NONINVASIVE EVALUATION OF MICROCIRCULATORY HEMODYNAMIC-CHANGES DURINGHEMORRHAGE FOLLOWED BY SALINE OR BLOOD-TRANSFUSION

The purpose of the study was to examine the ability of a system combin ing laser Doppler flowmetry (LDF), photoplethysmograph (PPG), and tran scutaneous oxygen tension (tc-PO2) to follow changes in the microcircu lation during hemorrhage and following blood or saline return, and to test the hypothesis that such changes precede and might predict change s in the systemic blood pressure. Measurements were performed on the s kin of anesthetized rabbits (n = 10) during mild (0-8%), moderate (9-2 4%), and severe (25-30% of blood volume) hemorrhage, and following com plete volume restitution by blood or saline. We found the following: 1 ) hemorrhage caused typical changes in the LDF, PPG, and tc-PO2, signa ls that could be formulated by mathematical models, 2) these signals i dentified blood as being more efficient than saline for volume restitu tion following hemorrhage, and 3) microcirculatory changes precede and might predict systemic hemodynamic events.