Stable and reliable measurement of intracapillary hemoglobin-oxygenation in human skin by EMPHO II

To evaluate the reliability of EMPHO II in human skin measurement, hemoglobin oxygenation (HbO(2)) and hemoglobin concentration (Hb(con)) behaviors were measured under ischemia and congestion. Functional evaluation of HbO(2) and Hb(con) of human skin at forearm or fingers of healthy volunteers had been obtained in visible range (500-628 nm) by a rapid micro-lightguide spectrophotometer (EMPHO II). In a first series of investigations, ischemia or congestion of the skin was induced by upper arm compression to 250 mmHg or 80 mmHg respectively. The data show that HbO(2) decreased under conditions of ischemia but also congestion, while Hb(con) increased enormously under congestion alone, in a second series of experiments, the local oxygen uptakes of the skin under various temperature conditions (5 to 45 degrees C) were determined from the decrease of intracapillary oxygen content (d(Hb(con)*HbO(2))/dt) which was induced by a stop of blood flow. We concluded that the measurement of intracapillary hemoglobin oxygenation of human skin by EMPHO Il is reliable and stable under several conditions. Furthermore, our data suggested that the changes in HbO(2), Hb(con) and O-2 uptake of the skin seem to be a very useful parameter which can quickly change when tissue hypoxia occurs by unbalance of O-2-demand and supply.