Method for detection of aberrant tissue spectra

• US 20080221414A1
• Filed: 03/09/2007
• Published: 09/11/2008
• Est. Priority Date: 03/09/2007
• Status: Active Grant

• Current Assignee: Covidien LP (Medtronic Plc)
• Original Assignee: Nellcor Puritan Bennett LLC (Medtronic Plc)
• Inventors: Baker, Clark R.
• Granted Patent: US 8,280,469 B2
• Time in Patent Office: Days
• US Class Current: 600/310
• 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 5/6843 Monitoring or controlling sensor contact pressure
• CPC Class Codes: A61B 5/7203 for noise prevention, reduction or removal

Abstract

A method is provided for determining contact of a sensor with a patient'"'"'s tissue. The method comprises comparing the intensity of detected light at a first wavelength to a threshold, wherein the first wavelength is not used to determine a physiological characteristic of the patient, and determining if the sensor is in contact with the patient'"'"'s tissue based on the comparison. In addition, a method is provided for determining the amount of light shunting during operation of the sensor. The method comprises comparing the intensity of detected light at a first wavelength to a threshold, wherein the first wavelength is not used to determine a physiological characteristic of the patient, and determining the amount of light shunting based on the comparison.

Claims

1. A method for determining contact of a sensor with a patient'"'"'s tissue, comprising:

emitting light at three or more wavelengths into a patient'"'"'s tissue, wherein the three or more wavelengths includes a first wavelength that is not used to determine a physiological characteristic of the patient;

detecting the light;

comparing the intensity of the detected light at the first wavelength to a threshold; and

determining if the sensor is in contact with the patient'"'"'s tissue based on the comparison.

2. The method of claim 1, wherein the threshold comprises a ratio of the intensity of the detected light at the first wavelength to a reference intensity of light at the first wavelength.

3. The method of claim 1, wherein the threshold comprises a ratio of the intensity of the detected light at the first wavelength to a reference intensity of the detected light at a different wavelength.

4. The method of claim 1, wherein the first wavelength is primarily absorbed by water.

5. The method of claim 4, wherein the first wavelength is between about 1,200 nanometers to about 1,600 nanometers.

6. The method of claim 1, wherein the first wavelength is primarily absorbed by myoglobin or hemoglobin.

7. The method of claim 6, wherein the first wavelength is between about 500 nanometers to about 600 nanometers.

8. The method of claim 1, wherein the sensor comprises at least one of a sensor configured to measure tissue hydration or a pulse oximetry sensor.

9. The method of claim 1, comprising providing a notification if the sensor is determined not to be in contact with the patient'"'"'s tissue.

10. A method for correcting light shunting, comprising:

emitting light at three or more wavelengths into a patient'"'"'s tissue, wherein the three or more wavelengths includes a first wavelength that is not used to determine a physiological characteristic of the patient;

detecting the light;

comparing the intensity of the detected light at the first wavelength to a threshold; and

determining the amount of light shunting between the at least one emitter and the at least one detector based on the comparison.

11. The method of claim 10, comprising correcting the intensity of the detected light at one or more of a second wavelength or a third wavelength based on the amount of light shunting.

12. The method of claim 11, comprising determining a physiological characteristic based upon the corrected intensity of the detected light at the second and third wavelengths.

13. The method of claim 10, wherein the threshold comprises a ratio of the intensity of the detected light at the first wavelength to a reference intensity of light at the first wavelength.

14. The method of claim 10, wherein the threshold comprises a ratio of the intensity of the detected light at the first wavelength to a reference intensity of the detected light at a different wavelength.

15. The method of claim 10, wherein the first wavelength is primarily absorbed by water.

16. The method of claim 15, wherein the wavelength of the detected light is between about 1200 nanometers to about 1600 nanometers.

17. The method of claim 10, wherein the sensor comprises a sensor configured to measure tissue hydration.

18. The method of claim 10, wherein the sensor comprises a pulse oximetry sensor.

19. A patient monitor, comprising:

an I/O port configured to connect to a sensor;

a processor configured to receive signals from the I/O port and to use the signals when executing an algorithm configured to compare a wavelength of detected light to a threshold, wherein the wavelength is not used to determine a physiological characteristic of the patient, wherein the processor is also configured to execute an algorithm configured to determine if a sensor is in contact with the patient'"'"'s tissue based on the comparison.

20. A sensor, comprising:

one or more light emitting components configured to emit light at three or more wavelengths, wherein at least one of the wavelengths is not used to determine a physiological characteristic but is used to determine the sufficiency of contact between the sensor and the tissue of a patient;

one or more light detecting components configured to detect the light emitted by the one or more light emitting components; and

a sensor body upon which the one or more light emitting components and the one or more light detecting components are disposed.

21. The sensor of claim 20, comprising an information coding element disposed in the sensor body or in a cable connected to the sensor body, wherein the information coding element encodes a threshold value, or information usable to ascertain the threshold value.

22. A sensor assembly, comprising:

a sensor body comprising;

an emitter configured to emit light at three or more wavelengths into a patient'"'"'s tissue; and

a detector configured to detect the light; and

a monitor configured to execute an algorithm configured to compare a wavelength of detected light to a threshold, wherein the wavelength is not used to determine a physiological characteristic of the patient, and an algorithm configured to determine if a sensor is in contact with the patient'"'"'s tissue based on the comparison.