Blood constituent monitoring apparatus and methods with frequency division multiplexing
First Claim
1. Apparatus for monitoring the level of a constituent of the blood within a body structure comprising:
- (a) illumination means for emitting light at a plurality of wavelengths and directing the emitted light through said body structure;
(b) photodetector means for detecting light from said illumination means transmitted through said body structure and producing at least one photodetector signal representing the intensity of said detected light;
(c) carrier frequency means for varying the amplitude of the light at each said wavelength emitted by said illumination means at a different carrier frequency whereby said at least one photodetector signal will include a component at each said carrier frequency bearing information relating to the optical transmissivity of said body structure at one of said wavelengths;
(d) separation means for subdividing said at least one photodetector signal by frequency so as to separate said components at said different carrier frequencies from one another; and
(e) interpretation means for determining the level of said constituent from said separated components.
3 Assignments
0 Petitions
Accused Products
Abstract
Apparatus and method for measuring the level of a constituent such as oxygen in the blood of a living subject. Light at a plurality of wavelengths is emitted and directed through the patient'"'"'s body to a photodetector. The amplitude of the emitted light at each wavelength is varied in accordance with a different carrier frequency, and the photodetector signal thus includes a component at each carrier frequency. Each such component represents transmissivity of the body structure at one wavelength of the emitted light. The photodetector signal is subdivided by frequency so as to separate the components at the different carrier frequencies. The constituent level is determined from these separated components.
394 Citations
19 Claims
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1. Apparatus for monitoring the level of a constituent of the blood within a body structure comprising:
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(a) illumination means for emitting light at a plurality of wavelengths and directing the emitted light through said body structure; (b) photodetector means for detecting light from said illumination means transmitted through said body structure and producing at least one photodetector signal representing the intensity of said detected light; (c) carrier frequency means for varying the amplitude of the light at each said wavelength emitted by said illumination means at a different carrier frequency whereby said at least one photodetector signal will include a component at each said carrier frequency bearing information relating to the optical transmissivity of said body structure at one of said wavelengths; (d) separation means for subdividing said at least one photodetector signal by frequency so as to separate said components at said different carrier frequencies from one another; and (e) interpretation means for determining the level of said constituent from said separated components. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 17)
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13. A method of monitoring the level of a constituent of the blood within a body structure comprising the steps of:
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(a) emitting light at a plurality of wavelengths while varying the amplitude of the emitted light of each said wavelength at a different carrier frequency and directing the emitted light through said body structure; (b) detecting light from said illumination means transmitted through said body structure and producing at least one photodetector signal representing the intensity of said detected light whereby said at least one photodetector signal will include a component at each said carrier frequency bearing information relating to the optical transmissivity of said body structure at one of said wavelengths; (c) subdividing said at least one photodetector signal by frequency so as to separate components at said different carrier frequencies from one another; and (d) determining the level of said constituent from said separated components. - View Dependent Claims (18, 19)
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Specification