Hemodynamic Responses to Tracheal Intubation Direct Laryngoscope and Videolaryngoscope in Elderly Patients

Overview

The intubation response to airway manipulation during direct laryngoscopy can cause hypertension, dysrhythmias and increased intracranial and intraocular pressures. This intense physiological response is proven to be associated with adverse outcomes especially in elderly patients. Increased QT dispersion is associated with increased risk of ventricular arrhythmias, which may increase the risk of sudden death caused by life-threatening arrhythmias. McGrath Videolaryngoscope would generate a lesser haemodynamic response than the conventional method of direct laryngoscopy. The objective of this study was to compare the hemodynamic response and QT during following tracheal intubation, using videolaryngoscope or direct laryngoscope to intubation. The postoperative airway morbidities is the investigators secondary outcome.

Ninety patients, aged over 65 years, scheduled for elective surgery under general anesthesia requiring tracheal induction will be included in this study. All patients will divided into two groups by a sealed envelope technique, Group Laryngoscope; n = 45 and Group Videolaryngoscope; n = 45 to receive tracheal intubation using either a Macintosh laryngoscope (Group L) or a McGRATH videolaryngoscope (Group V). Hemodynamic data will evaluated by an anesthesiologist who was blinded to the study group affiliations. Evaluation of ECG will performed by a cardiologist. None of the patients will premedicated with any drug. Standard monitors, including ECG (lead II), noninvasive systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP) and peripheral oxygen saturation (SpO2) measurements will be and mallampati classification, thyromental distance and mouth opening will be evaluated. After preoxygenation, anesthesia will induced with propofol 1.5 mg/kg. After loss of consciousness, rocuronium 0.5 mg/kg will injected intravenously (IV). Two minutes after rocuronium administration, fentanyl 2.0 μg/kg was given to each patient, and intubation will attempted with the direct laryngoscopy or McGrath Videolaryngoscopy. Anesthesia will maintained with sevoflurane in a mixture of 50% oxygen in 50% nitrous oxide. The following parameters will measured by a blind observer: number of intubation trials, intubation time (from insertion of the intubation device into the mouth to capnographic confirmation), airway trauma (detection of blood drops in the mouth, lip or the tube after removal). SBP, DBP, MAP heart rate and electrocardiography (ECG) will recorded at the following time points: before induction of anesthesia (pre-induction, T0), before tracheal intubation (post-induction, T1), 1,3,5 min post-intubation (T2, T3, T4, respectively). A 12-lead surface ECG was obtained from each subject while placed in the supine position. The 12-lead ECG was recorded at a standardized article speed of 50 mm/sec and 2.0 millivolt/cm. Measurement of QT interval duration will carried out manually using a caliper. Pharyngolaryngeal injury in all patients will assessed by asking about sore throat and hoarseness 24 h after the surgery using an 4-point scale: none, mild, moderate and severe.