Significance of beta-blocking agents in perioperative medicine. Part One: Basic concepts

Purpose: To review the pharmacologic and pathophysiologic information neces sary to-prescribe beta-blockers (BB) in perioperative medicine. Data source: Manual retrieval and electronic research of the literature usi ng MEDLINE (key-words: anesthesia and beta- blocker; surgery and beta-block er). Data synthesis: Cardioselective BB inhibit preferentially beta-1 receptors, inducing a decrease in heart rate and cardiac inotropism leading to reduct ion of oxygen myocardial consumption. Non-cardioselective BB inhibit also b eta-2 receptors, increasing bronchial and peripheral vascular resistances a nd uterine contractions. However, some BB are also vasodilators (carvedilol , celiprolol, labetalol). Contraindications to BB result logically from the ir pharmacological effects. Treatment with BB increases membrane beta-recep tor density; this explains sympathetic overactivity observed during weaning of treatment. Since the discovery of propranolol in 1964, the use of BB ha s been controversial in anesthesia. Formerly, the adverse effects of partia l sympatholysis during anesthesia and surgery were feared. However, since 1 973, experimental and clinical data have suggested a protective hemodynamic effect. Conclusion: Continued administration of BB up to the time of anesthesia has been encouraged except in patients with signs of intolerance such as hypot ension or excessive bradycardia.