MULTIPLE PEAK ANALYSIS IN A PHOTOACOUSTIC SYSTEM

• US 20130190589A1
• Filed: 01/25/2012
• Published: 07/25/2013
• Est. Priority Date: 01/25/2012
• Status: Abandoned Application

• Current Assignee: Covidien LP (Medtronic Plc)
• Original Assignee: Nellcor Puritan Bennett LLC (Medtronic Plc)
• Inventors: Chen, Bo, Li, Youzhi
• Application Number:
  US13/357,839
• Publication Number:
  US 20130190589A1
• Time in Patent Office: Days
• US Class Current: 600/407
• CPC Class Codes: A61B 5/0095 by applying light and detecting acoustic waves, i.e. photoacoustic measurements
• CPC Class Codes: A61B 5/145 Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissuemeasuring of blood pressure or blood flow A61B5/02; non-radiation detecting or locating of foreign bodies in blood A61B5/06

Abstract

A physiological monitoring system may use photoacoustic sensing to determine one or more physiological parameters of a subject. A photoacoustic signal generated in response to a photonic signal may include multiple peaks as a result of multiple blood vessels and other structures below the surface of the skin of a subject. A photoacoustic system may identify a first and second peak in the photoacoustic signal and determine values from the peaks indicative of physiological parameters. Physiological parameters, such as venous oxygen saturation and arterial oxygen saturation, may be determined based on the values.

Claims

1. A photoacoustic system for determining a physiological parameter, the system comprising:

a light source configured to provide a photonic signal to a subject;

an acoustic detector configured to detect an acoustic pressure signal from the subject, wherein the acoustic pressure signal is caused by absorption of at least some of the photonic signal by the subject; and

processing equipment communicatively coupled to the acoustic detector, the processing equipment configured to;

identify first and second peaks based on the acoustic pressure signal;

determine first and second values indicative of a physiological parameter, wherein the first value corresponds to the first peak and the second value corresponds to the second peak; and

determine the physiological parameter based on the first and second values.

2. The system of claim 1, wherein the first peak corresponds to an arterial blood vessel and the second peak corresponds to a venous blood vessel.

3. The system of claim 2, wherein the first and second values indicative of a physiological parameter are indicative of oxygen saturation.

4. The system of claim 3, wherein the processing equipment is further configured to:

analyze the first and second values; and

select a value corresponding to a lower oxygen saturation, wherein the determined physiological parameter is venous oxygen saturation.

5. The system of claim 3, wherein the processing equipment is further configured to:

analyze the first and second values; and

select a value corresponding to a higher oxygen saturation, wherein the determined physiological parameter is arterial oxygen saturation.

6. The system of claim 1, wherein the first and second values indicative of a physiological parameter are indicative of hemoglobin concentration.

7. The system of claim 1, wherein the processing equipment is further configured to identify the first and second peaks based on an analysis of the acoustic pressure signal and at least one threshold.

8. The system of claim 1, wherein the light source comprises one or more emitters and wherein the photonic signal comprises light of two different wavelengths between 600 nm and 1000 nm.

9. The system of claim 8, wherein the acoustic pressure signal comprises a first component corresponding to a first of the two different wavelengths and a second component corresponding to a second of the two different wavelengths, and wherein the processing equipment is further configured to determine the first and second values based on the first and second components.

10. The system of claim 8, wherein the one or more emitters emit the light of the two different wavelengths at different times.

11. A photoacoustic method for determining a physiological parameter, the method comprising:

providing a photonic signal to a subject from a light source;

detecting an acoustic pressure signal using an acoustic detector, wherein the acoustic pressure signal is caused by absorption of at least some of the photonic signal by the subject;

identifying first and second peaks based on the acoustic pressure signal;

determining first and second values indicative of a physiological parameter, wherein the first value corresponds to the first peak and the second value corresponds to the second peak; and

determining the physiological parameter based on the first and second values.

12. The method of claim 11, wherein identifying the first peak comprises the first peak corresponding to an arterial blood vessel and identifying the second peak comprises the second peak corresponding to a venous blood vessel.

13. The method of claim 12, wherein determining the first and second values indicative of a physiological parameter further comprises determining first and second values indicative of oxygen saturation.

14. The method of claim 13, further comprising:

analyzing the first and second values; and

selecting a value corresponding to a lower oxygen saturation, wherein the determined physiological parameter is venous oxygen saturation.

15. The method of claim 13, further comprising:

analyzing the first and second values; and

selecting a value corresponding to a higher oxygen saturation, wherein the determined physiological parameter is arterial oxygen saturation.

16. The method of claim 11, wherein determining the first and second values indicative of a physiological parameter further comprises determining first and second values indicative of hemoglobin concentration.

17. The method of claim 11, further comprising identifying the first and second peaks based on an analysis of the acoustic pressure signal and at least one threshold.

18. The method of claim 11, wherein the light source comprises one or more emitters and wherein the photonic signal comprises light of two different wavelengths between 600 nm and 1000 nm.

19. The method of claim 18, wherein detecting the acoustic pressure signal further comprises detecting a first component corresponding to a first of the two different wavelengths and a second component corresponding to a second of the two different wavelengths, and wherein the first and second values are based on the first and second components.

20. The method of claim 18, wherein the one or more emitters emit light of the two different wavelengths at different times.