Method for spectrophotometric blood oxygenation monitoring

• US 8,923,943 B2
• Filed: 03/11/2013
• Issued: 12/30/2014
• Est. Priority Date: 05/12/2005
• Status: Active Grant

• Current Assignee: Edwards Lifesciences Corporation
• Original Assignee: Cas Medical Systems Incorporated (Edwards Lifesciences Corporation)
• Inventors: Benni, Paul B.
• Primary Examiner(s): HINDENBURG, MAX F
• Application Number:
  US13/793,964
• Publication Number:
  US 20140094668A1
• Time in Patent Office: 659 Days
• Field of Search: 600/323, 600/331, 600/232
• US Class Current: 600/323
• 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 5/0261 using optical means, e.g. infrared light
• CPC Class Codes: A61B 5/14546 for measuring analytes not otherwise provided for, e.g. ions, cytochromes
• CPC Class Codes: A61B 5/14551 for measuring blood gases
• CPC Class Codes: A61B 5/14552 Details of sensors specially adapted therefor
• CPC Class Codes: A61B 5/14553 specially adapted for cerebral tissue
• CPC Class Codes: A61B 5/1495 Calibrating or testing of in-vivo probes
• CPC Class Codes: A61B 5/6814 Head
• CPC Class Codes: G01N 2021/3144 for oxymetry
• CPC Class Codes: G01N 21/359 using near infrared light
• CPC Class Codes: G01N 21/49 within a body or fluid

Abstract

According to the present invention, a method and apparatus for non-invasively determining the blood oxygen saturation level within a subject'"'"'s tissue is provided. The method includes the steps of: a) providing a spectrophotometric sensor operable to transmit light into the subject'"'"'s tissue, and to sense the light; b) detecting light after passage through the subject'"'"'s tissue using the sensor, and producing initial signal data from the light sensed; c) calibrating the sensor to that particular subject using the initial signal data, thereby accounting for the specific physical characteristics of the particular subject'"'"'s tissue being sensed; and d) using the calibrated sensor to determine the blood oxygen parameter value within the subject'"'"'s tissue.

Claims

1. A method for non-invasively determining a blood oxygen parameter value of a subject'"'"'s tissue, comprising the steps of:

providing a spectrophotometric sensor operable to transmit light into the subject'"'"'s tissue, and to sense the light;

detecting light after passage through the subject'"'"'s tissue using the sensor, and producing initial signal data from the light sensed;

calibrating the sensor to that particular subject using the initial signal data, thereby accounting for the specific physical characteristics of the particular subject'"'"'s tissue being sensed; and

subsequent to calibrating the sensor, using the calibrated sensor to determine the blood oxygen parameter value within the subject'"'"'s tissue.

2. The method of claim 1, wherein the blood oxygen parameter is oxyhemoglobin.

3. The method of claim 1, wherein the blood oxygen parameter is deoxyhemoglobin.

4. The method of claim 3, wherein the calibrating step includes processing the signal data to consider pigmentation of the subject'"'"'s tissue.

5. The method of claim 4, wherein the processing step includes the use of absorption coefficients for pigmentation in the subject'"'"'s tissue.

6. The method of claim 1, wherein the step of determining the blood oxygen parameter value within the subject'"'"'s tissue comprises processing signal data other than the initial signal data.

7. An apparatus for non-invasively determining a blood oxygen saturation level of the microvasculature within a subject'"'"'s tissue, the apparatus comprising:

a spectrophotometric sensor operable to transmit light into the subject'"'"'s tissue, to detect the light after passage through the subject'"'"'s tissue using the sensor, and to produce initial signal data from the light sensed;

a processor adapted to calibrate the sensor to that particular subject using the initial signal data, thereby accounting for the specific physical characteristics of the particular subject'"'"'s tissue being sensed, and adapted to use the calibrated sensor to determine the blood oxygen saturation level within the subject'"'"'s tissue.

8. The apparatus of claim 7, wherein the physical characteristics of the subject'"'"'s tissue include pigmentation of skin and tissue disposed below the skin.

9. The apparatus of claim 8, wherein the processor is adapted to create absorption coefficients representative of the pigmentation of the skin and tissue below the skin.

10. The apparatus of claim 9, wherein the processor is adapted to determine one or more calibration constants using the absorption coefficients for pigmentation, which calibration constants are used to determine the blood oxygen saturation level within the subject'"'"'s tissue.

11. The apparatus of claim 7, wherein the sensor is adapted to produce initial signal data that is attributable to non-pulsatile blood flow within the microcirculation of the subject'"'"'s tissue.

12. The apparatus of claim 7, wherein the processor is adapted to determine the blood oxygen saturation level within the subject'"'"'s tissue using signal data other than the initial signal data.

13. The apparatus of claim 7, wherein the processor is adapted to determine the concentration of at least one of oxyhemoglobin and deoxyhemoglobin of the microvasculature within the subject'"'"'s tissue using the calibrated sensor.

14. The apparatus of claim 7, wherein the spectrophotometric sensor includes at least one light source and at least one light detector, wherein the light source is operable to transmit light along a plurality of wavelengths into the subject'"'"'s tissue, and the light detector is operable to detect light from the light source after the light has traveled through the subject'"'"'s tissue.