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Abstract

A method and apparatus for improving the calculation of oxygen saturation and other blood constituents by non-invasive pulse oximeters. The method and apparatus permit more accurate determination of blood flow by collecting time-measures of the absorption signal at two or more wavelengths and processing the collected time-measure to obtain composite pulsatile flow data from which artifacts have been filtered. The processing may occur in the time domain or in the frequency domain. In the preferred time domain embodiment, successive portions of periodic information are weighted and added together in synchrony to obtain the composite pulse information. In the preferred frequency domain embodiment, the time-measure is Fourier transformed into its spectral components to form the composite information. A new method and apparatus for correlating the heartbeat and optical pulse is provided whereby a product of the ECG R-wave and optical pulse signals corresponding to the same heartbeat is obtained, and one signal is time shifted relative to the other until a maximum waveform product corresponding to the heartbeat is determined.

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First Claim