Abstract: Systems and methods for estimating a plethysmograph waveform are provided. In some aspects, a system includes a detector module configured to receive, from a single channel, an oximeter output signal indicative of light absorption in a patient. The oximeter output signal includes infrared light components and red light components. The system also includes a processing module configured to determine an indicator of a ratio of (i) an indicator of at least one of the infrared light components to (ii) an indicator of at least one of the red light components. The processing module is configured to determine, based on the indicator of the ratio, an indicator of a plethysmograph waveform of the patient.

Abstract: Systems and methods for estimating a saturation level of oxygen in hemoglobin (SpO2) are provided. In some aspects, a system includes a detector module configured to receive an oximeter output signal indicative of light absorption in a patient. The oximeter output signal alternates between infrared light components and red light components, and includes a first portion obtained at least partly during switching from at least one of the infrared components to at least one of the red components. The oximeter output signal also includes a second portion obtained at least partly during switching from at least one of the red components to at least one of the infrared components. The system also includes a processing module configured to estimate an SpO2 of the patient as a ratio between (i) a time derivative of the first portion and (ii) a time derivative of the second portion.