Methods and devices for reduction of motion-induced noise in pulse oximetry
First Claim
1. A method for reducing effects of motion when measuring blood oxygen saturation, comprising the following steps of:
- (a) transmitting light having a first wavelength, light having a second wavelength and light having a third wavelength through body tissue;
(b) receiving a portion of the light having the first wavelength, a portion of the light having the second wavelength and a portion of the light having the third wavelength;
(c) producing a first signal based on the received portion of light having the first wavelength, a second signal based on the received portion of light having the second wavelength, and a third signal based on the received portion of light having the third wavelength;
(d) determining a difference between the second signal and the first signal to produce a first plethysmography signal, and a difference between the third signal and the first signal to produce a second plethysmography signal;
adjusting a first ratio between an intensity of the light having the first wavelength and an intensity of the light having the second wavelength to thereby reduce motion artifacts associated with the first plethysmography signal; and
adjusting a second ratio between an intensity of the light having the first wavelength and an intensity of the light having the third wavelength to thereby reduce motion artifacts associated with the second plethysmography signal; and
(e) estimating blood oxygen saturation using the first and second plethysmography signals, wherein the estimating is performed using a processor.
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Accused Products
Abstract
Methods and devices are provided for reducing motion artifacts when measuring blood oxygen saturation. A portion of the light having the first wavelength, a portion of light having the second wavelength and a portion of the light having the third wavelength are received. A first signal is produced based on the received portion of light having the first wavelength. Similarly, a second signal is produced based on the received portion of light having the second wavelength, and a third signal is produced based on the received portion of light having the third wavelength. A difference between the second signal and the first signal is determined, wherein the difference signal is first plethysmography signal. Similarly, a difference is determined between the third signal and the first signal to produce a second plethysmography signal. Blood oxygen saturation is then estimated using the first and second plethysmography signals.
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Citations
33 Claims
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1. A method for reducing effects of motion when measuring blood oxygen saturation, comprising the following steps of:
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(a) transmitting light having a first wavelength, light having a second wavelength and light having a third wavelength through body tissue; (b) receiving a portion of the light having the first wavelength, a portion of the light having the second wavelength and a portion of the light having the third wavelength; (c) producing a first signal based on the received portion of light having the first wavelength, a second signal based on the received portion of light having the second wavelength, and a third signal based on the received portion of light having the third wavelength; (d) determining a difference between the second signal and the first signal to produce a first plethysmography signal, and a difference between the third signal and the first signal to produce a second plethysmography signal; adjusting a first ratio between an intensity of the light having the first wavelength and an intensity of the light having the second wavelength to thereby reduce motion artifacts associated with the first plethysmography signal; and adjusting a second ratio between an intensity of the light having the first wavelength and an intensity of the light having the third wavelength to thereby reduce motion artifacts associated with the second plethysmography signal; and (e) estimating blood oxygen saturation using the first and second plethysmography signals, wherein the estimating is performed using a processor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method for reducing effects of motion when measuring blood oxygen saturation, comprising the following steps of:
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(a) transmitting light having a first wavelength, light having a second wavelength and light having a third wavelength through body tissue; (b) receiving a portion of the light having the first wavelength, a portion of the light having the second wavelength and a portion of the light having the third wavelength; (c) producing a first signal based on the received portion of light having the first wavelength, a second signal based on the received portion of light having the second wavelength, and a third signal based on the received portion of light having the third wavelength; (d) determining a difference between the second signal and the first signal to produce a first plethysmography signal, and a difference between the third signal and the first signal to produce a second plethysmography signal; adjusting a first ratio between a gain of the first signal and a gain of the second signal to thereby reduce motion artifacts associated with the first plethysmography signal; and adjusting a second ratio between a gain of the first signal and a gain of the third signal to thereby reduce motion artifacts associated with the second plethysmography signal; and (e) estimating blood oxygen saturation using the first and second plethysmography signals, wherein the estimating is performed using a processor. - View Dependent Claims (12)
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13. A device for measuring blood oxygen saturation, comprising:
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a light source to transmit light having a first wavelength, light having a second wavelength and light having a third wavelength through body tissue; a light detector to receive a portion of the light having the first wavelength, a portion of the light having the second wavelength, and a portion of the light having the third wavelength, and to produce a first signal, based on the received portion of light having the first wavelength, a second signal, based on the received portion of light having the second wavelength, and a third signal, based on the received portion of the light having the third wavelength; a first comparator to subtract one of the first and second signals from the other to produce a first plethysmography signal; a second comparator to subtract one of the first and third signals from the other to produce a second plethysmography signal; means for adjusting one or more of the following ratios, to thereby reduce motion artifacts associated with at least one of the first and second plethysmography signals;
a ratio between an intensity of the light having the first wavelength and an intensity of the light having the second wavelength, a ratio between an intensity of the light having the first wavelength and an intensity of the light having the third wavelength, a ratio between a gain of the first signal and a gain of the second signal, and a ratio between a gain of the first signal and a gain of the third signal; andmeans for estimating the blood oxygen saturation using the first and second plethysmography signals. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33)
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Specification