NONINVASIVE ASSESSMENT OF REGIONAL AND TEMPORAL VARIATIONS IN TISSUE OXYGENATION BY NEAR-INFRARED SPECTROSCOPY AND IMAGING

A combination of near-infrared spectroscopy and discrete wavelength ne ar-infrared imaging is used to noninvasively monitor the forearm durin g periods of restricted blood outflow (venous outflow restriction) and interrupted blood inflow (ischemia), Multivariate analysis of image a nd spectral data time courses was used to identify highly correlated s pectral and regional domains, while fuzzy C-means clustering of image time courses was used to reveal finer regional heterogeneities in the response of stressed tissues, Localized near-infrared spectroscopy was used to investigate the magnitude of the bulk changes in the tissue o ptical properties and the variation in tissue oxygenation saturation d uring venous outflow restriction and complete forearm ischemia, The im aging and spectroscopic analyses revealed highly localized regional va riations in tissue oxygen saturation during forearm ischemia as compar ed to the more diffuse and global response of the forearm during venou s outflow restriction.