Patent ID: 7392075

Claim:
In an oximeter, a method for determining a physiological parameter in the presence of correlated artifact, comprising: obtaining two digital waveforms, x and y, said waveforms being representative of the absorption of two wavelengths of electromagnetic energy received from a blood-perfused tissue, and wherein each of said waveforms comprises a component corresponding to a plethysmographic waveform and a component corresponding to the correlated artifact; calculating a plurality of weighted difference waveforms of the form x−R*y, wherein R is a multiplier, by varying R over a range; evaluating said plurality of weighted difference waveforms using a shape characteristic of said weighted difference waveform; identifying a weighted difference waveform most closely representative of said plethysmographic waveform, using said evaluating; identifying a weighted difference waveform most different from said plethysmographic waveform, using said evaluating; determining a pleth-based physiological parameter using said waveform most closely representative of said plethysmographic waveform; determining at least one artifact-based physiological parameter using said waveform most different from said plethysmographic waveform; and rejecting other possible candidate values for said pleth-based physiological parameter using said artifact-based physiological parameter.