The effect of intravenous lidocaine on QT changes during tracheal intubation.

Laryngoscopy and tracheal intubation may provoke changes of cardiac repolarisation. The aim of this study was to assess the effect of intravenous lidocaine on the ECG changes induced by laryngoscopy and tracheal intubation. Forty-three female patients were randomly allocated to receive lidocaine (1.5 mg.kg(-1)) or placebo immediately after induction of anaesthesia and changes in the ECG and arterial blood pressure were recorded. Correction of QT interval was calculated using Bazett's formula (QTcb), Fridericia's correction (QTcf), and Framingham formula (QTcF). Transmural dispersion of repolarisation (TDR) was determined as Tpeak-Tend time. There were no changes in the QTc value in the lidocaine group. In the placebo group, significant increases in QTcb, QTcf and QTcF values were observed after intubation compared to either control measurements or to comparative measurements in the lidocaine group. There were no significant differences in TDR either between or within the groups. Lidocaine diminishes prolongation of QTc, induced by tracheal intubation but there is no effect of intubation on TDR.