Effect of esmolol on the heart rate, arterial pressure and electrocardiographic changes during laryngomicroscopy

Laryngomicroscopy causes considerable haemodynamic and ECG changes and therefore requires high doses of anaesthetic agents, which prolong recovery. In this double-blind randomized work, we studied the effect of esmolol, a short-acting beta-adrenergic receptor-blocking agent, on haemodynamic and ECG changes during laryngomicroscopy under thiopental-alfentanil-isoflurane-suxamethonium anaesthesia.

Forty ASA class I-II patients (mean age 43 +/- 11 yr) were allocated to receive either esmolol 1 mg.kg-1 + 200 micrograms.kg-1.min-1 (the esmolol group) or saline (the control group). Heart rate and arterial pressure were measured noninvasively and ECG was analyzed with the aid of a microcomputer. Comparisons between the groups were performed using two-way analysis of variance with repeated measures and the Student's t-test.

In the presence of esmolol, neither the heart rate nor the QTc interval of the ECG increased significantly when compared with the baseline values, with the exception that the QTc interval was increased after intubation. The increase in arterial pressure after insertion of the operating laryngoscope was not prevented in esmolol-treated patients. No cardiac arrhythmias occurred in either of the groups.

On the basis of the present study, esmolol-bolus + infusion during alfentanil-isoflurane anaesthesia in healthy, middle-aged patients is a useful treatment in circumstances where an increase of the heart rate, prolongation of the QTc interval and cardiac arrhythmias should be avoided.