PULSE OXIMETER WITH REDUCED CROSS TALK EFFECTS

• US 20090247846A1
• Filed: 04/01/2008
• Published: 10/01/2009
• Est. Priority Date: 04/01/2008
• Status: Abandoned Application

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Rantala, Borje
• Application Number:
  US12/060,489
• Publication Number:
  US 20090247846A1
• Time in Patent Office: Days
• US Class Current: 600/323
• CPC Class Codes: A61B 5/14551 for measuring blood gases
• CPC Class Codes: A61B 5/6816 Ear lobe
• CPC Class Codes: A61B 5/6826 Finger
• CPC Class Codes: A61B 5/6838 Clamps or clips

Abstract

A method of reducing the effect of cross talk in a pulse oximeter is disclosed herein. The method includes: setting an initial pulse width and pulse rate for an LED drive signal and measuring a cross talk generated within the pulse oximeter. Based on the measured cross talk, the pulse width of the LED drive signal is minimized. The pulse width is minimized based on a relationship between the cross talk and a threshold level.

Claims

1. A method for reducing the effect of cross talk in a pulse oximeter, comprising:

setting an initial pulse width and pulse rate for an LED drive signal;

measuring a cross talk generated within the pulse oximeter;

minimizing the pulse width of the LED drive signal with reference to the cross talk.

2. A method as in claim 1, wherein the step of measuring the cross talk includes:

measuring electrical cross-talk synchronous with the LED drive signal

3. A method as in claim 2, wherein the step of measuring the cross talk includes:

measuring the electrical cross talk resulting from at least one of capacitive, inductive and resistive power coupled within the pulse oximeter.

4. A method as in claim 1, wherein the step of measuring the cross talk includes:

estimating an error value in a measurement of arterial oxygen saturation (SpO2).

5. A method as in claim 1, wherein the step of minimizing the pulse width includes:

minimizing the pulse width until the cross talk reaches a threshold value, defined based on an SpO2 accuracy specification.

6. A method as in claim 1, wherein the step of minimizing the pulse width comprises:

adjusting the pulse rate of the LED drive signal with reference to the cross talk.

7. A method as in claim 1, further comprising:

reducing power consumption in the pulse oximeter by generating a modulated LED drive signal, the modulated LED drive signal being modulated based on the cross talk.

8. A method as in claim 7, wherein the method further comprises:

modifying the pulse width of the LED drive signal while monitoring SpO2.

9. A pulse oximetry method comprising the steps of:

setting initial pulse width and pulse rate for an LED drive signal;

obtaining cross talk generated within a pulse oximeter;

comparing value of the cross talk with a threshold value;

adjusting the duty cycle of the LED drive signal if the cross talk value is below the threshold value; and

initiating the measurement of oxygenation once the pulse width is adjusted to a desirable value.

10. A method as in claim 9, wherein the step of comparing value of the cross talk with the threshold value comprises:

comparing the cross talk value of each probe with the corresponding threshold value.

11. A method as in claim 9, wherein the step of adjusting the duty cycle of the LED drive signal comprises:

adjusting the duty cycle and pulse repetition rate of the LED drive signal corresponding to each probe.

12. A method of monitoring arterial oxygen saturation using a plurality of light emitters and at least one detector, comprising the steps of:

initiating monitoring of oxygen level using an emitter drive signal having preset initial characteristics;

obtaining cross talk generated within a pulse oximeter;

determining an error value generated in the monitored oxygen level due to the cross talk;

comparing the error value with a threshold value;

adjusting the duty cycle of the emitter drive signal until the error value is below the threshold value; and

identifying the arterial oxygen saturation.

13. A method as in claim 12, wherein the step of obtaining the cross talk includes:

obtaining electrical cross talk synchronous with the emitter drive signal.

14. A method as in claim 12, wherein the step of adjusting the duty cycle further comprises:

adjusting sampling moments of a detect signal based on the error value such that cross talk dies off from the detector signal before sampling.

15. A method of configuring a pulse oximeter to adapt multiple probes comprising:

selecting at least one probe from a plurality of probes,

activating the selected probe by a drive signal having preset initial characteristics;

accessing value of cross talk generated within the pulse oximeter in relation to the selected probe;

obtaining a threshold value of permissible cross talk for the selected probe; and

minimizing duty cycle of the drive signal in reference to the cross talk generated due to the probe, the duty cycle being minimized until the cross talk reaches the threshold value.

16. A method as in claim 15 further comprising:

identifying the selected probe and selecting a corresponding threshold value for the selected probe.

17. A pulse oximeter comprising:

at least one probe including at least two emitters configured to emit radiations in different wavelengths and at least one detector to receive radiations;

a drive unit for providing drive signal having preset initial characteristics to the emitters;

a cross talk identifier configured to identify electrical cross talk synchronous with the drive signal, generated within the pulse oximeter; and

a processor configured to adjust duty cycle of the drive signal in reference to the cross talk.

18. A pulse oximeter as in claim 17, wherein the preset initial characteristics of the drive signal include fixed initial duty cycle and pulse rate of the drive signal.

19. A pulse oximeter as in claim 17, wherein the processor is configured to adjust the duty cycle of the drive signal until the cross talk reaches a threshold value.

20. A pulse oximeter as in claim 19, wherein the threshold value is determined based on a standard value specified for each probe.

21. A pulse oximeter as in claim 17, wherein the cross talk detector detects the cross talk generated from at least one of capacitive, inductive, resistive power coupled within the pulse oximeter.

22. A pulse oximeter as in claim 17, wherein desired duty cycle for the drive signal is set prior to initializing operation of the pulse oximeter.

23. A pulse oximeter as in claim 17, wherein desired duty cycle is set for the driving signal, while the pulse oximeter is in operation.

24. A pulse oximeter as in claim 17, wherein the processor is further configured to adjust the duty cycle of detect signal, generated by the detector.