INFLUENCE OF PENTOBARBITAL, PROPOFOL AND KETAMINE ON SKELETAL-MUSCLE CAPILLARY PERFUSION DURING HEMORRHAGE - A COMPARATIVE-STUDY IN THE RABBIT

Anesthetics affect tissue blood flow, which is of importance especiall y in situations of inadequate perfusion, as in hemorrhage. The present study compared the effect of three commonly used anesthetic agents on skeletal muscle capillary and regional blood flow during and after re covery from hemorrhage. Three groups of rabbits were anesthetized rand omly with either pentobarbital, propofol or ketamine, chosen such that the anesthetic level, blood pressure and withdrawn blood volume were comparable in all groups. Capillary blood flow was measured using a lo cal hydrogen clearance technique with a multi-wire microelectrode, pla ced on the left vastus medialis muscle surface, and the contralateral site served for regional microcirculatory blood flow measurements usin g laser-Doppler flowmetry. Hemorrhage was induced by withdrawal of blo od to a mean arterial pressure of 40 mm Hg and monitoring was continue d during the subsequent spontaneous recovery period of 120 min. Both c apillary and regional blood flow decreased significantly during hemorr hage in all groups. The flow values in the pentobarbital group were gi ven a mean value of 100% and the other two groups were compared with t his. Local hydrogen clearance flow decreased from a relative baseline level of 100 to 64% during hemorrhage-with pentobarbital, from 87 to 4 3% with propofol and from 146 to 70% with ketamine. Laser-Doppler flow metry flow decreased from relative baseline levels of 100, 96 and 139% , to 71, 77 and 103%, respectively, during hemorrhage, whereas the per centage of zero capillary flow values increased from 4 to 34, 19 to 50 and 5 to 27% in the three groups, respectively. The results of the pr esent study indicate that capillary perfusion is best maintained in th e ketamine group followed by pentobarbital and propofol last. Furtherm ore, the flow distribution shapes for each anesthetic indicate a more pronounced deregulation of capillary blood flow in the propofol group than in the others, even at baseline.