The use of a selective beta-adrenergic receptor blocker for the preoperative preparation of thyrotoxic patients.

Metoprolol, a cardioselective beta-blocker, was used in two asthmatic, thyrotoxic patients in preparation for thyroidectomy. Adequate reduction in resting heart rate was achieved in both individuals without inducing clinically significant airway obstruction. Beta-1-blockade can be selectively employed in this clinical setting, but patients should be hospitalized and closely monitored for adverse effects on pulmonary function. Metoprolol therapy in patients with reversible airway obstruction is discussed with reference to recent studies on relative cardioselectivity.