The electrocardiographic and hemodynamic effect of metohexital and propofol with and without esmolol.

BACKGROUND: Metohexital and propofol are short-acting induction agents, which have a tendency to prolong the QTc interval of the ECG. We studied whether this increase could be prevented by combining a beta-blocking agent, esmolol, with these drugs. Simultaneously, we studied the hemodynamic effects of these combinations. METHODS: In a randomized, double-blind study, 80 ASA I-II young adults were premedicated with oxycodone and atropin and allocated to one of four groups: propofol (P), propofol + esmolol (P + E), metohexital (E) or metohexital + esmolol (M + E). The doses were 2 mg/kg propofol/metohexital and 1 mg/kg esmolol. Alfentanil 15 microg/kg was used in all groups. The hemodynamic parameters were measured non-invasively and the electrocardiographic parameters using the signal processing method. RESULT: The highest QTc values, which often exceeded the normal upper limit of 440 ms, were recorded at the baseline or immediately after the administration of the induction drugs. The intervals were significantly shorter if esmolol was co-administered with either propofol or metohexital. The heart rate increased in the group M and decreased in the group P + E but remained unchanged in the groups P and M + E. Systolic and diastolic arterial pressures decreased during the study in all groups, most prominently in group P + E. CONCLUSIONS: During the anesthesia induction, the QTc interval was significantly shorter when esmolol was co-administered with either propofol or metohexital. The hemodynamic responses were properly controlled with the combination of metohexital and esmolol as well as with propofol alone, but the combination of propofol and esmolol tended to cause hemodynamic depression.

Effect of esmolol on the hemodynamic and electrocardiographic changes during laryngomicroscopy under propofol-alfentanil anesthesia.

Laryngomicroscopy is a short-lasting procedure, which causes considerable hemodynamic and ECG changes. Therefore it sets specific demands on anesthetic care. In this double-blind randomized work, we studied hemodynamic and ECG changes in patients during laryngomicroscopy in jet ventilation under propofol-alfentanil anesthesia with and without esmolol, a short-acting beta1-adrenergic receptor blocking agent. Forty ASA class I-II patients were allocated to receive either esmolol 1 mg.kg-1 + 200 micrograms.kg-1.min-1 (the esmolol group) or saline (the control group) (mean age +/- SD 36 +/- 12 yrs in the esmolol group and 39 +/- 9 yrs in the control group). The heart rate and arterial pressure were measured non-invasively and ECG was analyzed with the aid of a microcomputer. In the control group, neither the heart rate nor the QTc interval of the ECG did change significantly when compared with the baseline values. In the presence of esmolol, the heart rate decreased and the QTc interval shortened during the procedure. Arterial pressure increased in the control group, but not in the esmolol group, when compared with the baseline values. No cardiac arrhythmias occurred in either of the groups. On the basis of the present study, propofol-alfentanil anesthesia combined with esmolol is a satisfactory method to meet specific demands of laryngomicroscopy in young and middle-aged ASA I-II patients. However, a combination of propofol and esmolol showed a tendency to decrease both the heart rate and arterial pressure and a caution is necessary when the combination were used in elderly patients.

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

BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

QT interval of the ECG, heart rate and arterial pressure during anaesthetic induction: comparative effects of alfentanil and esmolol.

In a double-blind study the effect of esmolol and alfentanil on the QT interval of the ECG corrected by the heart rate (QTc), heart rate and arterial pressure during anaesthetic induction was studied in 59 oxycodone- and atropine-premedicated ASA class I-(II) patients with a mean age of 26 yr (range 15-50 yr). The patients were randomly allocated to one of the four groups: saline, esmolol 2 mg.kg-1, esmolol 3 mg.kg-1 or alfentanil 0.03 mg.kg-1. Both doses of esmolol prevented the prolongation of the QTc interval after thiopental and suxamethonium, but not after laryngoscopy and intubation. Alfentanil prevented the prolongation of the QTc interval following thiopental, suxamethonium and laryngoscopy but not after intubation. Esmolol did not prevent the increase in the heart rate and arterial pressure in response to laryngoscopy and intubation. No cardiovascular responses to laryngoscopy and intubation occurred in the patients treated with alfentanil. No cardiac arrhythmias occurred in the esmolol 3 mg.kg-1 group, whereas the frequency of ventricular ectopic beats was 40% in the saline group and 13-20% in the other groups.

Modification of the haemodynamic responses to induction of anaesthesia and tracheal intubation with alfentanil, esmolol and their combination.

The purpose of this double-blind randomized work was to study the effect of alfentanil and esmolol and their half-dose combination on the increases of heart rate and arterial pressure and on the prolongation of the QTc interval of the ECG occurring during anaesthetic induction. Sixty ASA class I-II patient with mean age ranging from 26 to 32 yr among the groups. Patients were allocated to one of four equal groups to receive saline, esmolol 2 mg.kg-1, alfentanil 0.03 mg.kg-1 and alfentanil 0.015 mg.kg-1+esmolol 1 mg.kg-1. Anaesthesia was induced with thiopentone. Succinylcholine was used to facilitate tracheal intubation. Haemodynamic variables were measured non-invasively and the QTc interval with the aid of a microcomputer. Comparisons between the groups were performed using two-way analysis of variance with repeated measures. Both alfentanil and alfentanil-esmolol prevented the increase of heart rate and arterial pressure caused by intubation whereas esmolol prevented only the increase of the heart rate. None of the treatments prevented prolongation of the QTc interval after intubation and only alfentanil prevented that after succinylcholine. The present results suggest that in the prevention of the haemodynamic responses to tracheal intubation, the half-dose combination of alfentanil and esmolol is as effective as alfentanil and superior to esmolol. The combination is preferable to relatively large doses of either drug in circumstances where side effects, such as respiratory depression due to alfentanil or bradycardia due to both drugs should be minimized.