Active pulse blood constituent monitoring method
First Claim
1. A method of non-invasively determining an indication of a concentration of a blood constituent comprising the steps of:
- transmitting optical radiation through a fleshy medium having blood flowing in accordance with a substantially cyclic pattern, wherein the blood has a concentration of the blood constituent and the optical radiation traverses a path length through the medium, said optical radiation selected so as to be attenuated upon transmission through said flowing blood;
detecting the optical transmission after attenuation through a field of view portion of the fleshy medium;
generating an output signal indicative of optical characteristics of the medium;
actively influencing a change in the volume of blood in said medium in accordance with a predictable pattern with no more than minimal perturbation to the optical path length of the medium in the field of view portion to produce modulation in said output signal; and
analyzing said signal to determine the indication of the concentration of said blood constituent.
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Accused Products
Abstract
A monitoring method is disclosed which provides for inducing an active pulse in a blood volume of a patient. The induction of an active pulse results in a cyclic, and periodic change in the flow of blood through a fleshy medium under test. By actively inducing a change of the blood volume, modulation of the volume of blood can be obtained to provide a greater signal to noise ratio. This allows for the detection of constituents in blood at concentration levels below those previously detectable in a non-invasive system. Radiation which passes through the fleshy medium is detected by a detector which generates a signal indicative of the intensity of the detected radiation. Signal processing is performed on the electrical signal to isolate those optical characteristics of the electrical signal due to the optical characteristics of the blood.
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Citations
21 Claims
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1. A method of non-invasively determining an indication of a concentration of a blood constituent comprising the steps of:
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transmitting optical radiation through a fleshy medium having blood flowing in accordance with a substantially cyclic pattern, wherein the blood has a concentration of the blood constituent and the optical radiation traverses a path length through the medium, said optical radiation selected so as to be attenuated upon transmission through said flowing blood; detecting the optical transmission after attenuation through a field of view portion of the fleshy medium; generating an output signal indicative of optical characteristics of the medium; actively influencing a change in the volume of blood in said medium in accordance with a predictable pattern with no more than minimal perturbation to the optical path length of the medium in the field of view portion to produce modulation in said output signal; and analyzing said signal to determine the indication of the concentration of said blood constituent. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method of actively varying an attenuation of optical radiation due to blood in a fleshy medium in order to determine an indication of a blood constituent, comprising the steps of:
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transmitting optical radiation through a field of view area of said fleshy medium; detecting said optical radiation after attenuation through said fleshy medium; generating an output signal indicative of an intensity of the attenuated signal; actively influencing a change in the volume of blood in said fleshy medium in said field of view area according to a predictable pattern, with the level of influence below a level that causes significant variations in the optical properties in the fleshy medium in the field of view area; and determining said indication of a blood constituent level. - View Dependent Claims (8, 9, 10, 11, 12, 13)
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14. A method of actively varying an attenuation of optical radiation due to fluid in a fleshy medium comprising the steps of:
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transmitting optical radiation through said fleshy medium; detecting said optical radiation after attenuation through a field of view through said fleshy medium; generating an output signal indicative of the intensity of the attenuated signal; and applying pressure to said fleshy medium to influence a change in the volume of fluid in said fleshy medium in said field of view in accordance with a predictable pattern to produce modulation of said attenuated signal of about 1% to about 10%. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21)
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Specification