Effect of Dexmedetomidine Infusion Dose Versus Rapid Bolus Dose on Hemodynamic Changes During Laryngoscopy and Tracheal Intubation in Adults. A Randomized Comparative Study.

Preoperative assessment of all patients undergoing elective surgical procedures under general anaesthesia comprises history taking, clinical examination, laboratory testing (complete blood count, kidney function tests, liver function tests), electrocardiogram, and chest X-ray. The study protocol will be explained to the patients, and their consent will be obtained. The patients will be continuously monitored in the operating room for heart rate, blood pressure, and oxygen saturation (baseline values). Then a 20-gauge cannula will be inserted.

Patients will be randomly assigned into two groups: Group A will receive Dexmedetomidine infusion dose of 1 mcg/kg diluted to 100 ml normal saline infused over 10 minutes and Group B will receive Dexmedetomidine bolus dose of 0.3 mcg/kg diluted to 10 mL normal saline administered intravenously over 60 seconds. Then Patients will be induced with propofol 2mg/kg, followed by atracurium 0.5 mg/kg IV. After 3 minutes, tracheal intubation will be performed with an appropriate size of cuffed tracheal tube and connected to end tidal CO2 monitor. After confirmation of bilateral equal air entry, it is connected to mechanical ventilation using isoflurane 1.2% for maintaining anesthesia and keeping end tidal CO2 between 35-40 mmHg, Ringer's solution at a rate 5ml/kg/hour IV will be infused for fluid maintenance. If heart rate falls below 45 bpm, rescue dose (500 mcg) of atropine will be given. If MAP decreases below 50 mmHg, boluses of 10 mg ephedrine will be given, while escalation of MAP will be treated by boluses of 50 mg propofol.

At the end of surgery, the inhaled gas is off and the patient is reversed with neostigmine 0.05mg/kg and atropine 0.01mg/kg, then extubation is done. The two groups will be observed for changes in hemodynamic parameters i.e. heart rate (HR) and mean arterial blood pressure at preinduction period (baseline), after 1 min from dexmeditomedine taking, after induction, at intubation and 1,3,5 and 10 min after intubation. No intervention will be allowed during these 10 minutes and morphine at a dose 0.1mg/kg will be used as analgesia for surgery after 10 minutes.