Motion compatible sensor for non-invasive optical blood analysis

• US 20070299328A1
• Filed: 07/13/2007
• Published: 12/27/2007
• Est. Priority Date: 10/10/1996
• Status: Abandoned Application

• Current Assignee: Nellcor Puritan Bennett LLC (Medtronic Plc)
• Original Assignee: Nellcor Puritan Bennett LLC (Medtronic Plc)
• Inventors: Chin, Rodney, Mannheimer, Paul, Flewelling, Ross
• Application Number:
  US11/827,858
• Publication Number:
  US 20070299328A1
• Time in Patent Office: Days
• US Class Current: 600/324
• CPC Class Codes: A61B 5/14552 Details of sensors specially adapted therefor
• CPC Class Codes: A61B 5/6826 Finger
• CPC Class Codes: A61B 5/6833 Adhesive patches
• CPC Class Codes: A61B 5/6838 Clamps or clips
• CPC Class Codes: A61B 5/7207 of noise induced by motion artifacts

Abstract

A non-invasive optical sensor which uses the motion signal to calculate the physiological characteristic being measured. For pulse oximetry, a least squares or a ratio-of-ratios technique can be applied to the motion signal itself. This is made possible by selecting a site on the patient where variations in motion produce signals of two wavelengths which are sufficiently correlated. In particular, it has been determined that a sensor placed on a nail, in particular a thumbnail, exhibits the characteristics of having the red and infrared signals correlated when used for pulse oximetry, and the resulting signals correlate to arterial oxygen saturation.

Claims

1. An optical sensor comprising:

a sensor body configured to attach to a patient;

an light emitter recessed in the sensor body; and

a light detector recessed in the sensor body and spaced apart from the light emitter.

2. The optical sensor defined in claim 1, wherein the sensor comprises a pulse oximetry sensor.

3. The optical sensor defined in claim 1, wherein the sensor is configured to attach to a patient'"'"'s digit over a nail, and wherein the light emitter and the light detector are configured to be mounted adjacent to the nail.

4. The optical sensor defined in claim 1, wherein the sensor is a reflectance sensor.

5. The optical sensor defined in claim 1, wherein at least one of the light emitter or the light detector has a numerical aperture of less than 0.9.

6. The optical sensor defined in claim 1, wherein at least one of the light emitter or the light detector has a numerical aperture of less than 0.5.

7. The optical sensor defined in claim 1, comprising a display disposed on the sensor for displaying at least one of a blood oxygen saturation value or a pulse rate.

8. The optical sensor defined in claim 7, wherein the light emitter, the light detector, and the display are located in one housing of the sensor body.

9. The optical sensor defined in claim 7, comprising a button or switch for alternating between displaying the pulse rate and the oxygen saturation value.

10. A method of reducing light shunting in an optical sensor, comprising:

emitting light into a tissue by using an emitter recessed in a sensor body;

detecting the light from the tissue with a detector recessed in the sensor body, the detector being spaced apart from the emitter; and

generating a signal based on the detected light.

11. The method of claim 10, comprising determining a blood oxygen saturation value from the signal.

12. The method of claim 10, comprising displaying the blood oxygen saturation value on a display located on the sensor body.

13. An pulse oximetry system comprising:

a sensor configured to attach to a patient, the sensor having a light emitter recessed in a sensor body and a light detector recessed in the sensor body, the light detector spaced apart from the light emitter; and

a pulse oximetry monitor operatively connected to the sensor.

14. The pulse oximetry system defined in claim 13, wherein the sensor is configured to attach to a patient'"'"'s digit over a nail, and wherein the light emitter and the light detector are configured to be mounted adjacent to the nail.

15. The pulse oximetry system defined in claim 13, wherein the sensor comprises a reflectance sensor.

16. The pulse oximetry system defined in claim 13, wherein at least one of the light emitter or the light detector has a numerical aperture of less than 0.9.

17. The pulse oximetry system defined in claim 13, wherein at least one of the light emitter or the light detector has a numerical aperture of less than 0.5.

18. The pulse oximetry system defined in claim 13, comprising a display disposed on the sensor for displaying a blood oxygen saturation value or a pulse rate.

19. The pulse oximetry system defined in claim 18, wherein the light emitter, the light detector, and the display are located in one housing of the sensor body.

20. The pulse oximetry system defined in claim 18, comprising a button or switch for alternating between displaying the pulse rate and the oxygen saturation value.