Cardiovascular Effects of Esmolol in Anesthetized Humans

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Abstract
We studied the cardiovascular effects of esmolol, a newly synthesized β-adrenocepter antagonist, in anesthetized humans. Forty patients (four groups of 10 each) with ischemic heart disease and normal ventricular function were anesthetized with diazepam, pancuronium, and N2O in O2. Esmolol was given by continuous infusion in cumulative doses of 1100 fig/kg (group 1), 2000 μg/kg (group 2), and 2700 μg/kg (group 3); a control group received no esmolol. Infusion of esmolol was begun 3 min prior to and ended 4 min after tracheal intubation. All three doses of esmolol significantly (P < 0.001) attenuated the heart rate responses to intubation. Rate-pressure products were significantly (P < 0.001) lower in esmolol-treated patients than in controls after intubation, but ST-segment changes compatible with ischemia occurred in one patient in each group. Increases in heart rate were associated with significant increases in plasma norepinephrine levels (r = 0.45, P = 0.02) in the control group, but not in esmolol-treated patients, a demonstration that esmolol antagonizes the β-adrenergic effects of norepinephrine. The effect of esmolol on heart rate was absent 5 min after cessation of infusion, and plasma levels of esmolol were undetectable in 26 of 30 treated patients 15 min after the termination of esmolol infusion. Esmolol has a rapid onset and short duration of effect. It can be used safely during anesthesia in patients with normal ventricular function to attenuate cardiac response to sympathetic stimulation.