METHOD AND APPARATUS FOR SPECTROPHOTOMETRIC BASED OXIMETRY

• US 20090182209A1
• Filed: 10/18/2006
• Published: 07/16/2009
• Est. Priority Date: 10/21/2005
• Status: Active Grant

• Current Assignee: Edwards Lifesciences Corporation
• Original Assignee: Cas Medical Systems Incorporated (Edwards Lifesciences Corporation)
• Inventors: Benni, Paul
• Granted Patent: US 8,965,472 B2
• Time in Patent Office: Days
• US Class Current: 600/323
• CPC Class Codes: A61B 5/14553 specially adapted for cerebral tissue

Abstract

A near infrared spectrophotometric (NIRS) sensor assembly for non-invasive monitoring of blood oxygenation levels in a subject'"'"'s body is provided that includes a pad, at least one light source, a near light detector, a far light detector, and a cover. The light source is operative to emit near infrared light signals of a plurality of different wavelengths. The near light detector is separated from the light source by a first distance that is great enough to position the first light detector outside of an optical shunt field extending out from the light source. The far light detector is substantially linearly aligned with the near light detector and light source, and is separated from the near light detector by a second distance, wherein the second distance is greater than the first distance.

Claims

1. A near infrared spectrophotometric sensor assembly for non-invasive monitoring of blood oxygenation levels in a subject'"'"'s body tissue, said assembly comprising:

a flexible pad;

at least one light source operative to emit near infrared light signals of a plurality of different wavelengths;

a first light detector operative to measure light intensity values derived from light emitted by the light source and passing through the subject'"'"'s body tissue, wherein the first light detector is separated from the light source by a first distance that is great enough to position the first light detector outside of an optical shunt field extending out from the light source;

a second light detector operative to measure light intensity values derived from light emitted by the light source and passing through the subject'"'"'s body tissue, wherein the second light detector is substantially linearly aligned with the first light detector and the light source, and is separated from the first light detector by a second distance, wherein the second distance is greater than the first distance; and

a component tray connected to the pad, wherein the light source, first light detector and second light detector are locationally maintained by the component tray.

2. The sensor assembly of claim 1, wherein the light source includes one or more fiber optics, a light redirecting prism, and a housing.

3. The sensor assembly of claim 2, wherein the light directing prism is mounted within the housing and the fiber optics are optically coupled to the prism.

4. The sensor assembly of claim 3, wherein the housing is rotatably mounted relative to the component tray.

5. The sensor assembly of claim 1, wherein the first distance is at least 10 mm.

6. The sensor assembly of claim 1, wherein the at least one light source comprises a fiber optic light guide and a light redirecting prism.

7. The sensor assembly of claim 6, wherein at least a portion of the light redirecting prism extends outwardly from the pad to facilitate contact with the subject.

8. The sensor assembly of claim 6, wherein the light source further comprises a second light guide disposed contiguous with the prism.

9. The sensor assembly of claim 8, wherein the second light guide extends outwardly from the pad to facilitate contact with the subject.

10. The sensor assembly of claim 1, wherein one or both of the first and second light detectors include a photodiode and an optically transparent pane disposed contiguous with the photodiode.

11. The sensor assembly of claim 1, further including a connector operable to connect the sensor assembly to a NIRS system.

12. The sensor assembly of claim 11, wherein the connector includes a sensor identification encoder operable to identify the sensor assembly to the NIRS system.

13. A near infrared spectrophotometric (NIRS) sensor assembly for non-invasive monitoring of blood oxygenation levels in a subject'"'"'s body tissue, said assembly comprising:

a flexible pad;

a component tray connected to the pad;

at least one light source operative to emit near infrared light signals of a plurality of different wavelengths;

a first light detector operative to measure light intensity values derived from light emitted by the light source and passing through the subject'"'"'s body tissue, wherein the first light detector is separated from the light source by a first distance that is great enough to position the first light detector outside of an optical shunt field extending out from the light source; and

a second light detector operative to measure light intensity values derived from light emitted by the light source and passing through the subject'"'"'s body tissue, wherein the second light detector is substantially linearly aligned with the first light detector and the light source, and is separated from the first light detector by a second distance, wherein the second distance is greater than the first distance.

14. A method for non-invasively monitoring blood oxygenation levels in a subject'"'"'s body tissue, comprising the steps of:

providing at least one light source operative to emit near infrared light signals of a plurality of different wavelengths;

providing a first light detector and a second light detector, both operative to measure light intensity values derived from light emitted by the light source and passing through the subject'"'"'s body tissue;

positioning the first light detector outside of an optical shunt field extending out from the light source a first distance from the light source;

positioning the second light detector substantially linearly aligned with the first light detector and the light source, and separated from the first light detector by a second distance, wherein the second distance is greater than the first distance;

introducing the near infrared light signals into the subject'"'"'s body tissue; and

detecting the light resulting from the light introduced into the subject'"'"'s body tissue, using the first and second light detectors, producing signals representative of such detected light, and processing the signals to obtain data relating to the blood oxygenation level of the subject'"'"'s body tissue.

15. The method of claim 14, wherein the first distance is at least 10 mm.

16. The method of claim 14, wherein the at least one light source comprises a fiber optic light guide and a light redirecting prism.

17. The method of claim 16 further comprising the step of contacting the subject with the light source such that substantially all of an exit face of the prism is in contact with the subject.

18. The method of claim 16, wherein the light source further comprises a second light guide disposed contiguous with the prism.

19. The method of claim 18, further comprising the step of contacting the subject with the light source such that substantially all of a surface of the second light guide is in contact with the subject.

21. The method of claim 14, further comprising the steps of:

providing a connector at least in part attached to the sensor assembly, the connector operable to connect the sensor assembly to a NIRS system, the connector including an encoder; and

communicating to the NIRS system, using the encoder, information relating to the type of sensor assembly.

20. A method for non-invasively monitoring blood oxygenation levels in a subject'"'"'s body tissue, comprising the steps of:

providing a sensor assembly having at least one light source operative to emit near infrared light signals of a plurality of different wavelengths, a first light detector and a second light detector, both light detectors operative to measure light intensity values derived from light emitted by the light source and passing through the subject'"'"'s body tissue, wherein the first light detector is positioned outside of an optical shunt field extending out from the light source a first distance from the light source, and the second light detector is substantially linearly aligned with the first light detector and the light source, and separated from the first light detector by a second distance, wherein the second distance is greater than the first distance;

introducing the near infrared light signals into the subject'"'"'s body tissue; and

detecting the light resulting from the light introduced into the subject'"'"'s body tissue, using the first and second light detectors, producing signals representative of such detected light, and processing the signals to obtain data relating to the blood oxygenation level of the subject'"'"'s body tissue.

22. The method of claim 20, wherein the first distance is at least 10 mm.

23. The method of claim 20, wherein the at least one light source comprises a fiber optic light guide and a light redirecting prism.

24. The method of claim 23 further comprising the step of contacting the subject with the light source such that substantially all of an exit face of the prism is in contact with the subject.

25. The method of claim 23, wherein the light source further comprises a second light guide disposed contiguous with the prism.

26. The method of claim 25, further comprising the step of contacting the subject with the light source such that substantially all of a surface of the second light guide is in contact with the subject.

27. A near infrared spectrophotometric (NIRS) sensor assembly for non-invasive monitoring of blood oxygenation levels in a subject'"'"'s body tissue, said assembly comprising:

a component tray;

at least one light source operative to emit near infrared light signals of a plurality of different wavelengths, said light source rotatably mounted on the component tray; and

at least one light detector operative to measure light intensity values derived from light emitted by the light source and passing through the subject'"'"'s body tissue.

28. The sensor assembly of claim 27, wherein the light source includes one or more fiber optics, a light redirecting prism, and a housing.

29. The sensor assembly of claim 28, wherein the light directing prism is mounted within the housing and the fiber optics are optically coupled to the prism.

30. The sensor assembly of claim 29, wherein the housing is rotatably mounted relative to the component tray.

31. The sensor assembly of claim 29, wherein the prism is disposed within the sensor assembly so that it is in contact with the subject'"'"'s skin during use of the sensor assembly.

32. The sensor assembly of claim 29, further comprising a light guide having a thickness, wherein the light guide is disposed adjacent the prism.

33. The sensor assembly of claim 29, wherein the housing has an asymmetrical shape which is received within an aperture disposed within the component tray.

34. The sensor assembly of claim 33, wherein the housing can be selectively received within and removed from the component tray aperture.

35. The sensor assembly of claim 29, wherein the housing is received within an aperture disposed within the component tray and attached to the component tray mating features.

36. The sensor assembly of claim 28, wherein the fiber optics extend outwardly substantially perpendicular to the axis of rotation of the light source.