Controlled hypotension with fentanyl and halothane in neurosurgery. A clinical evaluation.

An anesthesia technique is described for clipping off a cerebral aneurysm. The patients are premedicated with Thalamonal and atropine. For induction is given: thiopental (Pentothal) 4 mg/kg and pancuronium (Pavulon) 0.1 mg/kg. Subsequently fentanyl 7 micrograms/kg and dehydrobenzperidol 0.25 micrograms/kg is given intravenously. The patient is moderately hyperventilated (PaCO2 30-35 mm Hg) with an O2/N2O gasmixture. Through a second intravenous infusion fentanyl (20 ml fentanyl dissolved in 500 ml glucose 10%) is given continuously to obtain a good painrelief during the whole procedure. Those conditions eliminate almost each cause of an increase of the blood pressure. Once the dura meter is opened, halothane is administered in a concentration between 0.5% and 3% to lower the mean arterial pressure to 60 mm Hg. Within 15 minutes the blood pressure is on the desired level. After clipping off the aneurysm, halothane is stopped and the blood pressure regains its normal level. Postoperatively the patient is ventilated during 24 hours (moderate hyperventilation). To prevent an increase of the blood pressure, the administration of the fentanyl solution is continued. Indeed, the blood pressure may not be allowed to increase because the autoregulation of the CBF is markedly disturbed after a hypotension. This technique has been used in 7 patients.