Pulse detection using patient physiological signals
View Patent ↗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 at a first intensity;
receiving light transmitted into the patient at the first intensity at a light detector;
generating a first light detection signal based on the received light transmitted into the patient at the first intensity;
transmitting light into the patient at a second intensity;
receiving light transmitted into the patient at the second intensity at the light detector;
generating a second light detection signal based on the received light transmitted into the patient at the second intensity;
extracting a dc component of the first light detection signal;
adjusting a gain of the light detector based on the extracted dc component; and
processing the first and second light detection signals to detect a physiological parameter indicative of presence of a cardiac pulse in the patient.
2. The method of claim 1 , further comprising providing at least one of treatment and information concerning treatment based on the physiological parameter.
3. The method of claim 1 , further comprising:
setting one or both of the first intensity and the second intensity according to the extracted dc component.
4. 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 the light transmitted into the patient at the first intensity to generate a first light detection signal and receives the light transmitted into the patient at the second intensity to generate a second light detection signal; and
a processor configured to extract a dc component of the first light detection signal and to adjust a gain of the light detector according to the extracted dc component, the process further configured to process the first and second light detection signals to detect a physiological parameter indicative of presence of a cardiac pulse in the patient.
5. The medical device of claim 4 , in which the processor is configured to provide at least one of treatment and information concerning treatment based on the physiological parameter.
6. The medical device of claim 4 , in which the processor is further configured to control the light source to set the second intensity according to the extracted dc component.
7. A system, comprising:
means for transmitting light into a patient at a first intensity;
means for receiving light transmitted into the patient at the first intensity at a light detector;
means for generating a first light detection signal based on the received light transmitted into the patient at the first intensity;
means for transmitting light into the patient at a second intensity;
means for receiving light transmitted into the patient at the second intensity at the light detector;
means for generating a second light detection signal based on the received light transmitted into the patient at the second intensity;
means for extracting a dc component of the first light detection signal;
means for adjusting a gain of the light detector based on the extracted dc component; and
means for processing the first and second light detection signals to detect a physiological parameter indicative of presence of a cardiac pulse in the patient.
8. The system of claim 7 , further comprising means for providing at least one of treatment and information concerning treatment based on the physiological parameter.
9. The system of claim 7 , further comprising means for setting one or both of the first intensity and the second intensity according to the extracted dc component.