Effect of desflurane at less than 1 MAC on QT interval prolongation induced by tracheal intubation.

BACKGROUND

Desflurane at more than 1 minimum alveolar concentration (MAC) has been shown to prolong the QT interval, but it is unclear whether this is the case at lower concentrations. The aim of this study was to determine whether desflurane concentrations of <1 MAC affect tracheal intubation-induced prolongation of the QT interval.

METHODS

Forty-four subjects received either inspired desflurane at 1 MAC in oxygen 100% at a fresh gas flow rate of 6 litre min(-1) (desflurane group) or only oxygen 100% (control group) beginning at anaesthesia induction with propofol, before tracheal intubation. The QT intervals were corrected by Bazett's (QTcB) and Fridericia's (QTcF) formulae. The primary outcome was the QTcB immediately after tracheal intubation. Secondary outcomes were the interval from the peak to the end of the T wave (Tp-e), mean arterial pressure (MAP), heart rate (HR), and bispectral index (BIS) score.

RESULTS

The QTc interval immediately after tracheal intubation did not differ between the control and the desflurane groups [QTcB, 451 (sd 23) vs 456 (27) ms, P=0.56; QTcF, 422 (24) vs 429 (22) ms, P=0.31, control vs desflurane group, respectively]. There was no difference in Tp-e or HR between the two groups in this study. However, MAP and the BIS score were significantly lower in the desflurane group until 1 min after tracheal intubation.

CONCLUSIONS

The administration of desflurane at an inspiratory concentration of 1 MAC during manually controlled ventilation after anaesthesia induction with propofol did not affect tracheal intubation-induced QTc prolongation.