性别差异对肛肠手术罗哌卡因骶管阻滞半数有效浓度的影响

Difference of EC_(50) values of ropivacaine in male and female patients for caudal anesthesia in anorectal surgery

目的:研究性别差异对罗哌卡因骶管麻醉应用于肛肠手术半数有效浓度(EC50)的影响。方法:本研究是双盲设计,前瞻性研究,选择ASA I级,择期在骶管麻醉下行肛肠手术患者70例,按性别分为男性组和女性组,每组35例。两组第一例患者罗哌卡因浓度均为0.2%(20mL),相邻浓度之差为0.025%,以对切皮无痛作为有效指标。罗哌卡因给药浓度的增加或减少根据前一个患者的反应决定。应用Dixon法和概率回归分析(Probit)法计算骶管麻醉罗哌卡因EC50。结果:Dixon计算得男性组和女性组罗哌卡因骶管麻醉应用于肛肠手术的EC50分别为0.296%(95%CI:0.286%-0.307%)和0.389%(95%CI:0.372%-0.407%);Probit法计算得EC50值分别0.295%(95%CI:0.173%-0.325%)和0.382%(95%CI:0.352%-0.405%);EC99值分别为0.364%(95%CI:0.330%-1.313%)和0.422%(95%CI:0.400%-0.646%),女性组EC50显著高于男性组(P<0.01)。结论:罗哌卡因骶管麻醉应用于肛肠手术时,女性患者的EC50较男性增加31%,提示应根据性别调整罗哌卡因的浓度实施骶管麻醉。

AIM：To investigate the effect of sex on the median effective concentration（EC50）of ropivacaine for caudal anesthesia. METHODS：In this double-blind,prospective study,we enrolled 70 ASA physical status I patients（35male and 35female）who were scheduled for anorectal surgery under caudal anesthesia,and classified them into two study groups（Group M and Group F）on the basis of their gender difference.Each participant received a single injection of 20 mL ropivacaine through a caudal catheter.Using Dixon＇s up-and-down sequential allocation,the first participant received 0.2% and subsequent concentrations were determined by the analgesic response of the previous patients to the initial skin incision. The concentration change was 0.025%. The up-and-down sequences were analyzed using the Dixon and Probit methods to quantify the caudal analgesic block effective concentrations in 50% of patients. RESULTS：From Dixon method, The EC50 values of ropivacaine for caudal analgesia were 0.296%（95% CI,0.286%-0.307%）in male patients and 0.389%（95% CI,0.372%-0.407%）in female patients.From Probit analysis,the EC50 values ropivacaine in Group M and Group F were 0.295%（95% CI,0.173%-0.325%）, 0.382%（95% CI, 0.352%-0.405%）respectively and EC99 was 0.364%（95% CI,0.330%-1.313%）,0.422%（95%CI,0.400%-0.646%）respectively.EC50 values of ropivacaine was significantly higher in Group F as compare with Group M（P〈0.01）.CONCLUSION：We concluded that the ropivacaine EC50 values for caudal anesthesia in female patients is 31% higher as compare to the male patients.The present findings provide suitable suggestion to anesthesiologists about ropivacaine concentration adjustment for caudal anesthesia based on gender difference.