Wavelength switching for pulse oximetry

Abstract

The present disclosure describes techniques that may provide more accurate estimates of arterial oxygen saturation using pulse oximetry by switching between a wavelength spectrum of at least a first and a second light source so that the arterial oxygen saturation estimates at low (e.g., in the range below 75%), medium (e.g., greater than or equal to 75% and less than or equal to 84%), and high (e.g., greater than 84% range) arterial oxygen saturation values are more accurately calculated. In one embodiment, light emitted from a near 660 nm and a near 900 nm emitter pair may be used when the arterial oxygen saturation range is high. In another embodiment, light emitted from a near 730 nm and a near 900 nm emitter pair may be used when the arterial oxygen saturation range is low. In yet another embodiment, light emitted from both a near 660 nm-900 nm emitter pair and light emitted from a near 730 nm-900 nm emitter pair may be used when the arterial oxygen saturation range is in the middle range. Priming techniques may also be used to reduce or eliminate start up delays of certain oximetry system components.

What is claimed is: 
     
         1 . A sensor, comprising:
 a first emitter configured to emit a first wavelength;   a second emitter configured to emit a second wavelength;   a third emitter configured to emit a third wavelength; and   a sensor cable configured to couple to an interface of a patient monitor, wherein the sensor cable is configured to receive light drive signals from the patient monitor;   wherein the sensor is configured to use the light drive signals received from the patient monitor to selectively activate at least two of the first emitter, the second emitter, or the third emitter.   
     
     
         2 . The sensor of  claim 1 , wherein the sensor cable comprises a multiplexer, and wherein the multiplexer is configured to receive the light drive signals from the patient monitor and to use the light drive signals received from the patient monitor to selectively activate at least two of the first emitter, the second emitter, or the third emitter. 
     
     
         3 . The sensor of  claim 2 , wherein the multiplexer is configured to convert the light drive signals received from the patient monitor into a series of signals to drive at least two of the first emitter, the second emitter, or the third emitter. 
     
     
         4 . The sensor of  claim 3 , wherein the multiplexer is configured to receive a light drive signal configured to drive only two of the first emitter, the second emitter, or the third emitter, and wherein the multiplexer is configured to convert the light drive signal into a series of signals to drive the first emitter, the second emitter, and the third emitter. 
     
     
         5 . The sensor of  claim 2 , wherein the multiplexer comprises a control line for selecting which emitters of the first emitter, the second emitter, and the third emitter to drive. 
     
     
         6 . The sensor of  claim 1 , wherein the first and second wavelengths are configured to substantially optimize physiologic measurements in patients having high oxygen saturation levels. 
     
     
         7 . The sensor of  claim 6 , wherein the first wavelength is between about 620 nanometers and about 700 nanometers, and the second wavelength is between about 860 nanometers and about 940 nanometers. 
     
     
         8 . The sensor of  claim 1 , wherein the second and third wavelengths are configured to substantially optimize physiologic measurements in patients having low oxygen saturation levels. 
     
     
         9 . The sensor of  claim 8 , wherein the second wavelength is about between about 690 nanometers and about 770 nanometers, and the third wavelength is between about 860 nanometers and about 940 nanometers. 
     
     
         10 . A system, comprising:
 a sensor comprising:
 a first emitter pair configured to emit a first wavelength and a second wavelength; 
 a second emitter pair configured to emit the second wavelength and a third wavelength; and 
 a sensor cable operatively coupled to the first emitter pair and the second emitter pair; and 
   a patient monitor comprising:
 an interface configured to couple to the sensor cable; and 
 drive circuitry configured to generate light drive signals; 
   wherein the sensor cable is configured to receive the light drive signals from the patient monitor, and wherein the sensor is configured to use the light drive signals received from the patient monitor to selectively activate at least one of the first emitter pair or the second emitter pair.   
     
     
         11 . The system of  claim 10 , wherein the sensor cable comprises a multiplexer, and wherein the multiplexer is configured to receive the light drive signals from the patient monitor and to use the light drive signals received from the patient monitor to selectively activate at least one of the first emitter pair or the second emitter pair. 
     
     
         12 . The system of  claim 11 , wherein the multiplexer is configured to convert the light drive signals received from the patient monitor into a series of signals to drive at least one of the first emitter pair or the second emitter pair. 
     
     
         13 . The system of  claim 12 , wherein the light drive signals generated by the drive circuitry are configured to drive only one emitter pair, and wherein the multiplexer is configured to convert the light drive signals into a series of signals to drive the first emitter pair and the second emitter pair. 
     
     
         14 . The system of  claim 11 , wherein the multiplexer comprises a control line for selecting which emitter pair of the first emitter pair and the second emitter pair to drive. 
     
     
         15 . A method of manufacturing a sensor, comprising:
 providing a first emitter pair configured to emit a first wavelength and a second wavelength;   providing a second emitter pair configured to emit the second wavelength and a third wavelength; and   coupling a sensor cable to the first emitter pair and the second emitter pair, wherein the sensor cable is configured to couple to an interface of a patient monitor and to receive light drive signals from the patient monitor; and   wherein the sensor is configured to use the light drive signals received from the patient monitor to selectively activate at least one of the first emitter pair or the second emitter pair.   
     
     
         16 . The method of  claim 15 , comprising providing a multiplexer configured to receive the light drive signals from the patient monitor and to selectively activate at least one of the first emitter pair or the second emitter pair. 
     
     
         17 . The method of  claim 16 , wherein the multiplexer is configured to convert the light drive signals received from the patient monitor into a series of signals to drive at least one of the first emitter pair or the second emitter pair. 
     
     
         18 . The method of  claim 16 , comprising providing a control line for the multiplexer to select which emitter pair of the first emitter pair and the second emitter pair to drive. 
     
     
         19 . The method of  claim 15 , wherein the first wavelength is between about 620 nanometers and about 700 nanometers, and the second wavelength is between about 860 nanometers and about 940 nanometers. 
     
     
         20 . The method of  claim 15 , wherein the second wavelength is about between about 690 nanometers and about 770 nanometers, and the third wavelength is between about 860 nanometers and about 940 nanometers.