Real-time estimation of oxygen concentration in micro-hemo-vessels

A real-time measurement system for non-invasive evaluation of oxygen concentration (PO/sub 2/) at the microcirculation level is developed. The system has been designed by exploiting the phenomenon of fluorescence quenching. The skin of an anaesthetized hamster, injected with porphyrin, is lighted with pulses; the fluorophore reacts with the oxygen in the blood, producing a fluorescence signal, and the value of the fluorescence lifetime is related to the oxygen concentration. This microcirculation-based instrumentation consists of an electro-optical system, a control circuit and signal processing procedure. The system allows the measurement of PO/sub 2/ in the range of 0-700 (mmHg) with a standard deviation of 4 (mmHg). Several experiments have been performed in order to characterize and test this system.