US-12616637-B2 - CPR chest compression system with tonometric input and feedback

Abstract

A CPR chest compression system which uses tonometric data as feedback for control of chest compression device.

Inventors

• Christopher L Kaufman
• Gary A Freeman

Assignees

• ZOLL MEDICAL CORPORATION

Dates

Publication Date

20260505

Application Date

20230104

Claims (20)

1. 1 . A computer-implemented method, for execution by at least one processor in association with a chest compressor and at least one sensor, to provide CPR compressions on a cardiac arrest patent, the method comprising: applying a plurality of initial sets of chest compressions on the patient, each of the initial sets of chest compressions being performed according to a distinct chest compression regime, each distinct chest compression regime having chest compression parameters comprising at least one of: depth, compression hold time, release time, intercompression pause, and compression rate; acquiring, for each of the initial sets of chest compressions, a corresponding CPR-induced time-domain pressure waveform generated using the at least one pressure sensor; identifying, for each pressure waveform, one or more parameters of the pressure waveform, the one or more parameters comprising: i) a secondary peak, occurring after an initial pressure peak and during a CPR compression hold portion of the pressure waveform, and ii) at least one pressure-time integral magnitude corresponding to at least a portion of the pressure waveform, determining whether the identified one or more parameters of each pressure waveform meet one or more predetermined criteria indicative of optimum blood flow; identifying which of the initial sets of chest compressions is associated with CPR-induced optimum blood flow, based at least in part on the comparison and determination that both the secondary peak and the pressure-time integral satisfy predetermined effectiveness criteria; and subsequent to the application of the plurality of initial sets of chest compressions, performing at least one subsequent set of chest compressions according to the chest compression regime of the initial set of chest compressions identified to be associated with optimum blood flow.
2. 2 . The method of claim 1 , wherein the pressure waveform comprises a pulse pressure waveform, and obtaining the CPR-induced pulse wave signals comprises obtaining the CPR-induced pulse wave signals using at least one non-invasive sensor.
3. 3 . The method of claim 1 , wherein obtaining the CPR-induced pulse wave signals comprises obtaining the CPR-induced pulse wave signals using at least one invasive sensor.
4. 4 . The method of claim 1 , wherein the at least one area comprises at least one of: a CPR diastolic pressure time integral (CPR-DPTI), a CPR systolic pressure time integral (CPR-SPTI), or a CPR total pressure time integral (CPR-TPTI).
5. 5 . The method of claim 1 , wherein the one or more parameters of the associated pressure waveform comprises a shelf corresponding to the CPR-SPTI.
6. 6 . The method of claim 1 , wherein the pressure waveform comprises a pulse pressure waveform.
7. 7 . The method of claim 1 , wherein the predetermined criteria comprise return time, wherein the return time is determined based on a time period between a start of a pressure waveform and an appearance of a reflected wave.
8. 8 . The method of claim 1 , wherein the plurality of initial sets chest compressions comprises at least two sets of chest compressions, and wherein identifying which one of the at least two sets of chest compressions is associated with optimum blood flow comprises identifying which of the at least two sets of chest compressions is more likely to provide better CPR-induced blood flow.
9. 9 . The method of claim 1 , wherein applying the plurality of initial sets of chest compressions comprises adjusting operation of the chest compressor.
10. 10 . The method of claim 9 , wherein adjusting operation of the chest compressor is based at least in part on the identified one or more parameters of the pressure waveform associated with each of the initial sets of chest compressions determined to be associated with optimum blood flow.
11. 11 . The method of claim 1 , wherein performing the at least one subsequent set of chest compressions according to the chest compression regime of the initial set of chest compressions identified to be associated with optimum blood flow comprises adjusting at least one of the chest compression parameters.
12. 12 . The method of claim 11 , wherein adjusting at least one of the chest compression parameters comprises adjusting at least one of: chest compression depth, chest compression rate, chest compression release velocity, chest compression rise time, or chest compression hold time.
13. 13 . The method of claim 1 , wherein applying the plurality of initial sets of chest compressions comprises applying: a first set of chest compressions under a first regime; a second set of chest compressions under a second regime; and a third set of chest compressions under a third regime; wherein each of the first regime, the second regime and the third regime are performed with a specified chest compression rate, a specified chest compression depth and a specified chest compression release time; and wherein each of the first regime, the second regime and the third regime are performed with at least one variation relative to each other and relating to at least one of chest compression rate, chest compression depth, and chest compression release time.
14. 14 . The method of claim 13 , wherein each of the first regime, the second regime and the third regime are performed according to a regime comprising a chest compression rate of between 80 and 100 compressions per minute (cpm), a chest compression depth of between 1.5 and 2.0 inches, and a release time of between 100 and 300 msecs.
15. 15 . The method of claim 13 , comprising determining a CPR pulse wave velocity associated with a chest compression performed on the patient by the chest compressor, based at least in part on signals received from the chest compressor and signals received from the at least one sensor.
16. 16 . The method of claim 13 , comprising estimating an arterial stiffness of the patient based at least in part on a CPR pulse wave velocity determined from the time delay between waveform features of the time-domain pressure waveform associated with the chest compressions.
17. 17 . The method of claim 16 , comprising, based at least on the estimated arterial stiffness, providing output relating to whether to administer epinephrine to the patient or to avoid administering epinephrine to the patient.
18. 18 . The method of claim 17 , wherein the provided output relating to whether to administer epinephrine to the patient or to avoid administering epinephrine to the patient comprises providing the output at a time during a period during which chest compressions are being performed on the patient.
19. 19 . The method of claim 1 , comprising allowing interruption between, or discontinuance of, sets of chest compressions for performance of rescue breathing on the patient.
20. 20 . The method of claim 1 , wherein identifying the one or more parameters of the pressure waveform comprises identifying a post-peak pressure wave feature occurring after the initial pressure peak of the CPR-induced pressure waveform, the post-peak pressure wave feature comprising at least one of a notch, a shoulder, or a shelf.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation of U.S. patent application Ser. No. 16/741,925, filed Jan. 14, 2020, which is a continuation of U.S. patent application Ser. No. 14/659,612, filed Mar. 16, 2015, which claims benefit under 35 U.S.C. § 119(e) to U.S. Provisional Application Ser. No. 61/955,109 filed Mar. 18, 2014. All subject matter set forth in each of the above referenced applications is hereby incorporated by reference in its entirety into the present application as if fully set forth herein. FIELD OF THE INVENTIONS The inventions described below relate to the field of CPR. BACKGROUND OF THE INVENTIONS The AutoPulse® chest compression device is used to provide chest compressions during the course of CPR in reviving a cardiac arrest victim. The AutoPulse® provides compressions according to a predetermined compression waveform which is optimized for a large variety of potential victims. We have previously proposed feedback control, based on sensed biological parameters, to alter the compression waveform applied by the chest compression device. The biological parameters proposed, including end-tidal CO2 and blood oxygen levels, are readily measured with non-invasive devices. The operation of chest compression devices can be improved with the use of more fundamental biological parameters, such as aortic blood flow volume, the aortic pulse pressure waveform, and other blood vessel parameters, as feedback for control of the chest compression device. Depending on the value of aortic blood flow volume and blood vessel parameters, the compression waveform provided by the chest compression device may be varied. The compression waveform may be varied from patient to patient, depending on the value of aortic blood flow volume and/or blood vessel parameters measured before or at the commencement of chest compressions. The compression waveform may be varied during the course of CPR chest compression on a single patient, depending on the value of aortic blood flow volume and/or blood vessel parameters measured over the course of resuscitation efforts and chest compressions. Chest compression waveform characteristics such as compression depth, compression rate, compression rise time, compression hold time, and release velocity can be varied to optimize compression induced blood flow in the cardiac arrest victim. Adjunct therapies, especially the administration of epinephrine, can be implemented, modified or avoided based on information gleaned from the biological parameters, such as arterial stiffness and/or pulse wave velocity. A number of terms relating to blood flow parameters are used in the art, including the following: The pulse pressure waveform is a depiction of pressure versus time in a particular blood vessel. SPTI refers to the systolic pressure-time integral, which is the area under the central aortic pressure wave curve during the systole portion of a heartbeat (when the left ventricle is contracting). SPTI is also referred to as left ventricular load, or LV load. Systole is that portion of the heartbeat starting at the closure of the atrioventricular (cuspid) valves and ending with the closure of the aortic valve. DPTI refers to the diastolic pressure-time integral, which is the area under the central aortic pressure wave curve during the diastole portion of a heartbeat (when the heart left ventricle is relaxing). Diastole is that portion of the heartbeat in which the heart is relaxing, starting with closure of the aortic valve and ending with the subsequent closure of the atrioventricular valves. Arterial Compliance, a measure of the stiffness, refers to the mechanical characteristic of blood vessels throughout the body. If refers to the ability or inability of blood vessels to elastically expand in response to pulsatile flow. It is quantified in terms of ml/mm Hg (the change in volume due to a given change in pressure). Elastance is a reciprocal concept, and refers to the tendency of blood vessels to recoil after distension. In relation to the aorta, aortic compliance/elastance affects the ability of the aorta to expand and contract during and after contraction of the heart which forces blood from the left ventricle. The aortic pulse pressure waveform can be determined non-invasively, based on peripheral pulse waveforms obtained with sensors mounted on the patient. Sensors can measure pressure and/or velocity at superficial locations of the radial artery, brachial artery, carotid and/or femoral artery. Various known models and “transfer functions” can be used to determine the aortic pressure wave from pressure waves measurements at peripheral locations such as the radial artery, brachial artery, carotid and/or femoral artery. See Chen, et al., Estimation of Central Aortic Pressure Waveform by Mathematical Transformation of Radial Tonometry Pressure, 95 Circulation 1827 (1997). The transfer function used for this estimate may be generalized, in the sense that the sa