Pulse oximeter sensor with piece-wise function

• US 20040171920A1
• Filed: 03/10/2004
• Published: 09/02/2004
• Est. Priority Date: 04/17/2000
• Status: Active Grant

• Current Assignee: Covidien LP (Medtronic Plc)
• Original Assignee: Nellcor Puritan Bennett Incorporated (Medtronic Plc)
• Inventors: Fein, Michael E., Mannheimer, Paul D., Porges, Charles E.
• Granted Patent: US 7,689,259 B2
• Time in Patent Office: Days
• US Class Current: 600/323
• CPC Class Codes: A61B 2562/085 combined with means for recording calibration data
• CPC Class Codes: A61B 5/14551 for measuring blood gases

Abstract

A memory in a sensor is used to store multiple coefficients for a physiological parameter. In one embodiment, not only are the sensor'"'"'s specific calibration coefficients stored in a memory in the sensor for the formula to determine oxygen saturation, but multiple sets of coefficients are stored. The multiple sets apply to different ranges of saturation values to provide a better fit to occur by breaking the R to SpO2 relationship up into different pieces, each described by a different function. The different functions can also be according to different formulas for determining oxygen saturation.

Claims

1. An oximeter sensor comprising:

a light emitter for directing light at a patient;

a light detector mounted to receive light from said patient; and

a memory storing coefficients for use in first and second different formulas for determining oxygen saturation.

2. The oximeter sensor of claim 1 wherein said coefficients are dependent on a mean wavelength of said light emitter.

3. The oximeter sensor of claim 1 wherein said memory further stores a value indicating a signal breakpoint between said first and second formulas.

4. The oximeter sensor of claim 1 wherein at least one of said different formulas is a nonlinear formula.

5. The oximeter sensor of claim 1 wherein said different formulas are linear formulas.

6. An oximeter sensor comprising:

a light emitter for directing light at a patient;

a light detector mounted to receive light from said patient; and

a memory storing coefficients for use in first and second different formulas for determining oxygen saturation,

said memory further storing an indication of a saturation for use in selecting between said first and second formulas.

7. The oximeter sensor of claim 6 wherein said coefficients are dependent on a mean wavelength of said light emitter.

8. The oximeter sensor of claim 6 wherein said memory further stores a value indicating a signal breakpoint between said first and second formulas.

9. The oximeter sensor of claim 6 wherein at least one of said different formulas is a nonlinear formula.

10. The oximeter sensor of claim 6 wherein said different formulas are linear formulas.

11. An oximeter sensor comprising:

a light emitter for directing light at a patient;

a light detector mounted to receive light from said patient; and

a memory storing a plurality of alternate values of oxygen saturation or ratio-of-ratio values used to determine oxygen saturation, said plurality of values corresponding to a mean wavelength of said light emitter.

12. The sensor of claim 11 wherein said values are usable for interpolation.