Apparatus and method for determination of the adequacy of dialysis by non-invasive near-infrared spectroscopy

A non-invasive method for measuring the concentration of urea in human tissue comprising the steps of:

• 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 absorption with subsequent calculation of tissue urea concentration utilizing an algorithm and a model.

A non-invasive method for measuring the concentration of urea in human tissue comprising the steps of:

• 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 absorption with subsequent calculation of tissue urea concentration utilizing an algorithm and a model.