SYSTEMS AND METHODS FOR DETERMINING BLOOD OXYGEN SATURATIONS VALUES USING COMPLEX NUMBER ENCODING
First Claim
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1. A physiological monitor that computes arterial oxygen saturation in tissue material, the physiological monitor 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 said encoded signals, and to output said 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.
98 Citations
12 Claims
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1. A physiological monitor that computes arterial oxygen saturation in tissue material, the physiological monitor 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 said encoded signals, and to output said saturation for caregiver review. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of determining measurements of physiological parameters of a monitored patient, the method comprising:
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receiving from a noninvasive optical sensor an input signal indicative of detected light after attenuation by body tissue; electronically demodulating 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 measurements of said physiological parameters from said complex ratios; and outputting said measurements 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 electronic signals indicative of one or more physiological parameters of a patient; and a processor configured to receive said electronic signals, to encode said electronic signals into a complex time domain, to determine ratios of said electronic signals without concern for a zero crossing, to determine measurement values from said ratios, and to output said measurement values for caregiver review. - View Dependent Claims (12)
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Specification