The effects of a single bolus of remifentanil on corrected QT interval change during sevoflurane induction.

Objective: Opioids may affect changes in the corrected QT interval (QTc) during anesthetic induction. This study examine whether a single bolus of remifentanil would prolong QTc after laryngeal mask airway (LMA) insertion during sevoflurane induction.

Methods: Forty women of American Society of Anesthesiologists physical status 1 (ASA PS1) undergoing gynecological surgery were studied. All patients were induced using three vital capacity inhalation inductions with 5% sevoflurane. Two minutes after induction, the inspiratory concentration of sevoflurane was reduced to 2%. Using double-blinded randomization, patients were allocated into one of two groups, receiving either saline (placebo group, n = 20) or 0.25 μg.kg⁻¹ remifentanil (remifentanil group, n = 20) over a period of thirty seconds. Sixty seconds later, LMA insertion was performed. Recordings were taken with a 12-lead electrocardiogram at baseline, 2 min after induction and 1 and 3 min after LMA insertion. QTc was calculated by Bazett's formula. The mean arterial pressure (MAP) and heart rate (HR) were also measured at each time point.

Results: The QTc interval was significantly prolonged in the placebo group as compared to the remifentanil group at 1 min after LMA insertion (467.8 ± 16.5 vs. 442.7 ± 21.3 ms, p < 0.001). However, there was no significant difference in QTc at 3 min after LMA insertion between the two groups. MAP and HR were significantly higher in the placebo group (p < 0.001).

Conclusions: A single bolus of remifentanil is safe method to attenuate prolonged QTc associated with insertion of LMA.