Apparatus and method for determination of the adequacy of dialysis by non-invasive near-infrared spectroscopy
First Claim
1. A method for assessing the need for hemodialysis, the progress of a hemodialysis procedure or the adequacy of a hemodialysis treatment, said method comprising the steps of:
- providing a means for optical analysis of tissue on a patient, said means providing an output spectrum at multiple wavelengths, wherein said output spectrum has varying intensities as related to absorption by said tissue;
coupling said tissue to said means for optical analysis and acquiring said output spectrum before, during or after hemodialysis for assessing the need for hemodialysis, the progress of a hemodialysis procedure or the adequacy of the hemodialysis treatment, respectively; and
, calculating a tissue urea concentration from a mathematical model relating said output spectrum to said tissue urea concentration.
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Abstract
Methods and apparatus for non-invasive tissue urea concentrations during or subsequent to hemodialysis using near-infrared spectroscopy are discussed. Near-infrared tissue spectra can be obtained by projecting near-infrared radiation into skin on the underside of human forearms and capturing the light reflected back and out through the tissue. An index matching medium is used to couple the tissue to the analyzer. The tissue spectrum collected preferably includes primarily diffuse reflected light reflected from the inner dermis. Multiple tissue spectra of known urea concentration are used to build a model from which the urea concentration of an unknown sample can be devised. The model is based on a partial least squares algorithm applied to multiple tissue scans and concomitant blood sample urea measurements. This model is then applied to an unknown tissue spectra.
498 Citations
22 Claims
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1. A method for assessing the need for hemodialysis, the progress of a hemodialysis procedure or the adequacy of a hemodialysis treatment, said method comprising the steps of:
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providing a means for optical analysis of tissue on a patient, said means providing an output spectrum at multiple wavelengths, wherein said output spectrum has varying intensities as related to absorption by said tissue;
coupling said tissue to said means for optical analysis and acquiring said output spectrum before, during or after hemodialysis for assessing the need for hemodialysis, the progress of a hemodialysis procedure or the adequacy of the hemodialysis treatment, respectively; and
,calculating a tissue urea concentration from a mathematical model relating said output spectrum to said tissue urea concentration. - View Dependent Claims (2, 3, 4, 5)
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6. A non-invasive method for measuring the concentration of urea in human tissue comprising the steps of:
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providing an apparatus for measuring infrared absorption, said apparatus including an energy source emitting infrared energy at multiple wavelengths, including selected wavelengths relevant to urea concentration due to absorption by said urea, operatively connected to an input element, said apparatus further including an output element operatively connected to a spectrum analyzer;
providing an index-matching medium, said index-matching medium having minimal absorption of infrared energy at said selected wavelengths, and disposing a quantity of said medium between said human tissue and said input element and output element to couple said elements to said urea-containing tissue through said index-matching medium; and
,irradiating said tissue through said input element with multiple wavelengths of infrared energy so that there is differential absorption of at least some of said wavelengths; and
,collecting at least a portion of the non-absorbed infrared energy with said output element for analysis of infrared energy absorption with subsequent calculation of tissue urea concentration utilizing a model relating said infrared energy absorption to said tissue urea concentration. - View Dependent Claims (7, 8, 9, 10, 11, 12)
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13. A non-invasive method for measuring the concentration of urea in analyte-containing human tissue comprising the steps of:
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providing an apparatus for measuring infrared absorption, said apparatus including an energy source emitting infrared energy at multiple wavelengths, including selected wavelengths relevant to urea concentration due to absorption by said urea, operatively connected to an input element, said apparatus further including an output element operatively connected to a spectrum analyzer;
providing an index-matching medium, said index-matching medium including a chlorofluorocarbon polymer, and disposing a quantity of said medium between said human tissue and said input element and output element to couple said elements to said analyte-containing tissue through said index-matching medium;
irradiating said tissue through said input element with multiple wavelengths of infrared energy so that there is differential absorption of at least some of said wavelengths; and
,collecting at least a portion of the non-absorbed infrared energy with said output element for analysis of infrared energy absorption with subsequent calculation of tissue urea concentration utilizing a model relating said infrared energy absorption to said tissue urea concentration. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22)
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Specification