The Effect of Intranasal Dexmedetomidine Premedication on the Minimum Alveolar Concentration of Sevoflurane for tracheal intubation in children

INTERVENTION: GroupD1 received 1mcg/Kg intranasal dexmedetomidine premedication 60 min before general anaesthesia; GroupD2 received 2mcg/Kg intranasal dexmedetomidine premedication 60 min before general anaesthesia.Before tracheal intubation was attempted, the end‐tidal concentration of sevoflurane was kept constant at the predetermined value at least 15 min, Once the response to tracheal intubation was recorded, further administration of anesthetic and analgesic agents was at the attending anesthesiologist’s discretion. CONDITION: inhalation induction of anesthesia and tracheal intubation in children PRIMARY OUTCOME: the minimum alveolar concentration of sevoflurane for tracheal intubation (MACTI); Patient’s responses to tracheal intubation were classified as ‘no movement’ or ‘movement’. ‘No movement’ was defined as the absence of purposeful movement of the extremities, movement of the vocal cords preventing intubation, and coughing or bucking during or immediately after intubation. The values of MACTI were obtained by calculating the midpoint concentration of all independent response cross‐overs in which a positive response was followed by a negative response. SECONDARY OUTCOME: included induction quality Incidence of adverse events(e.g.hypotention,bradycardia); ; ; Clinically significant hypotention or bradycardia, defined as > 30% decrease in mean arterial pressure or heart rate compared with baseline. INCLUSION CRITERIA: American Society of Anesthesiologists physical status I‐II children scheduled to undergo general anesthesia for elective minor surgery