Dexmedetomidine bolus dose may provide similar or less hemodynamic changes (less bradycardia and less hypertension) than infusion dose during induction of anaesthesia and tracheal intubation.
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 till loss of verbal contact, 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.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
SUPPORTIVE_CARE
Masking
DOUBLE
Enrollment
70
patients will receive Dexmedetomidine infusion dose of 1 mcg/kg over 10 min before induction.
patients will receive Dexmedetomidine bolus dose of 0.3 mcg/kg over 60 seconds.
If heart rate falls below 45 bpm, rescue dose (500 mcg) of atropine will be given.
Cairo University Hospitals
Giza, Egypt
RECRUITINGMean blood pressure upon laryngoscopy
mean blood pressure measurement (mmhg) during laryngoscopy
Time frame: 1 minute
Blood pressure & Heart rate
Heart rate (bpm), Systolic, Diastolic and Mean arterial blood pressure (mmhg)
Time frame: 1 min after dexmeditomedine, after induction, at intubation and 1,3,5 and 10 min after intubation
Propfol
total boluses dose needed for induction
Time frame: induction
Bradycardia
Number of events : If heart rate falls below 45 bpm, rescue dose (500 mcg) of atropine will be given.
Time frame: from start of dexmedetomidine injection before induction till 10 minutes after intubation
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If mean blood pressure decreases below 50 mmHg, boluses of 10 mg ephedrine will be given
Propofol 20 mg boluses till loss of contact