title: Acute beta-adrenoreceptor blockade and induced hypotension.
abstract: Thirty patients scheduled for major middle ear surgery and induced hypotension, with a trimetaphan/sodium nitroprusside infusion, were randomly allocated to receive a single oral dose of beta-adrenoreceptor antagonist 2 hours before surgery. In group 1 ten patients received metoprolol 50 mg, in group 2 ten patients received metoprolol 25 mg and in group 3 ten patients received oxprenolol 20 mg. There were ten controls for each group. The nitroprusside infusion rate was significantly reduced in groups 1 and 3. However, there was an unacceptably high incidence of profound bradycardia after induction of anaesthesia in those patients who had received beta-adrenoreceptor antagonists pre-operatively and this technique is not recommended for routine use.
mesh_terms: D000293:Adolescent; D000319:Adrenergic beta-Antagonists / Q000009:adverse effects / Q000494:pharmacology; D000328:Adult; D000368:Aged; D001794:Blood Pressure / Q000187:drug effects; D001919:Bradycardia / Q000139:chemically induced; D005292:Ferricyanides; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D007023:Hypotension, Controlled; D007431:Intraoperative Complications / Q000209:etiology; D008875:Middle Aged; D009599:Nitroprusside; D014294:Trimethaphan
chemical_list: D000319:Adrenergic beta-Antagonists; D005292:Ferricyanides; D009599:Nitroprusside; D014294:Trimethaphan