RESUMO
Objective:To evaluate the effects of different inhalation time on the minimum alveolar concentration (MAC) of sevoflurane in adult rats.Methods:Two hundred SPF healthy adult Sprague-Dawley rats (half male, half female), aged 8-10 weeks, weighing 200-260 g, were divided into 2 groups using a random number table method: inhalation of sevoflurane for 1 h group and inhalation of sevoflurane for 20 min group, with 100 rats in each group.Each group was subdivided into 10 subgroups with 10 rats in each subgroup, the initial concentration was preset at 1.50%, and the ratio between two successive concentrations r was 1.08.The tail clamping stimulus was applied to evaluate the efficacy of anesthesia in each subgroup, a positive response was defined as a body movement occurred within 1 min after tail clamping stimulus, and the response was defined as negative when no body movement occurred within 1 min after tail clamping.The Bliss method was used to calculate the MAC, EC 95 and 95% confidence interval (CI) of sevoflurane. Results:The MAC and EC 95 (95% CI) of sevoflurane were 2.09% (1.98%-2.20%) and 2.75% (2.56%-3.04%), respectively, in inhalation of sevoflurane for 1 h group, and 2.35% (2.22%-2.49%) and 3.10% (2.87%-3.45%), respectively, in inhalation of sevoflurane for 20 min group ( P<0.05). Conclusions:The MAC of sevoflurane in adult rats inhaled sevoflurane for 1 h is decreased than that inhaled for 20 min.