Abstract: Objective To evaluate the effects of dexmedetomidine on the median effective dose of fentanyl to prevent endotracheal intubation. MethodsA total of 40 ASA Ⅰ-Ⅱ patients who were scheduled for gynecologic laparoscopy under general anesthesia were enrolled in the study. The patients were randomly divided into two groups: a dexmedetomidine group (Group D) and a control group (Group C) (n=20). Before anesthestic induction, Group D received 0.6 μg/kg dexmedetomidine by intravenous infusion within 10 min, and Group C received an equal volume of normal saline with Group D. Propofol was given by target controlled infusion (TCI) at a target plasma concentration of 3 mg/L, while a predetermined dose of fentanil was injected over 30 s. The dose of fentanil was determined by up-and-down method (at a ratio of 1.2 between adjacent doses). When the patients became unconscious, intravenous rocuronium was given to facilitate tracheal intubation. Then, blood pressure (BP), heart rate (HR) and bispectral index (BIS) were recorded before anesthetic induction (T0), before intubation (T1), and 1 min and 5 min after intubation (T2 and T3). ResultsThe ED50 (the 95% confidence intervals) of fentanyl in Groups D and C were 3.06 μg/kg (2.82-3.31 μg/kg) and 4.32 μg/kg (3.96-4.71 μg/kg) respectively, during endotracheal intubation using visual laryngoscopy. The ED50 of fentanyl in Group D was lower than that in Group C (P<0.05). ConclusionsSingle infusion of 0.6 μg/kg dexmedetomidine prior to anesthetic induction can decrease the ED50 of fentanyl to prevent endotracheal intubation response, which indicates that dexmedetomidine enhances the potency of fentanyl to prevent endotracheal intubation response.