A comparison of QTc intervals following laryngoscopic intubation and i-gel insertion during propofol-sevoflurane anesthesia

Abstract

BACKGROUND: Laryngoscopic intubation and supraglottic airway device insertion can prolong the corrected QT (QTc) interval during anaesthetic induction even in healthy patients. No prior study has compared the effect of laryngoscopic intubation and supraglottic airway device, i-gel, insertion on the QTc interval change.

METHODS: Patients were randomised to either the intubation group (N.=25) or the i-gel group (N.=25) before induction. The QT interval was sequentially measured in lead II following a standard anaesthetic technique for induction using propofol and sevoflurane. Four sequential QT values were applied to the Bazett's formula to correct for the effect of heart rate on the QT interval, and then averaged. The peak QTc interval, the duration of QTc prolongation >20 ms compared to the QTc value immediately before intubation or i-gel insertion and the incidence of the QTc intervals >500 ms were measured.

RESULTS: The peak QTc interval was lower in i-gel group (458.4±24.3 ms) than in intubation group (488.6±32.6 ms) (P=0.001). The duration of QTc prolongation >20 ms compared to the QTc values at immediately before intubation or i-gel insertion was significantly longer in the intubation group (136.5±104.5 s) than that of the i-gel group (56.9±56.5 s) (P=0.031). The number of patients with QTc interval >500 ms was significantly lower in the i-gel group (4%) than in the intubation group (48%).

CONCLUSIONS: The insertion of the i-gel produces less QTc interval change than laryngoscopic intubation. The i-gel may be advantageous to patients who are at risk of QTc prolongation, high blood pressure and tachycardia.