Cardiovascular effects of propofol and of thiopentone anaesthesia in the sheep

We have examined the effects on the cardiovascular system and on regional blood flow of propofol and thiopentone when administered with IPPV (FIO2 0.4). A longitudinal study design was used in which 16 studies were performed in eight sheep for 30 min before, during the last 30 min of 70 min anaesthesia, and for 6 h after anaesthesia. During anaesthesia with propofol and thiopentone, mean total body oxygen consumption decreased, respectively, by 47% (P less than 0.001) and 24% (P less than 0.01) of pre-anaesthesia baseline values, mean heart rate increased by approximately 50% (P less than 0.05) with both agents, mean arterial pressures increased by approximately 50% (P less than 0.05) with both agents and the mean cardiac output was unaltered with propofol anaesthesia but was decreased by 20% (P less than 0.05) with thiopentone anaesthesia. The changes in arterial pressure and heart rate were unexpected and may have been a result of a species-specific effect. Mean hepatic blood flow decreased consistently by a mean of 17% (P less than 0.01) during propofol anaesthesia, and inconsistently during thiopentone anaesthesia so that it was not significantly different from baseline values. Mean renal blood flow decreased during propofol anaesthesia by 7% (P less than 0.05) and by 27% (P less than 0.001) during thiopentone anaesthesia. Whereas most variables returned to baseline values within 2 h after propofol anaesthesia, this took 5 h after thiopentone anaesthesia.