Effect of propofol and thiopentone on regional blood flow in brain and peripheral tissues during normoxia and hypoxia in the dog.

The effect of propofol and thiopentone on cerebral (CBF), myocardial (MBF), muscular, and arterial hepatic blood flow was assessed with radiolabelled microspheres in 12 chronically instrumented dogs, six given propofol and six thiopentone. Tissue blood flows were measured in the awake animal, after 30 min of normoxic anaesthesia (room air), and after 30 min of hypoxic anaesthesia using a mixture of 10% O2 and 3% CO2 in nitrogen. The decrease in CBF from awake to normoxic anaesthesia was similar with propofol and thiopentone (propofol: 77 +/- 8 to 38 +/- 3 ml min-1 100 g-1, P < 0.01; thiopentone: 66 +/- 3 to 33 +/- 2 ml min-1 100 g-1, P < 0.01). During hypoxia, CBF rose moderately in the two groups (respectively +19% and +28%, P < 0.05). The MBF increased in propofol and thiopentone groups after 30 min of anaesthesia with air (propofol: 97 +/- 23 to 137 +/- 15 ml min-1 100 g-1; thiopentone: 82 +/- 7 to 141 +/- 10 ml min-1 100 g-1) and increased still more during hypoxia. The increase in MBF was related to an increase in heart rate and blood pressure. The quadriceps blood flow decreased during anaesthesia in normoxia and in hypoxia. The diaphragmatic blood flow increased with thiopentone under hypoxia. The hepatic arterial blood flow was unchanged. It is concluded that the effects of propofol on regional blood flows are very similar to those of thiopentone.