Apparatus for over-riding shock decisions in an automatic external defibrillator

Abstract

A defibrillator (AED) that uses an ECG analysis model or algorithm that is capable of operating in two different modes. The ECG analysis model is particularly suited for analysis during the period of CPR. Both modes of operation arrive at a shock decision in substantially the same manner, wherein one or more segments of ECG data indicate a shockable cardiac condition. In one mode of operation, once a shock decision is made, the shock decision is irrevocable. In another mode of operation, the shock decision is revocable if one or more subsequent segments of ECG data indicate a no-shock decision. Improved specificity of the model is obtained without over-rejecting shockable ECGs.

Description

Technical Field

[0001] The present invention relates to an improved apparatus and method for treating victims of cardiac arrest, particularly for treating patients for whom treatment protocols include cardiopulmonary resuscitation (CPR) and defibrillation. Background Technology

[0002] A defibrillator delivers a high-voltage pulse to the heart to restore normal rhythm and systolic function in patients experiencing arrhythmias such as ventricular fibrillation (“VF”) without spontaneous circulation or ventricular tachycardia (“VT”). Several classes of defibrillators exist, including manual defibrillators and automated external defibrillators (“AEDs”). The difference between an AED and a manual defibrillator is that an AED can automatically analyze the electrocardiogram (“ECG”) rhythm to determine if defibrillation is needed. After determining that a shock is needed, the AED arm itself to deliver a therapeutic shock, and then prompts the user to press the shock button to deliver the defibrillation shock. AEDs that operate in this way are called semi-automatic. Fully automatic AEDs deliver a defibrillation shock without any user input. Fully automatic AEDs are often referred to as fully automatic defibrillators to reduce confusion in the terminology.

[0003] Figure 1 is an illustration of a defibrillator 1 used by user 2 to resuscitate patient 4 who has suffered cardiac arrest. Defibrillator 1 can be in the form of an AED or a fully automated defibrillator that can be used by a first responder. Defibrillator 1 can also be in the form of a manual defibrillator for use by caregivers or other trained medical personnel. User 2 applies two or more electrodes 6 across the chest of patient 4 to collect ECG signals from the patient's heart. Defibrillator 1 then analyzes the ECG signals using an ECG analysis algorithm targeting signs of cardiac arrhythmia. Whenever a shockable rhythm such as VF or nonperfusion ventricular tachycardia (VT) is detected, defibrillator 1 equips itself to deliver a high-voltage shock. Defibrillator 1 signals user 2 with a suggested shock via auditory or visual cues. User 2 then presses the shock button on defibrillator 1 to deliver the defibrillation shock.

[0004] It is generally accepted that the faster circulation (via CPR and defibrillation) is restored after a VF attack, the greater the patient's chance of survival in the event. For this reason, many AEDs, such as the one shown in Figure 1, also incorporate a user interface that includes audible, auditory, and visual cues to guide the user through programmed sequences of CPR and defibrillation shocks. The user interface may include detailed auditory cues for proper CPR compressions, an auditory metronome to guide the user to perform compressions at the appropriate rate, a visual display to show the status and progress of the event, an alarm, a flashing light, etc. These sequences are pre-programmed into the device according to a protocol established by the local medical institution.

[0005] Several ECG analysis algorithms exist that automatically analyze a patient's ECG to determine whether a defibrillation shock is appropriate to address an underlying cardiac rhythm. One such algorithm is broadly described in commonly assigned U.S. Patent US6,671,547, entitled "Adaptive analysis method for an electrotherapy device and apparatus," by Lyster et al., and is incorporated herein by reference. The described algorithm relates to Patient Analysis System (PAS) algorithms currently used in AEDs, such as the Heartstart AED manufactured by Koninklijke Philips of NV, Anduford, Massachusetts. TM FR3AED.

[0006] However, PAS and other existing ECG algorithms used to determine shockable conditions require relatively noise-free ECG signals. All existing protocol sequences require terminating CPR during analysis because CPR introduces artifacts in the ECG that can mask a vital sign (VF) when it occurs, or present as a VF when it doesn't. The former leads to an undesirable decrease in the sensitivity of the analysis, while the latter leads to an undesirable decrease in the specificity. Therefore, all existing protocols for CPR and defibrillation require periodic "release" intervals of at least several seconds to allow the defibrillator to analyze the ECG with sufficient accuracy to be safe, useful, and effective for the patient.

[0007] Several issues arise from the need to interrupt CPR for ECG analysis. It has been shown that even a mere few seconds of interruption in CPR compressions can reduce the likelihood of successful resuscitation. Therefore, CPR termination required for ECG analysis before delivering a defibrillation shock may reduce the chances of a successful patient outcome. Furthermore, delays in resuming CPR after defibrillation to assess the success of the shock may also affect the patient.

[0008] Several prior art solutions have been developed to address this problem, all of which aim to reduce the amount of delay. For example, one solution is to remove CPR noise artifacts from ECG signals using adaptive filtering. Such an adaptive filtering method is described by Snyder et al. in their jointly assigned U.S. Patent US6,553,257, entitled “Interactive Method of Performing Cardiopulmonary Resuscitation with Minimal Delay to Defibrillation Shocks,” which is incorporated herein by reference.

[0009] Another alternative method for analyzing ECGs in the presence of CPR noise artifacts involves wavelet transform analysis of the ECG data stream. An example of this method is described by Addison in U.S. Patent 7,171,269 entitled “Method of Analysis of Medical Signals,” which is incorporated herein by reference. US Patent 7,171,269 describes the use of wavelet transform analysis to decompose the signal into cardiac-related and CPR-related signals. Another example of this method is employed by Coult et al. in International Patent Application No. PCT / US2012 / 045292 entitled “Systems and Methods for Analyzing Electrocardiograms to Detectventricular Fibrillation.” Here, the ECG signal is probed using wavelets, such as Morlet wavelets, Myers wavelets, or Mexican Hat wavelets, before analysis, and is layered into shockable or non-shockable ECGs.

[0010] Unfortunately, all these methods tend to be computationally intensive and therefore difficult to implement in portable devices. Some methods also lack the accuracy required to reliably determine shockable rhythms in the presence of CPR noise artifacts while avoiding "false positive" shock decisions. These techniques are also susceptible to external electrical noise such as line noise and have not yet been adopted.

[0011] For these reasons, other solutions have been developed to reduce the amount of “release” ECG time required to accurately determine shockable rhythms. One such technique, described by Snyder et al. in co-assigned U.S. Patent US 7,463,922, entitled “Circuit and method for analyzing a patient's heart function using overlapping analysis windows,” to achieve faster shock decisions using temporally overlapping ECG data buffers, is also incorporated herein by reference. Unfortunately, these prior art solutions only reduce, rather than eliminate, the delay time.

[0012] Another problem with existing ECG analysis methods, in the presence of artifact noise from CPR, is the issue of refibrillation. Some patients who are successfully defibrillated—that is, restored to an organized heart rhythm or experience cardiac arrest—re-enter VF (ventricular fibrillation) after several seconds to several minutes. Some of these patients experience refibrillation during the fixed-duration CPR session, which is currently not suitable for ECG analysis. Therefore, there is currently no management strategy for refibrillation other than waiting for the protocol to release the analysis session at the end of the CPR session. This delay in managing refibrillation may not be optimal for patient outcomes.

[0013] A solution to the problem of severe fibrillation during CPR has been proposed, which involves a measure of cardiac “vitality” during CPR. One such measure is the so-called “probability of spontaneous circulation recovery” (pROSC) score determined during CPR, and is described in U.S. Patent Application No. 13 / 881380 entitled “Defibrillator with Dynamic Ongoing CPR Protocol” by Jorgenson et al., which is incorporated herein by reference.

[0014] Another measure used to predict VF is the so-called Amplitude Spectral Area (AMSA) score, described by Quan et al. in U.S. Patent Application No. 14 / 211681 entitled "Treatment Guidance Based on Victim Circulatory Status and Prior Shock Outcome". However, these methods only provide an indication of whether CPR should be interrupted for defibrillation purposes to perform ECG analysis. Therefore, these solutions introduce additional delays. Summary of the Invention

[0015] The inventors have recognized the limitations of existing technologies and have identified a need for a technique to analyze ECGs in the presence of CPR noise artifacts, providing robust and reliable indication of shockable rhythms. The required technique must have sufficient sensitivity and specificity to eliminate the delay between CPR and defibrillation, and to rapidly manage severe fibrillation after it occurs. The technique must be computationally efficient so that it can be incorporated into portable medical devices for real-time use during cardiac emergencies. The inventors have developed such a technique.

[0016] Improved techniques can be employed in the modified CPR rescue protocol, offering the benefits of increased onset time for CPR and the ability to manage severe fibrillation by alternating different CPR maneuvers. Specifically, a continuous CPR rescue maneuver can be employed relatively early in the rescue, with shocks delivered immediately upon detection of vital force (VF). Later in the rescue (where it is recognized that a higher proportion of CPR compressions relative to electrical stimulation may be more beneficial for cardiac arrest patients), the CPR protocol can automatically transition to a pre-arranged CPR rescue maneuver. In each maneuver, an ECG analysis algorithm is employed, capable of determining a shockable cardiac rhythm even in the presence of CPR-related noise.

[0017] ECG analysis algorithms operating within the context of ongoing CPR compressions can potentially analyze very long sequences of ECG data, typically spread over time periods. Therefore, it should be recognized that such ECG analysis models can alter their analytical decisions during the CPR process. Shock withdrawal decisions can be caused, for example, by real changes in the heart rhythm or by erroneous indications stemming from potential cumulative sensitivity and model specificity. Therefore, the inventors have recognized the need to dynamically control the conditions under which shock decisions can be withdrawn in order to enhance model robustness and capture the most probable conditions of a true transition from shockable to non-shockable heart rhythms.

[0018] Therefore, and based on the principles of the invention, the inventors have developed novel devices and methods that allow the revocation of electric shock decisions made by ECG analysis algorithms.

[0019] An AED is described, for example, comprising: an ECG signal input unit; a user interface having at least one of an auditory command output unit and a visual display; a shock delivery circuit; an ECG analyzer communicating with the input unit and operable to determine a shockable heart rhythm in the presence of CPR-related signal noise artifacts from the input unit; a memory for storing instructions related to a CPR rescue protocol, the CPR rescue protocol including both continuous CPR rescue operation modes and scheduled CPR rescue operation modes; and a processor communicating with the shock delivery circuit, the ECG analyzer, and the user interface, the processor operable to operate the AED in a sequence of continuous CPR rescue operation modes and the scheduled CPR rescue operation modes, and also operable to issue instructions to a user via the user interface.

[0020] When operating in the continuous CPR rescue mode and if the ECG analyzer determines a shockable heart rhythm, the processor equips the shock delivery circuitry for delivering the shock and then immediately issues an instruction via the user interface to stop the CPR delivery. When operating in the scheduled CPR rescue mode and if the ECG analyzer determines a shockable heart rhythm, the processor equips the shock delivery circuitry for delivering the shock and then immediately issues an instruction via the user interface to stop the CPR delivery after a predetermined period of uninterrupted CPR. The processor is operable to automatically rescind the decision only while the processor is operating in the continuous CPR rescue mode. The processor can be configured to rescind a shock decision based on a set of multiple sequential decisions (e.g., three (3) decisions) other than a "recommended shock". According to a further embodiment of the invention, an AED and method are described that also include a processor controlling an AED in an equipped operating mode, wherein the AED is ready to deliver a shock immediately. In the equipped mode, the processor prevents any rescinding decision. If the electric shock is not actually delivered from the equipped mode, the processor can be configured to terminate the equipped mode after a fixed period of time (preferably about thirty (30) seconds). Other embodiments include a user prompt feature that warns the user to cancel the electric shock. Attached Figure Description

[0021] In the attached diagram:

[0022] Figure 1 illustrates a defibrillator based on existing technology and its use during cardiac resuscitation.

[0023] Figure 2a The illustration shows a process flow example of the algorithm of the present invention used for ECG analysis in the presence of noise artifacts from CPR compressions.

[0024] Figure 2b The illustration shows a process flow for determining a shockable cardiac rhythm based on an analyzed ECG, according to an embodiment of the present invention.

[0025] Figure 3 The illustration shows the frequency characteristics of a set of filters according to the present invention for removing CPR artifacts and other signal noise from ECG signals.

[0026] Figure 4 The illustration shows a source according to an embodiment of the present invention. Figure 3 The example filter shown is the ECG output buffer.

[0027] Figure 5 The illustration shows an example two-dimensional determination surface for classifying damaged ECG signals as VF or undetermined according to an embodiment of the present invention.

[0028] Figure 6 A functional block diagram of the external defibrillator according to the present invention is shown.

[0029] Figure 7 An exemplary visual display of the charging status of an indicating device according to the present invention is illustrated.

[0030] Figure 8 The illustration shows a user interface on the outer surface of an AED according to an embodiment of the present invention.

[0031] Figure 9 The illustration shows a process flow for illustrating a continuous CPR rescue operation mode according to an embodiment of the present invention.

[0032] Figure 10 The illustration shows a process flow for a pre-arranged CPR rescue operation pattern according to an embodiment of the present invention.

[0033] Figure 11 The diagram illustrates the process flow of a cardiac rescue protocol that automatically switches between continuous CPR rescue operation modes and scheduled CPR rescue operation modes based on the progress of the rescue.

[0034] Figure 12 The illustration shows a timeline view of the auditory and visual information provided during cardiac resuscitation in a continuous CPR rescue operation mode.

[0035] Figure 13 The illustration shows a timeline view of the auditory and visual information provided during cardiac resuscitation in a pre-arranged CPR rescue procedure.

[0036] Figure 14An example of a process flow for a cardiac rescue protocol is illustrated, which automatically switches between two ECG analysis algorithms based on the progress of the rescue.

[0037] Figure 15 The diagram illustrates a detailed process flow approach for switching between two ECG analysis algorithms based on progress in cardiac rescue.

[0038] Figure 16 This is a flowchart illustrating a method for interrupting CPR during cardiac resuscitation to support the delivery of electrotherapy.

[0039] Figure 17a , Figure 17b , Figure 17c and Figure 17d An exemplary embodiment of a user input button and a visual display is illustrated, which displays information about the basic state of AED operation and contextual labels adjacent to the button.

[0040] Figure 18a The diagram illustrates the shock withdrawal protocol used during a custom (continuous) CPR procedure. Figure 18b The diagram illustrates the shock withdrawal protocol used during a scheduled CPR procedure.

[0041] Figure 19 The illustration shows the benefits of the present invention regarding the improvement in the specificity of the ECG analysis algorithm during prolonged CPR compressions. Detailed Implementation

[0042] The shock suggestion algorithm of this invention, known as the Optimal Arrhythmia Detection Technique (ART), typically applies the aforementioned wavelet transform analysis principles to the ECG signal stream, but replaces the wavelet transform with a series of fixed-frequency bandpass filters. This set of bandpass filters is preferably constructed with frequency windows similar to the Gaussian windows used to generate conventional Morlet wavelets.

[0043] The ART algorithm suppresses CPR artifact-related noise by selectively allowing relatively high-frequency components of potentially contaminated ECG signals to pass through. ART is based on the inventors' observation that although CPR and organized heart rhythms can occur at similar repetition rates of approximately 1 Hz to 2 Hz, typical CPR noise has relatively few high-frequency components in its signal; that is, the signal tends to have a smooth waveform. Due to the rapid polarization and depolarization of the heart during a single cycle, cardiac activity tends to have relatively more high-frequency components. These high-frequency components are captured and analyzed by ART.

[0044] Now turn to the diagram. Figure 2aAn embodiment of the process flow of the ART algorithm 200 of the present invention is illustrated for analyzing ECG in the presence of noise artifacts from CPR compressions. At step 202, the method first receives an ECG signal, preferably from two or more electrodes arranged to make electrical skin contact with the patient. The ECG signal is a time-varying voltage originating from the patient's heart and voltages possibly induced by CPR compressions applied to the patient. The signal may also include other artifact signals from outside the patient, such as patient pushing and movement, external electrical noise, etc. The ECG signal is preferably digitized into a signal data stream.

[0045] At filtering step 206, the digitized ECG signal stream is processed using the ART filtering algorithm. Here, each data point in the signal stream is filtered by a set of first to fourth parallel filters in the first to fourth parallel filtering steps 206', 206”, 206”', and 206””, each filter having a different bandpass characteristic. Each filter is preferably a finite impulse response filter. The number of filters and the bandpass characteristic of each filter may vary within the scope of this invention.

[0046] The preferred arrangement of the ART filter 306 is as follows and in Figure 3 The following is shown. Four basic filters can be used, which are typically applied in... Figure 2a The corresponding filtering step 206 in the process. One is called FLATS 306', and the other is called CLAS1 306', which tend to allow higher frequency components of the ECG signal to pass through and can feature: 1) distinguishing ventricular fibrillation from cardiac arrest rhythms; 2) distinguishing ventricular fibrillation from organized cardiac activity; 3) distinguishing ventricular fibrillation from cardiac arrest rhythms and organized cardiac activity. Both FLATS 306' and CLAS1 306' tend to attenuate data at frequencies associated with CPR artifacts, so that their output is about cardiac information separated from the CPR compression noise signal. Figure 3 As can be seen from the illustrative and exemplary embodiments, FLATS 306' has a center frequency of approximately 35 Hz, and CLAS1 306" has a center frequency of approximately 25 Hz. CLAS5 306"" is arranged to reject radio frequency (RF) noise. And CLAS4 306"' can be arranged to allow lower frequency components to pass through, which are useful for rejecting false positive indications of VF caused by specific artifacts (e.g., due to transport, muscle contraction, RF interference, etc.).

[0047] In the preferred arrangement, the digitized ECG signal input results in four filtered ECG signal streams being output.

[0048] from Figure 4It can be seen that there are many oscillations in the filtered signal, resulting in many zero and near-zero samples in the buffer. To remove these effects, an additional envelope filter can optionally be applied to the data to remove localized zeros and non-zeros. Figure 4 The illustration shows the effect of the optional envelope filtering step 405 on the oscillation output 402 of the CLAS1 filter 306”.

[0049] At buffering step 204, each stream of filtered ECG signal data is segmented into sequential time periods, i.e., buffered ECG1, ECG2, ..., ECGi. A preferred arrangement is non-overlapping consecutive buffers of 3.5 seconds in length. A sampling rate of 250 samples per second corresponds to 875 ECG samples per buffer. The time period length and sampling rate are predetermined and may vary within the scope of this invention. Each data point from each buffer has a value that depends on the input and the underlying filter. Figure 4 An example of a filtered ECG cache dataset for CLAS1 is shown in the figure.

[0050] Preferably and advantageously, the caching step 204 occurs after the filtering step 206. By performing filtering before caching, the method avoids filter transients at the edges of each cache. Otherwise, the method would require longer, overlapping caches, which would necessitate longer analysis times and delay patient outcomes.

[0051] At step 208, data from each ECG cache in the filtered ECG cache is compared to a threshold. The number of data points falling within the threshold for that filtered ECG cache (referred to as a score) is then calculated for use in analysis step 210. Of course, any mathematical representation equivalent to the number of data points (such as a ratio or fraction) can be substituted within the scope of this method step. For illustrative purposes, the score of the filtered ECG cache for the FLATS filter is designated as the FLATS score. The filtered ECG score for CLAS1 is designated as the CLAS score. Therefore, Figure 2a The illustration shows that the threshold comparison steps include threshold comparisons for each filtering step in the parallel filtering steps, namely, the first to fourth parallel threshold comparison steps 208', 208”, 208”' and 208”.

[0052] The threshold for each ECG cache score in the filtered ECG cache scores can be obtained in various ways, and its determination falls within the scope of this invention. The threshold can be fixed, for example, predetermined, or it can be adaptive, for example, calculated based on the average of all data points in a particular cache. For example, the FLATS cache dataset can be scored relative to a fixed threshold, and the CLAS cache dataset can be scored relative to an adaptive threshold.

[0053] Analysis step 210 begins by comparing the filtered ECG buffer scores to a predetermined decision surface. The decision surface, constructed using a database of ECG signal data with CPR contamination noise, defines whether a given set of buffer scores indicates "VF" or "undetermined," i.e., not VF. Figure 5 The diagram illustrates an example of a decision surface in the CLAS and FLATS dimensions. In this example, decision surface 510 includes a pair of scores from either the CLAS or FLATS scores. Score pairs falling within decision surface 510 indicate VF conditions. Score pairs falling outside decision surface 510 indicate undetermined conditions. Additional dimensions of the decision surface can be added as desired, using thresholds for additional filtered ECG caches, to create more accurate VF decisions. Although only two dimensions are shown here, three or more dimensions can also be used for decision surfaces incorporating additional CLAS scores.

[0054] Analysis step 210 continues by comparing two or more cache scores representing specific cardiac signal characteristics with a decision surface to determine whether it is VF or not. Figure 5 The example shown illustrates a pair of CLAS / FLATS scores at 520, indicating VF. Values ​​falling outside the determining surface 510 (e.g., above and / or to the right) at 530 indicate an undetermined condition, i.e., not a VF condition.

[0055] Therefore, the ECG cache for each original time segment can be designated as "suggested shock" (i.e., corresponding to VF) or "undetermined" (i.e., corresponding to "not VF"). Once an ECG cache is determined to be either suggested shock or undetermined, ART repeats the capture, acquisition, filtering, and analysis steps for the next ECG cache in the chronological order shown in step 212, "Selecting the Next ECG Cache". This repetitive process enables additional methods for combining each new cache with the previous cache to generate a continuous overall determination of the presence or absence of a VF.

[0056] The method described above has been shown to identify VF with sufficient accuracy to safely determine the shock during CPR application, without requiring further confirmation of the analysis during the "release" period. It has been demonstrated that, for a single buffer of ECG contaminated with CPR, ART has a sensitivity to VF exceeding 70%, meaning that ART will detect more than 70% of true VF occurrences. Similarly, for a single buffer of ECG, ART has been shown to have a specificity exceeding 95%, meaning that it will not produce false positive VF indications based on more than 95% of "not VF" occurrences.

[0057] It can also be noted that during "quiet" periods, ART performance is close to the performance already demonstrated in existing PAS algorithms. For ECG data uncontaminated by CPR artifacts, ART's sensitivity to VF exceeds 80%, comparable to approximately 94% for PAS in the case of similar data. ART and PAS exhibit almost identical specificity for spurious VF on cached "clean" ECG data.

[0058] Now go to Figure 2b The method continues. A preferred embodiment of the method includes steps 202-212 described above, which are executed in a separate processor, such as a DSP, according to the steps mentioned in the following paragraphs. This arrangement allows each ECG buffer to be analyzed and classified sequentially as VF or “undetermined,” relatively independently of the electro-decision and control processor, which primarily requires only the classification data stream from the ECG signal stream. Another preferred embodiment of the method includes further separating the process into multiple components. For example, the digitization of the input ECG signal at step 202 can be processed in a front-end chip, such as an ASIC, and the digital stream is fed to a DSP for filtering the digitized ECG signal stream into a separate filtered stream corresponding to method step 206. Then, another processor receives the filtered stream for final classification, decision-making, and response processing functions, as described in the following paragraphs.

[0059] If a VF (Vacuum Fluidity) is determined from the ECG cache at analysis step 210, i.e., a "suggested shock" result, then the baseline ECG rhythm is generally assumed to be a shockable cardiac rhythm. However, the optimal response to a VF determination may not be simply preparing the basic equipment to provide electrical therapy. Instead, it may be preferable to obtain confirmation of the determination, or otherwise communicate the determination to the user in a way that does not unduly interrupt the ongoing cardiac resuscitation. Therefore, for these purposes, a separate decision step 214 is necessary, and... Figure 2b The input is shown as being obtained from analysis step 210. Examples of such cases will be provided in the following paragraphs.

[0060] Because ART sequentially analyzes multiple ECG caches during a CPR session lasting several minutes, the cumulative sensitivity to ongoing patient conditions of VF is increased, i.e., a greater chance of detecting a true VF condition. However, the cumulative specificity is also expected to decrease, i.e., a greater chance of mistaking an "undetermined" condition for VF. To maintain the specificity of the entire method at an acceptable level over a relatively long period, optional multi-cache rules can be developed to make a shock decision based on VF / undetermined decisions on temporally successive ECG data caches. A second analysis step 210, a repeat of the second predetermined ECG cache, is then provided to a decision step 214. The decision step 214 then additionally bases its final decision on the second analysis step.

[0061] For example, analysis step 210 can determine that a cardiac rhythm is shockable only if three consecutive ECG buffers indicate VF. Otherwise, the analysis step indicates a non-shockable rhythm. It has been shown that under these rules, ART maintains >95% specificity and >70% sensitivity during prolonged CPR. In some cases, sensitivity can exceed 95% and specificity can exceed 98%. Such performance is acceptable for making a shock decision during CPR. In summary, given that decision step 214 essentially receives an ongoing stream of VF / undetermined ECG buffers, step 214 applies the rule for the final decision that the infrastructure should be operable to continue delivering defibrillation shocks.

[0062] The display step 215 can be activated immediately upon confirmation, such as a visual graphic or text message on the display, a light signal, or a slight audible signal. Preferably, the display step 215 is provided even before the device is fully ready to deliver shock, but in a non-intrusive manner that does not distract the user from continuing CPR until the device is ready to deliver the shock. On the other hand, there are operating modes in which it may be preferable not to provide the user with any information confirming the shock until the equipment is ready to deliver it. Some inexperienced users may be unnecessarily disturbed or startled from delivering CPR simply by the indication that the device is ready to deliver the shock.

[0063] In response to the determination from decision step 214 that a shockable cardiac rhythm exists and that electrical therapy should be delivered, preparation step 216 is initiated. Preparation step 216 may include charging the high-voltage charging circuit with sufficient energy to defibrillate the patient. Preparation step 216 may include auditory and / or visual indicators indicating that preparation has begun, along with some indication of progress toward full readiness for shock delivery step 217. For example, dynamic bar graph markers 720 on visual display 700 may display a gradual filling of the bar graph corresponding to the increasing charging status of the high-voltage circuit. Text message 710 on display 700 may also indicate that charging is in progress. ECG display 730 may be displayed simultaneously on the charging status display along with progress indicators. Figure 7 The illustration shows an exemplary embodiment of this display 700. The auditory progress indicator may include a continuous tone with an rising frequency that stops when a fully charged state is reached.

[0064] Upon completion of setup step 216, the electrotherapy device is fully prepared to deliver shocks. Following setup, it is preferable to automatically issue a user prompt 219 to stop CPR and thus proceed with the delivery of electrotherapy. Auditory prompts from speaker 830, an illuminated or flashing shock button light 820, and / or display indication 802 can be used to signal the user to stop CPR to proceed with shock delivery. For examples of these indicators on the user interface 818, see [link to relevant documentation]. Figure 8 In the case of an AED, the prompt may also instruct the user to press the shock button 892 to deliver a shock. In the case of a fully automated defibrillator, still at step 219, a shock can be delivered automatically immediately after the prompt appears. If the user is wearing electrically insulating gloves or other such protective gear, any prompt to “stop CPR” can optionally be omitted entirely at step 219.

[0065] In some cases, it may be desirable to delay issuing a user prompt to stop CPR at step 219 until a minimum amount of CPR has been provided. For example, it may be desirable to perform at least 30 seconds of uninterrupted CPR before delivering a shock. Optional delay step 218 may be incorporated into the method of the present invention to ensure such a minimum CPR time.

[0066] Immediately following the delivery of electrotherapy, the user can be automatically prompted to resume CPR at step 222. At step 220, the device can optionally be enabled to detect the delivery of electrotherapy. This detection can be achieved by sensing a continuous current, button press, etc. The process then returns to the steps of capturing, acquiring, filtering, and analyzing data based on the state of cardiac resuscitation.

[0067] The above-described method allows CPR to continue until the moment of delivery of electrical therapy, and then, immediately thereafter, resume CPR. As a result, the proportion of “on-hand” time during cardiac rescue is increased, thereby improving the overall effectiveness of the treatment. The idle time waiting for “release” ECG analysis is substantially eliminated, thus avoiding the loss of blood pressure and blood flow that occurs so rapidly when CPR is terminated. These benefits are achieved in conjunction with the method’s ability to manage the return of VF during CPR. If fibrillation occurs, the method simply detects VF and prepares for electrical therapy midway through ongoing CPR compressions.

[0068] The method of this invention offers further advantages. The inventors have discovered that using filters instead of wavelets slightly reduces the computational load required for VF analysis and more effectively suppresses interference from power line noise or similar high-frequency noise. Therefore, most method steps can be implemented in a single digital signal processor (DSP) arranged to receive the ECG signal stream, process the stream, and then output a continuous, time-aligned, and transformed ECG data stream. The DSP can also operate in parallel with a second processor that controls the final shock decision and delivery sequence in the AED. Similarly, the series of filters can be easily adjusted, thus also providing more robust rejection of signals caused by DC offset, 50Hz, and 60Hz external power line noise.

[0069] The above methods can be implemented in medical devices such as external defibrillators. Figure 6 This is a functional block diagram of an external defibrillator 10 according to one embodiment of the present invention. The defibrillator 10 is configured for use during cardiac resuscitation including CPR. It is designed with a small physical size, light weight, and a relatively simple user interface, enabling operation by personnel without a high level of training or otherwise unlikely to use the defibrillator 10 frequently. Although this embodiment of the invention is described with respect to its application in an AED, other embodiments include applications in different types of defibrillators, such as manual defibrillators, fully automated defibrillators, and medical assistive or clinical defibrillators / monitors.

[0070] The defibrillator 10 receives ECG signals from an input section 12, for example, two or more electrodes 16 connected to the patient. An ECG front-end circuit 14 is electrically communicated with the input section 12 via a connector plug or socket, etc. The ECG front-end circuit 14 operates to amplify, buffer, filter, and optionally digitize the electrical ECG signals generated by the patient's heart to produce a digitized ECG sample stream. The digitized ECG samples are provided to a controller 30, which may be a processor combining a DSP processor and an ARM processor. An exemplary controller is an application processor family manufactured by Texas Instruments. In one embodiment of the device, the DSP performs all the filtering described above according to the ART protocol, and then feeds multiple streams of filtered ECG data to the ARM processor. The ARM buffers the digitized ECG signal data stream into segments (buffers) corresponding to predetermined times. The ARM performs outcome analysis on the filtered ECG data to detect VF, shockable VT, or other shockable rhythms. According to the invention, the ARM uses outcome analysis to determine the most beneficial treatment option for the patient. These controller components 30 of the DSP and ARM therefore operate together with the ECG analyzer 32, as described in method steps 202 to 222 above. Of course, the scope of the invention is not limited to a specific DSP / ARM configuration. The above and following functions can be implemented equivalently in a single processor or distributed across multiple processors.

[0071] The ECG analyzer 32 incorporates an analysis algorithm capable of determining shockable rhythms in the presence of CPR-related signal noise artifacts with a sensitivity greater than approximately 70% and a specificity greater than approximately 95%. In the presence of CPR compression noise, the accuracy of the ECG analyzer is sufficient to safely and effectively assess the cardiac status of the input signal. One such analysis algorithm is ART as previously described.

[0072] If the ECG analyzer 32 determines a shockable rhythm based on the determination of a treatment plan indicating the need for a defibrillation shock, the processor 34, in response to the output of the ECG analyzer 32, sends a signal to the HV (high voltage) charging circuit 60 to charge the HV energy storage source 70 in preparation for delivering a shock. When the HV energy storage source 70 is fully charged, the processor 34 initiates... Figure 8 The shock button 92 on the user interface 818 begins to flash in order to redirect the user’s attention from the task of providing CPR compressions to the task of delivering electrotherapy.

[0073] As will be described in more detail, processor 34 is capable of immediately initiating preparation for defibrillation upon detection of a shockable cardiac rhythm (i.e., in continuous operating mode), and issuing a command to interrupt CPR compressions for electrical therapy once the device is equipped. Alternatively, processor 34 is capable of initiating preparation for defibrillation before the end of a predetermined period of CPR compressions, and issuing a command to simultaneously and immediately deliver electrical therapy at the end of the predetermined period. This last mode is referred to as scheduled mode.

[0074] In continuous or scheduled mode, the processor 34 controls the user interface 18 to issue audible cues to stop CPR and press the shock button to deliver a defibrillation shock. These cues should be issued together and in a rapid sequence to minimize the delay between stopping CPR and pressing the shock button. Similarly, the user interface 18 should issue audible cues via the audio speaker 20 to resume CPR as soon as possible after the processor 34 senses that a defibrillation shock has been delivered, for example by sensing button presses, current flow from the HV storage circuitry, etc., and corresponding visual cues can be issued simultaneously with the audible cues.

[0075] When the user presses the shock button 92 on the user interface 818, a defibrillation shock is delivered from the HV energy storage source 70 via the shock delivery circuit 80. In a preferred embodiment, the shock delivery circuit 80 is electrically connected via the output of the AED to the same electrode 16 that receives the raw ECG signal.

[0076] Processor 34 also provides control over the user interface (UI) output functionality of the device. User interface 18 is the primary means of guiding the user through the process of the cardiac rescue protocol and therefore includes at least one of auditory instruction output and visual display. Specifically, user interface 18 may include an audio speaker 20 to provide the user with auditory verbal or signal cues regarding the status of the rescue, instructions on the next steps to be taken in the rescue, or instructions in response to a determined shockable heart rhythm. User interface 18 may also transmit auditory information via a buzzer 24. User interface 18 may also provide visual text or graphic indications on display 22. User interface 18 may also transmit visual information via a flashing LED 26, which may illuminate adjacent graphics or buttons to be pressed. Preferably, processor 34 controls the user interface such that each of these cues is provided in a manner that optimizes the user's desired response. If one or more cues may diminish the desired response, it is not necessary to simultaneously issue auditory and visual cues related to the same information. For example, processor 34 may control the charging circuitry to fully charge the HV storage source to the equipment state before any instruction is fully issued. Alternatively, the processor 34 can drive the user interface to indicate the determination of a shockable heart rhythm on the visual display 22 before issuing relevant auditory commands on the speaker 20. And again refer to Figure 7 The processor 34 can drive the user interface to indicate the state of the HV charging circuit before issuing relevant auditory commands on the speaker 20.

[0077] Software instructions for operating the controller 30 are stored in the onboard memory 40. Instructions in the non-volatile memory may include algorithms for the ART algorithm, algorithms for PAS, instructions for CPR rescue protocols including the timing of CPR compressions, UI configurations for multiple user types, etc. Volatile memory may include embedded software recordings of device self-tests, device operation data, and audio and visual recordings of rescue events.

[0078] exist Figure 6 Other optional features of the defibrillator shown include a system monitor controller that receives signals from various buttons (e.g., power on, shock) and provides signals for a buzzer and LED. Changes in the state of the buttons and sensors are transmitted back to the processor 34 via a communication interface. This feature enables very low-power standby operation with wake-up sensing by means of button actuation and ready state output.

[0079] Figure 8 The illustration shows a structural embodiment of the user interface 818 on the outer surface of the AED 800, which roughly corresponds to... Figure 6User interface 18 of the functional block diagram. User interface 818 may include a visual display 802 that provides graphical and textual information related to the status of cardiac resuscitation. User interface 818 may also include a speaker 830 that emits auditory and audible cues. LED 840 may provide light-based signals for readiness or failure. User interface 818 may also include a first configurable button 854, a second configurable button 856, and a third configurable button 858, the functions of which change depending on the status of the resuscitation or the configuration of the device. The configurable button functions may also be indicated by context labels 804, 806, and 808 displayed on the visual display 802. For example, if the device is configured for advanced operating modes, the display 802 may indicate that the adjacent configurable button 854 is configured as an "Analyze" button 94. The Analysis button 94 can operate to truncate the ongoing resuscitation protocol. Truncation immediately terminates the CPR period and prepares the defibrillator for immediate delivery of electrical therapy. Embodiments of the Analysis button 94 and its function will be described in more detail below.

[0080] A preferred embodiment of the invention includes a defibrillator 10 operating with a CPR rescue protocol, characterized by the elimination of device-induced delay between the delivery of CPR compressions and the administration of shock. To achieve this, the aforementioned ECG analysis algorithm is incorporated, enabling accurate determination of shockable cardiac rhythms without inappropriate false alarms, even in the presence of motion-related signal noise caused by CPR compressions. ART is such an algorithm. ART allows for background detection of shockable cardiac rhythms, charging of the HV storage circuitry, and device preparation simultaneously with the application of CPR compressions. The defibrillator is then ready to deliver a shock simultaneously with the termination of CPR compressions.

[0081] Operating modes enabled by the method and apparatus of the present invention

[0082] The defibrillator described above can be configured with any of several different operating modes. As a result of the analytical method of this invention, novel operating modes become possible. These operating modes solve various new problems that may arise when the method of this invention is used in the device of this invention.

[0083] Each operating mode can be pre-loaded into the defibrillator memory 40. The device administrator or user can select the desired mode during device setup prior to cardiac intervention. A specific mode is selected based on local intervention protocols and / or the preferences of the local medical advisor.

[0084] Continuous CPR procedure

[0085] Figure 9The illustration shows one embodiment of a continuous CPR rescue operation mode 900. When the defibrillator is configured in continuous mode, the defibrillator's processor always initiates a defibrillation shock whenever the ART detects a VF and the processor makes a shock decision. In the context of the following description, the term "continuous" is considered to mean that defibrillation is administered immediately whenever a shockable rhythm is detected. This particular operation mode may also be referred to as a "custom analysis via CPR" mode.

[0086] At step 902, a continuous CPR rescue operation mode is entered, where the ART algorithm has begun evaluating the ECG buffer flow. CPR compressions may be underway at this point, but are not required for this mode. At step 904, the processor determines a shock decision, and if a "shock recommended" condition is determined, the processor begins preparing the defibrillator for delivery of electrical therapy. Therefore, this method is similar to... Figure 2b Continue as described in steps 215 to 222.

[0087] The recommended shock display step 915 can be initiated immediately upon confirmation, such as using visual graphics or text messages on the display, light signals, or mild audible signals. Preferably, the recommended shock display step 915 is provided even before the device is fully ready to deliver shocks, but in a non-intrusive manner that does not distract the user from continuing CPR until the device is ready to deliver shocks. On the other hand, there are operating modes in which it is preferable not to provide the user with any shock confirmation information until the equipment is ready to deliver shocks. Some inexperienced users may be unnecessarily disturbed or startled from delivering CPR simply by the indication that the device is ready to deliver shocks.

[0088] In response to the determination from decision step 904 that a shockable cardiac rhythm exists and that electrical therapy should be delivered, preparation step 916 is initiated. Preparation step 916 may include charging the high-voltage charging circuit with sufficient energy to defibrillate the patient. Preparation step 916 may include auditory and / or visual indicators indicating that preparation step has begun, as well as some indication of the progress of being fully ready for shock delivery at preparation progress display step 917. For example, dynamic bar graph markers 720 on visual display 700 may show the gradual filling of the bar graph corresponding to the increasing charging status of the high-voltage circuit. Text message 710 on display 700 may also indicate that charging is in progress. ECG display 730 may be displayed simultaneously on the charging status display along with the progress indicator. Figure 7 An exemplary embodiment of such a display 700 is illustrated.

[0089] Upon completion of setup step 916, the electrotherapy device is fully ready to deliver shocks. Preferably, an automatic user prompt 919 to stop CPR to deliver the electrotherapy occurs immediately after setup is complete. This can be signaled to the user to stop CPR immediately for shock delivery using auditory cues from speaker 830, an illuminated or flashing shock button light 820, and / or display indication 802. See [link to relevant documentation] for examples of these indicators on the user interface 818. Figure 8 In the case of an AED, the prompt may also instruct the user to press the shock button 892 to deliver a shock. In the case of a fully automated defibrillator, the shock is still delivered automatically immediately after the prompt occurs at step 919. A fully automated AED can use methods such as electrode impedance monitoring or analytical algorithms to determine the absence of CPR-related signal noise artifacts, to determine when the operator is no longer in contact with the patient, and to deliver a shock automatically accordingly. If the user is wearing electrically insulating gloves or other such protective gear, any prompt to “stop CPR” may optionally be omitted entirely at step 919.

[0090] Immediately following the delivery of electrotherapy, at step 922, the user should be prompted to resume CPR to minimize the release time. At step 920, the device may optionally be activated to detect the delivery of electrotherapy. Detection of delivery can be obtained by sensing a continuous current, button press, etc.

[0091] An optional step 924, verifying the completion of the shock set, can be performed after step 922 and before returning to the shock decision step 904. The shock set is a predetermined number of electrical shocks delivered within a period of time in a continuous CPR rescue operation pattern. The predetermined number of shocks can be set by the medical administrator according to local preferences. A preferred number of shocks in the shock set is three.

[0092] If the defibrillation completion check step 924 confirms that the defibrillation set is complete, then the method exits the continuous CPR rescue operation mode at exit step 926. Otherwise, the method continues to the continuous mode end decision step 906.

[0093] Step 906 determines whether the duration of the continuous operating mode has reached a predetermined time. The predetermined time can be one minute or two minutes, or it can be set by the medical administrator to another desired time based on local preferences. If the time has been reached, the method exits the continuous mode at exit step 926. Otherwise, the method returns to shock decision step 904 to continue analyzing the next(s) ECG buffer(s). The loop continues until one of the shock sets is completed or the continuous mode period is completed.

[0094] If the patient responds to shocks, or does not require shocks at all, the AED operated in continuous mode will be quietly analyzed in the background, while appropriate instructions will be provided periodically to check on the patient or continue CPR. The AED's shock delivery circuitry will not be unnecessarily charged, thus conserving battery power and extending operation time. This mode can be particularly beneficial during use in commercial aircraft, where cardiac resuscitation may sometimes be performed for extended periods during flight.

[0095] Figure 12 A diagram illustrating the information output provided during continuous CPR rescue operations is provided. The timeline 1200 includes three lines along a horizontal axis representing the time of cardiac rescue. The top line 1210 indicates the current status of the device. The middle line 1220 indicates the audible cues issued by the device in the current status. The bottom line 1230 indicates the display shown on the device's user interface in the current status.

[0096] At the start of a rescue operation in deployment state 1212, the electrodes may not yet be deployed. Preferably, in this state, auditory cues 1222 and visual displays 1232 are provided simultaneously to “apply pads” in order to emphasize instructions to the user to perform the necessary action.

[0097] After the electrodes are deployed, the device will sense that it is receiving an ECG signal and will enter a "analyze during CPR" state 1214. In this state, audio commands and timing signals 1224, as well as optional display information 1234, are provided to assist the user in providing effective CPR. During this time, the ECG analyzer and shock determination processor are running.

[0098] If the device detects a shockable heart rhythm, it enters a charging and preparation state 1216. However, unlike prior art devices, the device of this invention does not provide an audible alarm or only a very faint one, indicating a suggested shock and that the device is preparing itself to deliver treatment. Instead, CPR-related instructions continue at CPR state 1226. This feature is particularly useful for inexperienced users with little prior experience in cardiac resuscitation. By suppressing the audible cue of a suggested shock, the device prevents inexperienced users who might be concerned about a shock from prematurely stopping CPR. A non-intrusive display message indicating the charging status can be provided at charging display state 1236. Figure 12 The ongoing CPR and device charging status that can be seen can be displayed there in text, graphics, or a combination thereof.

[0099] An auditory cue for "delivering shock" is given to the user at state 1227 only when the device is equipped and ready to deliver a shock at state 1217. Simultaneously with the cue, at state 1240, the shock button illuminates or flashes to attract the user's attention to press the button. In this state, an auditory instruction such as "Stay clear of the patient, press the shock button now" is delivered.

[0100] After the shock button is pressed at state 1217, rescue is immediately resumed at post-shock state 1218. An auditory cue 1228 indicating "Resume CPR" is issued as quickly as possible after shock delivery, and an appropriate display instructing the user to resume compressions is given at 1238. The rescue cycle then returns to state 1214 until, or if another shockable rhythm is detected.

[0101] Scheduled operation mode

[0102] Scheduled CPR maneuvers are familiar to users of existing AEDs, but they actually operate in a significantly different manner. Unlike existing AEDs, AEDs operating in scheduled CPR maneuvers analyze the ECG even during CPR. However, in this scheduled CPR maneuver, the AED is prevented from prompting to stop CPR, regardless of the baseline sensed heart rhythm. Only after a predetermined, uninterrupted period of CPR has occurred will the device prompt the user to stop CPR and deliver a shock. The AED prepares the device for therapy immediately upon detecting a shockable rhythm or at an appropriate time before the end of that period, such that the device is ready to deliver a shock simultaneously with the end of the fixed period. This preparation preferably occurs in the background to reduce noise and confusion during CPR compressions. In the context of the following description, the term "scheduled" can be understood to mean: even if a shockable rhythm is detected during the period, defibrillation... treat The application was also postponed until the end of the scheduled period. This mode is also known as "analysis initiated via CPR".

[0103] Figure 10 An embodiment of a scheduled CPR rescue operation mode 1000 is illustrated. When the defibrillator is configured in scheduled mode, its processor delays initiating the defibrillation shock after the ART detects a VF and the processor makes a shock decision. Equipping the device with the delivered therapy is delayed until near the end of the predetermined period for uninterrupted CPR.

[0104] At step 1002, the scheduled CPR rescue operation mode is entered, where the ART algorithm has begun evaluating the ECG buffer flow as previously described. The AED may provide visual and auditory user cues via the user interface to apply CPR at this time, but this initial condition is unnecessary for this mode.

[0105] An ART evaluation of the ECG cache can be distinguished from the shock decision made from it. For example, in this scheduled CPR rescue operation mode, the individual ECG cache evaluation for "undetermined" or "suggested shock" at step 1002 for treatment delivery purposes can be ignored until the final part of the scheduled mode period. Alternatively, these evaluations can be accumulated and used later in the period used to make the decision.

[0106] At step 1004, the processor determines a shock decision. If step 1004 determines a “shock recommendation” condition, the processor begins the process of preparing the defibrillator for delivery of electrical therapy.

[0107] The recommended shock display step 1015 can be initiated immediately upon confirmation, such as using visual graphics or text messages on the display, light signals, or very faint audible signals. Preferably, the recommended shock display step 1015 is provided even before the device is fully ready to deliver shocks, but in a non-intrusive manner so as not to distract the user from continuing CPR until the device is ready to deliver shocks. On the other hand, there are operating modes in which it is preferable not to provide the user with any shock confirmation information until the equipment is complete. This is because some inexperienced users may be unnecessarily distracted or startled from delivering CPR simply by the indication that the device is ready to deliver shocks.

[0108] In response to the determination from decision step 1004 that a shockable cardiac rhythm is present and that electrical therapy should be delivered, equipment step 1016 begins. Equipment step 1016 may include charging the high-voltage charging circuit with sufficient energy to defibrillate the patient. Equipment step 1016 may include auditory and / or visual indicators indicating that equipment step has begun, as well as some indication of the progress of fully preparing for shock delivery at equipment progress display step 1017. For example, dynamic bar graph markers 720 on visual display 700 may show the gradual filling of the bar graph corresponding to the increasing charging status of the high-voltage circuit. Text message 710 on display 700 may also indicate that charging is in progress. ECG display 730 may be displayed simultaneously on the charging status display along with the progress indicator. Figure 7 An exemplary embodiment of such a display 700 is illustrated.

[0109] Note that the initiation of the equipment step 1016 can be timed so that the device reaches a fully equipped state at the end of the predetermined period of CPR and the uninterrupted period. This reduces the possibility of the CPR provider unintentionally delivering a shock. Regardless of when the equipment is started, the electrotherapy device is fully ready to deliver a shock upon completion of the equipment step 1016 and issues a command at that time.

[0110] After the equipment is prepared, delay step 1018 should be performed. Delay step 1018 is a predetermined period of time from the start of the scheduled mode, which ensures a complete and uninterrupted period of CPR before any possible electrotherapy delivery. The predetermined time can be one minute or two minutes, or can be set at any desired time by the medical administrator according to local preference. The preferred time period is two minutes, but it can also be in the range of thirty (30) seconds or longer.

[0111] After the delay step 1018 is completed, an automatic user prompt 1019 occurs to stop CPR for electric shock delivery. The user can be signaled to stop CPR for electric shock delivery using an auditory cue from speaker 830, an illuminated or flashing shock button light 820, and / or a display indicator 802. For examples of these indicators on the user interface 818, see [link to relevant documentation]. Figure 8 In the case of an AED, the prompt may also instruct the user to press the shock button 892 to deliver a shock. In the case of a fully automated defibrillator, the shock is still delivered automatically immediately after the prompt occurs, still at step 1019. If the user is wearing electrically insulating gloves or other such protective gear, any prompt to “stop CPR” may optionally be omitted entirely at step 1019.

[0112] Immediately following the delivery of electrotherapy, at step 1022, the user should be immediately prompted to resume CPR to minimize the release time. The device may optionally be enabled to detect the delivery of electrotherapy at step 1020. Delivery detection can be achieved by sensing a continuous current, button press, etc. Step 1020 can be used to generate a prompt to resume at step 1022. Alternatively, if step 1020 detects insufficient expected treatment delivery, the device can respond by repeating the prompt or by issuing a different prompt (not shown) indicating that no shock has been delivered and CPR should be resumed immediately. Then, at step 1026, the method exits the scheduled CPR rescue operation mode.

[0113] If the ART algorithm determines that the ECG is undetermined, it continues to evaluate subsequent ECG caches based on the shock recommendation decisions in the loop formed by decision step 1004 and exit decision step 1006. Exit decision step 1006 only determines whether uninterrupted CPR for a predetermined period has been completed before returning to analysis. If step 1006 determines that the period has been completed, then at step 1026, the method exits the scheduled CPR rescue operation mode. The uninterrupted CPR for the predetermined period at step 1006 may be the same as or shorter than the duration of the period at step 1018.

[0114] By employing the methods described above for scheduled modes and for patients who respond to electrical therapy or do not require it at all, the AED operated in scheduled mode will quietly analyze in the background while periodically providing appropriate guidance to continue CPR. The AED's shock delivery circuitry will not be unnecessarily charged, thus conserving battery power and extending operation time. This mode can also be particularly beneficial during use in commercial aircraft.

[0115] Existing cardiac rescue protocols require at least one brief confirmatory analysis and HV charging time after CPR is completed. In the absence of the delay between CPR and shock required in existing technology devices, scheduled mode AEDs offer a more efficient treatment. The steps of a scheduled mode of operation can be visualized as follows: Figure 2b The repeated loop of steps 214-222 in the middle, where, Figure 2a The analysis steps always occur in the background. The user prompt step 219 is always delayed at the delay step 218 until CPR compressions have been provided in a continuous and scheduled period.

[0116] Medical administrators prioritizing a high proportion of uninterrupted CPR in cardiac resuscitation may expect AEDs in scheduled patterns, rather than addressing VF conditions as quickly as possible. Fixed CPR schedules are also well-known to responders who prioritize consistent routines during resuscitation, such as shift changes of duties to prevent fatigue. However, the cost of consistent routines may be a delay in electrical therapy for patients with severe fibrillation.

[0117] In scheduled mode, the AED can issue auditory instructions and notifications in a manner distinct from visual instructions to maintain the consistency and "flow" of the CPR routine. For example, the AED can visually convey the shock decision and charging status only, preventing rescuers from being unnecessarily disturbed by auditory cues, which may include the distracting word "shock." As the CPR session nears its end, the AED may then issue instructions only regarding the detection of a shockable condition and the readiness to deliver shock. Then, at the end of the CPR session, the AED can issue both auditory and visual instructions to "stop CPR and deliver shock," while flashing the shock button 892. This guidance process thus minimizes the human delay between the end of CPR and the shock.

[0118] Figure 13 A diagram is provided showing the information output provided during a scheduled CPR rescue operation. The timeline 1300 includes three lines along a horizontal axis representing the time of cardiac rescue. The top line 1310 indicates the current status of the device. The middle line 1320 indicates the audible cues issued by the device in the current status. The bottom line 1330 indicates the display shown on the device's user interface in the current status.

[0119] The rescue status and auditory and visual cues in the pre-arranged CPR rescue operation patterns typically correspond to the continuous pattern in... Figure 12 Similar elements to those described above. However, there is a significant difference consistent with the nature of the scheduled CPR rescue mode. If the device determines that a shock should be delivered and is subsequently prepared to deliver it in charging and equipping state 1216, no additional audible or visual cues indicating that a shock should be delivered are provided until the uninterrupted CPR period 1350 has elapsed. The start of period 1350 coincides with the start of the session of CPR in state 1214 and may last for a predetermined time, such as two minutes. Only after the uninterrupted CPR period 1350 has elapsed does the device begin to issue audible and visual cues to deliver a shock in state 1217.

[0120] Continuous and scheduled patterns of electric shock sets

[0121] AEDs can also combine continuous and scheduled modes using protocols that alter the ratio of electrical stimulation opportunities to CPR compressions throughout cardiac resuscitation. The patient's response to these protocols can influence the switching between different operating modes. For example, if the patient is unresponsive to electrical stimulation, an AED operating in continuous mode may not allow sufficient uninterrupted CPR compression time; therefore, the AED may automatically switch to scheduled mode instead. If the patient repeatedly experiences severe fibrillation, it may be desirable for the AED to maintain or revert to continuous operating mode to address the situation more quickly.

[0122] exist Figure 11 The document describes a method of operating a CPR rescue protocol 1100 with a combination of shock sets. The combination method for providing electrical therapy during CPR includes step 1107, which involves automatically switching the protocol from a continuous CPR rescue protocol to a scheduled CPR rescue protocol after a predetermined number of shocks have been delivered during a continuous CPR rescue protocol period. A predetermined set of shocks delivered entirely within a single continuous CPR rescue protocol period is called a shock set. The combination mode method may also include automatically reverting from a scheduled mode to a continuous mode after a specific condition is met.

[0123] The combined approach begins at step 1102 and is generally understood to include providing a defibrillator having two or more external electrodes, a processor, a user interface, and shock delivery circuitry. Step 1102 begins when the device is deployed and activated and its electrodes are attached to the patient. The defibrillator may be a semi-automatic AED with a user-operated shock button, or it may be a fully automatic AED with automated shock delivery.

[0124] When first activated at step 1102, the AED can be configured to provide one of several initiation protocols or operating modes. The initiation protocol may be a “shock-first” protocol in which ECG analysis is performed immediately. If a shockable rhythm is present, the defibrillator is equipped to deliver a shock immediately. After the shock is delivered, the device continues with its rescue protocol. Alternatively, the initiation protocol or operating mode may be a “CPR-first” protocol, in which the AED guides the user through an uninterrupted period of CPR regardless of the baseline ECG rhythm. This second CPR-first initiation protocol is shown at step 1104 of the CPR initialization mode. At step 1104, a user prompt is automatically issued via the previously described device user interface to apply CPR compressions.

[0125] If the user properly follows the prompts in step 1104 to apply CPR, the ECG signal received by the device from the electrodes will be characterized by contamination from CPR compression noise artifacts. The aforementioned algorithm, such as ART, analyzes the received ECG signal to determine the presence of a shockable cardiac rhythm.

[0126] Before the device provides any guidance other than providing CPR compressions, initialization step 1104 may optionally include a predetermined period of time or an equivalent number of sensed compressions. It is believed that a short initial period (such as about 20 to 30 seconds or 30 compressions) is beneficial for some patients before delivering any electrical therapy. Initialization step 1104 exits to the initial ECG shock decision step 1106.

[0127] The initial ECG shock decision step 1106 is also an optional step related to the initialization step 1104. Step 1106 provides an initial shock decision, which determines which of several CPR rescue modes to use next. For example, if the initial shock decision at step 1106 is “undetermined,” it is preferable to begin regular, fixed-duration CPR compressions before any further electrical therapy. The method steps are as follows: Figure 11 The dotted line indicates that the procedure continues to the scheduled CPR rescue protocol step 1000. However, if the initial shock decision at step 1106 is "shock recommended," the method continues directly to the continuous CPR rescue protocol, as indicated by step 900.

[0128] The combined method 1100 continues at step 900, wherein the device begins operation in a continuous CPR rescue operation mode. This method is similar to the operation previously described for continuous mode, wherein, in response to a determination of a shockable cardiac rhythm in the analysis step, the processor equips a shock delivery circuit for delivering electrical therapy and then immediately issues a command via the user interface to stop CPR delivery. And as previously described, step 900 of the continuous mode method automatically terminates after the shock delivery circuit completes a predetermined set of therapeutic shocks of a predetermined number of shocks delivered within step 900. Alternatively, and as previously described, step 900 terminates if a shockable cardiac rhythm is consistently lacking for a predetermined time in the analysis step. Therefore, exit occurs in response to an early predetermined time or after the shock delivery circuit has delivered a predetermined number of therapeutic shocks. And as previously described, an alternative exit can occur in response to a sensed predetermined number of CPR compressions. Upon exiting, method 1100 automatically switches from operating in continuous mode at the automatic switching step 1107 to operating in the scheduled CPR rescue operation mode at the step 1000.

[0129] Method 1100 operates according to the scheduled operating mode as previously described in step 1000. Here, in response to the determination of a shockable cardiac rhythm in the analysis step, the device processor is equipped with the shock delivery circuit for delivering electrical therapy. After a predetermined period of uninterrupted CPR has elapsed, the processor issues a command via the user interface to stop CPR delivery. After the predetermined period has ended, scheduling mode 1000 exits to complete shock set determination step 1108.

[0130] Method 1100 tracks the cumulative number of shock sets completed at the previous step 900. Note that this number does not necessarily correspond to the number of times a continuous mode has been entered or exited at step 900, because step 900 may exit due to the expiration of a predetermined time period rather than due to the completion of a shock set. If the exit is caused by expiration, for example, the shock counter within step 900 is reset. Therefore, each time a continuous mode begins, another complete shock set or expiration of a predetermined time period is necessary for exit.

[0131] The shock set determines whether step 1108 is completed and whether method 1100 reverts to continuous CPR rescue protocol after exiting the scheduled CPR protocol. Reversion occurs unless a predetermined number of shock sets has been completed, corresponding to the number of times the patient exited continuous mode step 900 due to the completion of the shock set. If a reversion occurs, steps 900 and 1000 are repeated. The loop enabled by step 1108 repeats until the predetermined number of shock sets is completed. The preferred number of shock sets is three, but it can range from one to seven.

[0132] This cycle between continuous and scheduled modes is beneficial for patients requiring rapid electrical therapy early in the rescue effort, such as those with severe fibrillation. However, the cycle also allows for the evolution into a cardiac rescue sequence, providing an uninterrupted, full period of CPR between subsequent shocks within the sequence. Severe fibrillation patients who do not respond to rapid electrical therapy begin receiving full-duration CPR.

[0133] If the predetermined set of shocks has been completed, interruption step 1108 will halt further recovery. The method alternatively continues the scheduled CPR rescue protocol at step 1110. At step 1110, all subsequent electrical shocks will occur only between intervals of uninterrupted CPR, i.e., after each predetermined period of uninterrupted CPR. When CPR rescue is complete, method 1100 terminates by exiting at end step 1126, which can be initiated by manually turning off the device on a switch button.

[0134] Apparatus for alternating continuous method and arrangement method

[0135] Such as the above text Figure 6 and Figure 8 The AED shown can be operated according to any of the methods described above for interleaving CPR with electrotherapy. The AED is preferably controlled by a processor 34, which communicates with the ECG signal input unit 12, the user interface 18, the ECG analyzer 32, and the memory 40 to provide instructions to the user during cardiac resuscitation.

[0136] The processor 34 operates the AED, particularly in continuous CPR rescue operation modes and in sequences of scheduled CPR rescue operation modes, which is more beneficial to the patient than existing technology sequences. When operating in a continuous CPR rescue operation mode, and if the ECG analyzer determines a shockable heart rhythm, the processor equips the shock delivery circuitry for delivering electrical therapy and then immediately issues a command via the user interface to stop CPR for delivery. The AED processor immediately issues a command via the user interface to resume CPR once it senses the delivery of electrical therapy, minimizing "let go" time. When operating in a scheduled CPR rescue operation mode, and if the ECG analyzer determines a shockable heart rhythm, the processor equips the shock delivery circuitry for delivering electrical therapy. This equipping occurs immediately upon determination, or alternatively, charging begins promptly to be fully equipped at the end of the period. After a predetermined period of uninterrupted CPR (such as two minutes), the processor issues a command via the user interface to stop CPR for delivery.

[0137] The processor 34 also responds to the shock delivery circuitry that completes the predetermined set of electrotherapy shocks, after which the processor automatically switches from a continuous CPR rescue operation mode to a scheduled CPR rescue operation mode.

[0138] The AED can be configured such that each shock set includes a predetermined number of shocks delivered within a single instance of a continuous CPR rescue operation pattern. In a preferred embodiment, the AED can be programmable to be programmed with two to five shocks in each shock set.

[0139] The processor 34 is also operable to automatically revert the AED operating mode from the scheduled mode to the continuous mode after one or more instances of the scheduled CPR operating mode. Thus, a sequence of modes cyclically cycling between the continuous mode and the scheduled mode can be established. A preferred protocol is that the processor interrupts further reversion after the shock delivery circuitry has completed a predetermined number of shock sets. The AED then remains in the scheduled mode and delivers therapeutic shocks only between CPR intervals. In a preferred embodiment, the AED can be programmed to interrupt further reversion after one to seven shock sets have been completed. The AED can also be programmed to set the number of shock sets to infinity, so the cycle continues until the device is turned off.

[0140] An alternative embodiment of AED processor operation is that, if the "undetermined" duration is uncertain, the processor automatically switches from a continuous CPR rescue protocol to a scheduled CPR rescue protocol. This operation typically occurs near the start of the AED operation, such as at... Figure 11 The steps 1104 and 1106 are shown in the diagram. If no such determination continues, the processor will switch from continuous mode to scheduled mode according to the method described above.

[0141] Another embodiment of the AED uses the number of CPR presses sensed as a parameter, rather than the elapsed time. The number of CPR presses sensed can be obtained from one or more sources. Electrode noise artifact signals or common-mode current (CMC) can be used, or an external CPR sensing device, such as the Q-CPR device manufactured by Philips Electronics North America in Anduford, Massachusetts, or other similar sensors, can be used.

[0142] The AED and its operation described above can be implemented in semi-automatic or fully automatic devices. A semi-automatic AED naturally includes a user-operated shock button 92, and therefore should include corresponding instructions and indications for pressing the shock button where appropriate. A fully automatic AED will implement a slightly different set of instructions, which does not include instructions regarding the shock button, but it explicitly informs the user of the pending shock and instructs the user to avoid the patient if necessary.

[0143] Methods using two ECG analysis algorithms, such as ART and PAS.

[0144] The inventors have recognized that most patients do not have a shockable rhythm during cardiac arrest emergencies; therefore, any ECG analysis algorithm may operate for extended periods without providing a "shock recommended" determination. However, the inventors also recognize that the aforementioned ART algorithm is not as sensitive as PAS in detecting shockable cardiac rhythms. Therefore, ART has a higher probability of missing "truly positive" shockable rhythms during CPR. Similarly, the ART "indeterminate" determination does not distinguish between "non-shock recommended" (NSA) and "indeterminate" ECGs. For these reasons, periodically confirming ECG analysis using different ECG algorithms during CPR compressions may become important.

[0145] One solution to this problem would be to simply use PAS confirmation analysis periodically during rescue. However, this solution is not optimal because it may unnecessarily increase the total release time. Therefore, the inventors have recognized that PAS can be used for confirmation, but should be used as infrequently as possible, and only in cases where the release time would cause minimal harm to the patient. For example, this might be at the end of an additional scheduled period for CPR compressions.

[0146] Figure 14 The diagram illustrates a solution that reduces problems caused by unnecessarily interrupting CPR presses for confirmatory analysis. Figure 14 Similar to Figure 11 .but Figure 14The illustration shows a method modified to use both a first ECG analysis algorithm and a second ECG analysis algorithm. The first ECG analysis algorithm is exemplified by the previously described ART algorithm 200, which is particularly suitable for use in the presence of CPR-related signal-noise artifacts. The second ECG analysis algorithm is exemplified by the existing PAS algorithm, which is particularly suitable for use in the absence of CPR-related signal-noise artifacts.

[0147] Similar to Figure 11 The method, Figure 14 The illustration includes a method 1400 for providing electrical therapy during CPR. The method is activated at step 1102 in a defibrillator 1 having an ECG signal input section 12, a shock delivery circuit 80, and a user interface 18. The device and method also utilize two different ECG analysis algorithms. The first, like ART, is operable to determine one of “recommended shock” (SA) and “undetermined” based on the ECG signal in the presence of CPR-related signal noise artifacts. The second, like PAS, is capable of more specifically determining one of SA and “non-recommended shock” (NSA) based on the ECG signal in the absence of CPR-related signal noise artifacts. In step 1102, the defibrillator senses that the ECG signal input section 12 (such as electrodes) has been attached and is therefore ready to begin ECG analysis.

[0148] Figure 14 The method continues at step 1104 by analyzing the ECG signal using the first ECG analysis algorithm during the first time period to determine the presence of a shockable cardiac rhythm. Preferably, the defibrillator provides CPR guidance instructions in a scheduled CPR rescue operation mode during this time period. In the event of an SA determination, the defibrillator will prepare to deliver a shock at the end of step 1104. Additionally, the method continues at step 1406 based on whether the ECG signal indicates an SA determination or an "undetermined" determination. The preferred point for determination is at the end of the first time period, although the determination can also be based on the average or count of SAs over said time period, etc. Previously mentioned above relative to... Figure 11 Other aspects of steps 1102 and 1104 are described.

[0149] If the SA is determined during the first period of decision step 1406, the remaining steps of the CPR rescue procedure also correspond to... Figure 11The steps described in the method are as follows. Specifically, after SA determination, the heart rhythm is determined using a first ARTECG analysis algorithm during a second and successive period of continuous CPR 900 and scheduled CPR 1000. The subsequent SA determination enables the defibrillator to prepare for shocks according to the type of CPR period and issues CPR / shock delivery instructions. As previously described, a shock set can also be used to switch from a continuous CPR operation mode to a scheduled CPR operation mode. Thus, an optimized and customized rescue protocol is output from the defibrillator.

[0150] The second ECG analysis algorithm is employed only if any content other than the SA determination is determined in step 1406. If an "undetermined" determination occurs at step 1406, the method automatically switches from the first algorithm to the second algorithm at step 1407.

[0151] Following switching step 1407, the method employs the second ECG analysis algorithm (PAS) to analyze the ECG signal at PAS decision step 1410. Preferably, the defibrillator issues a user prompt at this step to “stop CPR” and / or “do not touch the patient,” enabling the PAS algorithm to analyze effectively in a low-noise environment. Two possible outcomes of PAS decision step 1410 are SA or “not recommended for shock” (NSA). PAS may also issue “artifact” decisions, which are not the subject of this invention and will not be discussed further.

[0152] The determination of SA in step 1410 of the PAS decision indicates that the ECG may present a shockable rhythm at or near the onset of the event (i.e., at step 1102), but the first algorithm failed to detect this. It is preferable to equip and deliver electrotherapy immediately after the SA determination at this step.

[0153] Evidence suggests that patients with an ECG rhythm presenting as an SA may benefit from receiving more electrical therapy earlier in the rescue. Therefore, the SA determination in step 1410 by PAS also triggers an automatic switch back to the first ECG analysis algorithm in the continuous CPR rescue protocol 900, which rapidly delivers electrical therapy after detecting a shockable rhythm. The continuous CPR rescue protocol 900 then operates as previously described.

[0154] However, the NSA determination at step 1410 indicates that the presented ECG is not shockable. Such patients can benefit from earlier, more CPR compressions during rescue. Therefore, the NSA determination by PAS at step 1410 causes an automatic switch back to the first ECG analysis algorithm in the scheduled CPR rescue protocol 1000, which delivers a greater relative amount of CPR. The scheduled CPR rescue protocol 1000 and the remainder of the cardiac rescue method operate as previously described.

[0155] Preferably, the duration of each segment of the PAS second ECG analysis algorithm operation is as short as possible, because it is highly desirable for the rescuer to "let go" during the analysis. A typical PAS analysis segment is less than about ten seconds, although it can be as short as four seconds. In most cases, this duration is shorter than the duration of a continuous CPR pattern or scheduled CPR pattern using the first ART algorithm. For the same reason, the frequency of PAS segments is also preferably as low as possible. Therefore, the method steps require switching to "let go" PAS analysis only when necessary.

[0156] exist Figure 15 The figure shows alternative and more detailed views of the method of the present invention. Figure 15 The method more clearly illustrates how electrical therapy is provided with minimal interruption to CPR, even after the initial ART algorithm period of CPR 1504. After the defibrillator is activated and electrodes are applied at step 1102, the initialization period at step 1504 begins immediately, including prompting for the application of CPR compressions and the use of the first ECG analysis algorithm. Step 1504 is preferably a scheduled CPR rescue operation mode with uninterrupted CPR, regardless of ART rhythm determination. Step 1504 is even more preferably a relatively short duration of about 20-30 seconds, or sufficient time to apply a minimum of about 30 CPR chest compressions. The method can sense the number or duration of chest compressions, after which a final ART rhythm determination is performed at step 1506. Therefore, at the start of rescue, step 1504 provides the benefit of a period of uninterrupted chest compressions for all patients.

[0157] If SA is indicated at decision step 1506, the method immediately proceeds to the equipment for electrotherapy step 1507 to allow delivery of therapeutic shocks. Following step 1507, the method enters a second period, a continuous CPR rescue mode protocol 900, which continues as previously described. The duration of the second period 900 can be approximately two minutes, but can also be configurable before device activation. The method then proceeds to the continuous mode termination decision step 1509.

[0158] If an SA determination exists at step 1509, the method is as previously described for... Figure 11The procedure continues as described. The procedure enters the equipment for electrotherapy step 1511 to allow delivery of therapeutic shocks. Then, at step 1000, the operating mode with the first ART algorithm automatically switches to the scheduled CPR rescue operating mode. As previously described, step 1000 continues by prompting the user with CPR instructions while analyzing the ECG rhythm in the background and by delaying any actions from the SA determination to the end of the time period. The scheduled time period 1000 can be approximately two minutes in duration.

[0159] If an SA determination is made at the end of step 1000, i.e., at decision step 1519, the method proceeds to the equipment for electrotherapy step 1521 to allow the delivery of therapeutic shocks. After the delivery of shocks, if the shock set has not been completed at check step 1108, the method may cycle back to continuous mode step 900. If the shock set is completed, the method switches to terminating the scheduled CPR rescue protocol at step 1110, where it remains in this state until the rescue is completed at step 1126.

[0160] from Figure 14 and Figure 15 As can be seen, the method continues as long as the SA state can be determined by the first ART algorithm, without requiring a second PAS analysis. Therefore, the method minimizes the "hands-off" time required for PAS.

[0161] However, if the first ART algorithm determines an "undetermined" state at any of the decision steps 1506, 1509, and 1519, the method automatically switches to the second PAS algorithm at the corresponding steps 1520, 1530, and 1540 for further determination. Steps 1520, 1530, and 1540 issue a "release" command and then analyze the ECG. These PAS periods can be short durations of 10 seconds or less to minimize the "release" time.

[0162] As in Figure 15 As can be seen, if any of the PAS analyses determines to be SA, then steps 1522, 1532, and 1542 immediately return the method to the corresponding starting point (i.e., after step 1506, step 1509, or step 1519) of the first ART algorithm sequence. The reason for this path is that ART analysis is generally superior to PAS analysis due to the overall reduced let-go time. Therefore, the method should switch back to ART when possible.

[0163] exist Figure 15As also seen, if the PAS analysis determines that any of the signals are NSA, the method automatically switches back to the first ART algorithm operating in the scheduled CPR mode at step 1000. The reason for this approach is that the PAS has confirmed that the ECG exhibits an unshockable rhythm, and therefore, for such patients, uninterrupted CPR is more beneficial.

[0164] Optional step 1523, following any NSA PAS determination, sets the current shock set to complete. This optional step thus moves method 1500 closer at step 1110 to the transition to the terminated and permanently scheduled CPR rescue operation mode at step 1108. The reason for this is that the inventors found that ultimately transitioning to a higher proportion of CPR-shocks in the scheduled mode may be more beneficial for patients who were indicated with an NSA ECG rhythm earlier in the rescue.

[0165] A device that interleaves PAS and ART algorithms in continuous and scheduled operation modes.

[0166] Such as the above text Figure 6 and Figure 8 The AED device shown can be operated according to any of the methods described above to interleave CPR and electrotherapy while incorporating two different ECG analysis algorithms. The AED is preferably controlled by a controller 30, which includes a processor 34 and an ECG analyzer 32. The controller 30 communicates with the ECG signal input unit 12, the user interface 18, and the memory 40 to provide instructions to the user during cardiac resuscitation. The controller 309 also controls communication with the electrotherapy delivery circuit 80.

[0167] Memory 40 stores instructions related to both a first ECG analysis algorithm and a second ECG analysis algorithm. The first ECG analysis algorithm is used to determine one of "recommended shock" (SA) and "undetermined" based on the ECG signal in the presence of CPR-related signal noise from the input. The second ECG analysis algorithm is used to determine one of "SA" and "non-recommended shock" (NSA) based on the ECG signal in the absence of CPR-related signal noise artifacts from the input. Memory 40 also stores instructions related to a CPR rescue protocol including at least two periods for providing CPR compressions.

[0168] The controller 30 operates the AED specifically in a continuous CPR rescue operation mode and in a scheduled sequence of CPR rescue operation modes, as previously described. Additionally, the controller 30 issues instructions via the user interface 18 and automatically prepares the shock delivery circuit 80 for delivering electrical therapy in response to an SA determination from either the first ECG analysis algorithm or the second ECG analysis algorithm. Finally, since the first ECG analysis algorithm may have lower sensitivity to shockable ECG rhythms during periods with CPR-related noise, the controller 30 can also automatically switch from the first ECG analysis algorithm to the second ECG analysis algorithm at the end of any determined period other than the SA determination, which is always within its duration. Therefore, the use of the second ECG analysis algorithm, which requires a suboptimal "let go" time for patients with cardiac arrest, is only employed when necessary.

[0169] Other aspects of the AED's device behavior reflect the previously described method. For example, if an SA (Severe Acute Respiratory Syndrome) is determined after automatically switching from the first ECG analysis algorithm to the second ECG analysis algorithm, the AED controller can automatically switch back to the first algorithm and automatically switch back to the scheduled CPR rescue operation mode. On the other hand, if an NSA (Non-Stage Ankylosis) is determined after automatically switching from the first ECG analysis algorithm to the second ECG analysis algorithm, the AED controller can automatically switch back to the first algorithm and automatically switch back to the scheduled CPR rescue operation mode.

[0170] The second ECG analysis algorithm can be the PAS algorithm, which can characterize the ECG rhythm in less than 10 seconds. Therefore, the duration of each period of the PAS operation should not exceed this duration.

[0171] An AED may functionally include an initialization period that occurs immediately after activation and while receiving ECG signals. This initialization period includes a scheduled CPR rescue operation mode using the first ECG analysis algorithm, wherein the scheduled CPR rescue operation mode provides uninterrupted CPR for a predetermined period, regardless of determination. The length of the initialization period may be relatively short compared to subsequent rescue protocol periods. For example, the initialization period may end at the point where approximately 30 CPR compressions have been sensed, and in existing CPR protocols, this would be completed in less than 30 seconds. Alternatively, the initialization period may be predetermined to a duration between approximately 20 and 30 seconds.

[0172] The AED and its operation described above can be implemented in semi-automatic or fully automatic devices. A semi-automatic AED naturally includes a user-operated shock button 92, and therefore should include corresponding instructions and indications for pressing the shock button where appropriate. A fully automatic AED will implement a slightly different set of instructions, which does not include instructions regarding the shock button, but explicitly informs the user of a delayed shock and, if necessary, instructs the user to avoid the patient.

[0173] Analysis button for truncating CPR

[0174] There may be situations where experienced users want to interrupt an ongoing AED protocol to quickly switch to another operating mode, and especially to deliver a defibrillation shock more rapidly. This invention simplifies the interruption process by providing a single button. Based on fundamental ECG analysis, the AED automatically selects the button press response that is most beneficial to the patient.

[0175] The defibrillator (AED) and the method of using it are incorporated into a user-activated button that interrupts the ongoing or otherwise uninterrupted CPR compressions to immediately execute different defibrillator-related functions. This interruption button is particularly useful in the previously described scheduled CPR rescue operation mode 1000. Therefore, this operation is simpler for the user, reduces the possibility of errors in protocol adherence, and minimizes delays caused by confusion during an event.

[0176] An exemplary AED with a cutoff feature can use two different ECG analysis algorithms with varying sensitivities to shockable cardiac rhythms. Pressing the cutoff button can automatically switch from the first ECG analysis algorithm to the second, more sensitive one. The button can also allow the ongoing analysis and CPR to be interrupted immediately in preparation for electrical therapy if a basic shockable cardiac rhythm has been detected.

[0177] Even when the cutoff button is activated, the AED and method reduce the release time between CPR compressions and electrotherapy. By way of example, if a baseline ECG analysis indicates a shockable rhythm, the AED can be charged in the background for treatment, while the cutoff button indicates "Charging" or "Analysis". Therefore, if the user presses the cutoff button, the AED can be immediately ready to deliver electrotherapy.

[0178] An AED with the control features described above modifies its response to a sensed press of the cutoff button based on the current state of the patient's ECG. If the AED determines that the underlying ECG is shockable, it may change the context label of its button to "Charging". When the AED senses that the cutoff button has been pressed, it immediately charges to deliver a defibrillation shock. If the ECG is not shockable, the button label may instead appear as "Analyzing". Pressing the same button will cause the AED to immediately switch from a first ART algorithm to a second PAS algorithm to confirm the current state. Alternatively, a sensed cutoff button press may immediately prompt the AED to "Avoid Patient" to increase the sensitivity of the current ART algorithm analysis.

[0179] By also periodically referencing Figures 17a to 17d The specific visual display and cutoff button shown can help to better understand Figure 16 The method steps are shown. Figure 17a , Figure 17b , Figure 17c and Figure 17d Various graphic displays 1706, 1714, 1718 and 1728 corresponding to AED visual displays such as visual display 802 are shown. Figure 17a Each image in -d shares a common layout. One or more guidance and informational messages are displayed in the upper banner area. Progress bars, such as CPR progress bars, may be placed adjacent to the upper banner area. At the center of the display is an area for showing the ongoing ECG trace or guidance graphic for placing electrodes, hands for CPR on the chest, etc. The bottom portion of the display preferably includes context labels, exemplified by context labels 804, 806, which can be changed based on the specific operating status of the defibrillator and the underlying ECG analysis.

[0180] In a preferred embodiment, input buttons 854 and 856 are positioned adjacent to displays 1706, 1714, 1718, and 1728, respectively, and are also adjacent to context labels 804 and 806, respectively. In an alternative embodiment, the visual display 802 may be a touch-sensitive display, such that input buttons 854 and 856 are effectively located below their respective context labels 804 and 806.

[0181] Turn now Figure 16The flowchart illustrates an exemplary method 1600 for interrupting CPR for the purpose of providing immediate electrical therapy. The method begins at step 1602 with a defibrillator featuring characteristics that work in conjunction with the method to perform it. Specifically, the defibrillator includes an ECG signal input unit 12, a user interface 818 including an input button 854 and a visual display 802, a shock delivery circuit 80, and a first ECG analysis algorithm operable to determine a shockable cardiac rhythm based on the ECG signal in the presence of CPR-related signal noise artifacts from the input unit. A defibrillator such as the AED 800 is merely one example of the device provided.

[0182] The AED 800 can include several different operating mode configurations pre-configured before use. Any or all of these modes can be stored in the AED memory 40. Exemplary operating modes are Advanced Mode, Pre-CPR Mode, and Semi-Automatic Mode. The possible actions that may occur with the cut-off button may vary slightly for each operating mode.

[0183] Advanced mode is a protocol that allows responders greater control over when the AED initiates ECG rhythm analysis and the equipment used for shock delivery. For example, advanced mode can be configured to provide "ANALYZE" and / or "CHARGE" option buttons at specific times during the protocol. Pressing the "ANALYZE" option button initiates immediate release analysis using PAS. Pressing the "CHARGE" button allows one or more of the following: release analysis, charging of the high-voltage energy storage source 70, and shock delivery.

[0184] After the AED 800 is activated and begins receiving ECG signals from input unit 12, it begins analyzing the ECG signal using a first ECG analysis algorithm (ART) during an optional initial period 1604. The initial period 1604 is preferably similar to step 1104, operating in an uninterrupted CPR compression mode as previously described. However, during this short initial period 1604, the cutoff button may be active to immediately switch from CPR compressions to ECG analysis or equipment used for electrotherapy. The reason for activating the cutoff button at period 1604 is to allow the operator to recognize that sufficient CPR has been provided before the AED arrives and is activated.

[0185] The visual display during the initial time period 1604 preferably corresponds to, as in Figure 17aThe “Analysis - Undetermined” screen 1706 is shown. The AED displays a context label for “Analysis” adjacent to the cutoff button 854. If the operator wishes to cut off the initial compression period for analysis, she presses the cutoff button 854. When the AED senses the button press, it immediately issues a “Avoid Patient” user prompt and begins ECG analysis using the 2PAS ECG analysis algorithm. During this time, the AED can display data from… Figure 17c The “Analysis - Avoid” screen 1728.

[0186] Tagging step 1606 follows optional step 1604. Tagging step 1606 sets the initial context tag corresponding to the previously analyzed ECG at the beginning of ART analysis period 1608. Preferably, the AED displays an "Analysis - Undetermined" screen 1706 to establish the next steps in the protocol.

[0187] The first analysis phase step 1608 follows the labeling step 1606. Step 1608 includes the device analyzing the ECG signal using a first (ART) ECG analysis algorithm, preferably in an uninterrupted scheduled CPR pattern. Therefore, step 1608 includes the defibrillator issuing audible and / or visual cues to continue CPR compressions. During this phase, the analyzed ECG signal will be "undetermined" or "shock recommended" as indicated at decision step 1610. Similarly, during this first analysis phase, the defibrillator controller 30 begins monitoring for activation of input button 854.

[0188] As in Figure 16 As can be seen, the subsequent steps in method 1600 depend on the ECG signal obtained from the baseline analysis. If the decision at steps 1608 and 1610 is "recommend shock," the left branch of the method continues. The AED can change the upper part of display 1706 to indicate guidance text at step 1612. Information messages such as "recommend shock" and / or as shown in... Figure 17b The "Cut Off Available-Shockable Rhythm" screen 1714 may display a prompt message indicating "Press the Analysis Button". Alternatively, a prompt message such as "Press the Analysis Button" may appear. Figure 17d The instruction message "Press the charging button" shown on the "Truncate Available - Charging" screen 1718. Auditory guidance at this step 1612 is also possible, but is less preferred than visual guidance alone to prevent undue disruption to the task of providing CPR. Alternatively, step 1612 may include issuing an auditory instruction to truncate button activity.

[0189] The "recommended shock" decision at step 1610 can also initiate a change to context label 804 at context label change step 1614. Context label 804 can be changed from an "analysis" indication to a "charging" indication. Alternatively, as in Figure 17b As seen in the image, a "Charging" context label / button combination and an "Analysis" indication at the second context label 806 adjacent to the second configurable button 856 can be displayed. The AED can then initiate background charging of the HV energy storage source 70 at background charging step 1616.

[0190] If the analyzed ECG signal indicates a shockable rhythm, the AED monitors for cutoff button activation at sensing step 1618. If no activation occurs, method 1600 simply loops back to analysis step 1608 to continue monitoring during that period.

[0191] If the AED detects cut-off button activation at sensing step 1618, the AED immediately proceeds to the equipped shock delivery state. If necessary, charging of the HV energy storage source 70 is completed at charging step 1620, and the shock button is equipped at equipped step 1622. Appropriate visual and auditory cues are provided during this process to guide and notify the user.

[0192] Some users prefer to omit the background charging of the HV circuit whenever CPR is applied. Therefore, the AED can be pre-configured to omit the background charging step 1616. In this configuration, when the AED senses button activation at sensing step 1618, it immediately proceeds to the charging state of the shock delivery circuit at charging step 1620. The AED then equips itself to deliver a shock at equipping step 1622.

[0193] Exit step 1624 exits the method after the AED has been equipped. After exiting step 1624, other methods can continue, such as looping back to step 1608, entering different protocols, etc.

[0194] If the decision at steps 1608 and 1610 is "undetermined," the right branch of the method continues. "Undetermined" is a determination other than shockable rhythms, including non-shockable rhythms and indeterminate rhythms. The first ECG analysis algorithm may also be unable to distinguish between shockable and non-shockable cardiac rhythms, especially in the presence of CPR-related signal noise, and will therefore return an indeterminate "undetermined" decision. The AED preferably displays an "Analysis-Undetermined" visual display 1706, an "Analysis" context label 804, and active monitoring of a pressed cutoff button 854 sensed in this state. The cutoff button sensing step 1626 actively monitors for a sensed cutoff button press without requiring further prompting to the operator. At sensing step 1626, if no pressed is sensed, the process simply loops back to analysis step 1608 to continue monitoring.

[0195] When the AED senses the cut-off button pressed at sensing step 1626, the method immediately interrupts the ongoing CPR compression protocol by ignoring the patient's visual and auditory cues. Figure 17c The “Analysis-Avoid” screen 1728 can be displayed at prompting step 1630, along with corresponding instructions to “Avoid Patient” for further ECG analysis. An auditory prompt can also preferably be issued at prompting step 1630.

[0196] In a preferred embodiment, the AED is provided with a second ECG analysis algorithm (PAS). At analysis step 1628 and after a “avoid” prompt has been issued from step 1630, the second ECG analysis algorithm analyzes the ECG to determine whether the heart rhythm is shockable or not. If the PAS determines “shock recommended,” i.e., a shockable heart rhythm, the method automatically begins charging and equipping the shock delivery circuitry at charging / equipping step 1634 for immediate shock delivery. Exit step 1636 exits the method after the AED has been equipped. After exit step 1636, other methods can continue, such as looping back to analysis step 1608, equipping for additional shocks, entering a different protocol, etc.

[0197] If the PAS determines "shock not recommended" at analysis steps 1628 and 1632, the AED transmits the result and corresponding instructions to the user at prompting step 1638. Preferably, auditory and visual instructions are provided to restart CPR. ECG analysis is also restarted at analysis step 1608 using the first ECG analysis algorithm.

[0198] An alternative embodiment of the right branch of method 1600 is to continue using the first ECG analysis algorithm after the "avoid" prompt at step 1630. The increased sensitivity of the first algorithm during quiet periods allows for the detection of shockable rhythms after eliminating CPR noise signal components. Therefore, analysis step 1628 can be used with the first ECG analysis algorithm instead of the second ECG algorithm. Subsequent steps 1632, 1634, 1636, and 1638 can be similar to those previously described in this embodiment.

[0199] An AED with the components described above can employ the method described above, which includes a cutoff button. Accordingly, the AED must include a controller 30, which is operable to set the defibrillator's operating state in response to both a sensed actuation of the input cutoff button 854 and a baseline-analyzed ECG signal.

[0200] Depending on the device configuration, the AED response to a sensed press of the analysis option button can vary slightly. For example, Table 1 illustrates the button's function during various configuration types and basic ECG states:

[0201] Table 1

[0202]

[0203]

[0204] Electric shock decision cancellation logic

[0205] In one embodiment, the ECG analysis algorithm of the present invention evaluates three sequential ECG data buffers, each approximately 3.5 seconds long, to assess heart rhythm for shock determination. In an AED ECG analyzer, this is a continuous process during programmed CPR intervals, with a new determination based on the previous three buffers every 3.5 seconds. The AED incorporates a '3-in-1' rule for shock determination. A 'recommended shock' decision from the three sequential buffers is required to result in a 'recommended shock' determination. The '3-in-1' rule reflects a specific design philosophy emphasizing specificity. Any single buffer not being shocked prevents a shock determination, thus increasing the '3-in-1' specificity relative to a single buffer. Similarly, the '3-in-1' sensitivity is reduced relative to a single buffer because any single non-shock result prevents a shock determination.

[0206] Once a shock recommendation has been made, the system enters the shock recommendation state. Once in the shock recommendation state, the AED processor exits or cancels the state using a '3-in-1' rule. In one embodiment, a decision is required from three sequentially cached "shock recommendations." This rule reflects the high probability of a truly shockable heart rhythm once a shock recommendation has been made.

[0207] How an AED responds to a shock withdrawal decision depends on which operating mode is then used by the processor. As previously described, analysis via CPR can be configured to be "on," resulting in a scheduled response determined by the ECG analyzer (ART); or it can be configured to be "custom," allowing an immediate response to an ART shock determination.

[0208] Figure 18aThe diagram illustrates the sequence of ART decisions at ECG data buffers 1810, 1812, 1814, 1816, 1818, and 1820 in a scheduled CPR operating mode. During this scheduled mode, the responder is typically instructed to perform CPR throughout the timed CPR interval. The AED is analyzed continuously but does not respond to shock determinations until the end of the programmed CPR interval. This operating mode provides improved sensitivity by analyzing throughout the entire CPR interval rather than just at the end, and it also improves specificity by allowing withdrawal of false positive shock determinations at 1830. The transition to recommended shock and withdrawal is based on the '3-line rule,' indicated by the "NS" decision at 1816, 1818, and 1820, as explained above. At the end of the interval, if the FR3 detects a shockable rhythm, it automatically charges and is ready to deliver a shock immediately without requiring confirmation of the necessary release analysis. A new CPR interval is initiated immediately after shock delivery. If the analysis of CPR does not recommend a shock decision at the end of the timed CPR interval, the responder is prompted to stop CPR, and the AED can automatically and arbitrarily run a release analysis using different ECG analysis algorithms to determine whether a shock is recommended.

[0209] Figure 18b A custom configuration for analysis via CPR is shown, allowing the FR3 to dynamically respond to the patient's heart rhythm during a specified basic CPR interval (response CPR interval). During the response CPR interval, the AED responds to detected shockable heart rhythms by charging (based on the '3-in-1 rule' explained above) and is equipped for immediate shock delivery without waiting for the end of the CPR interval and without requiring confirmation of release analysis. This allows the AED to provide early detection of shockable heart rhythms (such as defibrillation) and exit the CPR interval for defibrillation treatment before the CPR interval is completed. Once a recommended shock decision is made, the AED processor prevents the revocation of the shock decision regardless of the outcome of subsequent ECG data segmentation analysis. Figure 18b What we see are examples of ECG data caches 1816, 1818, and 1820 all indicating decisions other than "recommended electric shock". In any case, the revocation of the electric shock decision is prevented in 1840.

[0210] Once equipped, the AED remains in equipped operating mode until a shock is delivered, or for example, for thirty (30) seconds, after which the AED processor deequips the AED, exits equipped operating mode, and restarts the ECG analysis. The ECG analysis is preferably paused during the 30-second equipped period, allowing the user flexibility in delivering the shock. For example, CPR can continue with a set of 30 compressions without risking the cancellation of the equipped status due to a false negative algorithm determination. CPR can be resumed immediately after a shock delivery during a new CPR interval. The pause in CPR only needs to be long enough to ensure safe delivery of the shock. It should be noted that the AED processor follows this procedure so that a response protocol is only provided during the CPR interval following shock delivery when the likelihood of defibrillation is highest. If a shockable determination is not made during the CPR interval, a release analysis can be prompted at the end of the CPR interval. Thus, the defibrillation capability of the patient is at least equivalent to being able to disengage the AED.

[0211] Figure 19 The effect of the previously described method and apparatus on the cumulative sensitivity of the ECG analysis algorithm used during the CPR compression period is graphically illustrated 1900. It can be seen that the decrease in sensitivity experienced during long-term analysis during CPR can be partially mitigated by allowing shock withdrawal. For analysis during consecutive CPR operating modes where shock withdrawal is not permitted, the cumulative sensitivity 1910 no longer degrades after the first shock decision because the AED processor prevents further withdrawal during the CPR period until the shock is delivered from the equipment operating mode or until the equipment operating mode times out.

[0212] Figure 19 The results are also illustrated if the operation is performed in a pre-defined operating mode where shock withdrawal is permitted. For analysis during a pre-defined CPR operating mode where shock withdrawal is permitted, the cumulative sensitivity of 1920 is slightly improved after the shock decision is withdrawn because the AED processor allows the shock withdrawal decision. This operating mode will not indicate an interruption of CPR until the end of the period, so the effect of shock withdrawal will not distract the user. Therefore, this AED and method are adapted to situations where the cardiac rhythm spontaneously reverses to a structured (i.e., non-shockable) ECG rhythm during the CPR compression period, and the appropriate "not recommended shock" determination is effective at the end of the CPR compression period.

[0213] Modifications to the devices, methods, and displays described above are covered within the scope of this invention. For example, various configurations of user interface displays and auditory indicators for achieving the objectives of the described invention fall within the scope of the claims.

[0214] Component table

[0215]

[0216]

[0217]

[0218]

[0219]

[0220]

[0221]

Claims

1. An automated external defibrillator (AED) for use during cardiopulmonary resuscitation (CPR), comprising: ECG signal input section (12); User interface (18) having at least one of an auditory command output unit and a visual display; Electric shock delivery circuit (80); An ECG analyzer (32) communicates with the input unit and is operable to determine a shockable heart rhythm in the presence of signal noise artifacts related to cardiopulmonary resuscitation (CPR) from the input unit; A memory (40) for storing instructions related to a cardiopulmonary resuscitation (CPR) protocol, the CPR protocol including both a continuous CPR procedure and a scheduled CPR procedure; and The processor (34), which communicates with the shock delivery circuit, the ECG analyzer, and the user interface, is operable to operate the automated external defibrillator (AED) in a continuous cardiopulmonary resuscitation (CPR) rescue operation mode and a sequence of scheduled CPR rescue operation modes, and is also operable to issue commands to the user via the user interface. When operating in the continuous cardiopulmonary resuscitation (CPR) rescue mode and if the ECG analyzer determines a shockable heart rhythm, the processor is equipped with the shock delivery circuitry for delivering electrical therapy, and then immediately issues a command via the user interface to stop the CPR delivery. Furthermore, when operating in the pre-defined cardiopulmonary resuscitation (CPR) rescue mode and if the ECG analyzer determines a shockable heart rhythm, the processor is equipped with the shock delivery circuitry for delivering electrical therapy, and then, after a predetermined period of uninterrupted CPR, a command is issued via the user interface to stop the CPR delivery. Furthermore, the processor is operable to allow automatic revocation of the decision only if the processor is operating in the scheduled cardiopulmonary resuscitation (CPR) rescue mode.

2. The automated external defibrillator (AED) according to claim 1, wherein, The ECG analyzer: The ECG signal is segmented into multiple time-sequential segments of ECG data; The first set of ECG data segments were analyzed to determine the recommended shockable heart rhythm. The second analysis involved a subsequent and successive set of ECG data segments to determine the heart rhythm other than "recommended shock"; and The decision to "recommend electric shock" to shock the heart rhythm is revoked based on the operation of the second analysis.

3. The automated external defibrillator (AED) according to claim 2, wherein, The processor is also operable to operate the automated external defibrillator (AED) in an equipped operating mode characterized by an activated shock delivery circuit, and furthermore, the processor is operable to prevent any withdrawal decision when the operating mode is an equipped mode.

4. The automated external defibrillator (AED) according to claim 3, wherein, The processor is operable to pause the second analysis during the equipment operation mode.

5. The automated external defibrillator (AED) according to claim 3, wherein, The processor is operable to maintain the automated external defibrillator (AED) in the equipment operating mode for a fixed duration, after which the processor terminates the equipment operating mode.

6. The automated external defibrillator (AED) according to claim 5, wherein, The fixed duration is thirty (30) seconds.

7. The automated external defibrillator (AED) according to claim 1, wherein, If the operating mode is the continuous cardiopulmonary resuscitation (CPR) rescue operating mode, the processor prevents the automatic revocation of the decision.

8. The automated external defibrillator (AED) according to claim 2, wherein, The subsequent and successive set of ECG data segments consists of three ECG data segments.

9. The automated external defibrillator (AED) according to claim 1, wherein, The processor is operable to issue a user prompt at the user interface, the user prompt indicating the cancellation decision.

10. A computer program product comprising software instructions that, when executed by a controller, perform a method for canceling an electric shock determination of an automated external defibrillator (AED), the method comprising the steps of: Each ECG data segment in the temporal sequence of ECG data is analyzed to determine the "recommended shock" cardiac condition, wherein the temporal sequence of ECG data is sensed from multiple electrodes in communication with a defibrillator having both a continuous CPR rescue operation mode and a scheduled CPR operation mode, and the defibrillator operates in one of the continuous CPR rescue operation mode and the scheduled CPR operation mode. The second analysis examines multiple subsequent and successive ECG data segments to determine conditions beyond the "recommended shock" in each segment; and The determination of "recommended shock" from the steps of the second analysis and the operating mode is revoked based on both, wherein the revocation step occurs only if the operating mode is a scheduled CPR operating mode.

11. The computer program product according to claim 10, wherein, The defibrillator enters an equipment operating mode in response to the "recommended shock" cardiac condition, and furthermore, if the operating mode is equipment mode, the cancellation step does not occur.

12. The computer program product according to claim 11, wherein, The second analysis step is paused during the equipment operation mode.

13. The computer program product according to claim 12, wherein, The equipment operation mode includes a fixed duration after which the equipment operation mode is interrupted.

14. The computer program product according to claim 13, wherein, The fixed duration is thirty (30) seconds.

15. The computer program product according to claim 10, wherein, If the operating mode is the continuous CPR rescue operating mode, then the undo step does not occur.

16. The computer program product according to claim 10, wherein, The multiple subsequent and successive ECG data segments are three ECG data segments.

17. The computer program product according to claim 10, further comprising the following steps: A user prompt is issued, indicating that the cancellation is confirmed from the cancellation step.

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