持续输注去氧肾上腺素预防剖宫产腰麻后低血压的量效关系

目的探讨剖宫产术中持续输注去氧肾上腺素预防腰麻引起低血压的量效关系。方法选取需行剖宫产术的足月健康初产妇80例,随机均分为4组:A、B、C、D组。蛛网膜下腔注射重比重布比卡因10 mg和舒芬太尼5μg后分别输注去氧肾上腺素0.25、0.375、0.5、0.625μg·kg^-1·min^-1,胎儿娩出时停止输注。观察蛛网膜下腔阻滞开始至胎儿娩出期间产妇收缩压的变化,各组发生高血压、低血压、恶心呕吐等的例数,记录各组使用补救去氧肾上腺素和阿托品的次数、新生儿Apgar评分及脐动脉血pH值。研究期间无低血压发生的去氧肾上腺素剂量定义为有效剂量,采用Probit分析计算半数有效剂量(ED50)及95%有效剂量(ED95)。结果A、B组低血压的发生率显著高于C、D组(P<0.05),麻醉后30 min内D组收缩压的波动明显低于其他各组。C、D组的高血压发生率显著高于A、B组(P<0.05),但均为一过性,停止输注后即降至正常。4组产妇术中心动过缓、恶心呕吐及寒战发生率相似,差异无显著意义(P>0.05)。4组出生1 min Apgar评分及脐动脉血pH值无显著差异(P>0.05)。去氧肾上腺素预防低血压的ED50及ED95分别为0.31μg·kg^-1·min^-1(95%CI:0.24~0.36μg·kg^-1·min^-1)及0.63μg·kg^-1·min^-1(95%CI:0.52~1.00μg·kg^-1·min^-1)。结论去氧肾上腺素持续输注预防剖宫产腰麻引起的低血压的ED50及ED95分别为0.31及0.63μg·kg^-1·min^-1,0.625μg·kg^-1·min^-1(接近ED95)为推荐的输注剂量。

Dose-response relationship of continuous infusion of phenylephrine for preventing spinal anesthesia-induced hypotension in cesarean section

AIM To determine the dose-response relationship of phenylephrine continuous infusion in preventing spinal anesthesia-induced hypotension in cesarean section.METHODS Eighty healthy primiparous parturients scheduled for elective cesarean section were enrolled and randomly allocated into A,B,C and D groups,in which parturients received 0.25,0.375,0.5 or 0.625μg·kg^-1·min^-1 of phenylephrine infusion initiated immediately after intrathecal injection of hyperbaric bupivacaine 10 mg and sufentanil 5μg.Phenylephrine was terminated after baby delivery.Systolic pressure(SBP)during the study period from the initiate of spinal anesthesia to baby delivery was studied.The incidence of hypotension,hypertension,nausea and vomiting,and so on were studied.Dose requirements of rescue phenylephrine and atropine were compared.Apgar score and the pH value of umbilical artery were also studied.An effective dose of phenylephrine infusion to prevent hypotension was defined as the dose at which no hypotension occurs during the study period.Probit analysis was used to calculate the ED50 and ED95.RESULTS The incidence of hypotension was higher in group A and B than in group C and D(P<0.05).During the first 30 min after anesthesia,fluctuation of SBP was significantly alleviated in the group D.But the incidence of hypertension was higher in the group C and D than in the group A and B(P<0.05).However,hypertension was transient and return to normal after infusion ended.There was no significant difference in the incidence of bradycardia,nausea,vomiting,shivering,1 min Apgar score and umbilical artery pH value among four groups(P>0.05).The ED50 and ED95 of prophylactic phenylephrine infusion were 0.31μg·kg^-1·min^-1(95%CI:0.24 to 0.36μg·kg-1·min-1)and 0.63μg·kg^-1·min^-1(95%CI:0.52 to 1.00μg·kg^-1·min^-1).CONCLUSION The ED50 and ED95 of prophylactic phenylephrine which used in prevent spinal anesthesia-induced hypotension in cesarean section were 0.31 and 0.63μg·kg^-1·min^-1.To prevent effectively,0.625μg·kg^-1·min^-1 is recommended.