The effects of direct laryngoscopy and videolaryngoscopy in patients with double lumen tube, QTc interval, Tp-e interval and Tp-e/QTc ratio

The QT interval on the electrocardiogram (ECG) represents the depolarization and repolarization period of the ventricles. QT interval elongation is associated with an increased risk of ventricular arrhythmias such as polymorphic ventricular tachycardia and ventricular fibrillation. Tp-e interval and Tp-e / QTc ratio are accepted as the predictive value of risk for malignant ventricular arrhythmias and in some patients are used at the risk of sudden cardiac death. Laryngoscopy and intubation may cause changes in cardiac repolarization and prolongation of QT interval by a sympathetic response. Videolaringoscopes are alternative airway devices to direct laryngoscopes that provide a wide viewing angle with a high resolution camera and flat monitor. Previous studies reported that videolaryngoscopy provided better laryngeal view, higher intubation success at the first time, lower difficult intubation score, and a higher right position rate at double lumen tube (DLT) intubation. The effect of laryngoscope type during tracheal intubation on QT interval dispersion has not been adequately investigated in literature yet. Especially in DLT entübation, the effect of videolaryngoscopy dispersion has not been clearly examined on QTL for QT interval. The aim of this study; to compare the efficacy of McGRATH® MAC 5 videolaryngoscope and the Macintosh direct laryngoscopy on the QTc, Tp-e, Tp-e / QTc ratios and the hemodynamics, in patients underwent elective thoracic surgery used DLT for one lung ventilation. Materials and Methods A total of 83 patients, between the age of 18-65, American Society of Anesthesiologists (ASA) I-II, scheduled elective thoracic surgery with double lumen tube intubation were included into this prospective study. Patients were randomly allocated into two groups; patients who used videolaryngoscpes represented Group V, and those who used direct laryngoscpes represented Group L. Noninvasive blood pressure, electrocardiograph (ECG), peripheral oxygen saturation were monitored and the based ECG was recorded to the patients after arriving in the operation room. Standard general anesthesia was performed all patients. Neuromuscular blockade was monitored with Train-of-Four (TOF) and intubation was performed when the TOF ratio was reached to be 0/4. All intubations; was performed by the same experienced anesthetist with double lumen tube intubation. Modified Cormack-Lehane view of the glottis classification grade 1 (glottic opening clearly visible) and grade 2a (glottic opening partially visible) were included in the study. Double lumen tubing was selected according to the gender and length of the patients. 39-41 F for male patients and 37-39 F for female were used. After tube placement, the correct position was determined by capnography and auscultation and confirmed by fibreoptic bronchoscopy. Age, gender, length, weight, body mass index and ASA values of the patients were recorded. Heart rate (HR), systolic arterial pressure (SAP), diastolic arterial pressure (DAP), mean arterial pressure (MAP), oxygen SpO2 and ECG were recorded immediately before induction of anesthesia immediately after induction (T1), 2 minute after induction (T2), 1 minute after intubation (T3), 3 minutes after intubation (T4), 5 minutes after intubation (T5) and 10 minutes after intubation (T6). Cormack-Lehane classification, intubation trial numbers, intubation time, used DLT type and DLT number were noted. A 12 leads EKG device (Nihon Kohden, Tokyo) with 50mm / s rate was used and performed the records in supine position. All ECG recording was meticulously evaluated by an experienced anesthetist in this subject. The QTc interval was calculated with The Fridericia formula. Results Demographic characteristics of patients were similar. There was a significant difference between groups in the QTc, Tp-e and Tp-e / QTc ratio in all measurement periods except in T0 and T1 inrevals (p<0.05). There was no statistically significant difference between the groups at HR, SBP, DBP, OAB and Oxygen saturations. Cormack-Lehane scores, intubation times, type of DLT used (right or left), DLT were similar between the groups. Conclusion In the thoracic surgery patients used DTL for one-long ventilation, McGrath® MAC videolaryngoscopethe decrased ratio of QTc, Tp-e and Tp-e / QTc according to Macintosh direct laryngoscope. It was not superior to entubation stimulated hemodynamic response and entubation parameters. However, we believe that videolaryngoscopy may be more appropriate in DLT applications in patients who are known to have difficult intubation or predict difficult airway. Keywords: Double-Lumen tube, Endotracheal tube, hemodynamics, Tp-e wave dispersion, QTc dispersion, Tp-e/QTC ratio.