoint 1812d corresponds to product-displacement curve 1802d. Crosspoint 1812e corresponds to product-displacement curve 1802e.

[0248] In some implementations, processor 1202 can be configured to estimate the neutral position of the object's chest based on the intersection points 1812a-1812e for each product-displacement relationship curve 1802a-1812e. For example, the estimation 1214 of the neutral position of the object's chest for each product-displacement relationship curve 1802a-1812e may include displacement values ​​corresponding to each intersection point 1812a-1812e, respectively. In curve graph 1850, the corresponding displacement values ​​for each intersection point 1812a-1812e are different. For example, the displacement value corresponding to intersection point 1812a is slightly greater than 0 m. The displacement values ​​corresponding to intersection points 1812b, 1812c, and 1812d are approximately 0.005 m. The displacement value corresponding to intersection point 1812e is slightly less than 0.01 m.

[0249] In some implementations, the estimation of the neutral position 1214 includes a weighted function (e.g., a weighted average) of the displacement values ​​corresponding to the intersections 1812a-1812e. For example, weights can be applied to a function that correlates the intersection 1812b with the estimated neutral position. The values ​​of the weights can be based on historical data (e.g., collected from many patients over time), can be dynamically fine-tuned based on the current patient's previous compression cycles, can be manually adjusted (e.g., calibrated), and can be adjusted based on the hardware being used, etc.

[0250] Weights can be determined based on prior experimental and empirical data, yielding optimal estimates of neutral positions across the widest possible group of objects. Alternatively, predetermined weights can be based on estimates of one or more sternal / thoracic biomechanical parameters for a specific object, such as chest compliance, damping, mass, stiffness, viscosity, etc. Separate models can be estimated for the upper and lower strokes of the compression cycle. Separate models can be generated for compression or decompression at different depths. For example, weights can be proportional to relative stiffness, viscosity, and damping over the upper and lower strokes. Weights can be based on damping at the midpoint of the compression / decompression cycle. Predetermined weights can be further modified by estimates of one or more sternal / thoracic biomechanical parameters for a specific object.

[0251] In one example, the weighting function could be NP = a u *x u +a d *x d In the form of: weight a u and a d Used to adjust the displacement values ​​corresponding to intersections 1812a-1812e, and x u Corresponding to the intersection points during the previous journey, and x d Corresponding to the intersection points during the next travel period, and the weights are normalized so that the sum of all weights equals 1.

[0252] In some implementations, the estimate of the neutral position can always be greater than or less than local intersections 1812a-1812e. In some implementations, processor 1202 can output a probability (e.g., 90% probability, 100% probability, or any percentage value) that the neutral position is greater than or less than one or more intersections 1812a-1812e or a function of intersections 1812a-1812e. In some implementations, processor 1202 can provide a probability that the neutral position of the object's chest is greater than, less than, a displacement value near intersection 1808, or both.

[0253] The estimated neutral position value 1214 obtained using cross values ​​1812a-1812e can differ from the estimated neutral position value obtained using force-displacement zero cross points 1612a-1612e and / or product-displacement local minima 1712a-1712e. In some implementations, the neutral position estimate 1214 generated using product-displacement local minima 1712a-1712e, force-displacement zero cross points 1612a-1612e, and cross values ​​1812a-1812e can be combined into another function to improve the accuracy of the estimate 1214. In one example, the function is a weighted function as described above.

[0254] Go to Figure 19A Graph 1900 includes curves 1902a-1902e relating displacement to the time derivative of the force-displacement product (or instantaneous force-displacement product). These curves 1902a-1902e can be referred to as differential product-displacement relationship curves. The instantaneous product-displacement relationship curves 1902a-1902e show the relationship between the displacement value 1906 of the subject's chest and the corresponding instantaneous force-displacement product value 1904 of the force applied to the subject's chest during an ACD compression cycle. In other words, the product-displacement relationship curves 1902a-1902e each represent the change in the amount of force applied at each displacement value of the subject's chest. At a specific displacement value for each decompression percentage value, the change in force is equal for both decompression and compression. This is in Figure 19A The intersection point 1908 is shown and can be referred to as the equal force rate value.

[0255] Instantaneous product-displacement curves 1902a-1902e each represent the instantaneous product-displacement relationship for a compression cycle at different decompression percentages. Instantaneous product-displacement curve 1902a represents the instantaneous product-displacement relationship at 20% compression and 0% decompression above zero. Instantaneous product-displacement curve 1902b represents the instantaneous product-displacement relationship at 20% compression and 5% decompression above zero. Instantaneous product-displacement curve 1902c represents the instantaneous product-displacement relationship at 20% compression and 10% decompression above zero. Instantaneous product-displacement curve 1902d represents the instantaneous product-displacement relationship at 20% compression and 15% decompression above zero. Instantaneous product-displacement curve 1902e represents the instantaneous product-displacement relationship at 20% compression and 20% decompression above zero.

[0256] In some implementations, the product value 1904 of the instantaneous product-displacement relationship curves 1902a-1902e is based on data from a force sensor (e.g., Figure 12 The displacement value 1906 is determined by the measurement value of the force sensor 1208. In some implementations, the displacement value 1906 of the product-displacement relationship curve 1902a-1902e is based on the position sensor (e.g., Figure 12 Position sensor 1206) and / or accelerometer (e.g., Figure 12 It is determined by the measurement value of the accelerometer 1204.

[0257] In some implementations, Figure 12The processor 1202 is configured to estimate the neutral position of the object's chest based on the displacement value of the intersection point 1908 corresponding to the product-displacement relationship curves 1902a-1902e, as shown in graph 1900. The intersection point 1908 represents a displacement value in which the time derivative of the force-displacement product applied to the object's chest during both the compression and decompression phases is the same for a given displacement value.

[0258] Figure 19B This is a magnified portion (1950) of graph 1900. Crosspoints 1912a-1902e are marked for each instantaneous product-displacement curve 1902a-1902e. Crosspoint 1912a corresponds to instantaneous product-displacement curve 1902a. Crosspoint 1912b corresponds to instantaneous product-displacement curve 1902b. Crosspoint 1912c corresponds to instantaneous product-displacement curve 1902c. Crosspoint 1912d corresponds to instantaneous product-displacement curve 1902d. Crosspoint 1912e corresponds to instantaneous product-displacement curve 1902e.

[0259] In some implementations, processor 1202 can be configured to estimate the neutral position of the object's chest based on intersection points 1912a-1912e for each instantaneous product-displacement relationship curve 1902a-1902e. For example, the estimation 1214 of the neutral position of the object's chest for each instantaneous product-displacement relationship curve 1902a-1902e may include displacement values ​​corresponding to each intersection point 1912a-1912e, respectively. In curve 1950, the corresponding displacement values ​​for each intersection point 1912a-1912e are different. For example, the displacement value corresponding to intersection point 1912a is slightly less than 0m displacement. The displacement values ​​corresponding to intersection points 1912b-1912e are slightly greater than 0m displacement. In this case, the neutral position is estimated at points where the rate of change of the applied force (the product of force and displacement) is independent of direction and is therefore equal during the pressing and depressurization phases of the ACD cycle.

[0260] In some implementations, the estimation of the neutral position 1214 includes a weighted function (e.g., a weighted average) of the displacement values ​​corresponding to the intersections 1912a-1912e. For example, weights can be applied to a function that correlates intersection 1912b with the estimated neutral position. The values ​​of the weights can be based on historical data (e.g., collected from many patients over time), can be dynamically fine-tuned based on the current patient's previous compression cycles, can be manually adjusted (e.g., calibrated), and can be adjusted based on the hardware being used, etc.

[0261] Weights can be determined based on prior experimental and empirical data, yielding optimal estimates of neutral positions across the widest possible group of objects. Alternatively, predetermined weights can be based on estimates of one or more sternal / thoracic biomechanical parameters for a specific object, such as chest compliance, damping, mass, stiffness, viscosity, etc. Separate models can be estimated for the upper and lower strokes of the compression cycle. Separate models can be generated for compression or decompression at different depths. For example, weights can be proportional to relative stiffness, viscosity, and damping over the upper and lower strokes. Weights can be based on damping at the midpoint of the compression / decompression cycle. Predetermined weights can be further modified by estimates of one or more sternal / thoracic biomechanical parameters for a specific object.

[0262] In one example, the weighting function could be NP = a u *x u +a d *x d In the form of: weight a u and a d Used to adjust the displacement values ​​corresponding to intersections 1912a-1912e, and x u Corresponding to the intersection points during the previous journey, and x d Corresponding to the intersection points during the next travel period, and the weights are normalized so that the sum of all weights equals 1.

[0263] In some implementations, the estimate of the neutral position can always be greater than or less than the local intersections 1912a-1912e. In some implementations, the processor 1202 can output the probability (e.g., 90%, 100%, or any percentage value) that the neutral position is greater than or less than one or more of the intersections 1912a-1912e or a function of the intersections 1912a-1912e.

[0264] This situation may occur if there is pre-existing in-hospital injury caused by chest compressions (such as rib fractures or sternal cartilage separation); it may also occur if the delivery of gas during chest compressions causes brief periods of ventilation. The variability in the neutral position caused by ventilation can be measured and characterized statistically (e.g., through measures such as mean and standard deviation), and the probability of the neutral position being between local minima can be calculated.

[0265] The estimated neutral position value 1214 obtained using cross values ​​1912a-1912e can differ from the estimated neutral position value obtained using force-displacement zero cross points 1612a-1612e, product-displacement local minima 1712a-1712e, and / or cross values ​​1812a-1812e. In some implementations, the neutral position estimate 1214 generated using product-displacement local minima 1712a-1712e, force-displacement zero cross points 1612a-1612e, cross values ​​1812a-1812e, and cross values ​​1912a-1912e can be combined into another function to improve the accuracy of the estimate 1214. In one example, the function is a weighted function as described above.

[0266] Figure 20 An example process 2100 is shown for estimating a patient's neutral position during ACD therapy using the relationship between the force applied to the patient's chest during compression and the displacement of the patient's chest. This process can be applied to ACD therapy applied to a patient manually by a caregiver, as well as to ACD therapy applied to a patient automatically without the need for manual effort from the caregiver to apply the ACD. An ACD device 1200 is coupled (2102) to a patient. A processor 1202 is then configured to estimate the patient's neutral position. The processor 1202 is configured to perform (2104) active compression decompression therapy on the patient, including compression cycles. The processor 1202 is configured to identify (2106) compression cycles based on signals from motion and force sensors from the ACD device. The processor 1202 is configured to determine (2108) a first depth of chest compression corresponding to the force-displacement relationship of the compression phase. The processor 1202 is configured to determine (2110) a second depth of chest compression corresponding to the force-displacement relationship of the decompression phase. Processor 1202 is configured to estimate (2112) the neutral position of the patient's chest based on a first depth and a second depth (e.g., a first displacement and a second displacement). In some implementations, the first displacement and the second displacement may correspond to any point or combination of points 1612a-1612e, 1712a-1712e, 1812a-1812e, and / or 1912a-1912e. Processor 1202 is configured to determine (2114) whether (one or more) additional estimates (e.g., estimates from processing 2100 or other processing or previous estimates of both over time) are available. If "yes", processor 1202 is configured to combine the estimate with (one or more) other estimates (e.g., moving average, sliding average, etc.) (2116). Processor 1202 is configured to provide (2118) treatment feedback via a user interface based on (one or more) the estimates.

[0267] Figure 21An example process 2200 is shown for estimating a patient's neutral position during ACD therapy based on the force applied to the patient's chest during compressions, specifically involving when the force applied to the patient's chest is approximately zero. As discussed herein, this process can be applied to ACD therapy applied to a patient manually by a caregiver, as well as to ACD therapy applied to a patient automatically without the need for manual effort from a caregiver to apply the ACD. An ACD device 1200 is coupled (2202) to a patient. The processor 1202 is then configured to estimate the patient's neutral position. The processor 1202 is configured to perform (2204) active compression decompression therapy on the patient, including compression cycles. The processor 1202 is configured to identify (2206) compression cycles based on signals from motion and force sensors from the ACD device 1200. The processor 1202 is configured to determine (2208) a first depth of external chest compression corresponding to when approximately zero force is applied to the patient's chest during the compression phase. Processor 1202 is configured to determine (2210) a second depth of chest compression corresponding to when approximately zero force is applied to the patient's chest during the decompression phase. Processor 1202 is configured to estimate (2212) a neutral position of the patient's chest based on the first and second depths (e.g., first and second displacements). In some implementations, the first and second displacements may correspond to any of points 1612a-1612e. Processor 1202 is configured to determine (2214) whether (one or more) additional estimates (e.g., previous estimates using processing 2200 or other processing or both over time) are available. If "yes", processor 1202 is configured to combine the estimates with (one or more) other estimates (e.g., moving average, sliding average, etc.) (2216). Processor 1202 is configured to provide (2218) treatment feedback via a user interface based on (one or more) the estimates.

[0268] Figure 22An example process 2300 is shown for estimating a patient's neutral position during ACD treatment based on the product of the force applied to the patient's chest and the displacement of the patient's chest. This process can be applied to ACD treatment of a patient manually by a caregiver, as well as automatically by a caregiver without requiring manual effort from the caregiver to apply the ACD. An ACD device 1200 is coupled (2302) to the patient. The processor 1202 is then configured to estimate the patient's neutral position. The processor 1202 is configured to perform (2304) active compression decompression treatment on the patient, including compression cycles. The processor 1202 is configured to identify (2306) compression cycles based on signals from motion and force sensors of the ACD device 1200. The processor 1202 is configured to determine (2308) a first depth of chest compression corresponding to a first product of force and displacement during the compression phase. The processor 1202 is configured to determine (2310) a second depth of chest compression corresponding to a second product of force and displacement during the decompression phase. Processor 1202 is configured to estimate (2312) the neutral position of the patient's chest based on a first depth and a second depth (e.g., a first displacement and a second displacement). In some implementations, the first displacement and the second displacement may be any of points 1712a-1712e and / or points 1812a-1812e. Processor 1202 is configured to determine (2314) whether (one or more) additional estimates (e.g., estimates using processing 2300 or other processing or previous estimates of both over time) are available. If "yes", processor 1202 is configured to combine the estimate with (one or more) other estimates (e.g., moving average, sliding average, etc.) (2316). Processor 1202 is configured to provide (2318) treatment feedback via a user interface based on (one or more) the estimates.

[0269] Figure 23 Showing the use of based on about Figures 20 to 22 Example processing 2400 is a combination of processes 2000, 2100, and 2200 used to estimate the neutral position of a patient during ACD treatment. An ACD device 1200 is coupled (2402) to the patient. The processor 1202 is then configured to estimate the neutral position of the patient's chest. The processor 1202 is configured to perform (2404) active compression decompression therapy on the patient, including compression cycles. The processor 1202 is configured to identify (2406) compression cycles based on signals from motion and force sensors of the ACD device 1200.

[0270] Processor 1202 is configured to receive (2408) in Figure 20 The estimate calculated at step 2112. Processor 1202 is configured to receive (2410) at Figure 21The estimate calculated at step 2212. Processor 1202 is configured to receive (2412) at Figure 22 The estimate calculated at step 2312. Processor 1202 is configured to estimate (2414) the neutral position of the patient's chest based on the estimates received at steps 2408, 2410, and 2412 (such as by combining these estimates using an average, weighted average, or other functions). Processor 1202 is configured to determine (2416) whether (one or more) additional estimates (e.g., previous estimates over time using processing 2400 or other processing, or both) are available. If "yes", processor 1202 is configured to combine the estimate with (one or more) other estimates (e.g., moving average, sliding average, etc.) (2418). Processor 1202 is configured to provide (2420) treatment feedback via a user interface based on (one or more) estimates.

[0271] This article discusses how, because the chest is subjected to significant forces during CPR, it undergoes remodeling during the application of compressions and decompressions, and therefore its neutral position can often be altered. For example, when repetitive chest compressions are applied, the chest's neutral position will naturally shift downwards, and therefore, clinically, it may be desirable to adjust the application of CPR based on how the neutral position deviates.

[0272] Because embodiments of the present invention describe a method for estimating the neutral position of the chest during the CPR process (e.g., via displacement and force sensing), the estimated neutral position can be used to determine at least one target displacement range (e.g., a target depth range on the downstroke, a target lift range on the upstroke) while CPR is being applied. That is, the estimated neutral position can be used as input to one or more targets to appropriately adjust the target downstroke displacement (also known as compression depth) and / or the target upstroke displacement (also known as decompression displacement or decompression lift).

[0273] Estimating the neutral position can also be used to determine at least one target force range during CPR (e.g., a target force range on the down stroke, a target force range on the up stroke). For example, the estimated neutral position can be used as input to one or more targets to adjust the target down stroke force and / or target up stroke force. In some embodiments, feedback given to the user allows the user to apply more or less force on the up or down stroke based on whether the target displacement and / or force range is met. Alternatively, feedback can prompt the user to achieve a deeper or shallower displacement on the up or down stroke based on whether the target displacement and / or force range is met. For example, if the compression depth is too shallow (less than the target compression depth in amplitude), the user can be prompted to press down harder. Or, if the decompression lift displacement is too small, the user can be prompted to lift with more force.

[0274] Therefore, when updating the estimated neutral position, the compression depth and decompression lift(s) targets can be repeatedly updated. For example, if the neutral position of the chest cavity becomes significantly concave (i.e., significantly downward), it may be preferable to lift or decompress the chest to a greater extent than in other cases. As an example, it may be desirable to modify ACD treatment so that the neutral position is returned to the estimated zero point of the chest when compressions have initially begun. This increased decompression can have the effect of further enhancing circulation (potentially by balancing the flow in and out of the heart). Alternatively, if the neutral position of the chest shifts upward beyond the chest's natural resting equilibrium point (e.g., due to a significant upward force applied to the chest), it may be preferable to apply more compressions or less decompression to the chest.

[0275] Compression depth and decompression lift can be determined in a manner independent of the methods described above for determining the neutral position of the patient's chest. For example, compression depth and decompression lift can be determined by measuring the compression and decompression forces applied to the patient during a compression cycle. Using the measured compression force(s) and decompression force(s), an ACD device (e.g., ACD device 100, ACD device 1200, etc.) can be configured to determine the proportion of the total displacement of the patient's chest to the compression depth of the patient's chest. This also determines the proportion of the total displacement of the patient's chest to the decompression displacement or lift of the patient's chest, which is a corresponding value of the compression displacement.

[0276] An ACD device or corresponding processing system (such as a patient monitor, defibrillator, portable computing device, or other computing device for processing ACD-related information) is configured to multiply the compression ratio by the total travel to obtain the compression depth. Force sensors (e.g., force sensor 402, force sensor 1208, etc.) can be used to measure the compression and decompression forces. Force sensors may include force-measuring sensors coupled to signal processing and filtering circuitry and analog-to-digital converter (ADC) devices. Total displacement can be measured by a displacement sensor such as an optical encoder, linear potentiometer, laser interferometer, magnetic field-based distance sensor, or other distance-encoded sensor. In some implementations, as described above, displacement can be approximated by using motion sensors (e.g., accelerometers, velocity sensors).

[0277] More specifically, compression depth and decompression lift can be determined by determining the maximum compression force applied to the patient's chest during chest compressions and the maximum decompression force applied to the patient's chest during chest decompression. Typically, the force applied during active chest compression decompression (in amplitude) reaches the maximum compression value when the patient's chest is at maximum compression depth, and the force applied during active chest decompression decompression (in amplitude) reaches the maximum decompression value when the patient's chest is at maximum decompression lift. For some implementations, the maximum force values ​​(for both compression and decompression forces) are static and unaffected by any variations in the stiffness of the mechanical system (such as variations introduced by the elastic plunger of the ADC device).

[0278] The peak force values ​​at maximum decompression lift and maximum compression depth can be related to chest stiffness. If the stiffness of the patient's chest (e.g., relative to another stiffness of the patient's chest) increases, then a larger maximum (e.g., peak) compression and decompression force will be applied at a given chest displacement.

[0279] Figure 24A A graph 2450 illustrates the peak chest compression force associated with chest compressions to a patient. In graph 2450, compression depth (d) is shown. C )2452 is the maximum pressing force (f) expressed in Newtons (N). C The function 2454 is shown in centimeters (cm). An ACD device (or a similar device for generating model data) can be used to perform chest compressions and decompressions on a patient to obtain compression values ​​2456a, 2456b, and 2456c for different compression depths 2452. The ACD device may include a displacement sensor, such as an encoder, to obtain this data. A function 2458 is generated to model the relationship between compression force 2454 and compression depth 2452. In the graph 2450, function 2458 is a quadratic function. However, function 2458 can be a higher-order function, such as a cubic, quartic, nth-order, spline, or exponential function. Such a function may include constants determined by training a model (e.g., curve fitting to the data).

[0280] Similarly, Figure 24B Graph 2460 illustrates the peak decompression force associated with extrathoracic decompression in a patient. In graph 2460, the decompression rise (d) L )2462 is the maximum relief force (f) expressed in Newtons (N). LThe function 2464 is shown in centimeters (cm). An ACD device (or a similar device for generating model data) can be used to perform compression and decompression on the patient's chest to obtain decompression values ​​2466a, 2466b, 2466c, and 2466d for different lift displacements 2462. The ACD device may include a displacement sensor, such as an encoder, to obtain this data. A function 2468 is generated to model the relationship between decompression 2464 and lift displacement 2462. In graph 2460, function 2468 is a linear function. However, function 2468 can be a higher-order function, such as a quadratic, cubic, quartic, nth-order function, spline, or exponential function.

[0281] It is generally believed that, for the same displacement value, the peak value is determined by the pressure f. C Greater than peak pressure reduction f L It is generally believed that the pressure applied changes non-linearly with respect to the depth of pressure. A statistical model is generated based on this data:

[0282] d L (f L )=a·f L (1)

[0283]

[0284] Where, d L It is a decompression lifting displacement, d C It refers to the depth of pressure, f. L It is the force at the point of maximum decompression and lifting, f C This is the force at the maximum compression depth, and a, b, and c are constants. Assume the total chest displacement d. T It is the pressing depth d C and decompression lift d L The sum of these two models can be used to estimate the ratio of total chest travel to chest compressions as follows:

[0285]

[0286]

[0287] It can be simplified to:

[0288]

[0289] Then, the total chest displacement d can be measured in units of each press. T Multiply by the pressing ratio F C To calculate the pressing depth d C .

[0290] d C =dT *F C (f C ,f L (4)

[0291] Equations (3) and (4) together show the peak (e.g., maximum) pressing force f. C Peak (e.g., maximum) pressure f L and decompression depth d C The relationship between them. As mentioned above, the maximum pressure reduction f L This corresponds to the force applied to the patient's chest during the decompression phase. Similarly, the maximum compression force f C This corresponds to the force applied to the patient's chest during the compression phase. Force f C and f L This typically occurs during a compression cycle at or near the maximum compression and decompression points, respectively. In some instances, the maximum compression force (f) C The maximum force (f) can be calculated by averaging multiple force values ​​at or near the maximum pressure, or by taking a specific value at or near the maximum pressure. Similarly, the maximum deceleration force (f) L This can be calculated by averaging multiple force values ​​at or near the maximum decompression point, or by taking a specific value at or near the maximum decompression point. For example, the maximum pressing force and / or maximum decompression force input into the function described herein can be an approximate estimate of the actual maximum pressing force and / or maximum decompression force.

[0292] Figure 25 An example of user interface 2500 is shown. User interface 2500 shows a visual representation of a compression cycle (including example cycle 2502) of active compression decompression therapy. Although cycle 2502 is measured from peak to peak from the maximum decompression lift in the patient's chest, a compression cycle can be measured from peak to peak from the maximum compression depth, etc., by crossing the zero line 2504.

[0293] Compression depth represents the portion of a compression cycle that corresponds to a compression on the patient's chest. For example, compression depth is the difference between the patient's chest position at neutral position 2506 and the position of the patient's chest when compressed below neutral position (e.g., any point on line 2510 below neutral position line 2506). The maximum compression depth of cycle 2502 is shown at an approximate position 2512 on line 2510. As previously described, neutral position represents the position of the patient's chest after it has naturally recoiled from the previous compression cycle and come to rest. Typically, the neutral position 2506 of the patient's chest tends to deviate from the zero point (initial neutral position) of the patient's chest shown by line 2504. An example difference 2508 between neutral position 2506 and zero point 2504 is shown.

[0294] Similarly, decompression lift refers to the portion of a compression cycle that corresponds to the decompression of the patient's chest. For example, compression depth is the difference between the patient's chest position at neutral position 2506 and the patient's chest position when compressed below neutral position (e.g., any point on line 2510 above neutral position line 2506). The maximum decompression lift of cycle 2502 is shown at approximately position 2514 on line 2510.

[0295] The ACD device and / or associated processing device (e.g., defibrillator / monitor, patient monitor, AED, computing device, tablet, feedback device, server, cloud-based computing system, etc.) are configured to determine the total distance traveled by the patient's chest during a compression cycle (e.g., total chest displacement d). T The total distance traveled by the patient's chest for cycle 2502 is the difference between the value at the patient's chest position at point 2514 and the value at the patient's chest position at point 2512 (in Figure 25 (In the example, it is approximately 2.5 inches). A motion sensor (e.g., one of accelerometers 216a-216b, 404a-404b, etc.) generates a signal representing the motion of the ACD device during the press cycle, as described above. In some implementations, this signal can be double-integrated to determine the total travel distance d of the sensor. T The sensor can be coupled to the patient's chest, and thus the ACD device and / or associated processing device can determine the total distance traveled d along the patient's chest. T .

[0296] The motion sensor is also used to determine point 2512, representing the position of maximum compression, and point 2514, representing the position of maximum decompression of the patient's chest during the compression cycle. For example, when the direction of movement of the patient's chest changes, the ACD device and / or associated processing device can determine that such inflection points represent a change from compression to decompression or from decompression to compression.

[0297] The ACD device and / or associated processing device record the maximum pressing force f occurring at or near each point of maximum pressing point 2512 and maximum depressing point 2514. C and maximum lifting force f L The measured value of f can be obtained through one or more methods. C and f L The value of f. For example, the ACD device and / or associated processing device can measure individual force values ​​at various points 2512 and 2514 in each cycle to determine f. C and f LIn some implementations, the ACD device and / or associated processing unit can measure a series of force values ​​at or near points 2512 and 2514. The ACD device and / or associated processing unit can average or apply a weighted average (or other function) to the measured force values ​​to estimate f. C and f L Approximate values. However, it is understood that the compression ratio method described herein provides a simplification for estimating compression depth during ACD therapy because it does not require accurate time synchronization between force and displacement. For example, it is not necessary to align the data captures of both force and displacement in time (such as the data capture described in embodiments that use force and displacement curves to track and assess whether a specific relationship (e.g., zero-force crossover point of displacement, crossover point at product-displacement relationship curve, local minimum of product-displacement curve, etc.)). The values ​​of maximum compression force, maximum decompression force, and total displacement may be sufficient to estimate chest compression depth. Therefore, the measurement and calculation of force and displacement values ​​provided when using an ACD device do not necessarily need to be time-aligned. Instead, the ACD device and / or associated processing device associate specific compression forces (e.g., approximate maximum force, approximate minimum force) and total displacement travel during compression and decompression with specific compression cycles and / or multiple compression cycles. Time synchronization / alignment of force measurements and acceleration values ​​is not required when calculating compression depth and / or decompression lift. The ACD device and / or associated processing unit correlate the maximum and minimum force of the pressing cycle with the acceleration value of the cycle for each cycle resolution to determine the pressing depth and depressurization release for each pressing cycle.

[0298] In some implementations, the ACD device and / or associated processing device may store f, representing the value measured for each press cycle in a series of press cycles. C and f L The data is a sequence of values. Since the force applied to the patient's chest does not change significantly over several compression cycles (e.g., <five compression cycles), the value of f for the most recent compression cycle can be used as a reference. C and f L The value of f is determined by applying a moving average. C and f L The adjustment value. Alternatively, f can be used. C and f L The pressing depth d is calculated from the various values. C and pressing ratio F C Then, statistical or signal processing methods such as moving average, median filter, low-pass filter, Kalman filter, etc., can be used to determine the compression depth d. C and pressing ratio F CAveraging or smoothing is performed. In some implementations, the ACD device and / or the associated processing device for processing force and displacement information obtained from ACD therapy (e.g., feedback device, defibrillator / monitor, AED, patient monitor, tablet, server, computing device, cloud-based computing system, etc.) calculate d within several compression cycles. C or F C A moving average was used to estimate the compression depth and / or decompression lift within these compression cycles. C or F C This moving average compensates for the force f caused by the change in depth and / or lift value from one press cycle to the next press cycle of the moving average. C or f L The changes in force and / or displacement can be compensated for, alternatively or additionally, when estimating compression depth and / or decompression lift, by removing outliers in force and / or displacement to further compensate for significant changes in force or displacement. For d C or F C The advantage of these statistical or signal processing methods is that they compensate for changes in force caused by variations in pressing depth or lifting.

[0299] Once the ACD device or associated processing system / device estimates f C and f L The approximate value can be determined by the ACD device or associated processing device, for example, by the pressing ratio F provided by equation (3). C Pressing ratio F C It is the portion of the total displacement distance of the patient's chest corresponding to the compression depth. Equation (3) includes three constants, a, b, and c. The values ​​of these constants are determined using training data acquired from the ACD device. (See also: Regarding...) Figures 27A to 27B The training data is obtained by measuring the force applied by the ACD device to a chest that is physiologically similar to the patient's chest at a known displacement value.

[0300] Once the values ​​of a, b, and c are determined, the ACD device and / or associated processing device can determine the pressing ratio F. C ACD devices and / or associated processing devices use F C The value and total chest displacement d T The pressing depth d is determined according to equation (3). C (and decompression lift d) L Pressing depth d C Along with decompression, d L Together equals the total chest displacement d T .

[0301] The compression depth d can be determined in a manner independent of using dynamic mechanical data from the compression cycle. CSince equation (3) depends only on static measurements (force value f) C and f L Therefore, mechanical backlash that may be introduced from the ACD device during compression can be ignored. Assuming that the stiffness during lifting is proportional to the stiffness during compression, it is assumed that the patient's stiffness does not affect the determination of the compression ratio.

[0302] ACD devices and / or associated processing devices use pressing depth d C and decompression lift d L The value is used to generate a portion of the user interface 2500 to assist the user in operating the ACD device. The ACD device and / or associated feedback devices can display or present estimates of the compression depth or decompression release over time (such as when the user is performing a compression cycle) on the display. For example, this can be based on the value of the compression depth d. C and decompression lift d L The estimate is used to generate line 2510.

[0303] The compression / decompression meter 2520 displays on the user interface 2500 the amount of force being applied to compress or lift the ACD device. The compression meter 2520 displays the compression depth 2522 and decompression lift 2524 applied by the user to the patient's chest using the ACD device. The meter 2520 includes representations of a neutral position 2526, a zero point 2528 (e.g., in cases where the absolute depth is known, such as using a laser interferometer or optical encoder), the current chest position 2530, the most recent maximum compression depth 2532, and the most recent maximum decompression lift 2524. In some implementations, it is not necessary to know the zero point 2528 to determine or estimate the neutral position 2526. In cases where the absolute depth is unknown, the zero point 2528 can be estimated as the midpoint between the first compression depth and decompression lift value in CPR treatment. Total chest displacement d T It is the difference between the maximum compression depth 2532 and the maximum decompression release 2534. The compression depth d is calculated as described above. C And approximate the difference between the value of the neutral position 2526 and the value of the maximum compression depth 2532. For example, once the compression depth d is determined... CThis allows the neutral position 2526 to be determined / estimated. To refresh meter 2520 for a new press cycle, marker 2532 can be set to match the depth (or trough) of the previous press cycle. Neutral point 2526 can be calculated as the previous press depth 2532 in the meter plus the newly calculated press displacement, essentially dividing the meter into two parts: lift and depth. This causes the display of neutral point 2526 to move up and down in meter 2520 as the neutral point changes during a press cycle. In some implementations, to refresh meter 2520 for a new press cycle, neutral point 2526 is fixed at the appropriate position in meter 2520, and markers for lift 2534 and depth 2532 move in response to changes in press depth and depressurization lift from neutral point position 2526. In some examples, it can be based on the maximum press depth 2532 plus press depth d. C To estimate the neutral position 2526. Other similar examples can be used to display the neutral position 2526, the decompression lift 2524, and the compression depth 2532.

[0304] The ACD device and / or associated processing device can determine the compression depth d. C Or reduce pressure and lift d L Is it outside the acceptable range? For example, in... Figure 26 As seen in the user interface 2600, the latest press displacement value 2624 reached is indicated by the shaded area 2610, and the latest depressurization value 2622 reached is indicated by the shaded area 2608. Areas 2608 and 2610 are updated as the next cycle begins. In some implementations, these areas are presented as a "ghosting" effect on the bar and appear gradually weakened or diminished compared to the current displacement measurement to indicate to the user that these areas represent past downstroke and upstroke measurements. As the current displacement bar 2606 moves up and down in the displacement meter 2620, the shaded areas 2608 and 2610 are redrawn, and if the old areas are too old, they are gradually removed from the user interface or otherwise eliminated. The current displacement may also be referred to as the current upstroke displacement, the current downstroke displacement, the updated upstroke displacement, and the updated downstroke displacement, etc.

[0305] Ranges 2602a and 2602b can be updated by the ACD device 1200 and / or associated feedback / processing devices in response to various detected conditions. For example, the ACD device and / or associated feedback / processing devices can adjust at least one of the target lower stroke displacement range 2602b and the target upper stroke displacement range 2602a based on an updated estimate of the neutral position. The ACD device 1200 or other associated feedback / processing devices can adjust the target lower stroke displacement range 2602b from an initial target lower stroke displacement range to an updated target lower stroke displacement range based on whether the lower stroke displacement 2610 falls within the target lower stroke displacement range and / or based on an updated estimate of the neutral position. Similarly, the ACD device 1200 and / or associated feedback / processing devices can adjust the target upper stroke displacement range 2602a from an initial target upper stroke displacement range to an updated target upper stroke displacement range based on whether the upper stroke displacement 2608 falls within the target upper stroke displacement range and / or based on an updated estimate of the neutral position.

[0306] In some implementations, the updated target lower stroke displacement range 2602b is obtained from the initial target lower stroke displacement range after a predetermined interval (e.g., the number of compression cycles, elapsed time, etc.). Similarly, in some implementations, the updated target upper stroke displacement range 2602a is obtained from the initial target upper stroke displacement range after a predetermined interval (e.g., the number of compression cycles, elapsed time, etc.). Such updates to the target lower stroke displacement range and / or the target upper stroke displacement range may or may not be based on an updated estimate of the neutral position of the chest. For upper or lower stroke displacements, (e.g., in response to estimating the neutral position of the patient's chest), the target ranges 2602a, 2602b can be offset to represent a range with a larger amplitude, a range with a smaller amplitude, the compression range itself, or the extended range itself.

[0307] In some implementations, at least one of the target lower stroke displacement range 2602b and the target upper stroke displacement range 2602a may be based on clinically accepted guidelines. However, the target lower stroke displacement range 2602b may be greater than or less than the clinically accepted guidelines, and the target upper stroke displacement range 2602a may be greater than or less than the clinically accepted guidelines.

[0308] In some implementations, the ACD device 1200 or other associated feedback / processing devices are configured to determine how to reshape the patient's chest based on an estimated neutral position. Feedback signals received from sensors can enable a display to provide indications of chest reshaping. For example, the feedback device can simply provide an indication that substantial chest reshaping has occurred due to CPR treatment, making the user aware of the change in chest mechanics. This information can be a cue for the user to change the way CPR is delivered, for example, reducing the force applied to the patient to reduce the risk of injury, or providing more or less decompression treatment. As discussed above, when the chest's neutral position is significantly compromised due to chest reshaping, it may be desirable to reduce the depth of compression on the lower stroke and / or increase the decompression lift on the upper stroke. In some cases, the feedback device can provide the user with further indications to adjust the target lower stroke displacement and / or target upper stroke displacement or force, or to adjust aspects of the ACD treatment.

[0309] Figure 26 Further examples are shown regarding Figure 25 The waveform 2612 of the treatment is shown. Indicator 2616 can display the current displacement value of the patient's chest. In some implementations, the waveform can be traced from left to right. Elapsed time is shown on the horizontal axis, and displacement is shown on the vertical axis. Indicator 2616 is reflected by the current displacement bar 2606 on displacement meter 2620, and indicator 2616 is located near the center of waveform frame 2616. To the right of indicator 2616, the target compression cycle displacement is plotted over elapsed time. Here, the current time is approximately 2:04.5. To the right of the indicator, the target displacement trace 2608 is plotted. The maximum target displacement value 2606a for both compression and decompression is shown as a dashed line above target 2608. The minimum target displacement value 2606b for both compression and decompression is shown as a dashed line below target 2608. By displaying the target displacement range as a waveform, the ACD device 1200 or other feedback device guides the rescuer regarding both compression and decompression displacement and velocity, with the goal of ensuring that the rescuer applies compression and decompression in a manner that remains within the maximum and minimum values ​​set within the target range. The total range of decompression displacement is shown as 2602a in both the depth bar 2620 and the waveform frame 2616. Similarly, the total range of compression displacement is shown as 2602b in both the depth bar 2620 and the waveform frame 2616.

[0310] Target range values ​​2606a, 2606b and 2604a, 2604b can be determined in response to estimating the patient's neutral position. For example, the ranges 2602a, 2602b used to determine the values ​​of displacements 2606a, 2606b and 2604a, 2604b can be updated on a per-compression-cycle basis, after a series of compression cycles (e.g., 2 to 5 compression cycles) following a specific time period. Updated values ​​for ranges 2602a, 2602b can be determined based on the current and / or previously estimated neutral position of the patient's chest and / or the compression ratio method described herein. For example, updated ranges 2602a, 2602b can be based on the current neutral position estimate, the cyclic window of the neutral position estimate, and / or the average of the time window, etc. When estimating the neutral position, target waveform 2608 is updated, and further, target waveform 2608 is projected onto the user's current position and time prior. Here, a single cycle is shown in the projection. However, in some implementations, multiple press cycles can be projected and rescaled as needed.

[0311] Feedback from trace 2612 and depth measurement 2620 can each (e.g., to rescuers, to the treatment device) provide guidance on how to modify ACD CPR treatment so that the downstroke displacement falls within the target downstroke displacement range 2602b before the upstroke displacement falls within the target upstroke displacement range 2602a. For example, as previously described, displacement measurement can instruct rescuers to: push harder, pull harder, press more gently, pull more gently, push deeper, pull further, and change the compression frequency, etc.

[0312] Go to Figure 27A Graphs 2710, 2720, 2730, and 2740 show training data for the values ​​of a, b, and c used to train equation (3). Graph 2710 shows the compression displacement over time as measured using a motion sensor (e.g., one of accelerometers 216a-216b, 404a-404b, etc.). The ACD is configured to estimate the total chest displacement d in units of each stroke. T (Shown as curve 2640 (still)) Figure 27B (shown more prominently in the image). The ACD is configured to estimate how much of the total sensor displacement is caused by pressing using a press-proportion model. In this example, the ACD device and / or associated processing device are configured to use the model by training a model from Equation (3) with different datasets. To train the model, the ACD device and / or associated processing device use known press depths and depressurization lifts.

[0313] Based on the fitting of data from curves 2710, 2720, and 2730, the constants a, b, and c (or additional constants for higher-order equations) in equations (1), (2), and (3) are determined. Once these constants are determined, equation (3) can be used to calculate the pressure ratio F for each pressure. C . Figure 27B The curve 2740 shows the total press distance d. T Example estimates of compression depth d obtained from calculations of 2742 are 2744, 2746, 2748, and 2750. The ACD device and / or associated processing unit use training data from different experiments (datasets 2744, 2746, 2748, and 2750) used for validation to estimate the compression depth d. C Since not all training data yields the same results, a database of training data is used to train the model. The training dataset can include different features. For example, dataset 2746 is computed using a training set that does not have rising CPR. The results, particularly at treatment start 2752, show a difference between dataset 2746 and datasets 2744, 2748, and 2750, presumably because the training set has a higher force associated with CPR compared to the test set.

[0314] Figure 28 Includes graph 2800, which shows the results based on... Figures 24A to 27B The calculated pressure depth using the pressure ratio method discussed is 2804, and it is compared with the results obtained using... Figures 13 to 23 The estimated compression depths 2806, 2808, and 2810 obtained by the neutral position estimation method discussed are compared. Data 2802 shows the estimated total chest displacement d. T The previously described neutral position estimation technique can be used to validate the results of the compression ratio model. Neutral position estimation results can be obtained through exhaustive trials on animals or humans (or other surrogate subjects on the patient's chest). However, because the compression ratio method uses patient-specific training data, the results of the neutral position estimation method provide validation to ensure the accuracy of the compression estimation results.

[0315] In graph 2800, dataset 2804 represents the value of the compression depth determined using the compression ratio method. Dataset 2804 represents the value of the compression depth determined using... Figures 16A to 16B The compression depth determined by the zero-force neutral position estimation method. Dataset 2806 represents the compression depth determined using... Figures 17A to 17B The pressing depth is determined by the minimum force neutral position estimation method. Dataset 2808 represents the pressing depth determined using... Figures 18A to 18B The pressing depth is determined by the neutral position estimation method based on the equal force rate.

[0316] To validate the press-proportioning method, a deterministic sequential approach utilizing neutral point estimation was employed. First, the accuracy of the neutral point estimation method was determined using a small sample dataset with baseline data. Then, a large database without baseline data was collected, and pseudo-baseline data for training this larger set was obtained using the neutral point method. Finally, the press-proportioning method was trained using this large database with pseudo-baseline data.

[0317] Figure 29 An example of training the press-proportion method in this manner is shown. In graph 2900, the press-proportion method is trained using various neutral point estimation methods. Dataset 2904 represents the values ​​of press depth determined using the press-proportion method trained with press displacements predetermined according to the aforementioned research protocol. Dataset 2906 represents the values ​​of press depth determined using... Figures 16A to 16B The compression depth is determined by the compression ratio method trained using the zero-force neutral position estimation method. Dataset 2908 represents the compression depth determined by using... Figures 17A to 17B The compression depth is determined by the compression ratio method trained using the minimum force neutral position estimation method. Dataset 2910 represents the compression depth determined by using... Figures 18A to 18B The compression depth is determined by the compression ratio method trained by the equal force rate neutral position estimation method.

[0318] Even when the patient's neutral chest position is not determined, or when the patient's neutral position changes over time, the compression depth d can be updated. C and decompression lift d L Furthermore, the neutral position of the patient's chest can be determined based on an estimate of the decompression lift and compression depth, rather than based on an estimate of the neutral position as previously described.

[0319] The compression ratio method can use the same motion sensor used by a neutral point estimation method that can train the compression ratio method. The compression ratio method can reduce or eliminate estimation errors introduced by mechanical aspects of the ACD device (such as elastic plungers). Since the force measurements used in Equation (3) are peak forces, the forces are static measurements unaffected by the elastodynamics of the plungers (or other mechanical coupling systems of the ACD device). In addition, the data time synchronization between force measurements and acceleration has a tolerance. The ACD device and / or associated processing unit associate the individual force measurements with the compression cycles that measure these force measurements. Synchronous measurement of motion and force is not required; instead, force can be measured independently of measuring the patient's motion. As a result, the presentation of feedback on the user interface, communication of data to another device, and calculation of compression depth estimates are all simpler than when synchronized data is required. The various mechanical configurations of the ACD device can be associated with training data, making it possible to obtain highly accurate values ​​of a, b, and c.

[0320] In some implementations, an additional model can be expressed by formulating the available information during the measurement, including total chest displacement and peak forces during lifting and compression. The model presented above uses equation (3), but due to the total chest displacement d T It is the pressing depth d C and decompression lift d L The sum of these terms means that the pressure ratio model can be described by different terms such as the following:

[0321]

[0322] In addition, equation (2) and Figure 24A value Figure 24B The method for determining the peak pressure (f) has been shown. C Methods for calculating compression depth. Without needing to calculate the compression ratio (F) C In the case of measuring pressure reduction, the compression depth can be directly estimated using the model based on Equation 2.

[0323] Figure 30 Includes graph 3000, which shows a comparison of these alternative methods according to equations (3) and (5). A compression ratio model according to equation (3) is shown using dataset 3004, a model according to equation (5) is shown using dataset 3006, and a model according to equation (2) is shown using dataset 3008, where dataset 3002 represents the total chest displacement d as measured by a motion sensor. T .

[0324] The ACD device and / or associated devices that can be used to develop the model (e.g., feedback devices, defibrillators / monitors, AEDs, patient monitors, tablets, computing devices, cloud-based computing systems, etc.) use available training data to train the compression ratio method on Equations (3) and (5). In some implementations, a separate processing device(s) is used to train the model(s), and the model(s) are loaded onto the ACD device and / or other devices to provide feedback to the user. Training Equations (3) and (5) may involve: as previously described for Figures 24A to 24BThe values ​​of constants a, b, c, ..., n are set by fitting an equation or function to data collected from previous measurements. More specifically, in such embodiments, different force values ​​are measured for different known compression depths or decompression lift values. Compression and / or decompression are performed on one or more model chests with body characteristics similar to the patient's chest. The selected chest(s) can be based on different patient demographics. For example, different models can be selected for pediatric patients, as well as various combinations of female or male patients, etc. For each model chest, a given number of compression cycles are performed and the corresponding force is measured. When fitting the scale to the data, the order of the scale can be selected to find the best fit while avoiding over-modeling the chest by selecting an excessively high order. The resulting values ​​of constants a to n or other combinations of coefficients are determined.

[0325] When treating a patient, an appropriate model can be selected based on the patient's demographics. For example, a pediatric model can be selected for pediatric patients. In some implementations, it can be assumed that the patient's chest stiffness is similar across different patients, which is accomplished using only Equation (2) as the method. To accommodate this assumption, the ACD device can include multiple settings for stiffness-based target forces (and the resulting compression depth and decompression lift), allowing for adherence to a similar model in which the user specifies the stiffness level to utilize the correct training data. The ratio of lift to compression stiffness is typically static, so the methods using Equations (3) and (5) can be operated independently of this setting.

[0326] The results of the described methods can be combined to produce a final estimate. For example, a linear combination of any of these methods can be set as a weighted average, where the weights can be fine-tuned to take into account accuracy performance as seen from a large database. For example, the first value can be determined using equation (2), the second value using equation (3), and the third value using equation (5). If, for example, data 3008 performs to provide a less accurate model compared to data 3004 or 3006, the model from data 3008 can be weighted with smaller weights compared to other models used to approximate compression depth and / or decompression lift. In some implementations, the weights of the individual models can be adjusted based on the amount of training data collected for each model. For example, if little training data is collected for a particular patient demographic, the model that relies on that training data is associated with a smaller weight compared to other models, or with a smaller weight compared to the weight received for that model if more training data were available.

[0327] Figure 31 This illustrates the use of peak force values ​​to estimate the compression depth (d) in active compression decompression therapy. CExample processing 3100. ACD device (e.g., Figure 1 , 12 An ACD device 100 or 1200 (e.g., etc.) and / or associated processing device can be used to estimate compression depth and decompression lift using processing 3100. The ACD device is configured to allow a user to push down and pull up on the patient's chest. A force sensor is configured to measure the force applied by the user to the patient's chest using the ACD device. A motion sensor is configured to measure the displacement of the patient's chest. One or more processors are configured to execute computer-executable instructions stored in memory to estimate the compression depth (d) of active compression decompression therapy using peak force values ​​such as peak force values ​​associated with compression and decompression. C The ACD device and / or associated processing device determine (3102) the maximum compression force applied to the patient's chest during a compression cycle and the maximum decompression force applied to the patient's chest during a compression cycle, based on at least one signal from a force sensor. The ACD device and / or associated processing device estimate (3104) the total displacement of the patient's chest during a compression cycle for compression and decompression, based on at least one signal from a motion sensor. The ACD device and / or associated processing device estimate at least one of the compression depth and decompression displacement of the compression cycle, based on the determined compression force, the determined decompression force, and the estimated displacement. The user interface of the ACD device and / or associated processing / feedback device provides (3108) indications of one or more of the compression depth and neutral position of the patient's chest.

[0328] As discussed in this paper, various types of feedback can be provided to the user of a feedback device to guide the user in performing active compression decompression therapy on a patient. Visual feedback presented on the display of the user interface (e.g., on a defibrillator, patient monitor, portable computing device, etc.) may be particularly useful to the user.

[0329] In some embodiments further described below, visual feedback can provide an indication of the current displacement of the chest in the lower and upper strokes during ACD treatment, and can also provide an indication of past displacement of the chest in the lower and upper strokes during ACD treatment. For example, a series of sequential ACD bar graphs showing past compression depths and decompression lifts can be provided to the user to assess how ACD treatment has been recently delivered to the patient. By making such an assessment of past performance or actions, the user can better determine how ACD treatment should be adjusted.

[0330] In various embodiments, if the compression depth on the lower travel or the decompression lift on the upper travel is consistently displayed outside its respective target range on the ACD device or another device used to process ACD-related information (e.g., a patient monitor, defibrillator, portable computing device, other computing device), the user may be more motivated to modify the manner in which they deliver compressions or decompressions. For example, if the compression depth on the lower travel is consistently too shallow compared to the target presented by past lower travel displacement bars, the user may be more motivated to press harder. Or, if the decompression lift on the upper travel is consistently too large compared to the target presented by past upper travel displacement bars, the user may be more motivated to release the decompression lift to meet the preferred target range.

[0331] In some embodiments, which are further described below, visual feedback may take the form of a graph of current forces and displacements that the user can use to guide him / her in providing ACD treatment to the patient. In some cases, visual feedback may further provide the user with boundaries or other guidance to apply a specific combination of forces and displacements for each given moment. For example, feedback may be given to the user to provide ACD treatment in a manner that substantially produces or follows a specific desired force-displacement curve or waveform.

[0332] As described above, an ACD device (e.g., ACD device 100, 1200, etc.) or other suitable devices associated with resuscitation efforts (e.g., patient monitors, defibrillators, portable computing devices, other computing devices) can provide feedback, such as through a user interface 700, which can be provided on the ACD device and / or other devices described herein. This feedback may include information related to ACD treatment (such as CPR chest compressions and decompressions), which can assist rescuers in performing CPR more effectively. The ACD device or other suitable devices associated with ACD treatment can use data received from sensors to provide such feedback. For example, sensors of ACD device 100 (such as force sensor 216a, multiple accelerometers 216b, 216c (or a single accelerometer), and / or force sensor 402 and motion sensors such as accelerometers 404a, 404b (or a single accelerometer), etc.) can provide force and depth estimates that are used to provide compression and decompression feedback to rescuers when effective ACD treatment is applied to the patient. In another example, the position sensor 1206, accelerometer 1204, and force sensor 1208 of the ACD device 1200 can provide feedback on one or more of depth, rate, and force estimates for compression and / or decompression in CPR therapy.

[0333] Such as about Figure 8The feedback 718 described herein may include information to assist rescuers in providing optimal CPR treatment. For example, the user interface 700 may instruct rescuers to push harder during CPR compressions to deliver the desired amount of chest compressions to the patient. In some implementations, the feedback provided may include feedback related to decompression and compression. The user interface 700 may generate instructions and / or information to rescuers (or any other user of the ACD device 1200) that the amount of decompression can or should be adjusted. For example, the user interface may instruct rescuers to pull upwards more to further decompress the patient's chest and improve ACD CPR treatment. As discussed herein, in cases of significant chest remodeling in which the chest's natural resting or neutral position has been effectively moved downwards in response to repeated chest compressions, it may be beneficial to instruct rescuers to provide more decompression treatment to the chest.

[0334] Feedback provided by the ACD device 1200 and / or other suitable feedback devices may depend on a neutral position estimated by the ACD device or another device used to process ACD-related information (e.g., a patient monitor, defibrillator, portable computing device, other computing device). In some implementations, in response to estimating the neutral position (e.g., as per...), Figures 12 to 23 The ACD device 1200 or other suitable device may update the feedback presented on the user interface 700. That is, the estimate of the neutral position may be input to the feedback provided to the user via the user interface and / or other feedback devices. For example, in response to an estimate that the neutral position has moved approximately 1.0 inch below zero (e.g., the natural resting position of the chest has significantly moved below the initial position of the chest before compression), the ACD device 1200 and / or other devices used to provide feedback may instruct the rescuer to pull the patient's chest higher. If necessary, this instruction may assist the rescuer in adjusting his / her treatment to raise the neutral position back to zero. In another example, in response to determining that the neutral position has moved approximately 1.0 inch below zero, the ACD device 1200 and / or other devices used to provide feedback may update the feedback to provide the user with a higher lift target for external chest decompression of the patient (e.g., approximately 1.0 inch higher than a previously provided target, or approximately 1.0 to 2.0 inches above the initial zero). If rescuers continue to press on the patient's chest at the same level, the ACD device 1200 and / or other devices for providing feedback can provide instructions to the rescuers (e.g., audio prompts, voice, visual cues, and / or text) to lift the patient's chest higher.

[0335] like Figure 32As shown, visual representations used to assist users in providing high-quality CPR chest compressions may include indicators of CPR compression-decompression parameters, such as a CPR chest compression depth / height meter 3220 and a CPR chest compression information box 3224. The CPR chest compression depth / height meter 3220 can be automatically displayed on an appropriate device used to provide feedback during the detection of CPR chest compressions and decompressions.

[0336] On the CPR chest compression depth / height meter 3220, general instructions 3237 can be displayed to visually instruct rescuers in real-time guidance to perform actions via ACD CPR chest compression therapy at specific times. That is, based on sensor information from the ACD device, the system can provide feedback to rescuers and / or other devices used to administer ACD therapy in a desired manner to provide the most beneficial patient outcome possible. As shown, the CPR chest compression depth / height meter 3220 may include a display divided into sections indicating certain stages of ACD CPR chest compression therapy to assist rescuers in providing optimal therapy. For example, the system can assist the user in reaching the target release 3236 or target depth 3240 by highlighting specific instructions for each stage. For example, the display can highlight prompts such as lifting more 3235 or too shallow 3233 corresponding to the target release 3236. In some implementations, the display can provide qualitative cues including ACD CPR feedback, such as “good” 2431 or “too deep” 3232 when guiding rescuers to the target depth 2440.

[0337] CPR chest compression depth / height measurement 3220 can be configured to display an indicator of transition point 3234 (e.g., an estimate of a neutral position) to indicate transitions between different stages of ACD CPR chest compression therapy, or an estimate of where such a transition might occur. In some implementations, this can be as described regarding Figures 12 to 23The neutral position is determined or otherwise estimated. However, it should be understood that other methods can be used to estimate the neutral position. In some implementations, the transition point 3234 may appear static on the user interface, but the actual value or estimated location or position associated with the transition point 3234 can be updated when sensor measurement data is used with the ACD device 1200. Therefore, the feedback 3231, 3232 can be updated based on the determination of the depth, frequency, force, etc. of the compression and / or decompression in CPR treatment and the updated value of the transition point 3234. In some implementations, the position of the transition point 3234 on the user interface can be moved according to the determined or otherwise estimated neutral position. For example, if the estimated neutral position is 1 inch below zero (an approximate location where compression is considered to have begun), the user interface may show the transition point 3234 below the zero level. In some implementations, if it is desired to return the value of the transition point 3234 to zero, the feedback may instruct the user to pull harder, pull less, push harder, push less, etc., to achieve this goal. The user interface can be adjusted to help rescuers do this by making it easier to populate the PPI graphical indicator 3230.

[0338] although Figure 32 The example shown displays target release 3236 and target depth 3240 as written instructions, but in some additional examples, the target values ​​can be displayed as colors or barcodes corresponding to a range of preferred depths and heights. For example, multiple bars can be included on the depth meter 3220 to provide an acceptable range of compression depths (e.g., as shown in the image). Figure 33 The acceptable range is shown as upper and lower bounds, and the acceptable range of decompression height or lift is shown. Additionally, in some implementations, presses and decompressions with amplitudes outside the acceptable range can be highlighted with a different color than presses and decompressions with depths within the acceptable range of press depth.

[0339] When compressions and / or decompressions are detected (e.g., via a defibrillator, patient monitor, and / or other feedback device), a CPR chest compression information box 3224 can be automatically displayed. Information related to chest compressions and decompressions displayed in box 3224 includes rate 3228 (e.g., the number of compressions and decompressions per minute) and displacement 3226 (e.g., in inches or millimeters, representing the depth of compressions on the downstroke as negative and the lifting distance of decompressions on the upstroke as positive; or vice versa, representing the depth of compressions on the downstroke as positive and the lifting distance of decompressions on the upstroke as negative). The rate and depth of compressions and decompressions can be determined by analyzing accelerometer readings. (In addition to, or replacing, indications that the actual rate and displacement data are within or outside acceptable ranges) Displaying these values ​​can also provide useful feedback to rescuers. For example, if the acceptable range for chest compression depth is 25 to 60 mm, instructing rescuers to perform only 15 mm of compression and decompression can enable them to determine how to properly modify their chest compression and decompression (e.g., they can learn how much more force is needed to reach the optimal compression and decompression threshold).

[0340] The information related to chest compressions and chest tightening shown in box 3224 also includes a perfusion performance index (PPI) 3230. The PPI 3230 is a shape (e.g., diamond or other shape) with a filling volume that varies in shape over time to provide feedback related to both the rate and depth of compressions and / or decompressions. The entire index is filled when CPR chest compressions are being performed adequately within desired parameters (e.g., at a rate suitable for active compression-decompression (such as approximately 80 compressions and decompressions per minute (CPM), etc.), where the depth of each compression falls within the desired range for active compression-decompression). The filling volume decreases when the rate and / or depth fall below or above the aforementioned acceptable limits. The PPI 3230 provides a visual indication of the quality of CPR chest compressions, allowing rescuers to aim to keep the PPI 3230 fully filled.

[0341] In some additional embodiments, physiological information (e.g., physiological information such as that of the patient (and in some cases, the rescuer), such as end-tidal CO2 information, arterial pressure information, volumetric CO2, pulse oxygen saturation (possibly with waveform amplitude), and carotid blood flow (measured via Doppler) to provide feedback relating to the effectiveness of CPR chest compressions delivered at a specific target depth can be used. Based on the physiological information, the system can automatically determine the target CPR compression depth (e.g., calculate or find a new target CPR compression depth) or other CPR parameters (e.g., lift, rate, force), and provide feedback to the rescuer, for example, to increase or decrease the depth / rate of CPR compressions and decompressions. This feedback may include a desired sequence of positions to guide the rescuer in adjusting his / her body position and / or body movements to achieve a desired combination of CPR compressions and decompressions (e.g., depth, lift, rate, force, speed), rescuer fatigue, and / or physiological benefits. Therefore, the system can provide feedback on how rescuers consistently apply CPR compressions and decompressions with target parameters (e.g., depth, rate, lift, force, speed), and feedback on whether the target depth / rate / lift / force can be adjusted based on measured physiological parameters, along with how rescuers can enhance their body positioning while applying CPR chest compressions. If the rescuer does not respond to this feedback and continues with suboptimal CPR, the system can then display an additional message to replace the person performing CPR chest compressions and decompressions.

[0342] In some implementations, the system periodically monitors and adjusts target CPR parameters (e.g., depth, lift, rate, force, velocity). To determine the desired target parameters, the system makes slight adjustments to the target CPR parameters and observes how the changes in the parameters affect the observed physiological parameters before determining whether further adjustments should be made. For example, the system can determine an adjustment to the target compression depth as a fraction of an inch or centimeter and prompt the rescuer to increase or decrease the compression depth by the determined amount. For example, the system can adjust the target compression depth from 2.5 to 10 mm (e.g., 2.5 mm to 5 mm or approximately 5 mm) and provide the rescuer with feedback on the observed compression depth based on the adjusted target compression depth. Then, over a set time period, the system can observe the physiological parameters and, at the end of the set time period, determine whether further adjustments to the target compression depth are necessary based on the trends in the physiological parameters, without making further adjustments to the target compression depth.

[0343] It can monitor the actual performance of rescuers towards the revised target to determine when their performance falls below an acceptable level, thereby notifying rescuers and potentially other personnel to change the person performing chest compressions and decompressions. The relevant parameters of the patient's condition discussed in the various screenshots above can be one of the inputs to a process used to determine when it is appropriate (e.g., due to obvious fatigue shown by the first rescuer) to replace a rescuer performing a component of the rescue technique.

[0344] For example, the ACD device 1200 can provide instructions to rescuers to exchange with another person while providing ACD CPR. In some implementations, such as regarding Figures 26 to 33 The instruction is based on whether the lower stroke displacement falls within the target lower stroke displacement range or whether the upper stroke displacement falls within the target upper stroke displacement range to instruct rescuers to exchange positions.

[0345] Figures 34 to 36 Example screenshots show the range of pressure and decompression provided by an ACD device such as ACD device 1200 or 100, or other suitable device for providing CPR feedback, during ACD CPR therapy, along with sample screenshots. Go to... Figure 34 Example screenshot 3400 of the user interface used to provide CPR feedback shows the press waveform 3412 and depth measurement 3402.

[0346] The depth meter 3402 provides feedback for both upper-stroke displacement (e.g., lifting during chest decompression) and lower-stroke displacement (e.g., depth during chest compression). The depth meter 3402 can provide a maximum decompression range (e.g., range 2622). The depth meter 3402 can visualize the target compression and decompression displacements (e.g., lower stroke depth and upper stroke lifting, respectively). In this document, target values ​​for compression (e.g., lower stroke depth) or decompression (e.g., upper stroke lifting) include the expected value (e.g., amplitude) of the decompression or compression displacement of the patient's chest at the next compression or decompression in the current compression cycle of CPR treatment.

[0347] In some implementations, an estimated neutral position relative to the patient can be shown (such as regarding...). Figures 12 to 23The displacement of the neutral position (e.g., the neutral position). The neutral position can be represented by line 3404 in the depth / displacement meter. In some implementations, the target pressing and depressing displacements can be based on a zero point. In some implementations, the estimate of the neutral position 3404 can be fixed near the center of the displacement meter 3402, even when the estimate of the neutral position changes. In instances where a simplified user interface is preferred, fixing the estimate of the neutral position 3404 may be beneficial, as an estimate of the neutral position that moves along the meter 3402 could otherwise be confusing or otherwise challenging for the user to interpret intuitively. In some implementations, the position of the neutral position bar 3404 moves as the estimate of the neutral position is updated, and the center of the depth meter 3402 represents the zero point, or an estimate of the zero point. The difference between the estimated zero point and the estimated neutral position can be shown based on the placement of the neutral position bar 3404. Figure 34 In the middle, the estimated neutral position is shown at the center of depth measurement 3402.

[0348] Target decompression 3422 and target compression 3424 can each be determined (e.g., independently) based on an estimate of the neutral position. In some embodiments, the size of the meter 3402 can generally remain static, and different compression and decompression targets can be indicated by varying the scaling factor of the depth meter 3402. In some implementations, the scaling factor is fixed at the start of CPR treatment, and the range bar (e.g., Figure 35 The bars 3504 and 3506 shown are moved to indicate the target decompression and compression displacement, respectively. For example, position 3422 on displacement meter 3402 can indicate a 2-inch lift / decompression for the treatment of a first patient and a 1-inch lift / decompression for the treatment of a second patient. However, during the treatment of the first patient, even if the target decompression displacement changes, position 3422 can remain visually identical to indicating 2 inches. Although in some implementations, depth meter 3402 can be rescaled during treatment such that position 3422 represents the actual target decompression displacement and position 3424 represents the actual target compression displacement.

[0349] Displacement meter 3402 is configured to show the current displacement 3406 of the patient's chest during a CPR (compression and decompression) cycle. As compressions and decompressions are performed, the bar 3406 moves up and down within the displacement meter 3402. In some implementations, the displacement meter 3402 shows the previous compression depth (e.g., lower stroke displacement) and the previous decompression depth (e.g., upper stroke displacement). For example, a shaded area 3408 shows the decompression displacement of a previous compression cycle. The reached displacement is indicated by the decompression bar 3418. The bar 3418 and the previous decompression displacement bar 3420 can be compared to a target 3422 to determine if the correct compression or decompression displacement is being reached. The previous displacement bars 3418, 3420 can be used to adjust the compression and / or decompression of the current compression cycle.

[0350] Displacement meter 3402 is configured to show visual indications of the lower stroke displacement 3410, upper stroke displacement 3408, and estimated neutral position 3428 relative to each other. In some implementations, the difference 3430 between the estimated neutral position and zero point 3414 may be shown on either or both of the waveform frame 3432 and the compression meter 3402 (described below). In some implementations, the ACD device 1200 is configured to determine past estimates, past lower stroke displacements, and past upper stroke displacements (e.g., over time or over compression cycles) of the neutral position of the chest. In some implementations, the display provides visual indications of the current lower stroke displacement, current upper stroke displacement, past lower stroke displacement, and past upper stroke displacement together on the displacement meter 3402.

[0351] In some implementations, the visual indication of displacement measurement 3402 includes color or highlighting changes of at least a portion of the display based on whether the lower stroke displacement falls within the target lower stroke displacement range, or whether the upper stroke displacement falls within the target upper stroke displacement range. For example, when the appropriate target is achieved, the shaded areas 3408, 3410 may be different colors, flashes, etc. In some implementations, the visual indication includes color or highlighting changes of at least a portion of the display based on whether the lower stroke displacement falls outside the target lower stroke displacement range, or whether the upper stroke displacement falls outside the target upper stroke displacement range.

[0352] The actual target ranges 3502a and 3502b can vary. For example, the target lower stroke displacement range and / or target upper stroke displacement range can be between 0.5 and 3.0 inches, between 0.5 and 1.5 inches, between 1.5 and 2.5 inches, and between 2.0 and 2.4 inches, etc.

[0353] In some implementations, there is no visual indication on the user interface display showing how at least one of the updated estimate of the neutral position, the updated target lower travel displacement range, and the updated upper travel target displacement range has been updated. That is, for the benefit of a simplified user interface, the visible size, target, and / or other aspects of the displacement meter 3402 can remain substantially visually the same (e.g., although the target changes based on the updated estimate of the neutral position).

[0354] Figure 34 The displacement waveform 3412 in waveform frame 3432 is also shown, illustrating the compression and decompression displacements over time (measured on the horizontal axis). Axis 3414 typically represents the estimated zero point of zero displacement. Waveform 3412 can show the displacement and frequency of previous compression cycles to assist the user in adjusting the compression and decompression displacements and frequencies as needed. A trace showing the elapsed time and displacement value can be generated during treatment. Similar to depth measurement 3402, scaling can be kept fixed during the patient's treatment or dynamically adjusted as needed (e.g., if waveform 3412 exceeds the current maximum or minimum value). In some implementations, the waveform of the entire treatment can be displayed and saved in a patient-related log file, for example, by an administrator and / or physician, for later review of the case. In some implementations, a portion of the waveform (e.g., the most recent 20 seconds, 10 seconds, 5 seconds, etc.) can be shown. In response to events such as treatment pauses, compressions or decompressions exceeding appropriate thresholds, or sudden changes in chest compliance or neutral position estimates, a portion of the waveform can be saved to a log file.

[0355] Waveform 3412 includes an index 3416 that shows (e.g., measured by the position sensor of the ACD device 1200, or estimated from acceleration and displacement sensors, as previously described) the current displacement of the patient's chest. In some implementations, a displacement bar 3406 tracks index 3416 in real time. Over time (e.g., from right to left), a trace of waveform 3412 is plotted, and the index represents the actual current displacement of the patient's chest during treatment. In some implementations, to compensate for processing delays (e.g., neutral position and / or other position estimates), index 3416 may represent a prediction of the patient's chest displacement in the near future (e.g., 5 ms, 10 ms, etc.), such that the position behaves in sync with the compressions performed by the rescuer.

[0356] Go to Figure 35 , showing Figure 34Screenshot 3500 shows an example user interface of a more complex implementation of the ACD device 1200 or other suitable feedback device. The depth measurement 3402 includes ranges 3502a and 3502b for decompression and pressing, respectively. Range 3502a can be referred to in several ways: such as target decompression range, target upper stroke range, target upper stroke displacement range, and target lift displacement range. Range 3502b can be referred to in several ways: such as target pressing range, target lower stroke range, target lower stroke displacement range, and target pressing depth range.

[0357] Ranges 3502a and 3502b can be adjusted in response to updated estimates of neutral position 3404(1) or more. In some implementations, ranges 3502a and 3502b may begin as larger ranges but narrow over time as the neutral position estimate improves. For decompression range 3502a, maximum target decompression 3504a and minimum target decompression 3504b are shown. The ACD device 1200 may present positive feedback when the patient's chest is decompressed to a displacement between values ​​3504a and 3504b. Since the previous decompression (shown by shaded area 3408) indicates the previous decompression displacement within the target range 3502a, a text box 3510 including "good" feedback is shown in screenshot 3500. Therefore, shaded area 3408 may have a color (e.g., green) for indicating decompression (e.g., single decompression, average decompression over multiple cycles, etc.) within the target range. However, alternative feedback may also be used. For example, sounds can indicate when the appropriate stress level has been reached, such as positive-sounding cue tones and sounds that say "good" or similar, etc.

[0358] Similarly, displacement measurement 3402 shows a decompression range 3502b including a maximum target decompression 3506b and a minimum target decompression 3506a. The ACD device 1200 can present positive feedback when the patient's chest is compressed to a displacement between values ​​3506a and 3506b. Since the previous decompression (shown by shaded area 3410) indicates a previous compression displacement outside the target range 3502a, a text box 3512 including feedback 3512 of "press harder" is shown in screenshot 3500. Here, shaded area 3410 indicates that the compression 3520 did not reach far enough and the next compression should have a greater downward displacement to fall within the target lower travel displacement range. Therefore, shaded area 3410 can have a color (e.g., red, yellow) indicating that the compression is outside the target range and the next compression should be adjusted accordingly. However, alternative feedback can be used. For example, sounds can indicate when an inappropriate compression has been reached, such as a beep, and a voice saying "press harder" or similar, etc.

[0359] Typically, when within the target range, the corresponding shaded areas 3408, 3410 may have a color (e.g., green) indicating that one or more presses or depressors are within the target range and should maintain the manner in which one or more presses or depressors are indicated. When outside the target range, the corresponding shaded areas 3408, 3410 may have a color (e.g., red, yellow) indicating that one or more presses or depressors are outside the target range and need to be adjusted to fall within the target range in subsequent cycles.

[0360] like Figure 35 As shown, the latest press displacement value 3520 is indicated by shaded area 3410, and the latest depressurization value 3522 is indicated by shaded area 3408. At the start of the next cycle, areas 3408 and 3410 are updated. In some implementations, these areas are presented as "ghosting" on the bar and appear gradually weakened or diminished compared to the current displacement measurement to indicate to the user that these areas represent past downstroke and upstroke measurements. As the current displacement bar 3406 moves up and down in the displacement meter 3402, shaded areas 3408 and 3410 are redrawn, and if the old areas are too old, they gradually disappear from the user interface or otherwise. The current displacement may also be referred to as the current upstroke displacement, the current downstroke displacement, the updated upstroke displacement, and the updated downstroke displacement, etc.

[0361] Ranges 3502a and 3502b can be updated by the ACD device 1200 in response to various detected conditions. For example, the ACD device can adjust at least one of the target lower stroke displacement range 3502b and the target upper stroke displacement range 3502a based on an updated estimate of the neutral position. The ACD device 1200 or other associated feedback devices can adjust the target lower stroke displacement range 3502b from an initial target lower stroke displacement range to an updated target lower stroke displacement range based on whether the lower stroke displacement 3410 falls within the target lower stroke displacement range and / or based on an updated estimate of the neutral position. Similarly, the ACD device 1200 can adjust the target upper stroke displacement range 3502a from an initial target upper stroke displacement range to an updated target upper stroke displacement range based on whether the upper stroke displacement 3408 falls within the target upper stroke displacement range and / or based on an updated estimate of the neutral position.

[0362] In some implementations, the updated target lower stroke displacement range 3502b is obtained by adjusting from the initial target lower stroke displacement range after a predetermined interval (e.g., the number of compression cycles, elapsed time, etc.). Similarly, in some implementations, the updated target upper stroke displacement range 3502a is obtained by adjusting from the initial target upper stroke displacement range after a predetermined interval (e.g., the number of compression cycles, elapsed time, etc.). Such updates to the target lower stroke displacement range and / or the target upper stroke displacement range may or may not be based on an updated estimate of the neutral position of the chest. For upper or lower stroke displacements, (e.g., in response to estimating the neutral position of the patient's chest), the target ranges 3502a, 3502b can be offset to represent a range with a larger amplitude, a range with a smaller amplitude, the compression range itself, or the extended range itself.

[0363] In some implementations, at least one of the target lower stroke displacement range 3502b and the target upper stroke displacement range 3502a may be based on clinically accepted guidelines. However, the target lower stroke displacement range 3502b may be greater than or less than the clinically accepted guidelines, and the target upper stroke displacement range 3502a may be greater than or less than the clinically accepted guidelines.

[0364] In some implementations, the ACD device 1200 or other associated feedback devices are configured to determine how to reshape the patient's chest based on an estimated neutral position. Feedback signals received from sensors can enable the display to provide indications of chest reshaping. For example, the feedback device can simply provide an indication that substantial chest reshaping has occurred due to CPR treatment, making the user aware of the change in chest mechanics. This information can be a cue for the user to change the way CPR is delivered, for example, reducing the force applied to the patient to reduce the risk of injury, or providing more or less decompression treatment. As discussed above, when the neutral position of the chest has been significantly concave due to chest reshaping, it may be desirable to reduce the depth of compression on the lower stroke and / or increase the decompression lift on the upper stroke. In some cases, the feedback device can provide the user with further indications to adjust target lower stroke displacement and / or target upper stroke displacement, or to adjust various aspects of ACD treatment.

[0365] Figure 35 Further show about Figure 34The waveform 3412 of the treatment is shown. Indicator 3416 can display the current displacement value of the patient's chest. In some implementations, the waveform can be traced from left to right. Elapsed time is shown on the horizontal axis, and displacement is shown on the vertical axis. Indicator 3416 is reflected by the current displacement bar 3406 on displacement meter 3402, and indicator 3416 is located near the center of waveform frame 3516. To the right of indicator 3416, the target compression cycle displacement is plotted over elapsed time. Here, the current time is approximately 2:04.5. To the right of the indicator, the target displacement trace 3508 is plotted. The maximum target displacement value 3506a for both compression and decompression is shown as a dashed line above target 3508. The minimum target displacement value 3506b for both compression and decompression is shown as a dashed line below target 3508. By displaying the target displacement range as a waveform, the ACD device 1200 or other feedback device guides the rescuer regarding both compression and decompression displacement and velocity, with the goal of ensuring that the rescuer applies compression and decompression in a manner that remains within the maximum and minimum values ​​set within the target range. The total range of decompression displacement is shown as 3502a in both the depth bar 3402 and the waveform frame 3516. Similarly, the total range of compression displacement is shown as 3502b in both the depth bar 3402 and the waveform frame 3516.

[0366] Similar to Figure 34 The target displacement can be determined in response to estimating the patient's neutral position, specifying target range values ​​3506a, 3506b and 3504a, 3504b. For example, the ranges 3502a, 3502b determining the values ​​of displacements 3506a, 3506b and 3504a, 3504b can be updated on a per-compression-cycle basis, after a series of compression cycles (e.g., 2 to 5 compression cycles) following a specific time period. Updated values ​​for ranges 3502a, 3502b can be determined based on the current and / or previous estimated neutral position of the patient's chest. For example, updating ranges 3502a, 3502b can be based on the current neutral position estimate, the cyclic window of the neutral position estimate, and / or the average of the time window, etc. When estimating the neutral position, the target waveform 3508 is updated, and the target waveform 3508 is further projected onto the user's current position and time preceding it. Here, a single cycle is shown in the projection. However, in some implementations, multiple press cycles can be projected and rescaled as needed.

[0367] Feedback from trace 3412 and depth measurement 3402 can each (e.g., to rescuers, to the treatment device) provide guidance on how to modify ACD CPR treatment so that the lower stroke displacement falls within the target lower stroke displacement range 3502b before the upper stroke displacement falls within the target upper stroke displacement range 3502a. For example, as previously described, the displacement measurement can instruct rescuers to: push harder, pull harder, press more gently, pull more gently, and change the compression frequency, etc.

[0368] Go to Figure 36 Example screenshot 2800 of the user interface of ACD device 1200 or other suitable feedback device is shown. Figure 35 The screenshot 3500 shows different implementations. Here, shaded areas 3408 and 3410 represent different previous compression and decompression displacement values ​​reached during previous compression cycles. The previous decompression value 3606 is too small, and the feedback 3602 is adjusted to instruct the rescuer to "pull harder". Although the instruction can be updated for each compression cycle, it can be updated using a moving average of two or more cycles. For example, the instruction can only be updated to read "pull harder" if the decompression target has not been reached for three consecutive cycles based on a moving average of the previous three cycles (e.g., or two, four, five, etc. cycles) or some other specific combination of such cycles.

[0369] Similarly, such as Figure 36 As shown, the previous compression value 3608 was too high, and the feedback 3604 was adjusted to instruct the rescuer that "you are pressing too hard." While instructions can be updated for each compression cycle, they can be updated using a moving average of two or more cycles. For example, the instruction can only be updated to read "you are pressing too hard" if three consecutive cycles exceed the compression target based on a moving average of the previous three cycles (e.g., or two, four, five, etc. cycles) or some other specific combination thereof.

[0370] Figures 37 to 38 This is a sample screenshot showing compression frequency feedback provided by an ACD feedback device during ACD CPR therapy. Go to Figure 37 , such as regarding Figures 34 to 36 The screenshot 3700 of the user interface of the ACD feedback device shows waveform 3412, projected displacement waveform 3508, indicator 3416, and pressure bar 3402. In addition to displacement feedback, the ACD feedback device can be configured to provide pressure cycle frequency feedback (also known as pacing feedback).

[0371] The measurement trace 3412 and the estimated trace 3508 are shown on either side of the current displacement value 3416 (e.g., previous and future). The depth meter 3402 indicates that both the previous press and depressurization displacement values ​​are within the target ranges 3502b and 3502a, respectively, and reports "good" feedback in boxes 3702 and 3704. This can also be seen from the shaded areas 3408 and 3410 extending within the ranges 3502a and 3502b shown on the depth meter 3402.

[0372] However, the frequency of the compression cycle in this example is too fast. The completed compressions are shown on the waveform by section 3706, with a shorter time period than the projected waveform 3508 shown by section 3710. A feedback box 3708 appears (or may remain on the interface) to instruct the rescuer to "slow down." Alternatively, this instruction may be accompanied by a beep, beat, audio indication, etc. Instruction 2708 may also be read as "good rhythm," "too fast," "too slow," "accelerate," or other such variations of the frequency feedback.

[0373] In some implementations, indicator 3708 provides an indication to rescuers of the duration of hold following the downstroke or upstroke. In some implementations, the display provides a visual indication of the duration of hold following the downstroke or upstroke. For example, in some cases, it may be preferable to hold chest compressions at the maximum compression depth of the downstroke for a short period (e.g., 50 to 500 msec, approximately 100 msec), and / or hold decompressions at the maximum decompression lift of the upstroke for a short period (e.g., 50 to 500 msec, approximately 100 msec). Such a duration of hold can help enhance circulation in and out of the heart.

[0374] In some implementations, the ACD feedback device provides instructions for rescuers to adjust the speed of the downstroke or upstroke. For example, the speed can be changed to accelerate or slow down the compression cycle and to change the compression rate. In some instances, it may be preferable to increase the speed of the upstroke to rapidly generate negative intrathoracic pressure, thereby enhancing venous return of blood to the heart and improving overall circulation.

[0375] Figure 38 Including showing Figure 37 Screenshot 3800 shows an alternative example of the ACD feedback device user interface, shown as screenshot 3700. In this example, displacement meter 3802 operates in a manner similar to displacement meter 3402, except that there is no shaded area.

[0376] Figure 39Example screenshot 3900 shows the user interface of an ACD feedback device, including a normalized force-displacement graph for feedback provided by the ACD feedback device during ACD CPR therapy. Figures 34 to 38 Similarly, depth measurement 3402 is shown. Normalized force-displacement graph 3902 is shown in the graphics pane 3904 adjacent to depth measurement 3402.

[0377] Curve 3902 illustrates the press cycle as loop 3906. Indicator 3910 moves clockwise around loop 3906 as indicated by arrow 3914 (although a counter-clockwise direction can also be used). In some implementations, curve 3902 is... Figure 15 A scaled version of graph 1500 is used, where the axes of the graph are scaled so that loop 3906 appears circular. During compression, the force and displacement relationship is determined and plotted on graph 3902. A first tolerance value 3908a is shown as the outer loop, and a second tolerance value 3908b is shown as the inner loop. Rescuers can refer to graph 3902 and maintain the correct force and displacement so that index 3910 remains on the track shown between the second tolerance value 3908b and the first tolerance value 3908a. Line 3912 indicates the start of a new cycle. In some implementations, displacement meter 3402 can be replaced by a force meter, which shows the range of floating forces updated when the neutral position estimate is updated.

[0378] Figures 40 to 41 Example screenshots 4000 and 4100 show the user interface of the ACD feedback device. Screenshots 4000 and 4100 respectively show examples of the upper and lower ranges of the previous compression cycle, the upper and lower ranges of the current compression cycle, and the upper and lower ranges of the target compression cycle displayed as feedback during ACD CPR therapy.

[0379] Go to Figure 40A series of displacement measurements, along with displacement measurement 2402 on the right side of the interface, are shown as a bar graph. Previous compression cycles are shown as previous displacement measurements 4002, and target compression and decompression displacement values ​​are shown as dashed displacement measurements 4004 to indicate where the ACD treatment provider should aim. In this example, the measurements move from right to left over time. The current displacement measurement 4008 is shown near the center of screenshot 4000. Measurement 4008 may reflect displacement measurements 3402, including ranges 3502a, 3502b and range bars 3504a, 3504b, 3506a, 3506b. However, shaded areas 3408, 3410 are not shown on the current displacement measurement 4008, but are shown in shaded areas on the previous displacement measurement 4006 to the left of the current displacement measurement. Compression and decompression displacements from the previous cycle are shown in measurement 4006. Once the current cycle is complete, meter 3206 loses the shadow of areas 3408 and 3410, and areas 3408 and 3410 are updated to be included in meter 4008 (which becomes the previous meter 3406). This view assists rescuers in comparing the current compression cycle with previous compression cycles and preparing for target compression and decompression displacement values, which can be updated based on an estimate of the neutral position (as mentioned above). Figures 12 to 23 The above).

[0380] In some implementations, the target range 4004 and the previous range 4002 can be rescaled based on the estimated neutral position and the target and measured displacement values, if necessary. Here, line 3404 typically represents the estimated zero point.

[0381] Go to Figure 41 Screenshot 4100 shows another version of the user interface of the ACD feedback device shown in screenshot 4000. Here, the target displacement of one or both of the compressions and decompressions has changed, such as due to a change in the patient's estimated neutral position. Indication 4102 may be used to notify the rescuer that the target has been updated. On the user interface, the new target range may be displayed on the current displacement measurement 4112. Indications 4104, 4106 may be used to notify the user that the next compression or decompression should be changed. Even if the previous target is reached when the feedback is displayed, this may change the feedback reported as "good" to "reduced lift" 4104 due to the change in range. Line 4110 typically represents the estimated zero point. Line 4112 typically represents the current displacement of the patient's chest.

[0382] In some implementations, the display of the ACD device 1200 can show the same information as the display of the ACD device 1200. Figures 34 to 41Screenshots show similar user interfaces to models 3400, 3500, 3600, 3700, 3800, 3900, 4000, and 4100. In some implementations, the display is located on the ACD device's handle. (The last sentence appears to be incomplete and possibly refers to something like "Regarding..."). Figure 1 The handle, such as handle 108, can provide tactile feedback to provide guidance on how to modify ACD CPR treatment. In some implementations, a user interface similar to screenshots 3400, 3500, 3600, 3700, 3800, 3900, 4000, and 4100 may be shown on a patient monitor (e.g., a defibrillator / monitor, a monitor without defibrillation function) of the ACD device 1200, which has at least one sensor for obtaining physiological data from the patient. In some implementations, a user interface similar to screenshots 3400, 3500, 3600, 3700, 3800, 3900, 4000, and 4100 may be shown on a portable computing device (e.g., a tablet, a telephone, etc.), wherein the portable computing device can communicate with the ACD device and / or the patient monitor. For example, an ACD device or patient monitor may receive signals from one or more motion sensors or force sensors associated with ACD therapy, and processing of these signals may occur on the ACD device or patient monitor, with the result of such processing being sent to a portable computing device. Alternatively, the portable computing device may receive data from one or more motion sensors or force sensors associated with ACD therapy and may perform the processing itself required to generate user interface feedback for the feedback described herein.

[0383] Figure 42An example process 4200 is shown for providing feedback for use with an ACD device such as device 100 or 1200 during ACD CPR. Process 4200 includes: coupling (4202) an ACD device to a patient. Process 4200 includes: performing (4204) ACD treatment on the patient, such as by a rescuer using an ACD device. The ACD device or other associated device is configured to process (4206) displacement and force signals associated with ACD CPR treatment. For example, the displacement and force signals are generated during each compression cycle. The ACD device or other associated device is configured to estimate (4208) a neutral position of the chest based on the processed displacement and force signals. ACD device 1200 or other associated device measures displacement during the compression and decompression phases of a compression cycle. ACD device 1200 or other associated device is configured to determine (4210) downstroke and upstroke displacements based on the estimated neutral position. The ACD device 1200 or other associated device is configured to adjust (4212) at least one of the target lower travel displacement range and the target upper travel displacement range based on an estimated neutral position. For example, the ACD device 1200 or other associated device may estimate that the neutral position is 0.75 inches below zero. In response, the ACD device 1200 or other associated device may adjust the upper travel displacement (e.g., lift) to be greater than the previous upper travel displacement target, thereby effectively raising the neutral position back to a position closer to the point of initiation of the press. Similarly, the ACD device 1200 or other associated device may adjust the corresponding lower travel displacement (e.g., depression) to be less than the previous target lower travel displacement. Although these examples are provided for illustration, other adjustments may be made in response to the estimated neutral position (e.g., decreasing the target upper travel displacement and increasing the target lower travel displacement, decreasing both the upper and lower travel displacements, etc.). The ACD device 1200 or other associated device is configured to determine (4214) whether the lower travel displacement falls within the target lower travel displacement range and whether the upper travel displacement falls within the target upper travel displacement range. The ACD device 1200 or other associated device is configured to generate (4216) at least one feedback signal for the display to provide guidance on how to modify ACD CPR treatment based on the determination that the lower stroke displacement falls within the target lower stroke displacement range and the upper stroke displacement falls within the target upper stroke displacement range.

[0384] Go to Figure 43Example processing 4300 is shown for providing feedback for use of an ACD device such as device 100 or 1200 during ACD CPR treatment. Process 4300 includes: coupling (4302) an ACD device to a patient. Process 3500 includes: performing (4304) ACD treatment on the patient, such as by a rescuer using an ACD device. The ACD device or other associated device is configured to process (4306) displacement and force signals associated with the ACD CPR treatment. The ACD device 1200 or other associated device is configured to estimate (4308) a past neutral position of the chest and a current neutral position of the chest based on the processed displacement and force signals. In some implementations, the ACD device 1200 or other associated device may be as described above. Figures 12 to 23 The estimated neutral position. The ACD device 1200 or other associated devices are configured, such as regarding... Figures 40 to 41 The above, etc., determine (4310) the past lower stroke displacement and the past upper stroke displacement based on the estimated past neutral position. The ACD device 1200 or other associated devices are configured, such as regarding... Figures 12 to 23 The aforementioned parameters determine (3512) the current lower stroke displacement and the current upper stroke displacement based on the estimated current neutral position. The ACD device or other associated device is configured to generate (4314) at least one feedback signal for the display to provide visual indications of the current lower stroke displacement, the current upper stroke displacement, the past lower stroke displacement, and the past upper stroke displacement.

[0385] Figure 44 An example process 4400 is shown for providing feedback for use of an ACD device such as device 100 or 1200 during ACD CPR treatment. Process 4400 includes: coupling (4402) an ACD device to a patient. Process 4400 includes: performing (4404) ACD treatment on the patient, such as by a rescuer using an ACD device, etc. The ACD device or other associated device is configured to process (4406) displacement and force signals related to ACD CPR treatment. For example, the displacement and force signals are generated during each compression cycle. ACD device 1200 or other associated device is configured to determine (4408) the current displacement based on the processed displacement signal. ACD device or other associated device is configured to determine (4410) the current force based on the processed force signal. The ACD is configured to generate (4412) at least one feedback signal for a display to provide at least one graph of force and displacement showing the current displacement and current force, such as in Figures 15 to 16B and Figure 39 As shown in the figure. In some implementations, such as regarding Figure 39 The curves of current displacement and current force can be normalized to assist rescuers in providing ACD CPR treatment.

[0386] Figure 45 An example process 4500 is shown for providing feedback for use of an ACD device such as device 100 or 1200 during ACD CPR treatment. Process 4500 includes: coupling (4502) an ACD device to a patient. Process 4500 includes: performing (4504) ACD treatment on the patient, such as by a rescuer using an ACD device. The ACD device or other associated device is configured to process (4506) displacement and force signals associated with ACD CPR treatment. For example, the displacement and force signals are generated during each compression cycle. ACD device 1200 or other associated device is configured to estimate (4508) the neutral position of the chest based on the processed displacement and force signals. For example, ACD device 1200 or other associated device may be configured as described above. Figures 12 to 23 The estimated neutral position. The ACD device 1200 or other associated device is configured to estimate (4510) the initial zero point of the chest before the application of ACD CPR treatment, such as based on one or more initial readings of the patient's chest displacement. The ACD device 1200 or other associated device is configured to determine (4512) the difference in amplitude between the estimated initial zero point of the chest and the estimated neutral position of the chest. The ACD device 1200 or other associated device is configured to generate (4514) at least one feedback signal to modify the ACD CPR treatment, thereby reducing the difference in amplitude between the initial zero point of the chest and the neutral position of the chest.

[0387] Although the treatments 4200, 4300, 4400, and 4500 are described sequentially, they can be combined, run in parallel, or performed alternately for ACD CPR treatment.

[0388] Furthermore, although at least some of the embodiments described above describe techniques and displays used during manually delivered chest compressions and decompressions, similar techniques and displays can be used with automated chest compression devices such as the AUTOPULSE device manufactured by ZOLLMedical in Massachusetts. Therefore, target ACD parameters adjusted based on an estimated neutral position are applicable to ACD therapy delivered in both manual and automated modes. For example, in the case of automated ACD therapy, the estimated neutral position can be an input used to determine the target lower travel displacement and / or target upper travel displacement. Once such a target is determined, the automated chest compression device can be configured to deliver ACD therapy based on an updated or otherwise adjusted target. In the case of manually delivered ACD therapy, the estimated neutral position can also be an input used to determine the target lower travel displacement and / or target upper travel displacement. However, in the case of manual ACD therapy, appropriate feedback mechanisms are used to assist the user in achieving the target parameters (e.g., the current displacement falling within one or more desired ranges).

[0389] Several embodiments of the invention have been described. However, it should be understood that various modifications can be made without departing from the spirit and scope of the invention. Therefore, other embodiments are also within the scope of the appended claims.

Claims

1. A system for assisting in cardiopulmonary resuscitation (CPR), the system comprising: an active compression-decompression (ACD) device configured to push down and pull up on a patient's chest; a force sensor configured to measure a force applied to the patient's chest by the ACD device; a motion sensor configured to measure a displacement of the patient's chest; one or more computer-readable media for storing computer-executable instructions; and one or more processors configured to execute the computer-executable instructions, the execution to: identify a compression cycle based on one or more signals received from at least one of the force sensor and the motion sensor, the compression cycle comprising a compression phase and a decompression phase, determine a first depth of external chest compression corresponding to when zero force is applied to the patient's chest during the compression phase of the compression cycle, determine a second depth of external chest compression corresponding to when zero force is applied to the patient's chest during the decompression phase of the compression cycle, and estimate a neutral position of the patient's chest based on the first depth and the second depth. Estimating the neutral position of the patient's chest based on the first depth and the second depth comprises determining a depth of external chest compression representing the neutral position of the chest within a range defined by the first depth and the second depth.

2. The system of claim 1, wherein, Estimating the neutral position of the patient's chest based on the first depth and the second depth comprises determining a depth of external chest compression representing the neutral position of the chest outside a range defined by the first depth and the second depth.

3. The system of claim 1, wherein, Estimating the neutral position of the patient's chest based on the first depth and the second depth comprises determining a depth of external chest compression representing the neutral position of the chest as a function of an average of the first depth and the second depth.

4. The system of claim 1, wherein, The function of the average of the first depth and the second depth comprises a moving average of the first depth and the second depth for a plurality of compression cycles, the plurality of compression cycles comprising the compression cycle and one or more compression cycles immediately preceding the compression cycle.

5. The system of claim 4, wherein, Estimating the neutral position of the patient's chest based on the first depth and the second depth comprises determining a depth of external chest compression representing the neutral position of the chest as a function of the first depth and the second depth, wherein the first depth is weighted by a first weight value, and wherein the second depth is weighted by a second weight value different from the first weight value.

6. The system of claim 1, wherein, The compression phase comprises at least one of a compression lift portion and a compression non-lift portion.

7. The system of claim 1, wherein, The decompression phase comprises at least one of a decompression lift portion and a decompression non-lift portion.

8. The system of claim 1, wherein, A difference between the first depth and the second depth is based on a hysteresis of the compression cycle.

9. The system of claim 1, wherein, The ACD device comprises:

10. The system of claim 1, wherein, a first element configured to couple to the patient's chest; and a second element configured to be grasped by a rescuer, the second element coupled to the first element. The ACD device comprises at least one of the force sensor and the motion sensor.

11. The system of claim 1, wherein, The motion sensor comprises an accelerometer.

12. The system of claim 1, wherein, ​ 13. The system of claim 1, comprising a user interface configured to display data representative of one or more of the first depth and the second depth.

14. The system of claim 13, wherein, the user interface is configured to display data indicative of one or more of the force and the displacement.

15. The system of claim 13, wherein, the user interface is configured to display a press non-lift depth of the press phase.

16. The system of claim 13, wherein, the user interface is configured to display a decompression lift height of the decompression phase.

17. The system of claim 13, wherein, the user interface is configured to display a trend graph representative of chest remodeling.

18. The system of claim 13, wherein, the user interface is configured for display on a device external to the ACD device.

19. The system of claim 18, wherein, the device is remote from the ACD device.

20. The system of claim 18, wherein, the device comprises at least one of a smart phone, a smart watch, and a tablet device.

21. The system of claim 1, comprising a communication device configured to communicate data to and receive data from an external device.

22. The system of claim 1, wherein, the execution performs the following: determining a third depth of chest compression corresponding to a force-displacement relationship of a press phase of the press cycle, determining a fourth depth of chest compression corresponding to a force-displacement relationship of a decompression phase of the press cycle, and estimating a neutral position of the patient's chest based on the first depth, the second depth, the third depth, and the fourth depth.

23. The system of claim 22, wherein, the execution performs the following: determining a fifth depth of chest compression corresponding to a first product of force and displacement of the press phase of the press cycle, determining a sixth depth of chest compression corresponding to a second product of force and displacement of the decompression phase of the press cycle, and estimating a neutral position of the patient's chest based on the first depth, the second depth, the third depth, the fourth depth, the fifth depth, and the sixth depth.

24. The system of claim 23, wherein, estimating a neutral position of the patient's chest based on the first depth, the second depth, the third depth, the fourth depth, the fifth depth, and the sixth depth comprises a function of an average of the first depth, the second depth, the third depth, the fourth depth, the fifth depth, and the sixth depth.

25. The system of claim 22, wherein, the force-displacement relationship of the press phase is different from the force-displacement relationship of the decompression phase based on a hysteresis of the press cycle.

26. A system for assisting in cardiopulmonary resuscitation (CPR), the system comprising: an active compression-decompression (ACD) device configured to push down and pull up on a patient's chest; a force sensor configured to measure a force applied to the patient's chest by the ACD device; a motion sensor configured to measure a displacement of the patient's chest; one or more computer-readable media for storing computer-executable instructions; and one or more processors configured to execute the computer-executable instructions, the execution performing the following: identifying a press cycle based on one or more signals received from at least one of the force sensor and the motion sensor, the press cycle comprising a press phase and a decompression phase, determining a first depth of chest compression corresponding to a first product of force and displacement during the press phase of the press cycle, ​ determining a second depth of chest compression corresponding to a second product of force and displacement during a decompression phase of the compression cycle, and estimating a neutral position of the patient's chest based on the first depth and the second depth.

27. The system of claim 26, wherein, Estimating a neutral position of the patient's chest based on the first depth and the second depth includes determining a depth of chest compression representing the neutral position of the chest within a range defined by the first depth and the second depth.

28. The system of claim 26, wherein, Estimating a neutral position of the patient's chest based on the first depth and the second depth includes determining a depth of chest compression representing the neutral position of the chest outside a range defined by the first depth and the second depth.

29. The system of claim 26, wherein, Estimating a neutral position of the patient's chest based on the first depth and the second depth includes determining a depth of chest compression representing the neutral position of the chest as a function of an average of the first depth and the second depth.

30. The system of claim 29, wherein, The function of an average of the first depth and the second depth includes a moving average of the first depth and the second depth for a plurality of compression cycles, the plurality of compression cycles including the compression cycle and one or more compression cycles immediately preceding the compression cycle.

31. The system of claim 26, wherein, Estimating a neutral position of the patient's chest based on the first depth and the second depth includes determining a depth of chest compression representing the neutral position of the chest as a function of the first depth and the second depth, wherein the first depth is weighted by a first weight value, and wherein the second depth is weighted by a second weight value different from the first weight value.

32. The system of claim 26, wherein, The compression phase includes at least one of a compression lift portion and a compression non-lift portion.

33. The system of claim 26, wherein, The decompression phase includes at least one of a decompression lift portion and a decompression non-lift portion.

34. The system of claim 26, wherein, A difference between the first depth and the second depth is based on a lag of the compression cycle.

35. The system of claim 26, wherein, The ACD device includes: a first element configured to be coupled to a patient's chest; and a second element configured to be grasped by a rescuer, the second element coupled to the first element.

36. The system of claim 26, wherein, The ACD device includes at least one of the force sensor and the motion sensor.

37. The system of claim 26, wherein, The motion sensor includes an accelerometer.

38. The system of claim 26, including a user interface configured to display data representing one or more of the first depth and the second depth.

39. The system of claim 38, wherein, The user interface is configured to display data indicative of one or more of the force and the displacement.

40. The system of claim 38, wherein, The user interface is configured to display a compression non-lift depth of the compression phase.

41. The system of claim 38, wherein, The user interface is configured to display a decompression lift height of the decompression phase.

42. The system of claim 38, wherein, The user interface is configured to display a trend graph representing chest remodeling.

43. The system of claim 38, wherein, The user interface is configured for display on a device external to the ACD device.

44. The system of claim 43, wherein, The device is remote from the ACD device.

45. The system of claim 43, wherein, The device includes at least one of a smart phone, a smart watch, and a tablet device.

46. The system of claim 26, including a communication device configured to communicate data to and receive data from an external device.

47. The system of claim 26, wherein, the one or more processors are configured to: generate a compression cycle representation comprising a product of force and displacement for a plurality of displacement values during the compression phase and during the decompression phase.

48. The system of claim 47, wherein, a first product of force and displacement comprises a local minimum of the product of force and displacement for a compression phase portion of the compression cycle representation.

49. The system of claim 47, wherein, a second product of force and displacement comprises a local minimum of the product of force and displacement for a decompression phase portion of the compression cycle representation.

50. The system of claim 47, wherein, the first depth and the second depth each correspond to a compression depth at which the first product of force and displacement is equal to the second product of force and displacement.

51. The system of claim 47, wherein, the compression cycle representation comprises a first compression cycle representation, and wherein the one or more processors are configured to generate a second compression cycle representation comprising a derivative of the first compression cycle representation for a plurality of displacement values during the compression phase and during the decompression phase.

52. The system of claim 26, wherein, the first depth is equal to the second depth, and wherein the first product of force and displacement is equal to the second product of force and displacement.

53. The system of claim 26, wherein, the performing the following operations: determining a third depth of chest compression corresponding to a force-displacement relationship of a compression phase of the compression cycle, determining a fourth depth of chest compression corresponding to a force-displacement relationship of a decompression phase of the compression cycle, and estimating a neutral position of the patient's chest based on the first depth, the second depth, the third depth, and the fourth depth.

54. The system of claim 53, wherein, the performing the following operations: determining a fifth depth of chest compression corresponding to application of zero force to the patient's chest during a compression phase of the compression cycle, determining a sixth depth of chest compression corresponding to application of zero force to the patient's chest during a decompression phase of the compression cycle, and estimating a neutral position of the patient's chest based on the first depth, the second depth, the third depth, the fourth depth, the fifth depth, and the sixth depth.

55. The system of claim 54, wherein, estimating a neutral position of the patient's chest based on the first depth, the second depth, the third depth, the fourth depth, the fifth depth, and the sixth depth comprises a function of an average of the first depth, the second depth, the third depth, the fourth depth, the fifth depth, and the sixth depth.

56. The system of claim 53, wherein, the force-displacement relationship of the compression phase is different from the force-displacement relationship of the decompression phase based on a hysteresis of the compression cycle.

57. A computer program product storing instructions that, when executed by a processor, cause the processor to perform: identifying a compression cycle based on one or more signals received from at least one of a force sensor and a motion sensor, the compression cycle comprising a compression phase and a decompression phase, and the compression cycle being applied to a patient's chest by an active compression decompression device (ACD device), determining a first depth of chest compression corresponding to application of zero force to the patient's chest during a compression phase of the compression cycle, determining a second depth of chest compression corresponding to application of zero force to the patient's chest during a decompression phase of the compression cycle, and estimate a neutral position of the patient's chest based on the first depth and the second depth.

58. A computer program product storing instructions that, when executed by a processor, cause the processor to: identify a compression cycle based on one or more signals received from at least one of a force sensor and a motion sensor, the compression cycle comprising a compression phase and a decompression phase, and the compression cycle being applied to a patient's chest by an active compression decompression device (ACD device), determine a first depth of chest compression corresponding to a first product of force and displacement during the compression phase of the compression cycle, determine a second depth of chest compression corresponding to a second product of force and displacement during the decompression phase of the compression cycle, and estimate a neutral position of the patient's chest based on the first depth and the second depth.

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