Systems and methods for determining blood oxygen saturation values using complex number encoding
First Claim
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1. A physiological monitoring system that computes arterial oxygen saturation in tissue material, the physiological monitoring system comprising:
- a light emitter which emits light of at least first and second wavelengths;
a light detector responsive to light from said light emitter attenuated by body tissue, said light detector providing an output signal indicative of at least first and second intensity signals associated with said at least first and second wavelengths; and
a signal processor responsive to the first and second intensity signals to encode said first and second intensity signals in a complex time domain, to calculate arterial oxygen saturation from complex ratios of said encoded signals, and to output said arterial oxygen saturation for caregiver review.
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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.
826 Citations
20 Claims
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1. A physiological monitoring system that computes arterial oxygen saturation in tissue material, the physiological monitoring system comprising:
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a light emitter which emits light of at least first and second wavelengths; a light detector responsive to light from said light emitter attenuated by body tissue, said light detector providing an output signal indicative of at least first and second intensity signals associated with said at least first and second wavelengths; and a signal processor responsive to the first and second intensity signals to encode said first and second intensity signals in a complex time domain, to calculate arterial oxygen saturation from complex ratios of said encoded signals, and to output said arterial oxygen saturation for caregiver review. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of determining measurements of oxygen saturation of a monitored patient in a patient monitoring system, the method comprising:
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receiving at the patient monitoring system from a noninvasive optical sensor an input signal indicative of detected light after attenuation by body tissue; electronically demodulating, using a processor of the patient monitoring system, said input signal into at least first and second intensity signals corresponding to first and second wavelengths of said detected light; electronically transforming said first and second intensity signals into a complex time domain; electronically generating complex ratios of said transformed first and second intensity signals; electronically determining oxygen saturation of said monitored patient from said complex ratios; and outputting said oxygen saturation for caregiver review. - View Dependent Claims (9, 10)
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11. A patient monitor comprising:
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an input configured to receive sensor output signal from a noninvasive optical sensor, the sensor output signal responsive to attenuation of light of at least first and second wavelengths by a body tissue; and a processor configured to; receive said sensor output signal including a first intensity signal associated with the first wavelength and a second intensity signal associated with the second wavelength; encode said first and second intensity signals into a complex domain; and calculate oxygen saturation from a complex ratio said encoded first and second intensity signals. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification