Robust fractional saturation determination

A patient monitoring apparatus comprising:

• a housing;
• a memory device configured to store a signal generated by a noninvasive physiological sensor that monitors a patient, the signal being responsive to a physiological condition of the patient;
• and
• one or more hardware processors in communication with the memory device, the one or more hardware processors being configured to:
• determine a methemoglobin measurement and a carboxyhemoglobin measurement from the signal,
• adjust the carboxyhemoglobin measurement based on the methemoglobin measurement to obtain an adjusted carboxyhemoglobin measurement, and
• output for presentation an indicator responsive to the adjusted carboxyhemoglobin measurement.

A patient monitoring method comprising:

• storing, by a memory device, a signal generated by a noninvasive physiological sensor monitoring a patient, the signal being responsive to a physiological condition of the patient;
• determining, by one or more hardware processors, a methemoglobin measurement and a carboxyhemoglobin measurement from the signal;
• adjusting, by the one or more hardware processors, the carboxyhemoglobin measurement based on the methemoglobin measurement to obtain an adjusted carboxyhemoglobin measurement;
• and
• outputting, by the one or more hardware processors, for presentation an indicator responsive to the adjusted carboxyhemoglobin measurement.