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.