Self-emission noninvasive infrared spectrophotometer with body temperature compensation
First Claim
1. A noninvasive infrared spectrophotometer, comprising:
- means for detecting infrared emissions generated and emitted by a vascularized appendage of a person;
means for determining infrared absorption of at least one predetermined constituent of the person'"'"'s blood from said infrared emissions detected by said detecting means;
means for measuring an internal temperature of said person at a point of said vascularized appendage where said infrared emissions are detected by said detecting means; and
processing means for determining the infrared emissions corresponding to said internal temperature measured by said temperature measuring means and for calculating a concentration of said at least one predetermined constituent as a function of the infrared emissions detected by said detecting means and the determined infrared emissions corresponding to said internal temperature measured by said temperature measuring means.
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Abstract
A method and apparatus for monitoring glucose, ethyl alcohol and other blood constituents in a noninvasive manner. The measurements are made by monitoring infrared absorption of the desired blood constituent in the long infrared wavelength range where the blood constituent has a strong and distinguishable absorption spectrum. The long wavelength infrared energy emitted by the person as heat is monitored and the infrared absorption of particular constituents in the blood (such as glucose or blood alcohol) is measured at characteristic infrared absorption wavelengths for those constituents. The measurements are preferably synchronized with systole and diastole of the cardiac cycle so that the signal contribution caused by veins and tissues (which do not pulse) may be cancelled when a ratio of the detected signals is taken. On the other hand, if no synchronization is provided, the spectrophotometer may measure the arterial, venous and tissue constituent concentrations simultaneously, which may be desired in some circumstances. The internal "blackbody" energy level of an infrared emissions source such as a vascularized appendage prior to glucose absorption is measured and used to compensate temperature dependent effects in the concentration calculation. The internal energy level is then ratioed to the actual measured energy and used to compute the percentage of energy absorbed by the glucose. Discontinuities in the ratio are eliminated by converting the absorption measurements from voltages to watts.
147 Citations
29 Claims
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1. A noninvasive infrared spectrophotometer, comprising:
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means for detecting infrared emissions generated and emitted by a vascularized appendage of a person; means for determining infrared absorption of at least one predetermined constituent of the person'"'"'s blood from said infrared emissions detected by said detecting means; means for measuring an internal temperature of said person at a point of said vascularized appendage where said infrared emissions are detected by said detecting means; and processing means for determining the infrared emissions corresponding to said internal temperature measured by said temperature measuring means and for calculating a concentration of said at least one predetermined constituent as a function of the infrared emissions detected by said detecting means and the determined infrared emissions corresponding to said internal temperature measured by said temperature measuring means. - View Dependent Claims (2, 3, 4, 5)
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6. A noninvasive infrared spectrophotometer for determining a concentration of at least one predetermined constituent in a person'"'"'s blood, comprising:
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means for detecting infrared energy generated and emitted by the person in a wavelength range including n different wavelengths of at least 2.0 μ
m, said infrared energy containing energy at each of said n wavelengths which is differently absorbed by said at least one predetermined constituent whereby each predetermined constituent readily absorbs infrared energy at least one of said n wavelengths and minimally absorbs infrared energy at another of said n wavelengths, said detecting means outputting at least one detection signal representative of infrared energy at said n wavelengths which has been emitted by said person and selectively absorbed by said at least one predetermined constituent;means for measuring an internal temperature of said person at a point of said person where said infrared energy is detected by said detecting means; and processing means for determining the infrared emissions corresponding to said internal temperature measured by said temperature measuring means and for calculating the concentration of said at least one predetermined constituent as a function of the infrared energy detected by said detecting means and the determined infrared emissions corresponding to said internal temperature measured by said temperature measuring means. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. A method of noninvasively measuring a concentration of at least one predetermined, constituent in a person'"'"'s blood, comprising the steps of:
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detecting infrared emissions generated and emitted by a person; detecting a temperature of said person at a point of emission of the infrared emissions detected in said infrared emissions detecting step; determining infrared absorption of at least one predetermined constituent of a person'"'"'s blood using said infrared emissions detected in said infrared emissions detecting step; determining the infrared emissions corresponding to said temperature measured in said temperature measuring step; and calculating the concentration of said at least one predetermined constituent as a function of the infrared emissions detected in said infrared emissions detecting step and the determined infrared emissions determined in infrared emissions determining step. - View Dependent Claims (22, 23)
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24. A method of noninvasively measuring a concentration of at least one predetermined constituent in a person'"'"'s blood, comprising the steps of:
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detecting infrared energy generated and emitted by the person in a wavelength range including n different wavelengths of at least 2.0 μ
m, said infrared energy containing energy at each of said n wavelengths which is differently absorbed by said at least one predetermined constituent whereby each predetermined constituent readily absorbs infrared energy at least one of said n wavelengths and minimally absorbs infrared energy at another of said n wavelengths, and outputting at least one detection signal representative of infrared energy at said n wavelengths which has been emitted by said person and selectively absorbed by said at least one predetermined constituent;measuring an internal temperature of said person at a point where said infrared energy is detected in said detecting step; determining the infrared emissions corresponding to said internal temperature measured in said temperature measuring step; and calculating the concentration of said at least one predetermined constituent as a function of the infrared energy detected in said detecting step and the determined infrared emissions determined in infrared emissions determining step. - View Dependent Claims (25, 26, 27, 28, 29)
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Specification