Pulse detection apparatus, software, and methods using patient physiological signals

Abstract

The presence of a cardiac pulse in a patient is determined by evaluating physiological signals in the patient. In one embodiment, a medical device evaluates two or more different physiological signals, such as phonocardiogram (PCG) signals, electrocardiogram (ECG) signals, patient impedance signals, piezoelectric signals, and accelerometer signals for features indicative of the presence of a cardiac pulse. Using these features, the medical device determines whether a cardiac pulse is present in the patient. The medical device may also be configured to report whether the patient is in a VF, VT, asystole, or PEA condition, in addition to being in a pulseless condition, and prompt different therapies, such as chest compressions, rescue breathing, defibrillation, and PEA-specific electrotherapy, depending on the analysis of the physiological signals. Auto-capture of a cardiac pulse using pacing stimuli is further provided.

1 - 50 . (canceled) 
     
     
         51 . An electrotherapy device, comprising:
 (a) a sensor, that is external to and placed on a patient, and configured to sense a physiological signal in the patient;   (b) an electrotherapy generator, that is external to the patient, and is configured for delivering pacing stimuli to the patient through a skin of the patient; and   (c) processing circuitry, that is external to the patient, and configured to analyze the physiological signal and determine whether a cardiac pulse occurred in the patient following the delivery of a pacing stimulus of the pacing stimuli to the patient, the processing circuitry increasing a current of further pacing stimuli to be delivered to the patient if the cardiac pulse did not occur in the patient following the delivery of the pacing stimulus, in which the physiological signal is a phonocardiogram (PCG) signal and the processing circuitry is configured to analyze the PCG signal for a feature indicative of a cardiac pulse and determine whether a cardiac pulse occurred in the patient after delivery of the pacing stimulus.   
     
     
         52 . (canceled) 
     
     
         53 . The electrotherapy device of  claim 51 , in which the electrotherapy device is configured to deliver pacing stimuli to the patient two or more times and the processing circuitry is configured to analyze the physiological signal to determine whether a cardiac pulse occurred after the delivery of each pacing stimulus, the current of further pacing stimuli to be delivered to the patient being increased if a cardiac pulse does not consistently occur in the patient after the delivery of each pacing stimulus. 
     
     
         54 . The electrotherapy device of  claim 51 , in which prior to the current of the pacing stimuli being increased, the processing circuitry is configured to prompt a user of the device to increase the pacing stimuli current. 
     
     
         55 - 109 . (canceled) 
     
     
         110 . The electrotherapy device of  claim 51 , in which the processing circuitry analyzes a temporal energy of the PCG signal for the feature indicative of the cardiac pulse and determines whether the cardiac pulse occurred in the patient after delivery of the pacing stimulus based on the analysis of the temporal energy of the PCG signal. 
     
     
         111 . The electrotherapy device of  claim 110 , in which the processing circuitry estimates instantaneous and background energies in the PCG signal and compares the instantaneous energy with the background energy to analyze the temporal energy of the PCG signal for the feature indicative of the cardiac pulse. 
     
     
         112 . The electrotherapy device of  claim 51 , in which the electrotherapy generator delivers pacing stimuli to the patient via one or more electrodes coupled to the skin of the patient, and wherein the sensor is integrated with or attached to a back of at least one of the one or more electrodes. 
     
     
         113 . The electrotherapy device of  claim 51 , in which the electrotherapy generator delivers pacing stimuli to the patient via one or more electrodes coupled to the skin of the patient, and wherein the sensor is embodied in a flap that is connected to at least one of the one or more electrodes. 
     
     
         114 . The electrotherapy device of  claim 51 , in which the electrotherapy generator delivers pacing stimuli to the patient via one or more electrodes coupled to the skin of the patient, and wherein the sensor is coupled to the skin of the patient with wires not coupled to the one or more electrodes. 
     
     
         115 . The electrotherapy device of  claim 51 , in which the sensor is a first sensor adapted to sense the PCG signal, the electrotherapy device further comprising a second sensor adapted to receive an impedance-sensing signal from the patient, and in which the processing circuitry is configured to analyze each of the PCG and impedance-sensing signals for features indicative of a presence of the cardiac pulse and determine the presence of the cardiac pulse based on the features. 
     
     
         116 . The electrotherapy device of  claim 115 , in which the processing circuitry is further configured to analyze the impedance-sensing signal to determine a presence of respiration in the patient, the processing circuitry prompting a delivery of rescue breathing therapy to the patient if respiration is determined not present in the patient. 
     
     
         117 . The electrotherapy of  claim 115 , in which the processing circuitry is further configured to prompt the delivery of chest compressions or cardiopulmonary resuscitation to the patient if the patient is determined to be pulseless. 
     
     
         118 . The electrotherapy device of  claim 51 , further comprising:
 a defibrillation pulse generator in communication with the processing circuitry that is configured to automatically prepare a defibrillation pulse for delivery to the patient if the processing circuitry determines that the cardiac pulse is not present in the patient;   a display, in which the processing circuitry is configured to provide a message on the display prompting delivery of chest compressions or cardiopulmonary resuscitation to the patient if the cardiac pulse is determined not present in the patient, and in which the display is configured to report whether the cardiac pulse is present in the patient.   
     
     
         119 . The electrotherapy device of  claim 51 , further comprising an electrode adapted to sense electrocardiogram (ECG) signals in the patient, the processing circuitry being further configured to analyze the patient's ECG signal for ventricular tachycardia and prompt a delivery of defibrillation therapy to the patient if the patient is determined to be pulseless and experiencing ventricular tachycardia, and in which the processing circuitry is further configured to prompt the delivery of defibrillation therapy if the patient is determined to be pulseless and experiencing ventricular tachycardia with a rate exceeding 100 beats per minute. 
     
     
         120 . The electrotherapy device of  claim 51 , further comprising an electrode adapted to sense electrocardiogram (ECG) signals in the patient, the processing circuitry further being configured to analyze the patient's ECG signal for at least ventricular fibrillation (VF), ventricular tachycardia (VT), and asystole condition, and if the patient is determined to be pulseless and not in a VF, VT, or asystole condition, the processing circuitry being further configured to prompt delivery of electrotherapy to the patient designed specifically for pulseless electrical activity (PEA).