THE EFFECT OF ESMOLOL GIVEN DURING CARDIOPULMONARY BYPASS

beta-Adrenergic antagonism decreases the size of myocardial infarction and provides myocardial protection during hypothermic arrest for card iac surgery. However, concern regarding the negative inotropic and chr onotropic effects of beta-adrenergic antagonism persisting after cardi opulmonary bypass (CPB) has impeded the use of esmolol for this purpos e during cardiac surgery. This is a randomized, double-blind prospecti ve study of the effects of esmolol infused during CPB and the effects of hypothermic CPB on esmolol. Patients scheduled for CPB were randomi zed to receive intravenous esmolol (300.mu g.kg(-1).min(-1) during CPB after a bolus of 2 mg/kg prior to CPB) or placebo. Infusion was stopp ed at 10 min after release of aortic cross-clamp. Hemodynamics were me asured, as well as serum esmolol, catecholamines, lactate, and potassi um. Postoperative variables measured included electrocardiographic cha nges, creatine kinase (CK)-MB fractions, post-CPB dysrhythmias and dru gs, hospitalization time and cost, and mortality. Esmolol was administ ered to 16 patients and placebo to 14. Esmolol levels reached a high o f 10.5 +/- 0.9 mu g/mL during CPB, but decreased to 0.1 +/- 0.02 mu g/ mL within 30 min after stopping infusion. Cardiac indices (cardiac ind ex, stroke volume index, left cardiac work index, left ventricular str oke work index, right cardiac work index, and right ventricular stroke work index) were higher in the esmolol group for the first hour post- CPB (P < 0.05). Systemic arterial lactate and coronary sinus lactate w ere lower in the esmolol group after CPB (P < 0.05), but myocardial la ctate extraction was not significantly different between groups. After CPB, hemoglobin was lower in the esmolol group (P < 0.05) due to long er CPB and aortic cross-clamp time (P < 0.05), but oxygen consumption was less than in the control group (P < 0.05). Post-CPB serum potassiu m was higher in the esmolol group (P < 0.05). Results are confounded b y more chronically p-adrenergically blocked patients randomized to the esmolol group (P < 0.05). Esmolol infused during CPB in this series o f patients was associated with high concentrations during CPB but did not result in any adverse clinical effects after CPB.