SYSTEM AND METHOD FOR DIFFERENTIATING BETWEEN TISSUE-SPECIFIC AND SYSTEMIC CAUSES OF CHANGES IN OXYGEN SATURATION IN TISSUE AND ORGANS

• US 20090259117A1
• Filed: 04/10/2009
• Published: 10/15/2009
• Est. Priority Date: 04/11/2008
• Status: Active Grant

• Current Assignee: Covidien LP (Medtronic Plc)
• Original Assignee: Covidien LP (Medtronic Plc)
• Inventors: WIDMAN, RONALD A., WIDER, MICHAEL D., GONOPOLSKIY, OLEG
• Granted Patent: US 8,781,546 B2
• Time in Patent Office: Days
• US Class Current: 600/323
• CPC Class Codes: A61B 5/14551 for measuring blood gases
• CPC Class Codes: A61B 5/7264 Classification of physiological signals or data, e.g. using neural networks, statistical classifiers, expert systems or fuzzy systems neural networks per se G06N3/00; expert systems per se G06N5/00
• CPC Class Codes: G16H 50/20 for computer-aided diagnosis, e.g. based on medical expert systems

Abstract

A method for monitoring oxygen saturation that includes the following steps: (i) measuring an oxygen saturation of a target area of a person or animal over time; (ii) measuring an oxygen saturation of a reference area of the person or animal over time; and (iii) classifying the oxygen saturation status of the target area based upon a comparison of the oxygen saturation of the target area relative to the oxygen saturation of the reference area over time.

Claims

1. A method for classifying a condition causing a change in oxygen saturation of hemoglobin in a target area of a body of a person or animal as either a systemic condition or a local condition, comprising:

identifying a target area and a reference area on the body of a human or animal, where said target area and said reference area are chosen from the group consisting of tissue and organs;

periodically measuring oxygen saturation in the target area and an oxygen saturation in the reference area;

periodically comparing the oxygen saturation in the target area to the oxygen saturation in the reference area; and

classifying the condition causing the change in oxygen saturation of hemoglobin in the target area as systemic or local based upon said comparison.

2. The method of claim 1, wherein the condition is classified as “

systemic”

if the oxygen saturation in the target area changes and the oxygen saturation in the reference area changes in a parallel fashion to the target area over time.

3. The method of claim 1, wherein the condition is classified as “

local”

if the oxygen saturation in the reference area does not change in a parallel fashion to the oxygen saturation in the target area over time.

4. The method of claim 1, wherein the measuring step comprises:

receiving signals from a first NIRS sensor located on the body of the person or animal near the target area;

receiving signals from a second NIRS sensor on the body of the person or animal near the reference area;

calculating an oxygen saturation of the target area from said signals received from said first NIRS sensor and calculating an oxygen saturation of the reference area from said signals received from said second NIRS sensor.

5. The method of claim 1, wherein the measuring step comprises:

receiving signals from a first optical detector located on a sensor near the target area; and

receiving signals from a second optical detector on said sensor.

6. The method of claim 5, wherein the comparing step comprises calculating a ratio between said signal received from said first optical detector and said signal received from said second optical detector at a given time.

7. The method of claim 1, wherein the reference area is remote from the target area.

8. The method of claim 1, wherein the reference area is shallow tissue located above the target area.

9. The method of claim 1, further comprising the step of visually displaying the periodic oxygen saturations of the target area and the reference area concurrently.

10. The method of claim 9, further comprising the step of visually displaying the periodic oxygen saturations of the target area and the reference area in a manner that are visually distinctive from each other.

11. A method for monitoring oxygen saturation, comprising:

measuring an oxygen saturation of a target area of a person or animal over time, where said target area is chosen from the group consisting of tissue and organs;

measuring an oxygen saturation of a reference area of the person or animal over time, where said reference area is chosen from the group consisting of tissue and organs;

classifying the oxygen saturation status of the target area based upon a comparison of the oxygen saturation of the target area relative to the oxygen saturation of the reference area over time.

12. The method of claim 11, wherein the classifying step comprises classifying the oxygen saturation status of the target area to be compromised if the oxygen saturation of the target area decreases substantially over time.

13. The method of claim 12, wherein the classifying step comprises:

classifying the compromised status as being a result of a systemic condition if said oxygen saturation of said reference area decreases in parallel to the oxygen saturation of said target area over time;

classifying the compromised status as being a result of a local condition if said oxygen saturation of said reference area does not decrease in parallel to the oxygen saturation of said target area over time; and

classifying the oxygen saturation status to be stable and adequate if the oxygen saturation of the target area and the oxygen saturation of the reference area are both substantially constant and above a pre-determined threshold over time.

14. The method of claim 13, wherein said target area is the brain of the person or animal, and wherein the classifying step comprises classifying the oxygen saturation status to be indicative of an impending shock if the oxygen saturation level of the brain is decreasing over time and the oxygen saturation of the reference area is substantially stable.

15. The method of claim 14, further comprising the step of providing a visual or audible indicator of the classified oxygen saturation status.

16. A method for classifying a condition causing a change in blood flow determined by oxygen saturation of hemoglobin in a target area of a body of a person or animal as either a systemic condition or a local condition, comprising:

identifying a target area and a reference area on the body of a human or animal;

periodically measuring oxygen saturation in the target area and an oxygen saturation in the reference area;

periodically comparing the oxygen saturation in the target area to the oxygen saturation in the reference area; and

classifying the condition causing the change in blood flow in the target area as systemic or local based upon said comparison.