| 摘要 |
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, capturing the light reflected back, and out through the tissue. An index matching medium (22) is used to couple the tissue to the analyzer (30). The tissue spectrum collected preferably includes primarily diffuse 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.
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