The effects of different concentration of sevoflurane on the pharmacodynamics of atracurium

Objective: To observe the effects of different concentration of sevoflurane on the pharmacodynamics of atracurium.Methods: Thirty patients with ASA Ⅰ-Ⅲ undergoing head, neck or face elective surgical procedures, were randomly divided into three groups. They were anaesthetized to receive 50% N₂O for 15 min （group Ⅰ, n=10）, 1% end tidal concentration of sevoflurane in 50% N₂O for 15 min （group Ⅱ, n=10） and 1.5% end tidal concentration of sevoflurane in 50% N₂O for 15 min （group Ⅲ, n=10）, respectively. Following atracurium 0.5 mg·kg^1- was intravenously adimnistered by bolus injection, neuromuscular function was recorded by Accelography in response to train of four stimulation.Results: The onset time of atracurium was shorter in group Ⅲ （1.71±0.48 min） than in group Ⅰ （2.27±0.73 min） and group Ⅱ （2.28±0.38 min） （P＞0.05）. While the clinical duration, the 25% and 75% recovery time were longer in group Ⅲ than in group Ⅰ （P＜0.05） and group Ⅱ （P＞0.05）. The recovery index was significantly prolonged in group Ⅲ （16.60±3.63 min） than group Ⅰ （11.23±3.49 min, P＜0.05）. Blood pressure and heart rate were stable after intravenous atracucrium. Conclusion: This study indicates that sevoflurane may significantly enhance the neuromuscular blockade effect of atracurium. Along with the increasing of sevoflurand inhalation concentration, the onset time of atracurium is shortened and the clinical duration of action is significantly prolonged.