Unexplained hypertension during induction of a patient with phaeochromocytoma.

An unexplained hypertensive response during the induction of anaesthesia for phaeochromocytoma resection is described. This response was not accompanied by elevations in plasma catecholamine levels. It occurred despite heavy premedication and followed induction with etomidate, alfentanil, lignocaine, vecuronium and magnesium sulphate (MgSO4). A bolus of esmolol (0.5 mg/kg) lowered the blood pressure rapidly. Subsequent haemodynamic manipulations were carried out by varying the rate of an esmolol infusion. A constant background infusion of MgSO4 was maintained throughout the procedure. These produced satisfactory haemodynamic control despite marked rises in plasma catecholamine levels.