Method to determine fluid responsiveness

Abstract

A method for monitoring a patient and providing a fluid responsiveness indicator of the patient includes receiving, by a hemodynamic monitor, sensed hemodynamic data representative of an arterial pressure waveform of the patient; performing, by the hemodynamic monitor, waveform analysis of the hemodynamic data to determine a plurality of hemodynamic parameters; and determining, by the hemodynamic monitor based on the plurality of parameters, an indicator representing fluid responsiveness status for the patient.

Description

[0001] METHOD TO DETERMINE FLUID RESPONSIVENESS

[0002] CROSS-REFERENCE TO RELATED APPLICATION^ )

[0003] This application claims the benefit of U.S. Provisional Application No. 63 / 673,528, filed July 19, 2024, and entitled “METHOD TO DETERMINE FLUID RESPONSIVENESS,” the disclosure of which is hereby incorporated by reference in its entirety.

[0004] BACKGROUND

[0005] The present disclosure relates generally to fluid responsiveness, and in particular, to determining fluid responsiveness for a patient.

[0006] Fluid therapy is a first-line treatment for hemodynamically unstable patients to restore and / or maintain tissue perfusion. Fluid therapy is administered to patients who are hemodynamically unstable to restore cardiac output and oxygen delivery to the body. Fluid therapy involves using fluid to increase the preload of the right ventricle (and the left ventricle) of the heart to increase stroke volume, and thus, cardiac performance. However, fluid therapy is not always beneficial as excess fluid can have detrimental effects on tissues and organs, such as tissue and / or organ edema and hemodilution. If a patient is deemed fluid responsive, that patient would likely respond positively to fluid therapy. If a patient is deemed not fluid responsive, that patient would likely not respond positively to fluid therapy. It would be beneficial for health care workers to be able to predict whether a specific patient would positively respond to fluid therapy by estimating fluid responsiveness before administering fluid therapy to avoid potential harm.

[0007] SUMMARY

[0008] A method for monitoring a patient and providing a fluid responsiveness indicator of the patient includes receiving, by a hemodynamic monitor, sensed hemodynamic data representative of an arterial pressure waveform of the patient; performing, by the hemodynamic monitor, waveform analysis of the hemodynamic data to determine a plurality of hemodynamic parameters; and determining, by the hemodynamic monitor based on the plurality of parameters, an indicator representing fluid responsiveness status for the patient.

[0009] A method for monitoring of a patient and providing a fluid responsiveness indicator of the patient includes receiving, by a hemodynamic monitor, sensed hemodynamic data representative of an arterial pressure waveform of the patient and receiving, by a hemodynamic monitor, sensed hemodynamic data representative of a second pressure waveform of the patient. The method further includes performing, by the hemodynamic monitor, waveform analysis of the hemodynamic data representative of the arterial pressure waveform and hemodynamic data representative of a second pressure waveform to determine a plurality of hemodynamic parameters. The method further includes determining, by the hemodynamic monitor based on the plurality of hemodynamic parameters, an indicator representing fluid responsiveness status for the patient.

[0010] A system for determining a fluid responsiveness indicator of a patient includes a pressure sensor and an integrated hardware unit. The pressure sensor includes a housing, a fluid input port connected via tubing to a fluid source, a catheter-side fluid port connected to a catheter inserted within a patient, a pressure transducer in communication with the fluid source through the fluid port, and an I / O cable in electrical communication with the pressure transducer. The integrated hardware unit includes a system processor, a system memory, a display including a user interface, and an analog-to-digital (ADC) converter. The pressure sensor produces, on an ongoing basis, a hemodynamic sensor signal representative of an arterial pressure waveform of the patient. The system memory includes instructions that, when executed by the system processor, are configured to receive the hemodynamic sensor signal representative of the arterial pressure waveform of the patient, perform waveform analysis of the hemodynamic sensor signal representative of the arterial pressure waveform of the patient to determine a plurality of hemodynamic parameters, and determine an indicator representing fluid responsiveness status for the patient based on the plurality of parameters.

[0011] A system for monitoring a patient and providing a fluid responsiveness indicator of the patient includes a pressure sensor and an integrated hardware unit. The pressure sensor includes a housing, a fluid input port connected via tubing to a fluid source, a catheter-side fluid port connected to a catheter inserted within a patient, a pressure transducer in communication with the fluid source through the fluid port, and an I / O cable in electrical communication with the pressure transducer. The integrated hardware unit includes a system processor, a system memory, a display including a user interface, and an analog-to-digital (ADC) converter. The pressure sensor produces, on an ongoing basis, a first hemodynamic sensor signal representative of an arterial pressure waveform of the patient and a second hemodynamic sensor signal representative of a second pressure waveform of the patient. The system memory includes instructions that, when executed by the system processor, are configured to receive the first hemodynamic sensor signal representative of the arterial pressure waveform of the patient, receive the second hemodynamic sensor signal representative of the second pressure waveform of the patient, perform waveform analysis of the first hemodynamic sensor signal representative of the arterial pressure waveform and the second hemodynamic sensor signal representative of the second pressure waveform to determine a plurality of hemodynamic parameters, and determine an indicator representing fluid responsiveness status for the patient based on the plurality of hemodynamic parameters.

[0012] A system for determining fluid responsiveness in a patient includes a pressure sensor including a housing, a fluid input port connected via tubing to a fluid source, a catheter-side fluid port connected to a catheter inserted within a patient, a pressure transducer in communication with the fluid source through the fluid port, and an I / O cable in electrical communication with the pressure transducer. The system further includes an integrated hardware unit including a system processor, a system memory, a display including a user interface, and an analog-to-digital (ADC) converter. The pressure sensor produces, on an ongoing basis, a hemodynamic sensor signal representative of an arterial pressure waveform of the patient. The system memory includes instructions that, when executed by the system processor, are configured to receive the hemodynamic sensor signal representative of the arterial pressure waveform of the patient, perform waveform analysis of the arterial pressure waveform of the patient to determine a plurality of hemodynamic parameters, estimate a change in stroke volume or a change in pulse pressure and a change in preload based on the plurality of hemodynamic parameters from the arterial pressure waveform of the patient, determine a ratio of the change in stroke volume or the change in pulse pressure over the change in preload, and output the ratio of the change in stroke volume or the change in pulse pressure over the change in preload to the display for determining fluid responsiveness based on the ratio of the change in stroke volume or the change in pulse pressure over the change in preload.

[0013] A system for determining fluid responsiveness in a patient includes a pressure sensor including a housing, a fluid input port connected via tubing to a fluid source, a catheter-side fluid port connected to a catheter inserted within a patient, a pressure transducer in communication with the fluid source through the fluid port, and an I / O cable in electrical communication with the pressure transducer. The system further includes an integrated hardware unit including a system processor, a system memory, a display including a user interface, and an analog-to-digital (ADC) converter. The pressure sensor produces, on an ongoing basis, a hemodynamic sensor signal representative of an arterial pressure waveform of the patient and a second hemodynamic sensor signal representative of a second pressure waveform of the patient. The system memory includes instructions that, when executed by the system processor, are configured to receive the first hemodynamic sensor signal representative of the arterial pressure waveform of the patient, receive the second hemodynamic sensor signal representative of a second pressure waveform of the patient, perform waveform analysis of the arterial pressure waveform of the patient and the second pressure waveform of the patient to determine a plurality of hemodynamic parameters, estimate a change in stroke volume or a change in pulse pressure and a change in preload based on the plurality of hemodynamic parameters from the arterial pressure waveform of the patient and the second pressure waveform of the patient, determine a ratio of the change in stroke volume or the change in pulse pressure over the change in preload, and output the ratio of the change in stroke volume or the change in pulse pressure over the change in preload to the display for determining fluid responsiveness based on the ratio of the change in stroke volume or the change in pulse pressure over the change in preload.

[0014] A method for monitoring a patient and providing a fluid responsiveness indicator of the patient includes receiving, by a hemodynamic monitor, sensed hemodynamic data representative of an arterial pressure waveform of the patient; performing, by the hemodynamic monitor, waveform analysis of the arterial pressure waveform of the patient to determine a plurality of hemodynamic parameters, estimating, by the hemodynamic monitor, a change in stroke volume or a change in pulse pressure and a change in preload based on the plurality of hemodynamic parameters from the arterial pressure waveform of the patient; determining, by the hemodynamic monitor, a ratio of the change in stroke volume or the change in pulse pressure over the change in preload; and outputting, by the hemodynamic monitor, the ratio of the change in stroke volume or the change in pulse pressure over the change in preload to the display for determining fluid responsiveness based on the ratio of the change in stroke volume or the change in pulse pressure over the change in preload.

[0015] A method for monitoring a patient and providing a fluid responsiveness indicator of the patient includes receiving, by a hemodynamic monitor, sensed hemodynamic data representative of an arterial pressure waveform of the patient and sensed hemodynamic data representative of a second pressure waveform of the patient; performing, by the hemodynamic monitor, waveform analysis of the arterial pressure waveform of the patient and the second pressure waveform of the patient to determine a plurality of hemodynamic parameters, estimating, by the hemodynamic monitor, a change in stroke volume or a change in pulse pressure and a change in preload based on the plurality of hemodynamic parameters from the arterial pressure waveform of the patient and the second pressure waveform of the patient; determining, by the hemodynamic monitor, a ratio of the change in stroke volume or the change in pulse pressure over the change in preload; and outputting, by the hemodynamic monitor, the ratio of the change in stroke volume or the change in pulse pressure over the change in preload to the display for determining fluid responsiveness based on the ratio of the change in stroke volume or the change in pulse pressure over the change in preload.

[0016] A system for determining fluid responsiveness in a patient includes a pressure sensor including a housing, a fluid input port connected via tubing to a fluid source, a catheter-side fluid port connected to a catheter inserted within a patient, a pressure transducer in communication with the fluid source through the fluid port, and an I / O cable in electrical communication with the pressure transducer. The system further includes an integrated hardware unit including a system processor, a system memory, a display including a user interface, and an analog-to-digital (ADC) converter. The pressure sensor produces, on an ongoing basis, a hemodynamic sensor signal representative of a pressure waveform representative of intrathoracic pressure changes of the patient. The system memory includes instructions that, when executed by the system processor, are configured to receive the hemodynamic sensor signal representative of the pressure waveform representative of intrathoracic pressure changes of the patient, perform waveform analysis of the pressure waveform representative of intrathoracic pressure changes of the patient to determine a plurality of hemodynamic parameters, estimate a change in stroke volume or a change in pulse pressure and a change in preload based on the plurality of hemodynamic parameters from the pressure waveform representative of the intrathoracic pressure changes of the patient, determine a ratio of the change in stroke volume or the change in pulse pressure over the change in preload, and output the ratio of the change in stroke volume or the change in pulse pressure over the change in preload to the display for determining fluid responsiveness based on the ratio of the change in stroke volume or the change in pulse pressure over the change in preload.

[0017] A system for determining fluid responsiveness in a patient includes a non- invasive blood pressure sensor including an inflatable blood pressure bladder, a pressure controller pneumatically connected to the inflatable blood pressure bladder, and an optical transmitter and an optical receiver that are electrically connected to the pressure controller. The system further includes an integrated hardware unit including a system processor, a system memory, and a display including a user interface. The non-invasive blood pressure sensor produces, on an ongoing basis, a hemodynamic sensor signal representative of a pressure waveform representative of intrathoracic pressure changes of the patient. The system memory includes instructions that, when executed by the system processor, are configured to receive the hemodynamic sensor signal representative of the pressure waveform representative of intrathoracic pressure changes of the patient, perform waveform analysis of the pressure waveform representative of the intrathoracic pressure changes of the patient to determine a plurality of hemodynamic parameters, estimate a change in stroke volume or a change in pulse pressure and a change in preload based on the plurality of hemodynamic parameters from the pressure waveform representative of the intrathoracic pressure changes of the patient, determine a ratio of the change in stroke volume or the change in pulse pressure over the change in preload, and output the ratio of the change in stroke volume or the change in pulse pressure over the change in preload to the display for determining fluid responsiveness based on the ratio of the change in stroke volume or the change in pulse pressure over the change in preload.

[0018] A method for determining fluid responsiveness in a patient includes receiving, by a hemodynamic monitor, sensed hemodynamic data representative of a pressure waveform representative of the intrathoracic pressure changes of the patient. The method further includes performing, by the hemodynamic monitor, waveform analysis of the arterial pressure waveform of the patient to determine a plurality of hemodynamic parameters. The method further includes estimating, by the hemodynamic monitor, a change in stroke volume or a change in pulse pressure and a change in preload from the pressure waveform representative of the intrathoracic pressure changes of the patient. The method further includes determining, by the hemodynamic monitor, a ratio of the change in stroke volume or the change in pulse pressure over the change in preload. The method further includes outputting, by the hemodynamic monitor, the ratio of the change in stroke volume or the change in pulse pressure over the change in preload to the display for determining fluid responsiveness based on the ratio of the change in stroke volume or the change in pulse pressure over the change in preload.

[0019] BRIEF DESCRIPTION OF THE DRAWINGS

[0020] FIG. 1 is a perspective view of an example hemodynamic monitor that analyzes a pressure waveform to provide a ratio of a change in stroke volume over a change in preload to determine fluid responsiveness for a patient.

[0021] FIG. 2 is a perspective view of a catheter that can be inserted into the patient and connected to one or more hemodynamic sensors. FIG. 3 is a perspective view of an example minimally invasive pressure sensor for sensing hemodynamic data representative of a pressure waveform of the patient.

[0022] FIG. 4 is a perspective view of an example non-invasive pressure sensor for sensing hemodynamic data representative of an arterial blood pressure waveform of a patient.

[0023] FIG. 5 is a block diagram illustrating an example hemodynamic monitoring system that determines fluid responsiveness for the patient based on hemodynamic data.

[0024] FIG. 6 is a graph illustrating a ventricular function curve.

[0025] FIG. 7 A is a graph illustrating an example arterial blood pressure waveform trace.

[0026] FIG. 7B is a flow diagram illustrating a process for extracting an estimate of fluid responsiveness from an arterial blood pressure waveform.

[0027] FIG. 8A is a graph illustrating an example central venous pressure waveform trace.

[0028] FIG. 8B is a flow diagram illustrating a process for extracting an estimate of fluid responsiveness from a central venous pressure waveform, along with an arterial blood pressure waveform.

[0029] DETAILED DESCRIPTION

[0030] In general, the present disclosure describes predicting fluid responsiveness in a patient by estimating the slope of the ventricular function curve (VFS) at a particular operating point along the curve using a change in stroke volume, or pulse pressure, and a change in preload calculated from one or more pressure waveforms representative of preload changes and arterial hemodynamics, which results in increased accuracy in all patients, especially in spontaneously breathing patients or patients mechanically ventilated at changing ventilation rates and / or changing or lower tidal volumes. Further, normalizing the slope to account for changes in vital sign parameters including afterload and / or contractility further enhances the accuracy of the fluid responsiveness measurement.

[0031] FIG. 1 is a perspective view of hemodynamic monitor 10 that analyzes a pressure waveform to provide a ratio of a change in stroke volume or pulse pressure over a change in preload to determine fluid responsiveness for a patient. As illustrated in FIG. 1, hemodynamic monitor 10 includes display 12 that, in the example of FIG. 1, presents a graphical user interface including control elements (e.g., graphical control elements) that enable user interaction with hemodynamic monitor 10. Hemodynamic monitor 10 can also include a plurality of input and / or output (I / O) connectors configured for wired connection (e.g., electrical and / or communicative connection) with one or more peripheral components, such as one or more hemodynamic sensors, as is further described below. For instance, as illustrated in FIG. 1, hemodynamic monitor 10 can include I / O connectors 14. While the example of FIG. 1 illustrates five separate VO connectors 14, it should be understood that in other examples, hemodynamic monitor 10 can include fewer than five VO connectors or greater than five VO connectors. In yet other examples, hemodynamic monitor 10 may not include VO connectors 14, but rather may communicate wirelessly with various peripheral devices.

[0032] As further described below, hemodynamic monitor 10 includes one or more processors and computer-readable memory that stores fluid responsiveness software code, which is executable to determine fluid responsiveness in a patient based on sensed hemodynamic data of the patient. Hemodynamic monitor 10 can receive sensed hemodynamic data representative of a pressure waveform, such as a central venous pressure (CVP) waveform, a pulmonary artery pressure (PAP) waveform, or an arterial blood pressure (ABP) waveform, of the patient, via, for example, one or more hemodynamic sensors connected to hemodynamic monitor 10 via VO connectors 14. Hemodynamic monitor 10 executes the fluid responsiveness software code to obtain, using the sensed hemodynamic data, the fluid responsiveness for a patient, as is further described below.

[0033] As illustrated in FIG. 1, hemodynamic monitor 10 can present a graphical user interface at display 12. Display 12 can be a liquid crystal display (LCD), a lightemitting diode (LED) display, an organic light-emitting diode (OLED) display, or other display device suitable for providing information to users in graphical form. In some examples, such as the example of FIG. 1, display 12 can be a touch-sensitive and / or presence-sensitive display device configured to receive user input in the form of gestures, such as touch gestures, scroll gestures, zoom gestures, swipe gestures, or other gesture input.

[0034] Hemodynamic monitor 10 receives hemodynamic data from a patient via one or more hemodynamic sensors 16A, 16B, 16C, 16D,16E, and 16F (collectively hemodynamic sensors 16) (shown in FIGS. 2-6B). In response to receiving hemodynamic data of the patient, hemodynamic monitor 10 executes the fluid responsiveness software code to determine fluid responsiveness in a patient and display the fluid responsiveness on display 12. In some examples, hemodynamic monitor 10 can invoke a sensory alarm, such as an audible alarm, a haptic alarm, or other sensory alarm in response to determining that the patient has a very low or a very high fluid responsiveness. Accordingly, hemodynamic monitor 10 can provide a warning to medical personnel of an undesirable state of fluid responsiveness for the patient as determined by the medical personnel.

[0035] FIG. 2 is a perspective view of catheter 18 that can be inserted into the patient and connected to one or more hemodynamic sensors for providing hemodynamic data to hemodynamic monitor 10. For example, catheter 18 may be connected to one or more pressure-sensing hemodynamic sensors 16A for detecting central venous pressure (CVP) and / or pulmonary artery pressure (PAP). Protected by sheath 20, catheter 18 includes multiple lumens 22 that place fluid connectors 24, optical connector 26, thermistor connector 28, and thermal filament connector 30 in communication with one of ports 32, an embedded hemodynamic sensor 16E (e.g., a thermistor), or an embedded hemodynamic sensor 16F (e.g., a thermal filament). To facilitate insertion of catheter 18 within patient, or for certain hemodynamic measurements, catheter 18 includes balloon 34 located at tip 36 of catheter 18.

[0036] As shown in FIG. 2, catheter 18 includes distal port connector 24A communicating with port 32A at tip 36. Proximal injectate connector 24B communicates with proximal port 32B disposed approximately 30 cm from tip 36 and can be used for dispensing fluids and drugs into the patient’s heart. Central venous connector 24C communicates with central venous port 32C. which may be spaced approximately 19 cm from tip 36 or approximately 12 to 13 cm from tip 36. Connector 24C can be used for sensing a central venous pressure of the patient’s heart. Thermistor connector 28 electrically connects to hemodynamic sensor 16E (e.g., the thermistor) installed near tip 36 of catheter 18 for measuring core blood temperature within the pulmonary artery. In some examples of catheter 18, thermal filament connector 30 electrically connects to hemodynamic sensor (16F) (e.g., the thermal fdament) embedded within catheter 18 located within the patient’s right ventricle. In some examples, catheter 18 does not include a thermal filament or corresponding thermal filament connector 30. Balloon connector 24D communicates with balloon 34 and with the use of syringe 38 can be used to inflate and deflate balloon 34.

[0037] After insertion into the patient, e.g., via an introducer, distal port connector 24A and central venous connector 24C can be connected to separate pressure transducer sensors 16 A. A first pressure transducer sensor 16A provides pulmonary artery pressure waveform data to hemodynamic monitor 10 sensed at distal port 32 A located within the pulmonary artery while a second pressure transducer sensor 16A provides central venous pressure (CVP) waveform data sensed at central venous port 32C located in the vena cava close to the patient’ s heart. Catheter 18 is one example of a catheter that can be used to measure central venous pressure waveform data or pulmonary artery pressure waveform data. In other examples, any catheter configured to measure central venous pressure waveform data, arterial pressure waveform data, or pulmonary artery pressure waveform data can be used.

[0038] FIG. 3 is a perspective view of hemodynamic sensor 16A that can be attached to a patient for sensing hemodynamic data representative of a systemic arterial pressure waveform of the patient. As illustrated in FIG. 3, hemodynamic sensor 16A includes housing 40, fluid input port 42, catheter-side fluid port 44, and I / O cable 46. Fluid input port 42 is configured to be connected via tubing or other hydraulic connection to a fluid source, such as a saline bag or other fluid input source. Catheter-side fluid port 44 is configured to be connected via tubing or other hydraulic connection to a catheter (e.g., a radial arterial catheter or a femoral arterial catheter) that is inserted into an arm of the patient (i.e., a radial arterial catheter) or a leg of the patient (i.e., a femoral arterial catheter). I / O cable 46 is configured to connect to hemodynamic monitor 10 via, e.g., one or more of I / O connectors 14 (FIG. 1). Housing 40 of hemodynamic sensor 16A encloses one or more pressure transducers, communication circuitry, processing circuity, and corresponding electronic components to sense fluid pressure corresponding to central venous pressure, arterial blood pressure, or pulmonary artery pressure of the patient that is transmitted to hemodynamic monitor 10 (FIG. 1) via I / O cable 46.

[0039] In operation, a column of fluid (e.g., saline solution) is introduced from a fluid source (e.g., a saline bag) through hemodynamic sensor 16A via fluid input port 42 to catheter-side fluid port 44 toward the catheter inserted into the patient. Central venous pressure, arterial blood pressure, or pulmonary artery pressure is communicated through the fluid column to pressure sensors located within housing 40 which sense the pressure of the fluid column. Hemodynamic sensor 16A translates the sensed pressure of the fluid column to an electrical signal via the pressure transducers and outputs the corresponding electrical signal to hemodynamic monitor 10 (FIG. 1) via I / O cable 46. Hemodynamic sensor 16A therefore transmits analog sensor data (or a digital representation of the analog sensor data) to hemodynamic monitor 10 (FIG. 1) that is representative of substantially continuous beat-to-beat monitoring of the arterial blood pressure waveform of the patient to obtain beat-to-beat vital sign parameters.

[0040] FIG. 4 is a perspective view of hemodynamic sensor 16B for sensing hemodynamic data representative of arterial blood pressure of the patient. Hemodynamic sensor 16B, illustrated in FIG. 4, is one example of a non-invasive hemodynamic sensor that can be attached to the patient via one or more finger cuffs to sense data representative of arterial blood pressure of the patient. As illustrated in FIG. 4, hemodynamic sensor 16B includes inflatable finger cuff 49 and heart reference sensor 50. Inflatable finger cuff 49 includes an inflatable blood pressure bladder configured to inflate and deflate as controlled by a pressure controller (not illustrated) that is pneumatically connected to inflatable finger cuff 49. Inflatable finger cuff 49 also includes an optical (e.g., infrared) transmitter and an optical receiver that are electrically connected to the pressure controller (not illustrated). The optical transmitter and the optical receiver can measure the changing volume of the arteries under the cuff in the finger. The optical transmitter and the optical receiver can be positioned to transmit and receive light therebetween through the inflatable blood pressure bladder.

[0041] In operation, the pressure controller continually adjusts pressure within the finger cuff to maintain a constant volume of the arteries under the cuff in the finger (i.e., the unloaded volume of the arteries) as measured via the optical transmitter and optical receiver of inflatable finger cuff 49. The pressure applied by the pressure controller to continuously maintain the unloaded volume is representative of the blood pressure in the finger and is communicated by the pressure controller to hemodynamic monitor 10 shown in FIG. 1. Heart reference sensor 50 measures the hydrostatic height difference between the level at which the finger is kept and the reference level for the pressure measurement, which typically is heart level. Accordingly, hemodynamic sensor 16B transmits sensor data that is representative of substantially continuous beat-to-beat monitoring of the arterial blood pressure waveform of the patient to obtain beat-to-beat vital sign parameters.

[0042] FIG. 5 is a block diagram illustrating hemodynamic monitoring system 68 that analyzes a pressure waveform to determine change in stroke volume ASV, or change in pulse pressure (PP), and change in preload AP and provide a ratio of change in stroke volume ASV, or change in pulse pressure (PP), over change in preload AP for determining the fluid responsiveness for a patient based on the hemodynamic data. Hemodynamic monitoring system 68 also applies a normalization using a function of hemodynamic parameters. As such, a ratio of change in stroke volume ASV, or change in pulse pressure PP, over change in preload AP and normalized by change in stroke volume ASV, or change in pulse pressure PP, is the indicator that represents fluid responsiveness status of the patient. The following description will discuss stroke volume SV for the purposes of the example of FIG. 5, but pulse pressure PP can also be used in place of stroke volume. As illustrated in FIG. 5, hemodynamic monitoring system 68 includes hemodynamic monitor 10 and hemodynamic sensors 16 (including hemodynamic sensors 16A, 16B, 16C, and 16D). Hemodynamic monitoring system 68 can be implemented within a patient care environment, such as an ICU, an OR, or other patient care environment. As illustrated in FIG. 5, the patient care environment can include patient 70 and healthcare worker 72 trained to utilize hemodynamic monitoring system 68.

[0043] Hemodynamic monitor 10, as described above with respect to FIG. 1, can be an integrated hardware unit including system processor 74, system memory 76, display 12, analog-to-digital converter (ADC) 78, and digital-to-analog converter (DAC) 80. In other examples, any one or more components and / or described functionality of hemodynamic monitor 10 can be distributed among multiple hardware units. For instance, in some examples, display 12 can be a separate display device that is remote from and operatively coupled with hemodynamic monitor 10. Likewise, at least a portion of data processing within hemodynamic monitoring system 68 can occur via a smart cable that is connected between a catheter or sensor and hemodynamic monitor 10. In general, though illustrated and described in the example of FIG. 5 as an integrated hardware unit, it should be understood that hemodynamic monitor 10 can include any combination of devices and components that are electrically, communicatively, or otherwise operatively connected to perform functionality attributed herein to hemodynamic monitor 10.

[0044] As illustrated in FIG. 5, system memory 76 stores fluid responsiveness software code 82. Fluid responsiveness software code 82 includes stroke volume module 83, preload module 84, ventricular function curve slope (VFS) module 86, and normalization module 87. In alternate embodiments, fluid responsiveness software code 82 may not include normalization module 87. Display 12 provides user interface 88, which includes control elements 90 that enable user interaction with hemodynamic monitor 10 and / or other components of hemodynamic monitoring system 68. User interface 88, as illustrated in FIG. 5, also provides sensory alarm 92 to provide warning to medical personnel of a too high or too low state of fluid responsiveness of patient 70.

[0045] Hemodynamic sensors 16 can be attached to patient 70 to sense hemodynamic data representative of a central venous pressure waveform, an arterial blood pressure waveform, a right ventricular pressure waveform, a pulmonary artery pressure waveform of patient 70, or any combination of these hemodynamic data. Hemodynamic sensors 16 are operatively connected to hemodynamic monitor 10 (e.g., electrically and / or communicatively connected via wired or wireless connection, or both) to provide the sensed hemodynamic data to hemodynamic monitor 10. In some examples, hemodynamic sensors 16 provide the hemodynamic data of patient 70 to hemodynamic monitor 10 as an analog signal, which is converted by ADC 78 to digital hemodynamic data representative of the central venous pressure waveform, the arterial blood pressure waveform, or a pulmonary artery pressure waveform. In other examples, hemodynamic sensors 16 can provide the sensed hemodynamic data to hemodynamic monitor 10 in digital form, in which case hemodynamic monitor 10 may not include or utilize ADC 78. In yet other examples, hemodynamic sensors 16 can provide the hemodynamic data of patient 70 to hemodynamic monitor 10 as an analog signal, which is analyzed in its analog form by hemodynamic monitor 10.

[0046] Hemodynamic sensors 16 can include one or more non- invasive, minimally invasive, or invasive sensor attached to patient 70. For instance, hemodynamic sensors 16 can take the form of invasive hemodynamic sensor 16A, such as second pressure transducer 16A that provides central venous pressure waveform data sensed at central venous port 32C located in a vein above the heart of patient 70 (FIG. 3). Hemodynamic sensors 16 can also take the form of other invasive, minimally invasive, or non-invasive hemodynamic sensors.

[0047] In certain examples, hemodynamic sensors 16 can be configured to sense one or more of central venous pressure, arterial blood pressure, and pulmonary artery pressure of patient 70. For instance, one or more hemodynamic sensors 16 can be attached to patient 70 via a radial arterial catheter inserted into an arm of patient 70. In other examples, one or more of hemodynamic sensors 16 can be attached to patient 70 via a femoral arterial catheter inserted into a leg of patient 70. Such techniques can similarly enable multiple hemodynamic sensors 16 to provide substantially continuous beat-to-beat monitoring of the central venous pressure, arterial blood pressure, and pulmonary artery pressure of patient 70, or any combination of these hemodynamic data, over an extended period of time, such as minutes or hours. As such, beat-to-beat vital sign parameters, such as stroke volume, heart rate, mean arterial pressure, vascular resistance, cardiac contractibility, and dynamic arterial elastance, are obtained via waveform analysis and may be continuously determined over time.

[0048] System processor 74 executes fluid responsiveness software code 82, which implements stroke volume module 83, preload module 84, VFS module 86, and normalization module 87 to extract and utilize features of the CVP waveform, ABP waveform, PAP waveform, another intrathoracic pressure waveform, and / or a combination of these waveforms for monitoring and assessing fluid responsiveness in patient 70 and providing a fluid responsiveness indicator of patient 70. Examples of system processor 74 can include any one or more of a microprocessor, a controller, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other equivalent discrete or integrated logic circuitry.

[0049] System memory 76 can be configured to store information within hemodynamic monitor 10 during operation. System memory 76, in some examples, is described as computer-readable storage media. In some examples, a computer-readable storage medium can include a non-transitory medium. The term “non-transitory” can indicate that the storage medium is not embodied in a carrier wave or a propagated signal. In certain examples, a non-transitory storage medium can store data that can, over time, change (e.g., in RAM or cache). System memory 76 can include volatile and non-volatile computer-readable memories. Examples of volatile memories can include random access memories (RAM), dynamic random-access memories (DRAM), static random-access memories (SRAM), and other forms of volatile memories. Examples of non-volatile memories can include, e.g., magnetic hard discs, optical discs, flash memories, or forms of electrically programmable memories (EPROM) or electrically erasable and programmable (EEPROM) memories.

[0050] Display 12 can be a liquid crystal display (LCD), a light-emitting diode (LED) display, an organic light-emitting diode (OLED) display, or other display device suitable for providing information to users in graphical form. User interface 88 can include graphical and / or physical control elements that enable user input to interact with hemodynamic monitor 10 and / or other components of hemodynamic monitoring system 68. In some examples, user interface 88 can take the form of a graphical user interface (GUI) that presents graphical control elements presented at, e.g., a touch- sensitive and / or presence sensitive display screen of display 12. In such examples, user input can be received in the form of gesture input, such as touch gestures, scroll gestures, zoom gestures, or other gesture input. In certain examples, user interface 88 can take the form of and / or include physical control elements, such as a physical buttons, keys, knobs, or other physical control elements configured to receive user input to interact with components of hemodynamic monitoring system 68.

[0051] In operation, hemodynamic sensor 16A is connected to hemodynamic monitor 10 and catheter 18 (FIG. 2). Hemodynamic sensor 16A senses hemodynamic data representative of a CVP waveform, PAP waveform, or another waveform representative of intrathoracic pressure changes of patient 70. Hemodynamic sensor 16A provides the hemodynamic data (e.g., as analog sensor data), to hemodynamic monitor 10. ADC 78 converts the analog hemodynamic data to digital hemodynamic data representative of the CVP waveform, PAP waveform, or another waveform representative of intrathoracic pressure changes of patient 70.

[0052] System processor 74 executes fluid responsiveness software code 82 to detect, using the received hemodynamic data, the fluid responsiveness for patient 70. For instance, system processor 74 can execute fluid responsiveness software code 82 to perform waveform analysis of the received hemodynamic data over a certain period of time. Waveform analysis of the received hemodynamic data includes obtaining an estimation of change in stroke volume ASV, obtaining an estimation of change in preload AP, and obtaining beat-to-beat vital sign parameters to determine hemodynamic parameters. An estimation of change in stroke volume ASV is obtained by obtaining a beat-to-beat hemodynamic parameter representative of, related to, or proportional to stroke volume SV and determining a change of the hemodynamic parameter representative of, related to, or proportional to stroke volume SV over a period of time. An estimation of change in preload P is obtained by obtaining a hemodynamic parameter representative of, related to, or proportional to preload P and determining a change of the hemodynamic parameter representative of, related to, or proportional to preload P over a period of time.

[0053] Fluid responsiveness software code 82 uses stroke volume module 83 to determine change in stroke volume ASV of patient 70, including determining minimum and maximum amplitude values of the ABP waveform, the PAP waveform, or any other suitable waveform representative of intrathoracic pressure. Fluid responsiveness software code 82 uses preload module 84 to determine change in preload AP of patient 70 based on features of the CVP waveform, the ABP waveform, the PAP waveform, or any other suitable waveform representative of intrathoracic pressure, including minimum amplitudes and maximum amplitudes. Fluid responsiveness software code 82 may concurrently estimate change in stroke volume ASV and change in preload AP from the same or from different pressure waveforms of the patient. System processor 74 executes fluid responsiveness software code 82 to generate a ratio of change in stroke volume ASV over change in preload AP via VFS module 86. The ratio of change in stroke volume ASV over change in preload AP represents a slope of ventricular function curve VFS, which is an estimate of the fluid responsiveness of patient 70. Fluid responsiveness software code 82 uses normalization module 87 to apply a normalization of the ratio of change in stroke volume ASV over change in preload AP. Normalization module 87 uses a function of vital sign hemodynamic variables, including but not limited to afterload and contractility. The normalized ratio of change in stroke volume ASV over change in preload AP represents an even more accurate slope of ventricular function curve VFS, which is an estimate of the fluid responsiveness of patient 70.

[0054] Fluid responsiveness status is identified via ventricular function curve slope VFS, the ratio of change in stroke volume ASV over change in preload AP. The lower the value of ventricular function curve slope VFS, the less likely the patient is fluid responsive. The higher the value of ventricular function curve slope VFS, the more likely the patient is fluid responsive.

[0055] Hemodynamic monitor 10 uses hemodynamic sensors 16 to help assess the hemodynamic state of the patient. Accordingly, hemodynamic monitor 10 informs healthcare worker 72 of the fluid responsiveness status of patient 70, thereby enabling timely and effective patient care. Unlike current methods to determine fluid responsiveness, which require the patient to be under mechanical ventilation with specific tidal volume conditions, determining a ratio of change in stroke volume ASV over change in preload AP using a preload dependent pressure waveform is effective for predicting fluid responsiveness in spontaneously breathing patients, without restrictions on respiration rate or tidal volume. As a result, fluid responsiveness software code 82 has much broader applicability, allowing health care workers to predict fluid responsiveness in all patients, including the general intensive care unit (ICU) and operating room (OR) populations.

[0056] With further reference to FIG. 5, hemodynamic monitoring system 68 can include pump 93 that can provide intravenous or intra-arterial therapy to the patient. Hemodynamic monitor 10 can communicate with pump 93 (e.g. via a smart cable that is connected between hemodynamic monitor 10 and pump 93). Pump 93 is an infusion device that can be connected to the patient through a tube cannulated within a vessel of the patient. Pump 93 can be an infusion pump. For example, pump 93 can include a gravity infusion device, a syringe infusion pump, an elastomeric infusion pump, a volumetric infusion pump, a patient-controlled analgesia (PCA) pump, an ambulatory infusion pump, and / or any other kind of infusion pump.

[0057] Hemodynamic monitoring system 68 can utilize the hemodynamic data and the fluid responsiveness estimation to determine a therapy protocol for the patient and / or generate a pump command to cause pump 93 to deliver therapy to the patient according to the therapy protocol. For example, pump 93 can deliver a fluid that is substantially free of vasoactive medicaments to the patient and adjust delivery of the fluid to the patient based on the determined fluid responsiveness. According to one exemplary therapy protocol, a determination of fluid responsiveness of a patient (indicating that the patient is likely to benefit from fluid therapy) can cause hemodynamic monitoring system 68 to generate a pump command to deliver a bolus of fluid (e.g., fluid free of vasoactive medicaments). A determination of a lack of fluid responsiveness of the patient (indicating that the patient is not likely to benefit from fluid therapy) can cause hemodynamic monitoring system 68 to take no action, generate a pump command to halt delivery of fluid to the patient, or generate a pump command to only deliver a minimum fluid flow (e.g., 20-50 ml / hr to keep vessels open).

[0058] FIG. 6 is a graph illustrating ventricular function curve VFC. Preload P is along the x-axis and is measured in millimeters of mercury (mmHg). Stroke volume SV is along the y-axis and is measured in liters per minute (L / min). The following description will discuss stroke volume SV for the purposes of the example of FIG. 6, but pulse pressure PP can also be used in place of stroke volume.

[0059] Preload (or ventricular filling pressure) is the pressure required to filling the left ventricle to the end-diastolic volume and end-diastolic pressure. Stroke volume (or cardiac output) is the volume of blood pumped out of the left ventricle of the heart per beat. Thus, slope of ventricular function curve VFS is change in stroke volume ASV divided by change in preload AP. Slope of ventricular function curve VFS for a specific patient serves as an estimate of fluid responsiveness status for that patient.

[0060] Fluid responsiveness software code 82 (FIG. 5) estimates fluid responsiveness by generating slope of ventricular function curve VFS. Slope of the ventricular function curve VFS at a particular operating point along the curve is generated by computing respiratory induced changes in preload and stroke volume using pressure signals that are affected by respiratory modulation, such as central venous pressure, arterial blood pressure, pulmonary artery pressure, or any other suitable pressure representative of preload changes. Stroke volume module 83 (FIG. 5) generates change in stroke volume ASV. Preload module 84 (FIG. 5) generates change in preload AP. VFS module 86 (FIG. 5) calculates the ratio of change in preload AP over change in stroke volume ASV. Normalization module 87 calculates the normalized ratio of change in stroke volume ASV over change in preload AP to account for afterload, contractility, and or other hemodynamic variables.

[0061] A measure of fluid responsiveness can determine whether an unstable patient is likely to benefit from fluid therapy, a treatment for hemodynamically unstable patients meant to restore and / or maintain tissue perfusion. A fluid responsive patient will likely benefit from fluid therapy while a non-fluid responsive patient will likely not benefit from fluid therapy and could experience potential harm, such as tissue and / or organ edema. Only 50 percent or less of patients receiving fluid therapy positively respond to the therapy with the desired increase in stroke volume. As a result, a determination of fluid responsiveness will indicate to clinicians whether the patient is a good candidate for fluid therapy, helping the clinician decide whether fluid therapy should be administered or should be stopped, and will avoid potential harm to patients who are not, or are no longer, fluid responsive.

[0062] FIG. 7 A is a graph illustrating an example arterial blood pressure (ABP) waveform trace 94. FIG. 7B is a flow diagram illustrating process 132 for extracting an estimate of fluid responsiveness from an ABP waveform. FIGS. 7A and 7B will be discussed together. ABP waveform trace 94 includes maximum amplitudes 96, minimum amplitudes 98, and differences 100. Process 102 includes step 104, step 106, step 108, step 110, step 112, step 114, step 116, and step 118. The following description will discuss stroke volume SV for the purposes of the example of FIGS. 7A-7B, but pulse pressure PP can also be used in place of stroke volume.

[0063] ABP waveform trace 94 is an example of an ABP waveform that may be analyzed by stroke volume module 83, preload module 84, VFS module 86, and normalization module 87 of fluid responsiveness software code 82 (FIG. 5). The ABP waveform may be a radial arterial blood pressure waveform, a femoral arterial blood pressure waveform, or a pulmonary arterial blood pressure waveform. In alternate examples, a waveform of any suitable continuous pressure measurement representative of preload changes may be used with fluid responsiveness software code 82. ABP waveform trace 94 corresponds to hemodynamic data sensed by one of hemodynamic sensors 14A. ABP waveform trace 94 represents the ABP waveform, which modulates with breathing, over a 20-second timeframe. The 20-second timeframe of sampling can be sequential (e.g. every 20 seconds) or can overlap (e.g. every 5 seconds). As such, fluid responsiveness can be determined from the ABP waveform continuously, such as at a 20-second interval or at a 5-second interval. ABP waveform trace 94 includes indicia indicative of change in preload AP and change in stroke volume AP. Indicia are extracted from ABP waveform trace 94 via fluid responsiveness software code 82.

[0064] ABP waveform trace 94 has indicia including maximum amplitudes 96A, 96B, 96C, and 96D, minimum amplitudes 98A, 98B, 98C, and 98D, and differences 100A, IOOB, 1OOC, and 1OOD. Maximum amplitude 96A is paired with minimum amplitude 98A. Maximum amplitude 96B is paired with minimum amplitude 98B. Maximum amplitude 96C is paired with minimum amplitude 98C. Maximum amplitude 96D is paired with minimum amplitude 98D. Each pair of minimum amplitude 98 and maximum amplitude 96 represents one respiratory cycle. In this example, ABP waveform trace 94 contains four respiratory cycles. Difference 100A is the difference between maximum amplitude 96A and minimum amplitude 98A. Difference 100B is the difference between maximum amplitude 96B and minimum amplitude 98B. Difference 100C is the difference between maximum amplitude 96C and minimum amplitude 98C. Difference 100D is the difference between maximum amplitude 96D and minimum amplitude 98D.

[0065] ABP waveform trace 94 is generated via hemodynamic sensor signals representative of an ABP waveform received by, for example, hemodynamic monitor 10, as seen in step 104 of process 102. Preload module 84 of fluid responsiveness software code 82 analyzes ABP waveform trace 94 to calculate change in preload AP. Preload module 84 uses a band pass filter to extract the low frequency component of the ABP waveform, as seen at step 106. As a result, the frequencies of the ABP waveform that are in the range of respiratory modulation are isolated to yield ABP waveform trace 94. Paired maximum amplitudes 96A, 96B, 96C, and 96D and minimum amplitudes 98A, 98B, 98C, and 98D of ABP waveform trace 94 are detected, as seen at step 108. As seen at step 110, preload module 84 determines the differences 100A, 100B, 100C, and 100D between paired maximum amplitudes 96A, 96B, 96C, and 96D and minimum amplitudes 98A, 98B, 98C, and 98D. Minimum amplitude 98A is subtracted from maximum amplitude 96A to yield difference 100A. Minimum amplitude 98B is subtracted from maximum amplitude 96B to yield difference 100B. Minimum amplitude 98C is subtracted from maximum amplitude 96C to yield difference 100C. Minimum amplitude 98D is subtracted from maximum amplitude 96D to yield difference 100D. At step 112, a median of differences 100A, 100B,

[0066] IOOC, and 100D is determined to estimate change in preload AP. The median of calculated differences 100A, 100B, 100C, and 100D within the 20-second window of ABP waveform trace 94 is determined by preload module 84. The median of differences 100 A, 100B, 100C, and 100D is an estimation of change in preload AP.

[0067] VFS module 86 of fluid responsiveness software code 82 uses change in preload AP calculated by preload module 84 to calculate the ventricular function slope VFS. Stroke volume module 83 estimates change in stroke volume ASV using ABP waveform trace 94, as seen at step 114. Change in stroke volume ASV is computed on a beat-to-beat basis using ABP waveform trace 94 and a stroke volume algorithm, such as FloTrac or CoTrek. Once change in stroke volume ASV is computed, the ratio of change in stroke volume ASV over change in preload AP is determined by VFS module 86, as seen at step 116. The ratio of change in stroke volume ASV over change in preload AP is outputted to a display for determining fluid responsiveness, as seen at step 118. The ratio of change in stroke volume ASV over change in preload AP, or ventricular function curve slope VFS, indicates fluid responsiveness. The lower the value of ventricular function curve slope VFS, the less likely the patient is fluid responsive. The higher the value of ventricular function curve slope VFS, the more likely the patient is fluid responsive.

[0068] While process 102 estimates ventricular function curve slope VFS by taking change in preload AP into account, contractility, afterload, and ventricular-arterial coupling (VAC) can also be accounted for in estimating fluid responsiveness. In doing so, one or more additional parameters are factored into ventricular function curve slope VFS after accounting for change in preload AP. The changes in contractility are quantified by computing an index of contractility on a beat-to-beat basis using dP / dt. The changes in afterload, or aortic pressure, are quantified using mean arterial pressure (MAP) or systemic vascular resistance (SVR). The changes in VAC are quantified using Eadyn, or a measure of dynamic arterial elastance. As such, ventricular function curve slope VFS is normalized over the effects of afterload and / or contractility and / or VAC. As contractility, afterload, and VAC change the operating point of the patient on ventricular function curve VFC, normalizing ventricular function curve slope VFS to take changes in contractility and / or changes in afterload and / or changes in VAC into account results in an even more highly accurate fluid responsiveness estimate.

[0069] Current indexes used to determine fluid responsiveness, such as stroke volume variation (SVV), pulse pressure variation (PPV), and systolic pressure variation (SPV), can only accurately estimate fluid responsiveness of a patient in a limited number of scenarios. The patient is required to be on mechanical ventilation with a high, fixed tidal volume (Vt greater than 8 mL / kg), where preload can be assumed to be constant. Thus, the current methods do not actually calculate change in preload AP. SVV, for example, is computed using only stroke volume in determining fluid responsiveness, the maximum stroke volume minus the minimum stroke volume being divided by the mean stroke volume instead of a true change in preload. If any circumstance exists that changes preload P, such as spontaneous breathing or a change in tidal volume in a mechanically vented patient, the current methods of measuring fluid responsiveness cannot be used. Further, patients cannot have a low heart rate (HR) to respiratory rate (RR) ratio, an irregular heartbeat, increased abdominal pressure, or an open thorax. Cases complying with the limitations of the current methods, in which the current methods are accurate, account for about 10 percent of cases. The current methods are not available or have limited applicability for the general intensive care unit (ICU) and operating room (OR) patient populations because most of those patient populations are spontaneously breathing or breathing with the assistance of a ventilator having settings that are not those of respiratory modulation and change is preload AP is not constant.

[0070] Process 102 can accurately determine an estimate of fluid responsiveness in a large array of patients, including spontaneously breathing patients. Process 102 calculates a true ventricular function curve slope VFS by accounting for change in preload AP. A new parameter is introduced to determine change in preload AP for estimating fluid responsiveness. Preload responsiveness is inferred from the ABP waveform, the spontaneous intra-thoracic pressure changes due to spontaneous breathing (or mechanical ventilation), which continuously create changes in preload and related changes in stroke volume SV, being considered. Because process 102 uses a 20-second timeframe, the measurement will include several respiratory cycles, even if the respiratory cycles are relatively long. As such, the 20-second time frame is long enough to yield an accurate measurement and short enough to still represent a continuous measurement. Determining change in preload AP of the ventricle associated with the respiratory cycle by using an average of differences 100 between maximum amplitudes 96 and minimum amplitudes 98 across more than one respiratory cycle improves the robustness of change in preload AP, noise in ABP waveform trace 94 having less effect. As process 102 does not require the patient to be mechanically ventilated and has no restriction on tidal volume, process 102 yields a more accurate estimation of fluid responsiveness for a greater population of patients, including those in the general ICU and OR. Thus, process 102 is more useful in allowing health care workers to predict fluid responsiveness.

[0071] While FIGS. 7A and 7B describe process 102 for determining fluid responsiveness using a single pressure ABP waveform trace 124 from an ABP waveform, fluid responsiveness can also be determined using a trace from any suitable arterial pressure waveform that is measured inside the thorax, including a PAP waveform.

[0072] FIG. 8A is a graph illustrating example central venous pressure (CVP) waveform trace 120. FIG. 8B is a flow diagram illustrating process 128 for extracting an estimate of fluid responsiveness from a CVP waveform, along with an ABP waveform. FIGS. 8 A and 8B will be discussed together. CVP waveform trace 120 includes minimum amplitudes 122, maximum amplitudes 124, and differences 126. Process 128 includes step 130, step 132, step 134, step 136, step 138, step 140, step 142, and step 144. The following description will discuss stroke volume SV for the purposes of the example of FIGS. 8A and 8B, but pulse pressure PP can also be used in place of stroke volume. ABP waveform, as described with respect to FIGS. 7A and 7B, is used in conjunction with CVP waveform to extract an estimate of fluid responsiveness.

[0073] CVP waveform trace 120 is an example of a CVP waveform that may be analyzed by stroke volume module 83, preload module 84, VFS module 86, and normalization module 87 of fluid responsiveness software code 82 (FIG. 5). In alternate examples, a waveform of any suitable continuous pressure measurement representative of preload changes may be used with fluid responsiveness software code 82. CVP waveform trace 120 corresponds to hemodynamic data sensed by one of hemodynamic sensors 14 A. CVP waveform trace 120 represents the CVP waveform, which modulates with breathing, over a 20-second timeframe. The 20-second timeframe of sampling can be sequential (e.g. every 20 seconds) or can overlap (e.g. every 5 seconds). As such, fluid responsiveness can be determined from the CVP waveform continuously, such as at a 20-second interval or at a 5-second interval. CVP waveform trace 120 includes indicia indicative of change in preload AP. ABP waveform trace 94 includes indicia indicative of changes in stroke volume (ASV) or changes in pulse pressure (APP). Indicia are extracted from CVP waveform trace 120 and ABP waveform trace 94 via fluid responsiveness software code 82. As such, hemodynamic monitor 10 can perform waveform analysis of the hemodynamic data representative of an ABP waveform and hemodynamic data representative of a CVP waveform, or any other waveform representative of preload changes, to determine hemodynamic parameters for determining an indicator representing fluid responsiveness status. Waveform analysis of the hemodynamic data representative of the ABP waveform is performed to obtain an estimation of change in stroke volume ASV. Waveform analysis of the hemodynamic data representative of the CVP waveform is performed to obtain an estimation of change in preload AP. Beat-to-beat vital sign parameters are also obtained.

[0074] CVP waveform trace 120 has indicia including minimum amplitudes 122A, 122B, 122C, and 122D, maximum amplitudes 124A, 124B, 124C, and 124D, and differences 126A, 126B, 126C, and 126D. Minimum amplitude 122A is paired with maximum amplitude 124A. Minimum amplitude 122B is paired with maximum amplitude 124B. Minimum amplitude 122C is paired with maximum amplitude 124C. Minimum amplitude 122D is paired with maximum amplitude 124D. Each pair of minimum amplitude 122 and maximum amplitude 124 represents one respiratory cycle. In this example, CVP waveform trace 120 contains four respiratory cycles. Difference 126A is the difference between minimum amplitude 122 A and maximum amplitude 124 A. Difference 126B is the difference between minimum amplitude 122B and maximum amplitude 124B. Difference 126C is the difference between minimum amplitude 122C and maximum amplitude 124C. Difference 126D is the difference between minimum amplitude 122D and maximum amplitude 124D.

[0075] CVP waveform trace 120 is generated via hemodynamic sensor signals representative of a CVP waveform received by, for example, hemodynamic monitor 10, as seen in step 130 of process 128. Preload module 84 of fluid responsiveness software code 82 analyzes CVP waveform trace 120 to calculate change in preload AP. Preload module 84 uses a band pass filter to extract the low frequency component of the CVP waveform, as seen at step 132. As a result, the frequencies of the CVP waveform that are in the range of respiratory modulation are isolated to yield CVP waveform trace 120. Paired minimum amplitudes 122A, 122B, 122C, and 122D and maximum amplitudes 124A, 124B, 124C, and 124D of CVP waveform trace 120 are detected, as seen at step 134. As seen at step 136, preload module 84 determines the differences 126A, 126B, 126C, and 126D between paired maximum amplitudes 124A, 124B, 124C, and 124D and minimum amplitudes 122A, 122B, 122C, and 122D. Minimum amplitude 122A is subtracted from maximum amplitude 124A to yield difference 126A. Minimum amplitude 122B is subtracted from maximum amplitude 124B to yield difference 126B. Minimum amplitude 122C is subtracted from maximum amplitude 124C to yield difference 126C. Minimum amplitude 122D is subtracted from maximum amplitude 124D to yield difference 126D. At step 138, median 126M of differences 126A, 126B, 126C, and 126D is determined to estimate change in preload AP. A median of calculated differences 126A, 126B, 126C, and 126D within the 20-second window of CVP waveform trace 120 is determined by preload module 84. The median of differences 126A, 126B, 126C, and 126D is an estimation of change in preload AP.

[0076] VFS module 86 of fluid responsiveness software code 82 uses change in stroke volume ASV calculated by stroke volume module 83 and change in preload AP calculated by preload module 84 to calculate ventricular function curve slope VFS. Stroke volume module 83 estimates change in stroke volume ASV using ABP waveform trace 94, as seen at step 114 and described above with respect to FIGS. 7A and 7B and seen at step 140. Stroke volume module 83 calculates change in stroke volume ASV on a beat-to-beat basis using an ABP waveform , such as ABP waveform trace 94, or a pulmonary artery pressure (PAP) waveform trace, and a stroke volume algorithm, such as FloTrac or CoTrek. Once change in stroke volume ASV and change in preload AP are computed, the ratio of change in stroke volume ASV over change in preload AP is determined by VFS module 86, as seen at step 142. The ratio of change in stroke volume ASV over change in preload AP can be normalized by normalization module 87 using a function of vital sign parameters, such as afterload and contractility. The ratio of change in stroke volume ASV over change in preload AP is outputted to a display for determining fluid responsiveness, as seen at step 144. The ratio of change in stroke volume ASV over change in preload AP, or ventricular function curve slope VFS, indicates fluid responsiveness. The lower the value of ventricular function curve slope VFS, the less likely the patient is fluid responsive. The higher the value of ventricular function curve slope VFS, the more likely the patient is fluid responsive.

[0077] While process 128 estimates ventricular function curve slope VFS by taking change in preload AP into account, contractility, afterload, and ventricular-arterial coupling (VAC) can also be accounted for in estimating fluid responsiveness via normalization module 87. In doing so, one or more additional hemodynamic parameters, such as those indicative of contractility or afterload, are factored into ventricular function curve slope VFS after accounting for change in stroke volume ASV and change in preload AP. The changes in contractility are quantified by computing an index of contractility on a beat-to- beat basis using dP / dt. The changes in afterload, or aortic pressure, are quantified using mean arterial pressure (MAP) or systemic vascular resistance (SVR). The changes in VAC are quantif ied using Eadyn, or a measure of dynamic arterial elastance. As such, ventricular function curve slope VFS is normalized over the effects of afterload and / or contractility and / or VAC and / or other hemodynamic parameters. Ventricular function curve slope VFS is normalized using a function of any of such hemodynamic parameters or vital sign parameters, which include heart rate, mean arterial pressure, vascular resistance, cardiac contractibility, and dynamic arterial elastance, or a combination thereof, these relationships being linear or non-linear combinations. As contractility, afterload, and VAC change the operating point of the patient on ventricular function curve VFC, normalizing ventricular function curve slope VFS to take changes in contractility and / or changes in afterload and / or changes in VAC and / or other hemodynamic parameters into account results in an even more highly accurate fluid responsiveness estimate.

[0078] Current indexes used to determine fluid responsiveness, such as stroke volume variation (SVV), pulse pressure variation (PPV), and systolic pressure variation (SPV), can only accurately estimate fluid responsiveness of a patient in a limited number of scenarios. The patient is required to be on mechanical ventilation with a high, fixed tidal volume (Vt greater than 8 mL / kg), where preload changes are assumed to be constant. Thus, the current methods do not actually calculate change in preload AP. SVV, for example, is computed using only stroke volume in determining fluid responsiveness, the maximum stroke volume minus the minimum stroke volume being divided by the mean stroke volume instead of a true change in preload. If any circumstance exists that changes preload P, such as spontaneous breathing or a change in tidal volume in a mechanically vented patient, the current methods of measuring fluid responsiveness cannot be used. Further, patients cannot have a low heart rate (HR) to respiratory rate (RR) ratio, an irregular heartbeat, increased abdominal pressure, or an open thorax. Cases complying with the limitations of the current methods, in which the current methods are accurate, account for about 10 percent of cases. The current methods are not available or have limited applicability for the general intensive care unit (ICU) and operating room (OR) patient populations because most of those patient populations are spontaneously breathing or breathing with the assistance of a ventilator having settings that are not those of respiratory modulation and change is preload AP can be assumed to be not constant.

[0079] Process 128 can accurately determine an estimate of fluid responsiveness in a large array of patients, including spontaneously breathing patients. Process 128 calculates a true ventricular function curve slope VFS by accounting for change in preload AP. A new parameter is introduced to determine change in preload AP for estimating fluid responsiveness. Preload responsiveness is inferred from any pressure waveform measured inside the thorax, such as the CVP waveform, which corresponds to the spontaneous intra- thoracic pressure changes due to spontaneous breathing (or mechanical ventilation). Such pressure changes continuously create changes in preload and related changes in stroke volume SV. Because process 128 uses a 20-second timeframe, the measurement will include several respiratory cycles, even if the respiratory cycles are relatively long. As such, the 20-second time frame is long enough to yield an accurate measurement and short enough to still represent a continuous measurement. Determining change in preload AP of the ventricle associated with the respiratory cycle by using an average of differences 126 between maximum amplitudes 124 and minimum amplitudes 122 across more than one respiratory cycle improves the robustness of change in preload AP, noise in the pressure waveform having less effect. As process 128 does not require the patient to be mechanically ventilated and has no restriction on tidal volume, process 128 yields a more accurate estimation of fluid responsiveness for a greater population of patients, including those in the general ICU and OR. Thus, process 128 is more useful in allowing health care workers to predict fluid responsiveness.

[0080] While FIGS. 8 A and 8B describe process 128 for determining fluid responsiveness using ABP waveform trace 94 from an ABP waveform and CVP waveform trace 120 from a CVP waveform, fluid responsiveness can also be determined using a trace from any suitable pressure waveform that includes intrathoracic pressure changes, including a pulmonary artery pressure (PAP) waveform. Although, using a CVP waveform to calculate change in preload AP will probably yield the most reliable estimation of fluid responsiveness because CVP is the most direct, or closest to the pressure source (the intrathoracic pressure) that causes the modulation in preload P associated with the respiratory cycle. As such, there is a minimum phase lag between the source pattern and the effect pattern. Additionally, the amplitude of the modulation is of the same order of magnitude as the amplitude of the pulsations in the CVP pressure signal. Because CVP pressures are low and modulation pressures are low, a good signal-to-noise ratio exists for computation using CVP waveform.

[0081] Any of the various systems, devices, apparatuses, etc. in this disclosure can be sterilized (e.g., with heat, radiation, ethylene oxide, hydrogen peroxide, etc.) to ensure they are safe for use with patients, and the methods herein can comprise sterilization of the associated system, device, apparatus, etc. (e.g., with heat, radiation, ethylene oxide, hydrogen peroxide, etc.).

[0082] The treatment techniques, methods, steps, etc. described or suggested herein or in references incorporated herein can be performed on a living animal or on a non-living simulation, such as on a cadaver, cadaver heart, anthropomorphic ghost, simulator (e.g., with the body parts, tissue, etc. being simulated), etc.

[0083] DISCUSSION OF DETAILED EXAMPLES

[0084] The following are non-exclusive descriptions of possible examples of the present invention.

[0085] A method for monitoring a patient and providing a fluid responsiveness indicator of the patient includes receiving, by a hemodynamic monitor, sensed hemodynamic data representative of an arterial pressure waveform of the patient; performing, by the hemodynamic monitor, waveform analysis of the hemodynamic data to determine a plurality of hemodynamic parameters; and determining, by the hemodynamic monitor based on the plurality of parameters, an indicator representing fluid responsiveness status for the patient.

[0086] The method of the preceding paragraph can optionally include, additionally and / or alternatively, any one or more of the following features, configurations and / or additional components:

[0087] The arterial pressure waveform is a radial arterial blood pressure waveform, a pulmonary arterial blood pressure waveform, or a femoral arterial blood pressure waveform.

[0088] Wherein performing waveform analysis of the hemodynamic data to determine the plurality of hemodynamic parameters comprises: obtaining an estimation of a change in stroke volume or a change in pulse pressure ; obtaining an estimation of a change in preload; and obtaining beat-to-beat vital sign parameters.

[0089] The beat-to-beat vital sign parameters include one or more of stroke volume, heart rate, mean arterial pressure, vascular resistance, cardiac contractility, and dynamic arterial elastance.

[0090] Obtaining the estimation of the change in preload comprises: obtaining a hemodynamic parameter representative of, related to, or proportional to preload; and determining a change of the hemodynamic parameter representative of, related to, or proportional to preload over a period of time.

[0091] Obtaining the estimation of the change in stroke volume or a change in pulse pressure comprises obtaining a beat-to-beat hemodynamic parameter representative of, related to, or proportional to stroke volume or pulse pressure; and determining a change of the hemodynamic parameter representative of, related to, or proportional to stroke volume or pulse pressure over a period of time.

[0092] The indicator representing fluid responsiveness status for the patient is a ratio of a change in stroke volume or a change in pulse pressure over a change in preload.

[0093] The indicator representing fluid responsiveness status for the patient is a ratio of a change in stroke volume or a change in pulse pressure over a change in preload and normalized by the change in stroke volume or the change in pulse pressure.

[0094] The indicator representing fluid responsiveness status for the patient is a ratio of a change in stroke volume or a change in pulse pressure over a change in preload and further normalized by a linear or a non-linear combination of one or more hemodynamic or vital sign parameters including one or more of stroke volume, heart rate, mean arterial pressure, vascular resistance, cardiac contractility, and dynamic arterial elastance.

[0095] The indicator representing fluid responsiveness status for the patient is continuously determined.

[0096] The indicator representing fluid responsiveness status for the patient is determined at a 20-second interval.

[0097] The indicator representing fluid responsiveness status for the patient is determined at a 5-second interval.

[0098] A method for monitoring of a patient and providing a fluid responsiveness indicator of the patient includes receiving, by a hemodynamic monitor, sensed hemodynamic data representative of an arterial pressure waveform of the patient; receiving, by the hemodynamic monitor, sensed hemodynamic data representative of a second pressure waveform of the patient; performing, by the hemodynamic monitor, waveform analysis of the hemodynamic data representative of the arterial pressure waveform and the hemodynamic data representative of a second pressure waveform to determine a plurality of hemodynamic parameters; and determining, by the hemodynamic monitor based on the plurality of hemodynamic parameters, an indicator representing fluid responsiveness status for the patient.

[0099] The method of the preceding paragraph can optionally include, additionally and / or alternatively, any one or more of the following features, configurations and / or additional components:

[0100] The arterial pressure waveform is a radial arterial blood pressure waveform, a pulmonary arterial blood pressure waveform, or a femoral arterial blood pressure waveform.

[0101] The second pressure waveform is a central venous pressure waveform, a radial arterial blood pressure waveform, a pulmonary arterial blood pressure waveform, or a femoral arterial blood pressure waveform.

[0102] Performing waveform analysis of the hemodynamic data representative of the arterial pressure waveform and the hemodynamic data representative of a second pressure waveform to determine a plurality of hemodynamic parameters comprises: performing waveform analysis of the hemodynamic data representative of the arterial pressure waveform to obtain an estimation of a change in stroke volume or a change in pulse pressure; performing waveform analysis of the hemodynamic data representative of the second pressure waveform to obtain an estimation of a change in preload; and obtaining beat-to-beat vital sign parameters.

[0103] The beat-to-beat vital sign parameters include one or more of stroke volume, pulse pressure, heart rate, mean arterial pressure, vascular resistance, cardiac contractility, and dynamic arterial elastance.

[0104] Performing waveform analysis of the hemodynamic data representative of the second pressure waveform to obtain an estimation of a change in preload comprises: obtaining a hemodynamic parameter representative of, related to, or proportional to preload; and determining a change of the hemodynamic parameter representative of, related to, or proportional to preload over a period of time.

[0105] Performing waveform analysis of the hemodynamic data representative of the arterial pressure waveform to obtain the estimation of the change in stroke volume or the change in pulse pressure comprises: obtaining a beat-to-beat hemodynamic parameter representative of, related to, or proportional to stroke volume or pulse pressure; and determining a change of the hemodynamic parameter representative of, related to, or proportional to stroke volume or pulse pressure over a period of time.

[0106] The indicator representing fluid responsiveness status for the patient is a ratio of a change in stroke volume or a change in pulse pressure over a change in preload.

[0107] The indicator representing fluid responsiveness status for the patient is a ratio of a change in stroke volume or a change in pulse pressure over a change in preload and normalized by the change in stroke volume or the change in pulse pressure.

[0108] The indicator representing fluid responsiveness status for the patient is a ratio of a change in stroke volume or a change in pulse pressure over a change in preload and normalized by a linear or a non-linear combination of one or more hemodynamic or vital sign parameters including one or more of stroke volume, heart rate, mean arterial pressure, vascular resistance, cardiac contractility, and dynamic arterial elastance.

[0109] The indicator representing fluid responsiveness status for the patient is continuously determined.

[0110] The indicator representing fluid responsiveness status for the patient is determined at a 20-second interval.

[0111] The indicator representing fluid responsiveness status for the patient is determined at a 5-second interval. A system for determining a fluid responsiveness indicator of a patient, the system comprising: a pressure sensor including a housing, a fluid input port connected via tubing to a fluid source, a catheter-side fluid port connected to a catheter inserted within the patient, a pressure transducer in communication with the fluid source through the fluid port, and an I / O cable in electrical communication with the pressure transducer; and an integrated hardware unit including: a system processor; a system memory; a display including a user interface; and an analog-to-digital (ADC) converter; wherein the pressure sensor produces, on an ongoing basis, a hemodynamic sensor signal representative of an arterial pressure waveform of the patient; and wherein the system memory includes instructions that, when executed by the system processor, are configured to: receive the hemodynamic sensor signal representative of the arterial pressure waveform of the patient; perform waveform analysis of the hemodynamic sensor signal representative of the arterial pressure waveform of the patient to determine a plurality of hemodynamic parameters; and determine an indicator representing fluid responsiveness status for the patient based on the plurality of parameters.

[0112] The system of the preceding paragraph can optionally include, additionally and / or alternatively, any one or more of the following features, configurations and / or additional components:

[0113] The arterial pressure waveform is a radial arterial blood pressure waveform, a pulmonary arterial blood pressure waveform, or a femoral arterial blood pressure waveform.

[0114] Performing waveform analysis of the hemodynamic sensor signal representative of the arterial pressure waveform of the patient to determine the plurality of hemodynamic parameters comprises: obtaining an estimation of a change in stroke volume or a change in pulse pressure; obtaining an estimation of a change in preload; and obtaining beat-to-beat vital sign parameters.

[0115] The beat-to-beat vital sign parameters include one or more of stroke volume, heart rate, mean arterial pressure, vascular resistance, cardiac contractility, and dynamic arterial elastance.

[0116] Obtaining the estimation of the change in preload comprises: obtaining a hemodynamic parameter representative of, related to, or proportional to preload; and determining a change of the hemodynamic parameter representative of, related to, or proportional to preload over a period of time. Obtaining the estimation of the change in stroke volume or the change in pulse pressure comprises: obtaining a beat-to-beat hemodynamic parameter representative of, related to, or proportional to stroke volume or pulse pressure; and determining a change of the hemodynamic parameter representative of, related to, or proportional to stroke volume or pulse pressure over a period of time.

[0117] The indicator representing fluid responsiveness status for the patient is a ratio of a change in stroke volume or a change in pulse pressure over a change in preload.

[0118] The indicator representing fluid responsiveness status for the patient is a ratio of a change in stroke volume or a change in pulse pressure over the change in preload and normalized by the change in stroke volume or the change in pulse pressure.

[0119] The indicator representing fluid responsiveness status for the patient is a ratio of a change in stroke volume or a change in pulse pressure over a change in preload and further normalized by a linear or a non-linear combination of one or more hemodynamic or vital sign parameters including one or more of stroke volume, heart rate, mean arterial pressure, vascular resistance, cardiac contractility, and dynamic arterial elastance.

[0120] The indicator representing fluid responsiveness status for the patient is continuously determined.

[0121] The indicator representing fluid responsiveness status for the patient is determined at a 20-second interval.

[0122] The indicator representing fluid responsiveness status for the patient is determined at a 5-second interval.

[0123] A system for monitoring a patient and providing a fluid responsiveness indicator of the patient, the system comprising: a pressure sensor including a housing, a fluid input port connected via tubing to a fluid source, a catheter-side fluid port connected to a catheter inserted within the patient, a pressure transducer in communication with the fluid source through the fluid port, and an I / O cable in electrical communication with the pressure transducer; and an integrated hardware unit including: a system processor; a system memory; a display including a user interface; and an analog-to-digital (ADC) converter; wherein the pressure sensor produces, on an ongoing basis, a first hemodynamic sensor signal representative of an arterial pressure waveform of the patient and a second hemodynamic sensor signal representative of a second pressure waveform of the patient; and wherein the system memory includes instructions that, when executed by the system processor, are configured to: receive the first hemodynamic sensor signal representative of the arterial pressure waveform of the patient; receive the second hemodynamic sensor signal representative of the second pressure waveform of the patient, perform waveform analysis of the first hemodynamic sensor signal representative of the arterial pressure waveform and the second hemodynamic sensor signal representative of the second pressure waveform to determine a plurality of hemodynamic parameters; and determine an indicator representing fluid responsiveness status for the patient based on the plurality of hemodynamic parameters.

[0124] The system of the preceding paragraph can optionally include, additionally and / or alternatively, any one or more of the following features, configurations and / or additional components:

[0125] The arterial pressure waveform is a radial arterial blood pressure waveform, a pulmonary arterial blood pressure waveform, or a femoral arterial blood pressure waveform.

[0126] The second pressure waveform is a central venous pressure waveform, a radial arterial blood pressure waveform, a pulmonary arterial blood pressure waveform, or a femoral arterial blood pressure waveform.

[0127] Performing waveform analysis of the first hemodynamic sensor signal representative of the arterial pressure waveform and the second hemodynamic sensor signal representative of the second pressure waveform to determine the plurality of hemodynamic parameters comprises: performing waveform analysis of the hemodynamic data representative of the arterial pressure waveform to obtain an estimation of a change in stroke volume or a change in pulse pressure; performing waveform analysis of the hemodynamic data representative of the second pressure waveform to obtain an estimation of a change in preload; and obtaining beat-to-beat vital sign parameters.

[0128] The beat-to-beat vital sign parameters include one or more of stroke volume, pulse pressure, heart rate, mean arterial pressure, vascular resistance, cardiac contractility, and dynamic arterial elastance.

[0129] Performing waveform analysis of the first hemodynamic sensor signal representative of the arterial pressure waveform and the second hemodynamic sensor signal representative of the second pressure waveform to determine the plurality of hemodynamic parameters comprises: obtaining a hemodynamic parameter representative of, related to, or proportional to preload; and determining a change of the hemodynamic parameter representative of, related to, or proportional to preload over a period of time. Performing waveform analysis of the hemodynamic data representative of the arterial pressure waveform to obtain the estimation of the change in stroke volume or the change in pulse pressure comprises: obtaining a beat-to-beat hemodynamic parameter representative of, related to, or proportional to stroke volume or pulse pressure; and determining a change of the hemodynamic parameter representative of, related to, or proportional to stroke volume or pulse pressure over a period of time.

[0130] The indicator representing fluid responsiveness status for the patient is a ratio of a change in stroke volume or a change in pulse pressure over a change in preload.

[0131] The indicator representing fluid responsiveness status for the patient is a ratio of a change in stroke volume or a change in pulse pressure over a change in preload and normalized by the change in stroke volume or the change in pulse pressure.

[0132] The indicator representing fluid responsiveness status for the patient is a ratio of a change in stroke volume or a change in pulse pressure over a change in preload and normalized by a linear or a non-linear combination of one or more hemodynamic or vital sign parameters including one or more of stroke volume, heart rate, mean arterial pressure, vascular resistance, cardiac contractility, and dynamic arterial elastance.

[0133] The indicator representing fluid responsiveness status for the patient is continuously determined.

[0134] The indicator representing fluid responsiveness status for the patient is determined at a 20-second interval.

[0135] The indicator representing fluid responsiveness status for the patient is determined at a 5-second interval.

[0136] A system for determining fluid responsiveness in a patient, the system comprising: a pressure sensor including a housing, a fluid input port connected via tubing to a fluid source, a catheter-side fluid port connected to a catheter inserted within the patient, a pressure transducer in communication with the fluid source through the fluid port, and an I / O cable in electrical communication with the pressure transducer; and an integrated hardware unit including: a system processor; a system memory; a display including a user interface; and an analog-to-digital (ADC) converter; wherein the pressure sensor produces, on an ongoing basis, a hemodynamic sensor signal representative of an arterial pressure waveform of the patient; and wherein the system memory includes instructions that, when executed by the system processor, are configured to: receive the hemodynamic sensor signal representative of the arterial pressure waveform of the patient; perform waveform analysis of the arterial pressure waveform of the patient to determine a plurality of hemodynamic parameters; estimate a change in stroke volume or a change in pulse pressure and a change in preload based on the plurality of hemodynamic parameters from the arterial pressure waveform of the patient; determine a ratio of the change in stroke volume or the change in pulse pressure over the change in preload; and output the ratio of the change in stroke volume or the change in pulse pressure over the change in preload to the display for determining fluid responsiveness based on the ratio of the change in stroke volume or the change in pulse pressure over the change in preload.

[0137] The system of the preceding paragraph can optionally include, additionally and / or alternatively, any one or more of the following features, configurations and / or additional components:

[0138] The arterial pressure waveform is a radial arterial blood pressure waveform, a pulmonary arterial blood pressure waveform, or a femoral arterial blood pressure waveform.

[0139] Performing waveform analysis of the arterial pressure waveform of the patient to determine a plurality of hemodynamic parameters includes obtaining beat-to-beat vital sign parameters.

[0140] The beat-to-beat vital sign parameters include one or more of stroke volume, heart rate, mean arterial pressure, vascular resistance, cardiac contractibility, and dynamic arterial elastance.

[0141] Estimating a change in preload includes determining a hemodynamic parameter over a period of time.

[0142] Estimating a change in stroke volume or a change in pulse pressure includes determining a hemodynamic parameter over a period of time.

[0143] The system memory includes instructions that, when executed by the system processor, are configured to normalize the ratio of the change in stroke volume or the change in pulse pressure over the change in preload.

[0144] The ratio of the change in stroke volume or the change in pulse pressure over the change in preload is normalized by a linear or a non-linear combination of one or more hemodynamic or vital sign parameters including heart rate, mean arterial pressure, vascular resistance, cardiac contractibility, and dynamic arterial elastance.

[0145] The plurality of hemodynamic parameters are continuously determined.

[0146] The plurality of hemodynamic parameters are determined at a 20- second interval. The plurality of hemodynamic parameters are determined at a 5 -second interval.

[0147] A system for determining fluid responsiveness in a patient, the system comprising: a pressure sensor including a housing, a fluid input port connected via tubing to a fluid source, a catheter-side fluid port connected to a catheter inserted within the patient, a pressure transducer in communication with the fluid source through the fluid port, and an I / O cable in electrical communication with the pressure transducer; and an integrated hardware unit including: a system processor; a system memory; a display including a user interface; and an analog-to-digital (ADC) converter; wherein the pressure sensor produces, on an ongoing basis, a first hemodynamic sensor signal representative of an arterial pressure waveform of the patient and a second hemodynamic sensor signal representative of a second pressure waveform of the patient; and wherein the system memory includes instructions that, when executed by the system processor, are configured to: receive the first hemodynamic sensor signal representative of the arterial pressure waveform of the patient; receive the second hemodynamic sensor signal representative of the second pressure waveform of the patient; perform waveform analysis of the arterial pressure waveform of the patient and the second pressure waveform of the patient to determine a plurality of hemodynamic parameters; estimate a change in stroke volume or a change in pulse pressure and a change in preload based on the plurality of hemodynamic parameters from the arterial pressure waveform of the patient and the second pressure waveform of the patient; determine a ratio of the change in stroke volume or the change in pulse pressure over the change in preload; and output the ratio of the change in stroke volume or the change in pulse pressure over the change in preload to the display for determining fluid responsiveness based on the ratio of the change in stroke volume or the change in pulse pressure over the change in preload.

[0148] The system of the preceding paragraph can optionally include, additionally and / or alternatively, any one or more of the following features, configurations and / or additional components:

[0149] The arterial pressure waveform is a radial arterial blood pressure waveform, a pulmonary arterial blood pressure waveform, or a femoral arterial blood pressure waveform.

[0150] The second pressure waveform is a central venous pressure waveform, a radial arterial blood pressure waveform, a pulmonary arterial blood pressure waveform, or a femoral arterial blood pressure waveform. Performing waveform analysis of the arterial pressure waveform of the patient and the second pressure waveform of the patient to determine the plurality of hemodynamic parameters includes obtaining beat-to-beat vital sign parameters.

[0151] The beat-to-beat vital sign parameters include one or more of stroke volume, heart rate, mean arterial pressure, vascular resistance, cardiac contractibility, and dynamic arterial elastance.

[0152] Estimating a change in preload includes determining a hemodynamic parameter over a period of time.

[0153] Estimating a change in stroke volume or a change in pulse pressure includes determining a hemodynamic parameter over a period of time.

[0154] The system memory includes instructions that, when executed by the system processor, are configured to normalize the ratio of the change in stroke volume or the change in pulse pressure over the change in preload.

[0155] The ratio of the change in stroke volume or the change in pulse pressure over the change in preload is normalized by a linear or a non-linear combination of one or more hemodynamic or vital sign parameters including heart rate, mean arterial pressure, vascular resistance, cardiac contractibility, and dynamic arterial elastance.

[0156] The plurality of hemodynamic parameters are continuously determined.

[0157] The plurality of hemodynamic parameters are determined at a 20- second interval.

[0158] The plurality of hemodynamic parameters are determined at a 5 -second interval.

[0159] A method for monitoring a patient and providing a fluid responsiveness indicator of the patient, the method comprising: receiving, by a hemodynamic monitor, sensed hemodynamic data representative of an arterial pressure waveform of the patient; performing, by the hemodynamic monitor, waveform analysis of the arterial pressure waveform of the patient to determine a plurality of hemodynamic parameters; estimating, by the hemodynamic monitor, a change in stroke volume or a change in pulse pressure and a change in preload based on the plurality of hemodynamic parameters from the arterial pressure waveform of the patient; determining, by the hemodynamic monitor, a ratio of the change in stroke volume or the change in pulse pressure over the change in preload; and outputting, by the hemodynamic monitor, the ratio of the change in stroke volume or the change in pulse pressure over the change in preload to a display for determining fluid responsiveness based on the ratio of the change in stroke volume or the change in pulse pressure over the change in preload.

[0160] The method of the preceding paragraph can optionally include, additionally and / or alternatively, any one or more of the following features, configurations and / or additional components:

[0161] The arterial pressure waveform is a radial arterial blood pressure waveform, a pulmonary arterial blood pressure waveform, or a femoral arterial blood pressure waveform.

[0162] Performing waveform analysis of the arterial pressure waveform of the patient to determine the plurality of hemodynamic parameters includes obtaining beat-to- beat vital sign parameters.

[0163] The beat-to-beat vital sign parameters include one or more of stroke volume, heart rate, mean arterial pressure, vascular resistance, cardiac contractibility, and dynamic arterial elastance.

[0164] Estimating a change in preload includes determining a hemodynamic parameter over a period of time.

[0165] Estimating a change in stroke volume or a change in pulse pressure includes determining a hemodynamic parameter over a period of time.

[0166] Normalizing, by the hemodynamic monitor, the ratio of the change in stroke volume or the change in pulse pressure over the change in preload.

[0167] The ratio of the change in stroke volume or the change in pulse pressure over the change in preload is normalized by a linear or a non-linear combination of one or more hemodynamic or vital sign parameters including heart rate, mean arterial pressure, vascular resistance, cardiac contractibility, and dynamic arterial elastance.

[0168] The plurality of hemodynamic parameters are continuously determined.

[0169] The plurality of hemodynamic parameters are determined at a 20- second interval.

[0170] The plurality of hemodynamic parameters are determined at a 5 -second interval.

[0171] A method for monitoring a patient and providing a fluid responsiveness indicator of the patient, the method comprising: receiving, by a hemodynamic monitor, sensed hemodynamic data representative of an arterial pressure waveform of the patient and sensed hemodynamic data representative of a second pressure waveform of the patient; performing, by the hemodynamic monitor, waveform analysis of the arterial pressure waveform of the patient and the second pressure waveform of the patient to determine a plurality of hemodynamic parameters; estimating, by the hemodynamic monitor, a change in stroke volume or a change in pulse pressure and a change in preload based on the plurality of hemodynamic parameters from the arterial pressure waveform of the patient and the second pressure waveform of the patient; determining, by the hemodynamic monitor, a ratio of the change in stroke volume or the change in pulse pressure over the change in preload; and outputting, by the hemodynamic monitor, the ratio of the change in stroke volume or the change in pulse pressure over the change in preload to the display for determining fluid responsiveness based on the ratio of the change in stroke volume or the change in pulse pressure over the change in preload.

[0172] The method of the preceding paragraph can optionally include, additionally and / or alternatively, any one or more of the following features, configurations and / or additional components:

[0173] The arterial pressure waveform is a radial arterial blood pressure waveform, a pulmonary arterial blood pressure waveform, or a femoral arterial blood pressure waveform.

[0174] The second pressure waveform is a central venous pressure waveform, a radial arterial blood pressure waveform, a pulmonary arterial blood pressure waveform, or a femoral arterial blood pressure waveform.

[0175] Performing waveform analysis of the arterial pressure waveform and the second pressure waveform of the patient to determine the plurality of hemodynamic parameters includes obtaining beat-to-beat vital sign parameters.

[0176] The beat-to-beat vital sign parameters include one or more of stroke volume, heart rate, mean arterial pressure, vascular resistance, cardiac contractibility, and dynamic arterial elastance.

[0177] Estimating the change in preload includes determining a hemodynamic parameter over a period of time.

[0178] Estimating the change in stroke volume or the change in pulse pressure includes determining a hemodynamic parameter over a period of time.

[0179] Normalizing, by the hemodynamic monitor, the ratio of the change in stroke volume or the change in pulse pressure over the change in preload.

[0180] The ratio of the change in stroke volume or the change in pulse pressure over the change in preload is normalized by a linear or a non-linear combination of one or more hemodynamic or vital sign parameters including heart rate, mean arterial pressure, vascular resistance, cardiac contractibility, and dynamic arterial elastance.

[0181] The plurality of hemodynamic parameters are continuously determined.

[0182] The plurality of hemodynamic parameters are determined at a 20- second interval.

[0183] The plurality of hemodynamic parameters are determined at a 5-second interval.

[0184] A system for determining fluid responsiveness in a patient, the system comprising: a pressure sensor including a housing, a fluid input port connected via tubing to a fluid source, a catheter-side fluid port connected to a catheter inserted within the patient, a pressure transducer in communication with the fluid source through the fluid port, and an I / O cable in electrical communication with the pressure transducer; and an integrated hardware unit including: a system processor; a system memory; a display including a user interface; and an analog-to-digital (ADC) converter; wherein the pressure sensor produces, on an ongoing basis, a hemodynamic sensor signal representative of a pressure waveform representative of intrathoracic pressure changes of the patient; and wherein the system memory includes instructions that, when executed by the system processor, are configured to: receive the hemodynamic sensor signal representative of the pressure waveform representative of the intrathoracic pressure changes of the patient; perform waveform analysis of the pressure waveform representative of the intrathoracic pressure changes of the patient to determine a plurality of hemodynamic parameters; estimate a change in stroke volume or a change in pulse pressure and a change in preload based on the plurality of hemodynamic parameters from the pressure waveform representative of the intrathoracic pressure changes of the patient; determine a ratio of the change in stroke volume or the change in pulse pressure over the change in preload; and output the ratio of the change in stroke volume or the change in pulse pressure over the change in preload to the display for determining fluid responsiveness based on the ratio of the change in stroke volume or the change in pulse pressure over the change in preload.

[0185] The system of the preceding paragraph can optionally include, additionally and / or alternatively, any one or more of the following features, configurations and / or additional components:

[0186] The system memory includes instructions that, when executed by the system processors, cause the system to extract a low frequency component of the pressure waveform representative of the intrathoracic pressure changes of the patient. The system memory includes instructions that, when executed by the system processors, cause the system to detect paired minimum amplitudes and maximum amplitudes from the pressure waveform representative of the intrathoracic pressure changes of the patient.

[0187] The system memory includes instructions that, when executed by the system processors, cause the system to determine differences between the paired maximum amplitudes and minimum amplitudes.

[0188] The system memory includes instructions that, when executed by the system processors, cause the system to determine a median of the differences to estimate a change in preload.

[0189] The pressure waveform representative of the intrathoracic pressure changes of the patient is a central venous pressure waveform, and the maximum amplitudes and the minimum amplitudes are extracted from the central venous pressure waveform in a time domain.

[0190] The pressure waveform representative of the intrathoracic pressure changes of the patient is an arterial blood pressure waveform, and the maximum amplitudes and the minimum amplitudes are extracted from the arterial blood pressure waveform in a time domain.

[0191] The pressure waveform representative of the intrathoracic pressure changes of the patient is a central venous pressure waveform.

[0192] The pressure waveform representative of the intrathoracic pressure changes of the patient is an arterial blood pressure waveform.

[0193] Fluid responsiveness is continuously determined based on the ratio of the change in stroke volume or the change in pulse pressure over the change in preload.

[0194] Fluid responsiveness is determined based on the ratio of the change in stroke volume or the change in pulse pressure over the change in preload at a 20-second interval.

[0195] Fluid responsiveness is determined based on the ratio of the change in stroke volume or the change in pulse pressure over the change in preload at a 5-second interval.

[0196] The system memory includes instructions that, when executed by the system processors, cause the system to concurrently estimate the change in preload and the change in stroke volume or the change in pulse pressure from the pressure waveform representative of the intrathoracic pressure changes of the patient.

[0197] A system for determining fluid responsiveness in a patient, the system comprising: a non-invasive blood pressure sensor including an inflatable blood pressure bladder, a pressure controller pneumatically connected to the inflatable blood pressure bladder, and an optical transmitter and an optical receiver that are electrically connected to the pressure controller; and an integrated hardware unit including: a system processor; a system memory; and a display including a user interface; wherein the non-invasive blood pressure sensor produces, on an ongoing basis, a hemodynamic sensor signal representative of a pressure waveform representative of intrathoracic pressure changes of the patient; and wherein the system memory includes instructions that, when executed by the system processor, are configured to: receive the hemodynamic sensor signal representative of the pressure waveform representative of the intrathoracic pressure changes of the patient; perform waveform analysis of the pressure waveform representative of the intrathoracic pressure changes of the patient to determine a plurality of hemodynamic parameters; estimate a change in stroke volume or a change in pulse pressure and a change in preload based on the plurality of hemodynamic parameters from the pressure waveform representative of the intrathoracic pressure changes of the patient; determine a ratio of the change in stroke volume or the change in pulse pressure over the change in preload; and output the ratio of the change in stroke volume or the change in pulse pressure over the change in preload to the display for determining fluid responsiveness based on the ratio of the change in stroke volume or the change in pulse pressure over the change in preload.

[0198] The system of the preceding paragraph can optionally include, additionally and / or alternatively, any one or more of the following features, configurations and / or additional components:

[0199] The system memory includes instructions that, when executed by the system processors, cause the system to extract a low frequency component of the pressure waveform representative of the intrathoracic pressure changes of the patient.

[0200] The system memory includes instructions that, when executed by the system processors, cause the system to detect paired minimum amplitudes and maximum amplitudes from the pressure waveform representative of the intrathoracic pressure changes of the patient.

[0201] The system memory includes instructions that, when executed by the system processors, cause the system to determine differences between the paired maximum amplitudes and minimum amplitudes.

[0202] The system memory includes instructions that, when executed by the system processors, cause the system to determine a median of the differences to estimate the change in preload. The pressure waveform representative of the intrathoracic pressure changes is an arterial blood pressure waveform, and the maximum amplitudes and the minimum amplitudes are extracted from the arterial blood pressure waveform in a time domain.

[0203] The pressure waveform representative of the intrathoracic pressure changes of the patient is an arterial blood pressure waveform.

[0204] Fluid responsiveness is continuously determined based on the ratio of the change in stroke volume or the change in pulse pressure over the change in preload.

[0205] Fluid responsiveness is determined based on the ratio of the change in stroke volume or the change in pulse pressure over the change in preload at a 20-second interval.

[0206] Fluid responsiveness is determined based on the ratio of the change in stroke volume or the change in pulse pressure over the change in preload at a 5-second interval.

[0207] The system memory includes instructions that, when executed by the system processors, cause the system to concurrently estimate the change in preload and the change in stroke volume or the change in pulse pressure from the pressure waveform representative of the intrathoracic pressure changes of the patient.

[0208] A method for determining fluid responsiveness in a patient, the method comprising: receiving, by a hemodynamic monitor, sensed hemodynamic data representative of a pressure waveform representative of the intrathoracic pressure changes of the patient; performing, by the hemodynamic monitor, waveform analysis of the pressure waveform representative of the intrathoracic pressure changes of the patient to determine a plurality of hemodynamic parameters; estimating, by the hemodynamic monitor, a change in stroke volume or a change in pulse pressure and a change in preload from the pressure waveform representative of the intrathoracic pressure changes of the patient; determining, by the hemodynamic monitor, a ratio of the change in stroke volume or the change in pulse pressure over the change in preload; and outputting, by the hemodynamic monitor, the ratio of the change in stroke volume or the change in pulse pressure over the change in preload to the display for determining fluid responsiveness based on the ratio of the change in stroke volume or the change in pulse pressure over the change in preload.

[0209] The method of the preceding paragraph can optionally include, additionally and / or alternatively, any one or more of the following features, configurations and / or additional components:

[0210] Extracting, by the hemodynamic monitor, a low frequency component of the pressure waveform representative of the intrathoracic pressure changes of the patient. Detecting, by the hemodynamic monitor, paired minimum amplitudes and maximum amplitudes from the pressure waveform representative of the intrathoracic pressure changes of the patient.

[0211] Determining, by the hemodynamic monitor, differences between the paired maximum amplitudes and minimum amplitudes.

[0212] Determining, by the hemodynamic monitor, a median of the differences to estimate the change in preload.

[0213] The pressure waveform representative of the intrathoracic pressure changes is a central venous pressure waveform.

[0214] The pressure waveform representative of the intrathoracic pressure changes is an arterial blood pressure waveform.

[0215] The above method(s) can be performed on a living animal or on a simulation, such as on a cadaver, cadaver heart, anthropomorphic ghost, simulator (e.g., with body parts, heart, tissue, etc. being simulated).

[0216] While the invention has been described with reference to an exemplary example(s), it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular example(s) disclosed, but that the invention will include all examples falling within the scope of the appended claims.

Claims

CLAIMS:

1. A system for determining fluid responsiveness in a patient, the system comprising: a pressure sensor including a housing, a fluid input port connected via tubing to a fluid source, a catheter-side fluid port connected to a catheter inserted within the patient, a pressure transducer in communication with the fluid source through the fluid port, and an I / O cable in electrical communication with the pressure transducer; and an integrated hardware unit including: a system processor; a system memory; a display including a user interface; and an analog-to-digital (ADC) converter; wherein the pressure sensor produces, on an ongoing basis, a hemodynamic sensor signal representative of an arterial pressure waveform of the patient; and wherein the system memory includes instructions that, when executed by the system processor, are configured to: receive the hemodynamic sensor signal representative of the arterial pressure waveform of the patient; perform waveform analysis of the arterial pressure waveform of the patient to determine a plurality of hemodynamic parameters; estimate a change in stroke volume or a change in pulse pressure and a change in preload based on the plurality of hemodynamic parameters from the arterial pressure waveform of the patient; determine a ratio of the change in stroke volume or the change in pulse pressure over the change in preload; and output the ratio of the change in stroke volume or the change in pulse pressure over the change in preload to the display for determining fluid responsiveness based on the ratio of the change in stroke volume or the change in pulse pressure over the change in preload.

2. The system of claim 1, wherein the arterial pressure waveform is a radial arterial blood pressure waveform, a pulmonary arterial blood pressure waveform, or a femoral arterial blood pressure waveform.

3. The system of claim 1, performing waveform analysis of the arterial pressure waveform of the patient to determine the plurality of hemodynamic parameters includes obtaining beat-to-beat vital sign parameters.

4. The system of claim 3, wherein the beat-to-beat vital sign parameters include one or more of stroke volume, heart rate, mean arteri al pressure, vascular resistance, cardiac contractibility, and dynamic arterial elastance.

5. The system of claim 1, wherein estimating a change in preload includes determining a hemodynamic parameter over a period of time.

6. The system of claim 1 , wherein estimating a change in stroke volume or a change in pulse pressure includes determining a hemodynamic parameter over a period of time.

7. The system of claim 1, wherein the system memory includes instructions that, when executed by the system processor, are configured to normalize the ratio of the change in stroke volume or the change in pulse pressure over the change in preload.

8. The system of claim 7, wherein the ratio of the change in stroke volume or the change in pulse pressure over the change in preload is normalized by a linear or a nonlinear combination of one or more hemodynamic or vital sign parameters including heart rate, mean arterial pressure, vascular resistance, cardiac contractibility, and dynamic arterial elastance.

9. The system of claim 1 , wherein the plurality of hemodynamic parameters are continuously determined.

10. The system of claim 9, wherein the plurality of hemodynamic parameters are determined at a 20-second interval.

11. The system of claim 9, wherein the plurality of hemodynamic parameters are determined at a 5-second interval.

12. The system of claim 1, further comprising an infusion device configured to deliver a fluid to a patient, wherein the infusion device is configured to adjust delivery of the fluid to the patient based on the determined fluid responsiveness.

13. The system of claim 12, wherein the infusion device is an infusion pump and the fluid is substantially free of vasoactive medicaments.

14. The system of claim 1 , wherein the pressure sensor produces, on an ongoing basis, a second hemodynamic sensor signal representative of a second pressure waveform of the patient, and wherein the system memory includes instructions that, when executed by the system processor, are configured to: receive the second hemodynamic sensor signal representative of the second pressure waveform of the patient; and perform waveform analysis of the second pressure waveform of the patient to determine a plurality of hemodynamic parameters.

15. The system of claim 14, wherein the second pressure waveform is a central venous pressure waveform, a radial arterial blood pressure waveform, a pulmonary arterial blood pressure waveform, or a femoral arterial blood pressure waveform.

16. The system of claim 14, wherein performing waveform analysis of the arterial pressure waveform of the patient and the second pressure waveform of the patient to determine the plurality of hemodynamic parameters includes obtaining beat-to-beat vital sign parameters.

17. A method for monitoring a patient and providing a fluid responsiveness indicator of the patient, the method comprising: receiving, by a hemodynamic monitor, sensed hemodynamic data representative of an arterial pressure waveform of the patient; performing, by the hemodynamic monitor, waveform analysis of the arterial pressure waveform of the patient to determine a plurality of hemodynamic parameters; estimating, by the hemodynamic monitor, a change in stroke volume or a change in pulse pressure and a change in preload based on the plurality of hemodynamic parameters from the arterial pressure waveform of the patient; determining, by the hemodynamic monitor, a ratio of the change in stroke volume or the change in pulse pressure over the change in preload; and outputting, by the hemodynamic monitor, the ratio of the change in stroke volume or the change in pulse pressure over the change in preload to a display for determining fluid responsiveness based on the ratio of the change in stroke volume or the change in pulse pressure over the change in preload.

18. The method of claim 17, wherein the arterial pressure waveform is a radial arterial blood pressure waveform, a pulmonary arterial blood pressure waveform, or a femoral arterial blood pressure waveform.

19. The method of claim 17, wherein performing waveform analysis of the arterial pressure waveform of the patient to determine the plurality of hemodynamic parameters includes obtaining beat-to-beat vital sign parameters.

20. The method of claim 19, wherein the beat-to-beat vital sign parameters include one or more of stroke volume, heart rate, mean arterial pressure, vascular resistance, cardiac contractibility, and dynamic arterial elastance.

21. The method of claim 17, wherein estimating a change in preload includes determining a hemodynamic parameter over a period of time.

22. The method of claim 17, wherein estimating a change in stroke volume or a change in pulse pressure includes determining a hemodynamic parameter over a period of time.

23. The method of claim 17, further including normalizing, by the hemodynamic monitor, the ratio of the change in stroke volume or the change in pulse pressure over the change in preload.

24. The method of claim 23, wherein the ratio of the change in stroke volume or the change in pulse pressure over the change in preload is normalized by a linear or a non-linear combination of one or more hemodynamic or vital sign parameters including heart rate, mean arterial pressure, vascular resistance, cardiac contractibility, and dynamic arterial elastance.

25. The method of claim 17, wherein the plurality of hemodynamic parameters are continuously determined.

26. The method of claim 25, wherein the plurality of hemodynamic parameters are determined at a 20-second interval.

27. The method of claim 25, wherein the plurality of hemodynamic parameters are determined at a 5-second interval.

Images