Method and apparatus for facilitating compatibility between pulse oximeters and sensor probes

• US 5,807,247 A
• Filed: 12/20/1995
• Issued: 09/15/1998
• Est. Priority Date: 12/20/1995
• Status: Expired due to Term

• Current Assignee: Nellcor Puritan Bennett Incorporated (Medtronic Plc)
• Original Assignee: Nellcor Puritan Bennett Incorporated (Medtronic Plc)
• Inventors: Merchant, Adnan I., Fein, Michael E., Venkatachalam, K. L.
• Primary Examiner(s): Bahr, Jennifer
• Assistant Examiner(s): YARNELL, BRYAN KEITH
• Application Number:
  US08/575,256
• Time in Patent Office: 1,000 Days
• Field of Search: 128/633, 128/664-7, 356/39-41, 73/1 R, 324/601, 439/909, 600/310, 600/322, 600/323
• US Class Current: 600/310
• CPC Class Codes: A61B 2562/085 combined with means for recording calibration data
• CPC Class Codes: A61B 5/14551 for measuring blood gases
• CPC Class Codes: A61B 5/1495 Calibrating or testing of in-vivo probes

Abstract

A sensor probe operable to transmit light of a first wavelength for scattering by a tissue sample is described for use with a pulse oximeter designed to operate with another type of sensor probe which transmits light of a second wavelength. The sensor probe includes at least one source of light for transmitting light of the first wavelength for scattering and/or absorption by the tissue sample. At least one detector is included for detecting light of the first wavelength affected by the tissue sample and generating a signal in response thereto. An encoder in the sensor probe transforms the signal to a form which may be employed by the oximeter.

Claims

1. A sensor probe operable to transmit light of a first wavelength for scattering by a tissue sample and to generate a first probe signal in response thereto, the sensor probe being for use with a meter, the meter being operable to receive a meter signal representative of light of a second wavelength scattered by the tissue sample and to calculate a blood parameter from the meter signal using coefficients based at least in part on a value of the second wavelength, the sensor probe comprising:

at least one source of light for transmitting the light of the first wavelength for scattering by the tissue sample;

at least one detector for detecting the light of the first wavelength scattered by the tissue sample and generating the first probe signal in response thereto; and

a signal transformer for manipulating the first probe signal thereby generating a transformed signal having a predetermined mathematical relationship to the first probe signal, the transformed signal being used by the meter to calculate the blood parameter using the coefficients based at least in part on the value of the second wavelength.

2. The sensor probe of claim 1 wherein the sensor probe comprises a pulse oximetry probe, the meter comprises a pulse oximeter, and the blood parameter comprises oxygen saturation of arterial hemoglobin, the at least one source of light comprising red and infrared light emitting diodes.

3. The sensor probe of claim 2 wherein the red and infrared light emitting diodes transmit a first combination of wavelengths of light, the first probe signal including any combination of a second probe signal generated by the first wavelength, a third probe signal generated by light of a third wavelength, and a calculated probe signal obtained by manipulating and combining the second and third probe signals, the transformer manipulating any combination of any of the probe signals to generate a desired number of transformed signals for use by the meter.

4. The sensor probe of claim 3 wherein the coefficients are based on a single wavelength value.

5. The sensor probe of claim 3 wherein the coefficients are based on a combination of wavelength values.

6. The sensor probe of claim 1 further comprising translation circuitry for providing electrical compatibility between the sensor probe and the meter.

7. The sensor probe of claim 1 wherein the signal transformer is operable to manipulate the first probe signal by multiplying the first probe signal by a constant.

8. The sensor probe of claim 1 wherein the signal transformer is operable to manipulate the first probe signal by multiplying the first probe signal by a first constant to form a product and adding a second constant to the product.

9. The sensor probe of claim 1 wherein the meter employs an intermediate parameter to calculate the blood parameter, the sensor probe further comprising processing circuitry for calculating the intermediate parameter from at least the first probe signal and deriving a transformation function therefrom by which the signal transformer manipulates at least one of the first probe signal and the intermediate parameter.

10. The sensor probe of claim 1 further comprising calibration code circuitry for transmitting a desired calibration code to the meter thereby selecting the coefficients based at least in part on a value of the second wavelength for calculation of the blood parameter.

11. The sensor probe of claim 1 wherein the meter comprises at least one power terminal for providing power to external circuitry of the probe, the sensor probe further comprising power circuitry for coupling to the at least one power terminal and diverting power from the external circuitry to provide power to the signal transformer for generating the transformed signal.

12. The sensor probe of claim 11 wherein the at least one power terminal provides a first voltage for driving the at least one source of light and the power circuitry, the sensor probe further comprising means for transforming the first voltage to a second voltage for use by the signal transformer.

13. A method for facilitating compatibility between a sensor probe operable to transmit light of a first wavelength for scattering by a tissue sample and to generate a first probe signal in response thereto, and a meter operable to receive a meter signal representative of light of a second wavelength scattered by the tissue sample and to calculate a blood parameter from the meter signal using coefficients based at least in part on a value of the second wavelength, the method comprising the steps of:

transmitting light of the first wavelength towards the tissue sample to be scattered thereby;

detecting light of the first wavelength scattered by the tissue sample;

generating the first probe signal in response to the detecting step;

manipulating the first probe signal, thereby generating a transformed signal having a predetermined mathematical relationship to the first probe signal, the transformed signal being used by the meter to calculate the blood parameter using the coefficients based at least in part on the value of the second wavelength.

14. The method of claim 13 wherein the first probe signal includes any combination of a second probe signal generated by the first wavelength, a third probe signal generated by light of a third wavelength, and a calculated probe signal obtained by manipulating and combining the second and third probe signals, the manipulating step comprising manipulating any combination of any of the probe signals to generate a desired number of transformed signals for use by the meter.

15. The method of claim 14 wherein the coefficients are based on a single wavelength value.

16. The method of claim 14 wherein the coefficients are based on a combination of wavelength values.

17. The method of claim 13 further comprising the step of providing electrical compatibility between the sensor probe and the meter.

18. The method of claim 13 wherein the manipulating step comprises multiplying the first probe signal by a constant.

19. The method of claim 13 wherein the manipulating step comprises multiplying the first probe signal by a first constant to form a product and adding a second constant to the product.

20. The method of claim 13 wherein the meter employs an intermediate parameter to calculate the blood parameter, the method further comprising the steps of calculating the intermediate parameter from at least the first probe signal and deriving a transformation function therefrom by which the signal transformer manipulates at least one of the first probe signal and the intermediate parameter.

21. The method of claim 13 further comprising the step of transmitting a desired calibration code to the meter thereby selecting the coefficients based at least in part on the value of the second wavelength for calculation of the blood parameter.

22. The method of claim 21 further comprising the steps of:

preventing transmittal of a first calibration code from the sensor probe to the meter; and

generating the desired calibration code for transmittal to the meter in place of the first calibration code.