Anesthetic management with propofol during pheochromocytoma resection under bispectral index monitoring

In three patients undergoing pheochromocytoma resection under propofol/fentanyl anesthesia, bispectral index (BIS) was monitored for assessment of hypnotic effect. In two patients, arterial blood concentrations of propofol were measured by high performance liquid chromatography (HPLC), and compared with those of the estimated blood concentrations. Until resection of the tumor, propofol was infused at a rate of 10 mg x kg(-1) x hr(-1). After resection of the tumor, propofol dosage was reduced to 3-6 mg x kg(-1) x hr(-1), keeping the BIS values around 60. Rapid infusion of fluid and norepinephrine was required to maintain blood pressure after removal of the tumor in two patients. In one patient, blood pressure was maintained well without rapid infusion of fluid or vasopressor. Arterial blood concentration of propofol after resection of the tumor was equal to the estimated blood concentration (3.04 vs 3.02 microg x ml(-1)) in a patient without rapid infusion of fluid. In a patient with rapid infusion of fluid, the arterial blood concentration was lower than the estimated blood concentration (2.59 vs 3.58 microg x ml(-1)). The anesthetic depth can not be estimated accurately by hemodynamic changes in the patients undergoing pheochromocytoma resection. BIS monitoring should be recommended for adjustment of propofol dosage after pheochromocytoma resection.