Cardiovascular effects of local adrenaline infiltration during halothane anaesthesia and adrenergic beta-receptor blockade in man.

Adrenergic beta-receptor blocking agents, alprenolol, propranolol and practolol were given as a prophylactic measure to patients undergoing middle-ear microsurgery where adrenaline was deliberately infiltrated during halothane-N2O/O2 anaesthesia. These three beta blockers did not differ in their action on heart rate, arterial blood pressure, right ventricular pressure, CVP or peripheral pulse wave in equipotent doses, which were 0.04 mg/kg for alprenolol and propranolol and 0.4 mg/kg for practolol in this study. Atropine caused a highly significant increase in heart rate in the spontaneously ventilating group and maintained blood pressure at higher levels, although the latter difference was not significant. Alprenolol and propranolol offered partial protection for over 40 min against adrenaline-induced arrhythmias. Occasionally occuring tachyarrhythmias were easily terminated with a further dose of a beta blocker. The effective half-life of practolol was less than 15 min and doses up to 0.4 mg/kg were unable to prevent arrhythmias during adrenaline challenge.