Cerebral effects of propofol following bolus administration in sheep

The effects of bolus administration of propofol (50 mg, 100 mg and 200 mg) on cerebral blood flow and cerebral metabolic rate for oxygen were examined in a chronically catheterized sheep preparation. Depth of anaesthesia was simultaneously measured using a withdrawal response to a noxious electrical stimulus and it was demonstrated that the 100 mg dose induced moderate sedation while the 200 mg dose induced relatively deep anaesthesia. Propofol caused transient dose-dependent decreases in cerebral blood flow, despite minimal changes in blood pressure. These were accompanied by parallel decreases in cerebral metabolic rate but no change in cerebral oxygen extraction. As cerebrovascular responses in the sheep appear similar to those in man, the parallel changes in cerebral bloodflow and metabolic rate demonstrated in this study supports the suitability of propofol as a neuroanaesthetic agent.