Photoacoustic monitoring technique with noise reduction

• US 9,380,981 B2
• Filed: 03/15/2013
• Issued: 07/05/2016
• Est. Priority Date: 03/15/2013
• Status: Active Grant

• Current Assignee: Covidien LP (Medtronic Plc)
• Original Assignee: Covidien LP (Medtronic Plc)
• Inventors: Kang, DongYel, Li, Youzhi, Huang, Qiaojian, Dean, William Kit
• Primary Examiner(s): Cattungal, Sanjay
• Application Number:
  US13/836,531
• Publication Number:
  US 20140275941A1
• Time in Patent Office: 1,208 Days
• Field of Search: 600437-469, 600473-480
• US Class Current: 1/1
• CPC Class Codes: A61B 2562/0233 Special features of optical sensors or probes classified in A61B5/00
• CPC Class Codes: A61B 5/0095 by applying light and detecting acoustic waves, i.e. photoacoustic measurements
• CPC Class Codes: A61B 5/0275 using tracers, e.g. dye dilution
• CPC Class Codes: A61B 5/029 Measuring or recording blood output from the heart, e.g. minute volume A61B8/065 takes precedence
• CPC Class Codes: A61B 5/08 Detecting, measuring or recording devices for evaluating the respiratory organs A61B5/0205 takes precedence
• CPC Class Codes: A61B 5/1451 for interstitial fluid
• CPC Class Codes: A61B 5/7203 for noise prevention, reduction or removal
• CPC Class Codes: A61B 5/7228 Signal modulation applied to the input signal sent to patient or subject; demodulation to recover the physiological signal modulation H03C
• CPC Class Codes: A61B 5/7278 Artificial waveform generation or derivation, e.g. synthesising signals from measured signals A61B5/327 takes precedence

Abstract

Various methods and systems for photoacoustic patient monitoring are provided. A photoacoustic system includes a light emitting component that emits one or more wavelengths of light into an interrogation region of a patient and an acoustic detector that detects acoustic energy generated by the interrogation region of the patient in response to the emitted light. The system also includes an optical detector that detects the emitted light and provides a signal that is used as an input to remove noise from the signal generated by the acoustic detector.

Claims

1. A photoacoustic monitoring system, comprising:

a memory storing instructions for;

receiving a first signal from an acoustic detector configured to detect a photoacoustic effect from light emitted into a patient'"'"'s tissue, wherein the first signal is representative of an indicator dilution;

receiving a second signal from a photodetector configured to detect the light, wherein the first signal and the second signal include an overlapping time period; and

determining a physiological parameter based at least in part on the first signal and the second signal, wherein determining the physiological parameter based at least in part on the first signal and the second signal comprises using the second signal to determine a level of noise in the first signal; and

a processor configured to execute the instructions.

2. The system of claim 1, wherein the instructions for determining the physiological parameter based at least in part on the first signal and the second signal comprise scaling the second signal to generate a scaled signal and subtracting the scaled signal from the first signal.

3. The system of claim 1, wherein the first signal and the second signal are negatively correlated.

4. The system of claim 1, wherein the physiological parameter comprises a cardiac output.

5. The system of claim 1, comprising a photoacoustic sensor comprising a light source, the acoustic detector, and the optical detector, wherein the photoacoustic sensor is configured to generate the first signal and the second signal.

6. The system of claim 5, wherein the acoustic detector and the optical detector are disposed adjacent to one another on the photoacoustic sensor.

7. The system of claim 6, wherein the light source is disposed adjacent to the acoustic detector on the photoacoustic sensor in a reflectance-type configuration.

8. The system of claim 6, wherein the light source is configured to be disposed opposite the patient'"'"'s tissue relative to the acoustic detector on the photoacoustic sensor in a transmission-type configuration and wherein the first signal and the second signal are positively correlated.

9. A method, comprising:

using a processor;

receiving a first signal from an acoustic detector configured to detect a photoacoustic effect from light emitted into a patient'"'"'s tissue;

receiving a second signal from a photodetector configured to detect the light;

correcting the first signal based on the second signal to generate a corrected first signal; and

determining a physiological parameter based on the corrected first signal.

10. The method of claim 9, wherein the physiological parameter comprises a cardiac output or an extravascular lung water estimation.

11. The method of claim 9, comprising providing an indication of the physiological parameter on a display.

12. The method of claim 9, wherein correcting the first signal based on the second signal comprises scaling the second signal to generate a scaled signal and subtracting the scaled signal from the first signal.

13. The method of claim 9, comprising determining a signal quality based on a correlation between the first signal and the second signal.

14. The method of claim 13, wherein a negative correlation above a threshold is indicative of good signal quality.

15. A photoacoustic sensor, comprising:

a light emitting component configured to emit one or more wavelengths of light into a tissue of a patient;

an acoustic detector configured to detect a photoacoustic effect from the light emitted into the patient'"'"'s tissue and to generate a first signal based on the detected photoacoustic effect; and

an optical detector configured to detect the light scattering through the patient'"'"'s tissue and to generate a second signal based on the detected light, wherein the optical detector is disposed adjacent to the acoustic detector on the photoacoustic sensor, and wherein the first signal and the second signal are negatively correlated.

16. The photoacoustic sensor of claim 15, wherein the light emitting component comprises one or more light emitting diodes, one or more laser diodes, a pulsed laser, a continuous wave laser, or a vertical cavity surface emitting laser.

17. The photoacoustic sensor of claim 15, wherein the acoustic detector comprises an ultrasound transducer.

18. The photoacoustic sensor of claim 15, wherein a first housing of the optical detector contacts a second housing of the acoustic detector.

19. The photoacoustic sensor of claim 15, comprising an encoder disposed on the photoacoustic sensor or a cable coupled to the photoacoustic sensor, wherein the encoder is configured to store calibration information or information representative of a sensor geometry.