Effect of Nebulized Lidocaine, Dexmedetomedine and Their Combination on Haemodynamics During Direct Laryngoscopy Surgery. A Randomized Controlled Clinical Trial.

Patients will be transferred to the induction room 30 min prior to surgery. Standard monitors will be applied [pulse oximetry, non invasive blood pressure (NIBP) and electrocardiogram (ECG)]. Basal HR, systolic (SBP), diastolic (DBP) and mean arterial blood pressure (MAP) will be recorded. An intravenous 22-G cannula will be inserted, and all patients will be pre-medicated with intravenous midazolam 0.02 mg/kg, granisetrone 2mg and ranitidine 30 mg.

Patients will then be randomly and evenly allocated to one of 4 groups (45 patients each).

Nebulized solutions will be prepared by a pharmacist not participating in the study. Nebulization will be done with 100% oxygen (10 L/min) through facemask attached to a nebulizer. Patients will be asked to breath normally. Nebulization will continue till the solution in the nebulizer is all aerosolized.

Upon arrival to the operating room, routine monitors will be applied in addition to neuromuscular monitor and end tidal CO2 (ETCO2). General anaesthesia will be induced, after 5 min of preoxygenation, by intravenous fentanyl 1 μg/kg, propofol 1.5-2 mg/kg titrated to a loss of verbal response and rocuronium 1 mg/kg to facilitate endotracheal intubation. Mackintosh laryngoscope will be introduced when train of four (TOF) count reaches 1. High volume-low pressure endotracheal tube (size 5-5.5) will be inserted by senior anaesthesiologist. HR, SBP, DBP and MAP will be recorded immediately after intubation.

Anaesthesia will be maintained by sevoflurane 2-3% in oxygen to air ratio 1:1. Rocuronium 0.1 mg/kg when required. Positive pressure ventilation will be set to maintain ETCO2 30-35 mmHg.