Cardiovascular effects of isoflurane-induced hypotension for cerebral aneurysm surgery

Deliberate hypotension was induced with isoflurane in 13 patients, undergoing craniotomy for clipping of aneurysms. Cardiovascular function and gas exchange were monitored before, during, and after hypotension. In all cases, the desired level of hypotension [40 +/- 1 (SEM) mm Hg] was achieved readily with prompt onset (5.7 +/- 1.0 min) and recovery (6.3 +/- 0.7 min). Cardiac output during hypotension (4.6 +/- 0.3 L/min) was not significantly different from the control normotensive value (4.80 +/- 0.3 L/min). Gas tensions during hypotension and during normotension were; PaO2 116 +/- 6 and 111 +/- 8 mm Hg; PaCO2 33 +/- 1 and 34 +/- 1 mm Hg; respectively. No complication could be attributed to the use of isoflurane. We conclude that isoflurane can be employed safely and effectively as a hypotensive agent in neurosurgery.