肥胖因素对异丙酚镇静效力的影响

Effect of obesity on potency of propofol for sedation

目的 评价肥胖因素对异丙酚镇静效力的影响.方法 选择全身麻醉下行择期手术患者60例,性别不限,年龄35～55岁,ASA分级Ⅰ或Ⅱ级.根据BMI将患者分为2组（n=30）：正常体重组（C组）,BMI＜25 kg/m2;肥胖组（O组）,BMI 30～40 kg/m2.靶控输注异丙酚,初始血浆靶浓度为1.2 μg/ml,达到血浆靶浓度30 s后增加0.3 μ g/ml,直至患者意识消失（OAA/S评分=1分）.记录各阶段异丙酚的血浆靶浓度,采用概率单位法计算异丙酚使患者意识消失的半数有效浓度（EC50）及95％可信区间.结果 C组和O组异丙酚使患者意识消失的EC50及95％可信区间分别为3.82（3.73～3.90）和3.29（3.20～3.37）μg/ml.与C组相比,O组EC50降低（P＜0.05）.结论 肥胖因素可增强异丙酚的镇静效力.

Objective To evaluate the effect of obesity on the potency of propofol for sedation.Methods Sixty patients of both sexes, aged 35-55 yr, of American Society of Anesthesiologists physical status Ⅰ or Ⅱ , scheduled for elective operation under general anesthesia, were enrolled in the study.The patients were divided into 2 groups （n=30 each） according to the body mass index （BMI） ： normal body weight （BMI 〈 25 kg/m2） group （group C） and obesity （BMI 30-40 kg/m2） group （group O）.No patients received premedication.Propofol was given by target-controlled infusion.The initial target plasma concentration of propofol was set at 1.2 μg/ml.After the target concentration was steadily maintained for 30 s, it was increased in 0.3 μg/ml increment until the patients lost consciousness （OAA/S score =1）.The target plasma concentration of propofol was recorded during each period.The median effective concentration （EC50） and 95% confidence interval of propofol for loss of consciousness was calculated using probit analysis.Results The EC50 and 95% confidence interval of propofol for loss of consciousness were 3.82 （3.73-3.90） and 3.29 （3.20-3.37） μg/ml in group C and group O, respectively.Compared with group C, the EC50 was significantly decreased in group O （P〈0.05）.Conclusion Obesity can enhance the potency of propofol for sedation.