Large dose thiopental anesthesia for intracranial aneurysm surgery

Twenty patients undergoing intracranial aneurysm clipping were anesthetized with doses of thiopental sufficient to produce electroencephalographic burst suppression, nitrous oxide, oxygen, and morphine sulfate. Diuresis was induced with a combination of furosemide and mannitol. The cardiovascular effects of this anesthetic technique were studied. The central venous, pulmonary artery, pulmonary artery wedge, and systemic arterial blood pressures and the cardiac output were determined. The cardiac index and the systemic and pulmonary vascular resistance were calculated. The systemic blood pressure remained unchanged throughout the procedure except during the period of induced hypotension. The cardiac index decreased on the average from 3.3 during the control period to 2.15 litres/minute/m2 after the induction of anesthesia and diuresis (P less than 0.05). During sodium nitroprusside-induced hypotension, there was a further decrease in the cardiac index to 1.81 litres/minute/m2 (P less than 0.05). Changes in the cardiac index were associated with a significant decrease in the central venous and pulmonary artery wedge pressures from 2.5 to 0.1 and 5.9 to 0.2 torr, respectively) and an increased systemic vascular resistance. Cardiovascular performance recovered quickly after termination of the induced hypotension and remained stable in the postoperative period. This anesthetic technique seems to be useful in the surgical repair of intracranial aneurysms.