Effects of vecuronium priming and ephedrine pretreatment on the onset time of neuromuscular blockade of vecuronium during induction period

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Objective To evaluate the effect of vecuronium priming, ephedrine pretreatment, and vecuronium priming combined with ephedrine pretreatment on the onset time of neuromuscular blockade of vecuronium, intubation conditions and their hemodynamic effects during induction period. Methods Forty-eight adult patients with ASA grade Ⅰ or Ⅱ , scheduled for elective surgery were randomly allocated to four groups with 12 cases in each. Just 3 min before induction, the patients were injected with ephedrine 70 μg/kg and vecuronium priming 0.01 mg/kg in group Ⅰ , vecuronium 0.01 mg/kg in group Ⅱ , ephedrine 70 μg/kg in groupⅢ, and normal saline 0.5 ml in group Ⅳ. Followed by a four min priming or/and pretreatment interval, the intubation dose of vecuronium was injected (vecuronium 0.09 mg/kg in group Ⅰ and group Ⅱ , vecuronium 0.1 mg/kg in group Ⅲ and Ⅳ ). The neuromuscular block was monitor by acceleromyography (TOF Watch SX, Organon) using train of four stimulation (TOF) every 15 s.Endotracheal intubation was performed by a blinded investigator in 2 min. Time to maximal twitch depression was recorded, Intubation conditions were assessed, heart rate and mean blood pressure were observed and recorded as well right before the induction, 1 min after the induction and every minute after endotracheal intubation for 5 min. Results The onset times in group Ⅰ , Ⅱ , Ⅲ and Ⅳwere (99±13), (131±24), (143±20) and (185±26) s, respectively. The onset time of vecuronium in group Ⅰ , Ⅱ and Ⅲ was significantly shorter than that in group Ⅳ (P＜0.001). The onset time of vecuronium in group Ⅰ was faster than that in group Ⅱ and group Ⅲ (P＜0.005). The intubation conditions were better in group Ⅰ , Ⅱ and Ⅲ than those in groupⅣ.There were no significant change in mean blood pressure during the induction in all patients, but heart rates in group Ⅰ , Ⅲ (both with ephedrine pretreatment) were much higher( P＜0.05 ). Conclusion Either vecuronium priming or ephedrine pretreatment can shorten the onset time of vecuronium. The combination of vecuronium priming with ephedrine pretreatment accelerates the onset of vecuronium; In combination with ephedrine, it has no effect on hypotension induced by propofol injection. Key words: Vecuronium; Ephedrine; The onset time; Hemodynamics; The intubating conditions