Detection of oximetry sensor sites based on waveform characteristics

• US 20080221462A1
• 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 8,221,326 B2
• Time in Patent Office: Days
• US Class Current: 600/485
• 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 5/024 Detecting, measuring or recording pulse rate or heart rate A61B5/0205, A61B5/021 take precedence
• CPC Class Codes: A61B 5/02416 using photoplethysmograph signals, e.g. generated by infrared radiation A61B5/14552 takes precedence
• CPC Class Codes: A61B 5/061 Determining position of a probe within the body employing means separate from the probe, e.g. sensing internal probe position employing impedance electrodes on the surface of the body A61B1/00158 takes precedence
• 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 5/1495 Calibrating or testing of in-vivo probes

Abstract

In accordance with an embodiment of the present technique, there is provided methods and systems for detecting the location of a sensor and determining calibration algorithms and/or coefficients for calculation of physiological parameters based on the detected location. An exemplary embodiment includes receiving a signal corresponding to absorption of at least one wavelength of light by a patient'"'"'s tissue, generating a plethysmographic waveform from the signal, determining an identifying characteristic of the plethysmographic waveform, and determining a location of the sensor based on a comparison of the identifying characteristic with at least one defined criterion.

Claims

1. A method for detecting sensor placement, comprising:

receiving a signal corresponding to absorption of at least one wavelength of light by a patient'"'"'s tissue;

generating a plethysmographic waveform from the signal;

determining an identifying characteristic of the plethysmographic waveform; and

determining a location of the sensor based on a comparison of the identifying characteristic with at least one defined criterion.

2. The method of claim 1, comprising determining calibration algorithms, calibration coefficients, or a combination thereof based on the location of the sensor.

3. The method of claim 2, comprising calculating a physiological parameter based on the calibration algorithms, calibration coefficients, or combination thereof.

4. The method of claim 1, wherein the identifying characteristic of the plethysmographic waveform comprises a shape of a pulse in the plethysmographic waveform.

5. The method of claim 4, wherein the pulse shape comprises a ratio of at least two of a systolic time component of the pulse, a diastolic time component of the pulse, and a total pulse time.

6. The method of claim 4, wherein the pulse shape comprises a skewness of a derivative of the pulse.

7. The method of claim 6, wherein the at least one defined criterion is determined by a patient'"'"'s pulse rate.

8. The method of claim 1, wherein the identifying characteristic of the plethysmographic waveform comprises a strength of a low frequency portion of the plethysmographic waveform at about a respiratory rate of the patient.

9. The method of claim 1, wherein the identifying characteristic of the plethysmographic waveform comprises a strength of a high-frequency portion of the plethysmographic waveform at about a harmonic of the pulse rate of the patient.

10. The method of claim 1, wherein the at least one defined criterion comprises a threshold value.

11. The method of claim 1, comprising enabling detection of venous pulsation based on the location of the sensor.

12. A system for detecting sensor placement, comprising:

a sensor comprising;

an emitter configured to emit light into a patient'"'"'s tissue;

a detector configured to detect the light; and

a monitor comprising;

a processor configured to generate a plethysmographic waveform from the detected light;

a waveform characteristic detector configured to determine an identifying characteristic of the plethysmographic waveform; and

a comparator configured to determine a location of the sensor based on a comparison of the identifying characteristic with at least one criterion.

13. The system of claim 12, wherein the processor is configured to determine calibration algorithms, calibration coefficients, or a combination thereof based on the location of the sensor.

14. The system of claim 13, wherein the monitor comprises a memory configured to store the calibration algorithms, the calibration coefficients, or the combination thereof.

15. The system of claim 13, wherein the processor is configured to calculate a physiological parameter based on the calibration algorithms, the calibration coefficients, or the combination thereof.

16. The system of claim 12, wherein the comparator comprises a hardware comparator, a comparison algorithm, or a combination thereof.

17. The system of claim 12, wherein the identifying characteristic of the plethysmographic waveform comprises a shape of a pulse in the plethysmographic waveform, a strength of a low frequency portion of the plethysmographic waveform at about a respiratory rate of the patient, a strength of a high-frequency portion of the plethysmographic waveform at about a harmonic of the pulse rate of the patient, or a combination thereof.

18. The system of claim 12, wherein the at least one criterion comprises a threshold value.

19. The system of claim 12, wherein the processor is configured to enable venous pulsation detection based on the location of the sensor.

20. One or more tangible, machine readable media, comprising code executable to perform the acts of:

calculating an identifying characteristic of a plethysmographic waveform; and

determining a location of the sensor based on a comparison of the identifying characteristic with at least one defined criterion.

21. The tangible, machine readable media of claim 20, comprising code executable to perform the act of determining calibration algorithms, calibration coefficients, or a combination thereof based on the location of the sensor.

22. The tangible, machine readable media of claim 21, comprising code executable to perform the act of calculating a physiological parameter based on the calibration algorithms, the calibration coefficients, or the combination thereof.

23. The tangible, machine readable media of claim 20, wherein the identifying characteristic of the plethysmographic waveform comprises a shape of a pulse in the plethysmographic waveform, a strength of a low frequency portion of the plethysmographic waveform at about a respiratory rate of the patient, a strength of a high-frequency portion of the plethysmographic waveform at about a harmonic of the pulse rate of the patient, or a combination thereof.

24. The tangible, machine readable media of claim 20, wherein the at least one defined criterion comprises a threshold value.

25. The tangible, machine readable media of claim 20, comprising code executable to perform the act of detecting venous pulsation.

26. A device for detecting sensor placement, comprising:

a processor configured to generate a plethysmographic waveform from a plurality of signals corresponding to absorption of light received from a sensor emitter;

a waveform characteristic detector configured to determine an identifying characteristic of the plethysmographic waveform; and

a comparator configured to determine a location of the sensor based on a comparison of the identifying characteristic with at least one criterion.

27. The device of claim 26, wherein the processor is configured to determine calibration algorithms, calibration coefficients, or a combination thereof based on the location of the sensor.

28. The device of claim 27, wherein the processor is configured to calculate a physiological parameter based on the calibration algorithms, the calibration coefficients, or the combination thereof.

29. The device of claim 26, wherein the identifying characteristic of the plethysmographic waveform comprises a shape of a pulse in the plethysmographic waveform, a strength of a low frequency portion of the plethysmographic waveform at about a respiratory rate of the patient, a strength of a high-frequency portion of the plethysmographic waveform at about a harmonic of the pulse rate of the patient, or a combination thereof.

30. The device of claim 26, wherein the at least one criterion comprises a threshold value.

31. The device of claim 26, wherein the processor is configured to enable venous pulsation detection based on the location of the sensor.