Noninvasive measurement of glucose through the optical properties of tissue
First Claim
1. A method for noninvasive measurement of a target analyte in a tissue sample, comprising the steps of:
- measuring a spectrum of a tissue sample;
detecting at least one optical property of said tissue sample related to fluid shift between extravascular and intravascular tissue compartments triggered by changes in concentration of said analyte, as manifested by at least one spectral feature reflecting said fluid shift; and
either correcting a direct analyte measurement on the basis of said at least one optical property;
or measuring said analyte indirectly on the basis of said at least one optical property.
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Abstract
Methods and apparatus for noninvasive determination of blood analytes, such as glucose, through NIR spectroscopy utilize optical properties of tissue as reflected in key spectroscopic features to improve measurement accuracy and precision. Physiological conditions such as changes in water distribution among tissue compartments lead to complex alterations in the measured absorbance spectrum of skin and reflect a modification in the effective pathlength of light, leading to a biased noninvasive glucose measurement. Changes in the optical properties of tissue are detected by identifying key features responsive to physiological variations. Conditions not conducive to noninvasive measurement of glucose are detected. Noninvasive glucose measurements that are biased by physiological changes in tissue are compensated. In an alternate embodiment, glucose is measured indirectly based on natural physiological response of tissue to glucose concentration. A spectroscopic device capable of such measurements is provided.
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Citations
66 Claims
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1. A method for noninvasive measurement of a target analyte in a tissue sample, comprising the steps of:
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measuring a spectrum of a tissue sample;
detecting at least one optical property of said tissue sample related to fluid shift between extravascular and intravascular tissue compartments triggered by changes in concentration of said analyte, as manifested by at least one spectral feature reflecting said fluid shift; and
either correcting a direct analyte measurement on the basis of said at least one optical property;
ormeasuring said analyte indirectly on the basis of said at least one optical property. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37)
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38. An apparatus for noninvasive measurement of a target analyte in a tissue sample comprising:
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means for measuring a spectrum of a tissue sample;
means for detecting at least one optical property of said tissue sample related to fluid shift between extravascular and intravascular tissue compartments triggered by change in concentration of said analyte, as manifested by at least one spectral features reflecting said fluid shifts; and
either correcting a direct analyte measurement on the basis of said at least one optical property;
ormeasuring said analyte indirectly on the basis of said at least one optical property. - View Dependent Claims (39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63)
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64. A method for noninvasive measurement of a target analyte property in a tissue sample, comprising the steps of:
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noninvasively measuring a spectrum of a tissue sample in vivo;
detecting at least one optical property of said tissue sample related to physiologic state of said tissue resulting from change in concentration of said analyte, as manifested by at least one spectral feature reflecting said physiologic state; and
either correcting a direct analyte measurement on the basis of said at least one optical property;
ormeasuring said analyte indirectly on the basis of said at least one optical property.
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65. A method for noninvasive measurement of glucose concentration in a tissue sample, comprising the steps of:
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measuring a spectrum of a tissue sample;
detecting at least one optical property of said tissue sample related to state of said tissue resulting from change in concentration of glucose, as manifested by at lest one spectral feature reflecting said state; and
either correcting a direct glucose measurement on the basis of said at least one optical property;
ormeasuring said glucose concentration indirectly on the basis of said at least one optical property.
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66. A method for noninvasive measurement of a target analyte in a tissue sample, comprising the steps of:
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measuring a spectrum of a tissue sample;
detecting conditions not conducive to analyte measurement;
if conditions are conducive to analyte measurement, detecting at least one optical property of said tissue sample related to physiology of said tissue resulting from change in concentration of said analyte, as manifested by at least one spectral feature reflecting said physiology; and
either correcting a direct analyte measurement on the basis of said at least one spectral feature;
ormeasuring said analyte indirectly on the basis of said at least one optical property.
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Specification