Method and apparatus for detecting and analyzing variations in a physiologic parameter
The present disclosure is generally directed to identifying and/or analyzing high resolution variations in a measured physiologic parameter, such as blood oxygen saturation (SpO 2 ) measured using pulse oximetry. Present embodiments may include a system including a sensor comprising an emitter capable of emitting light at different wavelengths into a tissue bed, and a detector capable of detecting the light from the emitter after dispersion and/or reflection by the tissue bed. Further, the system may include a pulse oximeter capable of receiving signals from the sensor that are indicative of characteristics of the light detected by the detector, and utilizing the signals to estimate blood oxygen saturation values over time at a high resolution to facilitate detection of variations in the blood oxygen saturation values that are smaller in magnitude than an accuracy, display precision, and/or calibration of the blood oxygen saturation values.
1. A pulse oximetry system, comprising:
a sensor comprising: an emitter configured to emit light at different wavelengths into a tissue bed; and a detector configured to detect the light from the emitter after dispersion and/or reflection by the tissue bed; and
a pulse oximeter configured to:
receive signals from the sensor that are indicative of characteristics of the light detected by the detector;
utilize the signals to estimate blood oxygen saturation values over time at a high resolution;
detect variations in the blood oxygen saturation values that are smaller in magnitude than an accuracy, display precision, and/or calibration of the blood oxygen saturation values; and
perform control and/or pattern detection functions based on the variations.
2. The pulse oximetry system of claim 1 , wherein the pulse oximeter is configured to estimate the blood oxygen saturation values with a precision of 0.1%, 0.01% or 0.001%.
3. The pulse oximetry system of claim 1 , wherein the pulse oximeter is configured to report changes in a value of partial pressure of oxygen in blood based on the detection of variations in the blood oxygen saturation values.
4. The pulse oximetry system of claim 1 , wherein the emitter is configured to emit light having a wavelength in a bounded range of 600-660 nm.
5. The pulse oximetry system of claim 4 , wherein the emitter comprises at least two light emitting diodes, wherein one of the at least two light emitting diodes is configured to emit light in the bounded range of 600-620 nm.
6. A method of performing pulse oximetry, comprising:
emitting light from an emitter component of a pulse oximeter sensor at first and second wavelengths useful for measuring oxygen saturation;
detecting the light with a detector component of the pulse oximeter sensor;
transmitting signals indicative of characteristics of the detected light to a pulse oximeter;
estimating blood oxygen saturation values over time at a high resolution based on the signals with the pulse oximeter;
detecting variations in the blood oxygen saturation values that are smaller in magnitude than an accuracy, display precision, and/or calibration of the blood oxygen saturation values; and
detecting a patient condition and/or controlling a physiologic parameter based on the variations.
7. The method of claim 6 , wherein the first wavelength is between 650-670 nm.
8. The method of claim 6 , wherein the first wavelength is within a range of 600-620 nm and the second wavelength is within a range of 800-940 nm.
9. The method of claim 6 , comprising controlling a partial pressure of oxygen in a patient's blood based on the variations in the blood oxygen saturation values.
10. The method of claim 9 , wherein controlling the partial pressure of oxygen comprises controlling delivery of oxygen to the patient based on the variations in the blood oxygen saturation values.
11. The method of claim 6 , comprising identifying a pattern indicative of sleep apnea based on the variations in the blood oxygen saturation values.
12. The method of claim 6 , comprising displaying the blood oxygen saturation values at the high resolution on a display screen.
13. A pulse oximeter sensor configured to facilitate detection of high precision changes in blood oxygen saturation estimates obtained via pulse oximetry, comprising:
a sensor body;
a plurality of emitters positioned within the sensor body, wherein each of the plurality of emitters is configured to emit light at a different wavelength, and wherein at least one of the plurality of emitters is selected for sensitivity to small changes in blood oxygen saturation by emitting light within a bounded range of wavelengths;
a detector configured to detect the light emitted by the plurality of emitters; and
a processor configured to calculate a value of blood oxygen saturation based on the detected light with a precision of 0.1, 0.01, or 0.001.
14. The pulse oximeter sensor of claim 13 , wherein one of the plurality of emitters is configured to emit light having a wavelength in a bounded range of 600-620 nm.
15. The pulse oximeter sensor of claim 13 , wherein one of the plurality of emitters is configured to emit light having a wavelength between 650-670 nm and another one of the plurality of emitters is configured to emit light having a wavelength between 940-1000 nm.
16. The pulse oximeter sensor of claim 14 , wherein the plurality of emitters comprise an orange LED configured to emit light having a wavelength in a bounded range of 600-620 nm, and an infrared LED configured to emit light having a wavelength in a bounded range of 800-940 nm.
17. The pulse oximeter sensor of claim 14 , wherein the plurality of emitters comprise an orange LED configured to emit light having a wavelength in a bounded range of 600-620 nm, and a red LED configured to emit light having a wavelength in a bounded range of 640-740 nm.