Pulse oximeter sensor with piece-wise function

• US 6,801,797 B2
• Filed: 04/16/2001
• Issued: 10/05/2004
• Est. Priority Date: 04/17/2000
• Status: Expired due to Term

• Current Assignee: Covidien LP (Medtronic Plc)
• Original Assignee: Nellcor Puritan Bennett Incorporated (Medtronic Plc)
• Inventors: Fein, Michael E., Mannheimer, Paul D., Porges, Charles E.
• Primary Examiner(s): Hindenburg, Max F.
• Assistant Examiner(s): KREMER, MATTHEW J
• Application Number:
  US09/836,050
• Publication Number:
  US 20020035318A1
• Time in Patent Office: 1,268 Days
• Field of Search: 600/309-310, 600/322-324, 600/336, 600/331
• 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 at least one formula for determining oxygen saturation, said coefficients including at least a first set of coefficients and a second set of coefficients for said light emitter;

wherein said first and second sets of coefficients are used in the same formula.

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 sets of coefficients.

4. 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 at least one formula for determining oxygen saturation, said coefficients including at least a first set of coefficients and a second set of coefficients for said light emitter;

wherein said first and second sets of coefficients are used in different formulas;

wherein said different formulas are nonlinear formulas.

5. 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 at least one formula for determining oxygen saturation, said coefficients including at least a first set of coefficients and a second set of coefficients for said light emitter;

wherein said first and second sets of coefficients are used in different formulas;

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 a formula for determining oxygen saturation, said coefficients including a first set of coefficients and a second set of coefficients,

said memory further storing an indication of a saturation for use in selecting between said first and second sets of coefficients;

wherein said first and second sets of coefficients are used in the same formula.

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

8. An oximeter system comprising:

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 signal ratiometric values used to determine oxygen saturation, said plurality of values being dependent on a mean wavelength of said light emitter; and

an oximeter in communication with said oximeter sensor for receiving said plurality of values and a light detector signal, said oximeter being programmed to determine oxygen saturation from said light detector signal by fitting said oxygen saturation to a curve defined by said values stored in said memory.