QUANTITATIVE REFLECTION SPECTROPHOTOMETRY - SPATIAL AND TEMPORAL VARIATION OF HB OXYGENATION IN HUMAN SKIN

Applying a fast scanning reflection spectrophotometer and multicompone nt spectra analysis, oxygen saturation (S-Hb) and relative concentrati on (C-Hb) Of hemoglobin in the skin were determined at eight skin site s in 11 healthy persons. S-Hb was significantly higher at the tip of t he index finger and big toe (90 +/- 3.9 and 92 +/- 4.2%, respectively) compared with the forehead, volar forearm, back of hand, abdomen, cal f and forefoot where mean values varied between 52 and 67% (p < 0.001) . C-Hb also was higher at acral sites (big toe: 2.04 +/- 0.14 arbitrar y units (AU); index finger: 2.13 +/- 0.19 AU) than at the other locati ons (p < 0.0001) where it was between 0.56 +/- 0.12 AU (abdomen) and 0 .95 +/- 0.28 AU (forefoot). In the course of time, rhythmical oscillat ions of both parameters at a frequency of 3-5/min were seen in 68% of the measurements, predominantly at the six proximal sites. Heating the measuring site to 44 degrees C caused a biphasic increase of C-Hb and S-Hb which was significant at the proximal sites (p < 0.0001). S-Hb v alues came into the range of arterial blood. Temporal and spatial vari ation of both parameters decreased. Reflection spectrophotometry gives the possibility to directly assess dermal hemoglobin saturation, its physiological variability and reactions to provocation stimuli. Concen tration and saturation of hemoglobin in dermal vessels appear definite ly different at acral compared with proximal sites.