Robust fractional saturation determination
First Claim
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1. An improved pulse oximeter system for determining at least one fractional oxygen saturation measurement, the improvement increasing the accuracy and reliability of the fractional oxygen saturation measurement by accounting for the relationship between carboxyhemoglobin and methemoglobin in high and low methemoglobin conditions, the improved pulse oximeter system comprising:
- at least one optical sensor in communication with a pulse oximeter, the at least one optical sensor configured to emit light of a plurality of wavelengths directed at a measurement site of tissue of a patient and detect the light after attenuation by the tissue in order to produce a signal representative of the detected light after attenuation;
at least one hardware processor configured to receive the signal and further configured to determine, using the signal, a functional oxygen saturation measurement, a methemoglobin measurement, and a carboxyhemoglobin measurement, the at least one hardware processor further configured to determine at least one fractional oxygen saturation measurement using the functional oxygen saturation measurement, the methemoglobin measurement, and the carboxyhemoglobin measurement; and
at least one display configured to display the at least one fractional oxygen saturation measurement,wherein the at least one hardware processor is configured to;
determine that the methemoglobin measurement is unreliable for use in the determination of the at least one fractional oxygen saturation measurement, wherein the determination of unreliability comprises determining that the methemoglobin measurement is higher than a first predetermined threshold;
in response to the determination that the methemoglobin measurement is unreliable, change the carboxyhemoglobin measurement to a default carboxyhemoglobin value for use in the determination of the at least one fractional oxygen saturation measurement;
determine that the methemoglobin measurement is lower than a second threshold, thereby indicating a low methemoglobin condition;
in response to the determination that the methemoglobin measurement indicates the low methemoglobin condition, change the carboxyhemoglobin measurement for use in the determination of the at least one fractional oxygen saturation measurement to a weighted measurement, wherein the weighted measurement is correlated to the carboxyhemoglobin measurement; and
determine the at least one fractional oxygen saturation measurement with the changed carboxyhemoglobin measurement based on the determination that the methemoglobin measurement was unreliable or that the methemoglobin measurement indicated the low methemoglobin condition.
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Abstract
The present disclosure describes the derivation and measurement of a fractional oxygen saturation measurement.
917 Citations
10 Claims
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1. An improved pulse oximeter system for determining at least one fractional oxygen saturation measurement, the improvement increasing the accuracy and reliability of the fractional oxygen saturation measurement by accounting for the relationship between carboxyhemoglobin and methemoglobin in high and low methemoglobin conditions, the improved pulse oximeter system comprising:
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at least one optical sensor in communication with a pulse oximeter, the at least one optical sensor configured to emit light of a plurality of wavelengths directed at a measurement site of tissue of a patient and detect the light after attenuation by the tissue in order to produce a signal representative of the detected light after attenuation; at least one hardware processor configured to receive the signal and further configured to determine, using the signal, a functional oxygen saturation measurement, a methemoglobin measurement, and a carboxyhemoglobin measurement, the at least one hardware processor further configured to determine at least one fractional oxygen saturation measurement using the functional oxygen saturation measurement, the methemoglobin measurement, and the carboxyhemoglobin measurement; and at least one display configured to display the at least one fractional oxygen saturation measurement, wherein the at least one hardware processor is configured to; determine that the methemoglobin measurement is unreliable for use in the determination of the at least one fractional oxygen saturation measurement, wherein the determination of unreliability comprises determining that the methemoglobin measurement is higher than a first predetermined threshold; in response to the determination that the methemoglobin measurement is unreliable, change the carboxyhemoglobin measurement to a default carboxyhemoglobin value for use in the determination of the at least one fractional oxygen saturation measurement; determine that the methemoglobin measurement is lower than a second threshold, thereby indicating a low methemoglobin condition; in response to the determination that the methemoglobin measurement indicates the low methemoglobin condition, change the carboxyhemoglobin measurement for use in the determination of the at least one fractional oxygen saturation measurement to a weighted measurement, wherein the weighted measurement is correlated to the carboxyhemoglobin measurement; and determine the at least one fractional oxygen saturation measurement with the changed carboxyhemoglobin measurement based on the determination that the methemoglobin measurement was unreliable or that the methemoglobin measurement indicated the low methemoglobin condition. - View Dependent Claims (2, 3, 4, 5, 6)
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7. An improved method of determining a fractional oxygen saturation measurement based on an indication of functional oxygen saturation and dishemoglobins, the improvement increasing the accuracy and reliability of the fractional oxygen saturation measurement by accounting for the relationship between carboxyhemoglobin and methemoglobin in high and low methemoglobin conditions, the improved method comprising:
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directing light of a plurality of wavelengths from a pulse oximeter in communication with at least one optical sensor at a tissue site; detecting the light at the at least one optical sensor after attenuation by the tissue site; determining, using at least one hardware processor, an indication of a functional oxygen saturation measurement, an indication of a methemoglobin measurement, and an indication of a carboxyhemoglobin measurement from the detected light; adjusting the carboxyhemoglobin measurement if a high or low methemoglobin condition is determined, wherein the adjustment comprises; determining that the methemoglobin measurement is unreliable for use in the determination of at least one fractional oxygen saturation measurement, wherein the determination of unreliability comprises determining that the methemoglobin measurement is higher than a first threshold; in response to the determination that the methemoglobin measurement is unreliable, changing, using the at least one hardware processor, the carboxyhemoglobin measurement to a default value for use in the determination of the at least one fractional oxygen saturation measurement; determining that the methemoglobin measurement is lower than a second threshold, thereby indicating a low methemoglobin condition; and in response to the determination that the methemoglobin measurement indicates the low methemoglobin condition, changing the carboxyhemoglobin measurement for use in the determination of the at least one fractional oxygen saturation measurement to a weighted measurement, wherein the weighted measurement is correlated to the carboxyhemoglobin measurement; determining, using the at least one hardware processor and based on the indication of the functional oxygen saturation measurement and the changed carboxyhemoglobin measurement, the at least one fractional oxygen saturation measurement; and displaying, using at least one display, the at least one fractional oxygen saturation measurement. - View Dependent Claims (8, 9, 10)
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Specification