Pulse detection 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 optical characteristics of light transmitted into a patient to ascertain physiological signals, such as pulsatile changes in general blood volume proximate a light detector module. 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 . A method comprising: 
 transmitting light into a patient;    receiving light that has been transmitted into the patient;    generating a light detection signal in response to the received light;    processing the light detection signal over a period of time to detect a trend in pulsatile changes in blood volume; and    providing at least one of treatment and information concerning treatment based on the trend in pulsatile changes blood volume.    
     
     
         2 . The method of  claim 1 , further comprising: 
 detecting a temperature; and    compensating the light detection signal based on the detected temperature.    
     
     
         3 . The method of  claim 1 , wherein transmitting light include transmitting a first light into the patient at a first wavelength, and transmitting a second light into the patient at a second wavelength, and receiving light includes receiving the first light and the second light.  
     
     
         4 . The method of  claim 3 , wherein the first light is red light and the second light is near-infrared light.  
     
     
         5 . A method comprising: 
 transmitting first light into a patient at a first wavelength;    transmitting second light into a patient at a second wavelength;    receiving the first and second light that has been transmitted into the patient;    generating a light detection signal in response to the received light; and    processing the light detection signal to detect a physiological parameter indicative of a cardiac pulse.    
     
     
         6 . The method of  claim 5 , wherein the first light is red light and the second light is near-infrared light.  
     
     
         7 . The method of  claim 5 , wherein transmitting light includes transmitting the first light from a first light source, and transmitting the second light from a second light source.  
     
     
         8 . The method of  claim 5 , further comprising indicating at least one of prompting for CPR, a spontaneous return to circulation, Pulseless Electrical Activity, a modification in pacing stimuli, and delivery of defibrillation therapy in response to the presence of a pulse.  
     
     
         9 . The method of  claim 5 , further comprising identifying an artifact in the light detection signal, wherein the artifact is caused by at least one of an environmental artifact and an optical artifact.  
     
     
         10 . A medical device comprising: 
 a light source to transmit light into a patient;    a sensor to receive light that has been transmitted into the patient;    a circuit to generate a light detection signal in response to the received light; and    a processor to process the light detection signal to detect presence of a cardiac pulse, and provide at least one of treatment and information concerning treatment based on the presence of the cardiac pulse.    
     
     
         11 . The medical device of  claim 10 , further comprising a temperature sensor to generate a temperature signal from a temperature sensor, wherein the processor compensates the light detection signal based on the temperature signal.  
     
     
         12 . The medical device of  claim 10 , wherein the light source transmits a first light into the patient at a first wavelength, and transmits a second light into the patient at a second wavelength, and the sensor receives both the first light and the second light.  
     
     
         13 . The medical device of  claim 12 , wherein the first light is red light and the second light is near-infrared light.  
     
     
         14 . A medical device comprising: 
 a light source to transmit a first light into a patient at a first wavelength and a second light into the patient at a second wavelength;    a sensor to receive the first and second light that has been transmitted into the patient;    a circuit to generate a light detection signal in response to the received light;    a processor to process the light detection signal to detect a physiological parameter indicative of presence of a cardiac pulse, and provide at least one of treatment and information concerning treatment based on physiological parameter.    
     
     
         15 . The device of  claim 14 , further comprising a temperature sensor to generate a temperature signal from a temperature sensor, wherein the processor compensates the light detection signal based on the temperature signal.  
     
     
         16 . The device of  claim 14 , wherein the light source includes a first light source to transmit the first light into the patient, and a second light source to transmit the second light into the patient.  
     
     
         17 . The device of  claim 16 , wherein the first light is red light and the second light is near-infrared light.  
     
     
         18 . The device of  claim 14 , wherein the processor indicates at least one of a spontaneous return to circulation, prompting for CPR, Pulseless Electrical Activity, a modification in pacing stimuli, and delivery of defibrillation therapy in response to the trend in pulsatile changes blood volume.  
     
     
         19 . A method comprising: 
 applying a defibrillation electrode with a pulse detector to a first position of a patient;    performing a first pulse detection;    detaching the pulse detector from the defibrillation electrode; and    placing the detached pulse detector at a second position of the patient.    
     
     
         20 . The method of  claim 19 , further comprising performing a second pulse detection with the pulse detector placed at the second position.  
     
     
         21 . The method of  claim 20 , further comprising reattaching the pulse detector to the defibrillation electrode.  
     
     
         22 . The method of  claim 20 , wherein the pulse detector is an optical pulse detector.  
     
     
         23 . The method of  claim 20 , wherein the pulse detector is a mechanical detector.  
     
     
         24 . A medical device comprising: 
 a defibrillation electrode; and    a pulse detector detachably coupled to the defibrillation electrode.    
     
     
         25 . The device of  claim 24 , further comprising a processor to detect a pulse based on a first pulse detection performed at a first position of a patient, and a second pulse detection performed upon detachment of the pulse sensor at a second position of a patient.  
     
     
         26 . The device of  claim 24 , wherein the pulse sensor is reattachable to the defibrillation electrode upon detachment.  
     
     
         27 . The device of  claim 24 , wherein the pulse sensor is an optical pulse sensor.  
     
     
         28 . The device of  claim 24 , wherein the pulse detector is a mechanical detector.  
     
     
         29 . A medical device comprising: 
 a defibrillation electrode; and    a light source for a pulse detector embedded in the defibrillation electrode.    
     
     
         30 . A method comprising: 
 transmitting light into a patient at a first intensity;    receiving light transmitted into the patient at the first intensity to generate a first light detection signal;    transmitting light into the patient at a second intensity;    receiving light transmitted into the patient at the second intensity to generate a second light detection signal; and    processing the light detection signals to detect a physiological parameter indicative of presence of a cardiac pulse.    
     
     
         31 . The method of  claim 30 , further comprising providing at least one of treatment and information concerning treatment based on the physiological parameter.  
     
     
         32 . The method of  claim 30 , further comprising: 
 extracting a dc component of the first light detection signal; and    setting the second intensity according to the extracted dc component.    
     
     
         33 . The method of  claim 30 , further comprising: 
 extracting a dc component of the first light detection signal; and    adjusting a gain of a light detector used to receive the light according to the extracted dc component.    
     
     
         34 . A medical device comprising: 
 a light source that transmits light into a patient at a first intensity and a second intensity;    a light detector that receives light transmitted into the patient at the first intensity to generate a first light detection signal, and receives light transmitted into the patient at the second intensity to generate a second light detection signal; and    a processor that processes the light detection signals to detect a physiological parameter indicative of presence of a cardiac pulse.    
     
     
         35 . The medical device of  claim 34 , wherein the processor provides at least one of treatment and information concerning treatment based on the physiological parameter.  
     
     
         36 . The medical device of  claim 34 , wherein the processor extracts a dc component of the first light detection signal, and controls the light source to set the second intensity according to the extracted dc component.  
     
     
         37 . The medical device of  claim 34 , wherein the processor extracts a dc component of the first light detection signal, and adjusts a gain of the light detector according to the extracted dc component.  
     
     
         38 . A method comprising: 
 transmitting light into a patient;    receiving light that has been transmitted into the patient;    generating a light detection signal in response to the received light;    processing the light detection signal to detect pulsatile changes in blood volume; and    providing at least one of treatment and information concerning treatment based on the trend in pulsatile changes blood volume.    
     
     
         39 . The method of  claim 38 , further comprising indicating at least one of prompting for CPR, a spontaneous return to circulation, Pulseless Electrical Activity, a modification in pacing stimuli, and delivery of defibrillation therapy in response to the presence of a pulse.