PULSE DETECTION USING PATIENT PHYSIOLOGICAL SIGNALS

• US 20120035485A1
• Filed: 10/21/2011
• Published: 02/09/2012
• Est. Priority Date: 08/26/2002
• Status: Active Grant

• Current Assignee: Physio-Control Incorporated (Stryker Corporation)
• Original Assignee: Physio-Control Incorporated (Stryker Corporation)
• Inventors: Owen, James M., Jayne, Cynthia P., Crone, William E.
• Granted Patent: US 8,992,432 B2
• Time in Patent Office: Days
• US Class Current: 600/479
• CPC Class Codes: A61B 5/0059 using light, e.g. diagnosis by transillumination, diascopy, fluorescence A61B5/0093, A61B5/1455, A61B5/02416 and A61B5/0261 take precedence
• CPC Class Codes: A61B 5/02 Detecting, measuring or recording pulse, heart rate, blood pressure or blood flow; Combined pulse/heart-rate/blood pressure determination; Evaluating a cardiovascular condition not otherwise provided for, e.g. using combinations of techniques provided for in this group with electrocardiography or electroauscultation; Heart catheters for measuring blood pressure
• CPC Class Codes: A61B 5/0205 Simultaneously evaluating both cardiovascular conditions and different types of body conditions, e.g. heart and respiratory condition
• CPC Class Codes: A61B 5/02108 from analysis of pulse wave characteristics
• CPC Class Codes: A61B 5/02416 using photoplethysmograph signals, e.g. generated by infrared radiation A61B5/14552 takes precedence
• CPC Class Codes: A61B 5/02427 Details of sensor
• CPC Class Codes: A61B 5/082 Evaluation by breath analysis, e.g. determination of the chemical composition of exhaled breath A61B5/083, A61B5/091 take precedence
• CPC Class Codes: A61B 5/4836 Diagnosis combined with treatment in closed-loop systems or methods A61B5/0036 takes precedence
• CPC Class Codes: A61B 5/4848 Monitoring or testing the effects of treatment, e.g. of medication
• CPC Class Codes: A61B 5/746 Alarms related to a physiological condition, e.g. details of setting alarm thresholds or avoiding false alarms alarms per se G08B
• CPC Class Codes: A61B 8/06 Measuring blood flow measuring volume flow in general G01F, e.g. G01F1/66, G01F1/72; measuring speed of fluids in general G01P5/00
• CPC Class Codes: A61B 8/488 involving Doppler signals
• CPC Class Codes: A61N 1/3625 External stimulators
• CPC Class Codes: A61N 1/365 controlled by a physiological parameter, e.g. heart potential evoked response A61N1/371
• CPC Class Codes: A61N 1/36557 controlled by chemical substances in blood
• CPC Class Codes: A61N 1/3904 External heart defibrillators [EHD]
• CPC Class Codes: A61N 1/39044 in combination with cardiopulmonary resuscitation [CPR] therapy
• CPC Class Codes: A61N 1/3987 characterised by the timing or triggering of the shock

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.

Claims

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,

in which transmitting light comprises:

transmitting a first light into the patient at a first wavelength; and

transmitting a second light into the patient at a second wavelength, and

in which receiving light comprises receiving the first light and the second light.

4. The method of claim 3, in which the first light is red light and the second light is near-infrared light.

5. The method of claim 1,

in which transmitting light comprises:

transmitting a first light into the patient at a first intensity; and

transmitting a second light into the patient at a second intensity, and

in which receiving light comprises receiving the first light and the second light.

6. 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.

7. The method of claim 6, further comprising providing at least one of treatment and information concerning treatment based on the physiological parameter.

8. The method of claim 6, further comprising:

extracting a dc component of the first light detection signal; and

setting the second intensity according to the extracted dc component.

9. The method of claim 6, 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.

10. 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.

11. The medical device of claim 10, in which the processor provides at least one of treatment and information concerning treatment based on the physiological parameter.

12. The medical device of claim 10, in which 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.

13. The medical device of claim 10, in which 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.

14. 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.

15. The method of claim 14, further comprising, in response to the presence of a pulse, at least one of:

prompting for CPR;

indicating a spontaneous return to circulation;

indicating Pulseless Electrical Activity;

modifying pacing stimuli; and

delivering defibrillation therapy.