Pulse detection method and apparatus using patient impedance

• US 9,950,178 B2
• Filed: 01/15/2010
• Issued: 04/24/2018
• Est. Priority Date: 12/06/2001
• Status: Expired due to Term

• Current Assignee: Physio-Control Incorporated (Stryker Corporation)
• Original Assignee: Physio-Control Incorporated (Stryker Corporation)
• Inventors: Stickney, Ronald E., Taylor, James W., O'Hearn, Patricia, Jayne, Cynthia P., Lank, Paula, Hampton, David R.
• Primary Examiner(s): Carey, Michael
• Assistant Examiner(s): Dinga, Roland
• Application Number:
  US12/688,729
• Publication Number:
  US 20100114219A1
• Time in Patent Office: 3,021 Days
• Field of Search: 600508, 600509, 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. An electrotherapy device, comprising:

(a) electrodes adapted to sense an electrocardiogram (ECG) signal from a patient and adapted to communicate an impedance-sensing signal through 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 a user for delivery of chest compressions;

analyze the impedance-sensing signal to determine the presence of chest compressions being delivered to the patient and if chest compressions are not determined to be present during a cardiopulmonary resuscitation (CPR) period, prompt delivery of chest compressions to the patient;

filter the impedance signal through a bandpass filter; and

analyze the filtered impedance-sensing signal to determine the presence of respiration in the patient by comparing impedance signal data that is based on the impedance-sensing signal to a previously identified impedance signal data pattern known to be indicative of a presence of respiration, the processing circuitry further configured to prompt the delivery of rescue breathing therapy to the patient if respiration is determined not present in the patient,

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

2. The electrotherapy device of claim 1, in which the processing circuitry is further configured to analyze the impedance signal data by determining cardiac output in terms of a stroke volume and use the determined cardiac output as an additional feature indicative of the presence of a cardiac pulse, the processing circuitry is further configured to prompt a message on a display reporting whether a cardiac pulse is present in the patient.

3. A method comprising:

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

analyzing, with the automated external defibrillator, the ECG signal for asystole, filtering the impedance signal through a bandpass filter, and analyzing the filtered impedance signal data to determine the presence of respiration in the patient by comparing the impedance signal data to a previously identified impedance signal data pattern known to be indicative of a presence of respiration;

prompting, with the automated external defibrillator, a user for delivery of chest compressions in response to the analysis determining 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.

4. The method of claim 3, further comprising:

analyzing, with the automated external defibrillator, the impedance-sensing signal to determine the presence of chest compressions being delivered to the patient by comparing impedance signal data to a previously identified impedance signal data pattern known to be indicative of a presence of chest compressions; and

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

5. The electrotherapy device of claim 3, in which the processing circuitry is further configured to analyze the impedance signal data by determining cardiac output in terms of a rate of output and use the determined cardiac output as an additional feature indicative of the presence of a cardiac pulse, the processing circuitry is further configured to prompt a message on a display reporting whether a cardiac pulse is present in the patient.