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A simple, manually controlled infusion scheme for continuous administration of propofol was derived by simulation of a computer algorithm designed to achieve a predetermined blood concentration of propofol within 2 minutes and to maintain a constant blood level for the duration of surgery. The manual infusion scheme for a target blood propofol concentration of 3 micrograms/ml, consisted of a loading dose of 1 mg/kg followed immediately by an infusion of 10 mg/kg/hour for 10 minutes, 8 mg/kg/hour for the next 10 minutes and 6 mg/kg/hour thereafter. An overall mean blood propofol concentration of 3.67 micrograms/ml was achieved within 2 minutes and maintained stable for the subsequent 80-90 minutes of surgery. The decrease of systolic and diastolic arterial pressures at induction was much less than that previously described after larger induction doses of propofol and there was a negligible haemodynamic response to laryngoscopy and intubation or to the subsequent surgery. The quality of induction and maintenance of anaesthesia was satisfactory in every patient.

Despite adverse side effects, phenoxybenzamine has been widely used for the preoperative management of patients with pheochromocytoma. Doxazosin, a specific a 1-adrenoceptor antagonist, has a pharmacologic profile more suited to controlling blood pressure in such patients. A sequential study of 35 patients with pheochromocytoma encompassed a definite and prescribed change in preoperative drug management from phenoxybenzamine to doxazosin. Hemodynamic, pharmacologic, and biochemical indicators of a- and b-adrenoceptor blockade were measured before, during, and after anesthesia and surgery in 8 patients pretreated with phenoxybenzamine and 27 patients pretreated with doxazosin. Doxazosin (2-16 mg/day) was as effective as phenoxybenzamine in controlling arterial pressure and heart rate before and during surgery, but doxazosin caused fewer undesirable side effects both before and after surgery. Following phenoxybenzamine therapy substantial a 1-adrenoceptor blockade, detected as a right shift of phenylephrine dose-response curves, persisted for more than 2 days postoperatively, whereas after doxazosin it was undetectable on the first postoperative day. Doxazosin provided safe, efficacious pre- and perioperative control of arterial pressure. In patients with predominantly norepinephrine-secreting tumors, pretreatment 24-hour urinary norepinephrine excretion gave an indication of the daily doxazosin requirement.