Photoacoustic Spectroscopy Method And System To Discern Sepsis From Shock

• US 20110071598A1
• Filed: 09/13/2010
• Published: 03/24/2011
• Est. Priority Date: 09/24/2009
• Status: Active Grant

• Current Assignee: Covidien LP (Medtronic Plc)
• Original Assignee: Nellcor Puritan Bennett LLC (Medtronic Plc)
• Inventors: McKenna, Edward M.
• Granted Patent: US 8,798,704 B2
• Time in Patent Office: Days
• US Class Current: 607/62
• CPC Class Codes: A61B 5/0095 by applying light and detecting acoustic waves, i.e. photoacoustic measurements
• CPC Class Codes: A61B 5/0261 using optical means, e.g. infrared light
• CPC Class Codes: A61B 5/412 Detecting or monitoring sepsis
• CPC Class Codes: A61B 5/7275 Determining trends in physiological measurement data; Predicting development of a medical condition based on physiological measurements, e.g. determining a risk factor
• 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

Abstract

According to various embodiments, a medical system and method for determining a microcirculation parameter of a patient may include a photoacoustic sensor. Specifically, a signal from a photoacoustic sensor may be used to determine if a patient is likely to have sepsis or shock. Although sepsis and shock present similarly with regard to many patient parameters, they may be differentiated by characteristic microcirculation changes.

Claims

1. A method, comprising:

using a processor;

receiving a signal from a photoacoustic spectroscopy sensor, wherein the signal from which a microcirculatory parameter of a patient may be determined;

determining the micro circulatory parameter based at least in part on the signal; and

determining whether the patient has shock and/or sepsis based at least in part on the microcirculatory parameter.

2. The method of claim 1, comprising providing an indication of the microcirculatory parameter.

3. The method of claim 1, comprising triggering an alarm when the microcirculatory parameter is less than a predetermined level or outside of a predetermined range.

4. The method of claim 1, comprising determining if the patient'"'"'s blood pressure, heart rate, respiration rate, respiration effort, and/or temperature is indicative of shock or sepsis;

and activating the photoacoustic spectroscopy sensor.

5. The method of claim 1, comprising providing an indication that shock therapy should be started if it is determined the patient has shock.

6. The method of claim 1, comprising providing an indication that sepsis therapy should be started if it is determined the patient has sepsis.

7. The method of claim 1, wherein determining if the patient has shock comprises monitoring the microcirculation parameter over a period of time and determining if a decrease in the microcirculation parameter is followed by a rise in the microcirculation parameter.

8. The method of claim 1, wherein determining if the patient has sepsis comprises monitoring the microcirculation parameter over a period of time and determining if a decrease in microcirculation parameter is not followed by a rise in the microcirculation parameter.

9. A monitor, comprising:

a processor, the processor being capable of carrying out instructions for;

receiving a signal from a photoacoustic sensor;

calculating a microcirculation parameter based at least in part on the signal from a photoacoustic sensor; and

providing an indication of a patient'"'"'s likelihood of having shock or sepsis based on the microcirculation parameter.

10. The monitor of claim 9, wherein the photoacoustic sensor comprises a continuous wave photoacoustic sensor.

11. The monitor of claim 9, wherein the processor comprises instructions to trigger an alarm when the microcirculatory parameter is less than a predetermined level or outside of a predetermined range.

12. The monitor of claim 9, wherein the calculating the microcirculation parameter is based at least in part on one or more of a patient'"'"'s blood pressure, heart rate, respiration rate, respiration effort, or temperature is indicative of shock and/or sepsis.

13. The monitor of claim 9, wherein the processor is programmed to provide an indication that shock therapy should be started if it is determined the patient has shock.

14. The monitor of claim 9, wherein the processor is programmed to provide an indication that sepsis therapy should be started if it is determined the patient has sepsis.

15. The monitor of claim 9, wherein the patient'"'"'s likelihood of having shock is based at least in part on determining if a decrease in the microcirculation parameter is followed by a rise in the microcirculation parameter.

16. The monitor of claim 9, wherein the patient'"'"'s likelihood of having sepsis is based at least in part on determining if a decrease in microcirculation parameter is not followed by a rise in microcirculation parameter.

17. A method, comprising:

using a processor;

receiving a signal related to one or more of a patient'"'"'s blood pressure, heart rate, respiration rate, respiration effort, and/or temperature;

determining if the signal is associated with possible sepsis and/or shock; and

activating a photoacoustic sensor if the signal is associated with possible sepsis or shock.

18. The method of claim 17, receiving a signal from the photoacoustic sensor and determining a microcirculatory parameter based on the signal.

19. The method of claim 18, comprising triggering an alarm when the microcirculatory parameter is less than a predetermined level or outside of a predetermined range.

20. The method of claim 18, comprising determining if a patient has sepsis or shock based on the microcirculatory parameter.