PULSE DETECTION METHOD AND APPARATUS USING PATIENT IMPEDANCE

• US 20100114219A1
• Filed: 01/15/2010
• Published: 05/06/2010
• Est. Priority Date: 12/06/2001
• Status: Active Grant

• Current Assignee: Physio-Control Incorporated (Stryker Corporation)
• Original Assignee: Medtronic Physio-Control Manufacturing Corp.
• Inventors: Hampton, David R., Taylor, James W., O'Hearn, Patricia, Jayne, Cynthia P., Stickney, Ronald E., Lank, Paula
• Granted Patent: US 9,950,178 B2
• Time in Patent Office: Days
• US Class Current: 607/5
• CPC Class Codes: A61B 5/024 Detecting, measuring or recording pulse rate or heart rate A61B5/0205, A61B5/021 take precedence
• CPC Class Codes: A61B 5/0809 by impedance pneumography
• CPC Class Codes: A61B 5/363 Detecting tachycardia or bradycardia
• CPC Class Codes: A61B 5/7239 using differentiation including higher order derivatives
• CPC Class Codes: A61B 5/7246 using correlation, e.g. template matching or determination of similarity
• CPC Class Codes: A61B 5/7278 Artificial waveform generation or derivation, e.g. synthesising signals from measured signals A61B5/327 takes precedence
• CPC Class Codes: A61N 1/36521 the parameter being derived from measurement of an electrical impedance
• CPC Class Codes: A61N 1/3712 Auto-capture, i.e. automatic adjustment of the stimulation threshold
• CPC Class Codes: A61N 1/3925 Monitoring; Protecting

Abstract

The presence of a cardiac pulse in a patient is determined by evaluating fluctuations in an electrical signal that represents a measurement of the patient'"'"'s transthoracic impedance. Impedance signal data obtained from the patient is analyzed for a feature indicative of the presence of a cardiac pulse. Whether a cardiac pulse is present in the patient is determined based on the feature in the impedance signal data. Electrocardiogram (ECG) data may also be obtained in time coordination with the impedance signal data. Various applications for the pulse detection of the invention include detection of PEA and prompting PEA-specific therapy, prompting defibrillation therapy and/or CPR, and prompting rescue breathing depending on detection of respiration.

Claims

1-32. -32. (canceled)

33. An electrotherapy device, comprising:

(a) electrodes adapted to sense an electrocardiogram (ECG) signal from a patient and adapted to communicate an impedance-sensing signal from the patient;

(b) an electrotherapy generator in communication with the electrodes for delivering electrotherapy to the patient; and

(c) processing circuitry in communication with the electrodes and the electrotherapy generator and configured to;

analyze the patient'"'"'s ECG signal for asystole, and if the patient is determined to be in asystole condition, prompt the user for delivery of chest compressions; and

analyze the impedance-sensing signal to determine the presence of chest compressions being delivered to the patient, and if chest compression are not detected during a CPR period, prompt delivery of chest compressions to the patient,

in which the electrotherapy generator and the processing circuitry are implemented in an automated external defibrillator.

36. The electrotherapy device of claim 33, in which the processing circuitry is further configured to analyze the impedance-sensing signal to determine the presence of respiration in the patient, the processing circuitry prompting the delivery of rescue breathing therapy to the patient if respiration is determined not present in the patient.

39. The electrotherapy device of claim 33, further comprising:

a conversion circuit in communication with the electrodes for converting the sensed impedance-sensing signal into digital impedance signal data,

in which the processing circuitry is further configured to;

analyze the impedance signal data for a feature indicative of the presence of a cardiac pulse in the patient by evaluating energy in the impedance signal data; and

determine whether a cardiac pulse is present in the patient based on the feature in the impedance signal data.

40. The electrotherapy device of claim 39, in which the processing circuitry is configured to evaluate energy in the impedance signal data by selecting impedance signal data for an energy calculation and calculating the energy in the selected impedance signal data.

41. The electrotherapy device of claim 40, in which the calculated energy is the feature indicative of the presence of a cardiac pulse, the processing circuitry being further configured to compare the feature to a predetermined energy threshold to determine whether a cardiac pulse is present in the patient.

42. The electrotherapy device of claim 39, in which the processing circuitry is further configured to analyze the impedance signal data by determining cardiac output in terms of a stroke volume or rate of output and use the determined cardiac output as an additional feature indicative of the presence of a cardiac pulse, the processing unit is further configured to prompt a message on a display reporting whether a cardiac pulse is present in the patient.

43. The electrotherapy device of claim 39, in which the conversion circuit is further configured to convert the ECG signal into digital ECG data, and in which the processing circuitry is further configured to determine a presence of a QRS complex in the ECG data, and select impedance signal data corresponding in time with the QRS complex for analysis of the impedance signal data.

44. The electrotherapy device of claim 33, further comprising:

a conversion circuit in communication with the electrodes for converting the sensed impedance-sensing signal into digital impedance signal data,

in which the processing circuitry is further configured to;

analyze the impedance signal data for a feature indicative of the presence of a cardiac pulse in the patient by comparing the impedance signal data to a previously-identified impedance signal data pattern known to predict a presence of a cardiac pulse; and

determine whether a cardiac pulse is present in the patient based on the feature in the impedance signal data.

45. The electrotherapy device of claim 44, in which the comparison produces a pattern match statistic that is the feature indicative of the presence of a cardiac pulse, the processing circuitry being further configured to compare the feature to a predetermined pattern match threshold to determine whether a cardiac pulse is present in the patent.

46. The electrotherapy device of claim 44, in which the processing circuitry is configured to analyze the impedance signal data for two or more features indicative of the presence of cardiac pulse, in which one of the features is determined from the comparison of the impedance signal data with a previously-identified impedance signal data pattern and in which one of the other features is determined from an evaluation of an amplitude of the impedance signal data or an energy impedance signal data.

34-35. -35. (canceled)

37-38. -38. (canceled)

47. A method comprising:

obtaining, with an automated external defibrillator, an electrocardiogram (ECG) signal and data derived from an impedance-sensing signal from a patient;

analyzing, with the automated external defibrillator, the ECG signal for asystole and the impedance-sensing signal to determine the presence of respiration in the patient;

prompting, with the automated external defibrillator, a user for delivery of chest compressions when the analysis determines the patient to be in an asystole condition; and

prompting, with the automated external defibrillator, the user for delivery of rescue breathing therapy to the patient if the respiration is determined not present in the patient.

48. The method of claim 47, further comprising:

analyzing, with the automated external defibrillator, the impedance-sensing signal to determine the presence of chest compressions being delivered to the patient; and

prompting, with the automated external defibrillator, delivery of chest compressions to the patient if chest compressions are not detected during a CPR period.

49. The method of claim 47, further comprising:

analyzing the obtained impedance signal for a feature indicative of the presence of a cardiac pulse, in which analyzing the impedance signal includes evaluation energy in the impedance signal; and

determining whether a cardiac pulse is present in the patient based on the feature in the impedance signal.

50. The method of claim 49, in which evaluating energy in the impedance signal comprises selecting data from the obtained impedance signal for an energy calculation, and calculating an energy in the selected impedance signal.

51. The method of claim 50, in which the calculated energy is the feature indicative of the presence of a cardiac pulse, the method further comprising comparing the feature to a predetermined energy threshold to determine whether a cardiac pulse is present in the patient.