Systems and methods for determining blood oxygen saturation values using complex number encoding
AssigneeMasimo Laboratories, Inc.
InventorMohamed K. Diab
Life of this patent
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Abstract
The disclosure includes pulse oximetry systems and methods for determining point-by-point saturation values by encoding photoplethysmographs in the complex domain and processing the complex signals. The systems filter motion artifacts and other noise using a variety of techniques, including statistical analysis such as correlation, or phase filtering.
Claims17
A digital signal processing device which determines one or more physiological parameters of a patient, the digital signal processing device comprising:
- an input configured to accept first data corresponding to a first optical signal attenuated by tissue of a patient and to accept second data corresponding to a second optical signal attenuated by tissue of a patient;
- a first generator configured to transform the first signal into a first modified signal which includes only non-zero values;
- a second generator configured to transform the second signal into a second modified signal which includes only non-zero values;
- a divider which determines ratios of the first modified signal to the second modified signal;
- and
- a calculator which uses one or more calibration curves and the ratios to determine output values of one or more physiological parameters of the patient.
A method of determining a measure of a patient's blood oxygen saturation, the method comprising:
- receiving data corresponding to a plurality of photoplethysmographs;
- encoding each of the plurality of photoplethysmographs as a complex signal;
- combining the plurality of complex signals into complex numbers;
- and
- determining values of a measure a patient's blood oxygen saturation from the complex numbers.
A method of processing signals representative of a photodetector output, wherein the photodetector output is indicative of light attenuated by body tissue carrying pulsing blood, the processing performed to assist in a determination of a characteristic of said body tissue, the method comprising:
- receiving data from at least one signal from a photodetector, said at least one signal being indicative of light attenuated by body tissue carrying pulsing blood;
- storing values of said data in the real domain;
- converting said real domain values of said data for each of said at least one signal to separate signals in the complex domain;
- processing said values in the complex domain;
- and
- determining a characteristic of said body tissue.
Dependencies are inferred from the claim text.