US 9,808,188 B1
Robust fractional saturation determination
Philip Perea, Whittier, CA (US); Ammar Al-Ali, San Juan Capistrano, CA (US); and Massi Joe E. Kiani, Laguna Niguel, CA (US)
Assigned to MASIMO CORPORATION, Irvine, CA (US)
Filed by MASIMO CORPORATION, Irvine, CA (US)
Filed on Mar. 8, 2013, as Appl. No. 13/791,633.
Application 13/791,633 is a continuation in part of application No. 13/650,730, filed on Oct. 12, 2012, abandoned.
Claims priority of provisional application 61/703,688, filed on Sep. 20, 2012.
Claims priority of provisional application 61/547,001, filed on Oct. 13, 2011.
Int. Cl. A61B 5/1455 (2006.01); A61B 5/00 (2006.01)
CPC A61B 5/14551 (2013.01) [A61B 5/7203 (2013.01)] 10 Claims
OG exemplary drawing
 
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.