QTc Interval During Desflurane Anesthesia: The Effects of Intravenous Lidocaine Prior to Intubation

Objective: Prolongation of the corrected QT (QTc) interval is an important predictor for the risk of polymorphic ventricular tachycardia and ventricular fibrillation. Volatile inhalational anaesthetics and intubation may cause prologation in the QTc interval. Lidocaine can be useful in preventing intubation-related cardiovascular responses. The aim of this study was to investigate whether administration of intravenous (iv) lidocaine prior to intubation would prevent the prolongation of QTc interval occuring after tracheal intubation (TI) during desflurane anesthesia. Material and Methods: The study group included 82 patients, all admitted for elective surgery. Anesthesia induction was provided with midazolam (0.3 mg/kg). After loss of eyelash reflex, the anaesthetic circuit was filled with desflurane and oxygen, then manually controlled ventilation was started. Cisatracurium besylate (0.15 mg/kg) was administered for muscle relaxation. After administration of muscle relaxant, either 1.5 mg/kg iv lidocaine or placebo were administered to the patients in study group (n=41) and control group (n=41), respectively. Two minutes after the administration of drugs, TI was performed at first attempt. The electrocardiography (ECG) recordings were obtained at four occasions; before anesthesia induction, after reaching steady state concentration of end tidal desflurane, just after intubation and 10 minutes after intubation. The QTc intervals, QT dispersion (QTd) and QTcd (QTcmax-QTcmin) were calculated. Results: QTc interval was prolonged after anesthesia induction. After intubation, QTc interval was significantly prolonged and remained so for 10 more minutes. Conclusion: In this study, lidocaine could not prevent prolongation of the QTc interval occuring after TI during desflurane anesthesia.