苯肾上腺素预注射用于剖宫产术脊麻后低血压的剂量效应

Dose effects of phenylephrine pre-injection for hypotension after spinal anesthesia in cesarean delivery

目的探讨苯肾上腺素对剖宫产术脊麻后低血压的合适预注射剂量.方法择期行剖宫产术产妇80例,ASAⅠ或Ⅱ级,随机分成4组（n=20）苯肾上腺素预注射50μg（P1组）、100μg（P2组）、150μg（P3组）和对照组（C组,无预注射）,快速输注羟乙基淀粉130/0.4氯化钠至胎儿取出前（控制总量≤500mL,于L3～4间隙鞘内注入布比卡因9mg＋吗啡0.2mg,注药后随即产妇平卧位静脉注射上述不同剂量的苯肾上腺素,胎儿取出前若发生产妇低血压,给予适当（50μg或100μg）苯肾上腺素静脉注射.结果胎儿取出前低血压发生率组间差异无统计学意义（P〉0.05）,心动过缓发生率组间差异有统计学意义（P〈0.05）;所有产妇未发生反应性高血压;随着苯肾上腺素预注射剂量增加,各组产妇胎儿取出前平均最低收缩压（SBP）增加,但差异无统计学意义（P〉0.05）,并且随着鞘内苯肾上腺素预注射剂量的增加低血压出现时间延迟且低血压出现的次数及苯肾上腺素总干预剂量逐渐减小,组间差异均有统计学意义（P〈0.05）.术中恶心呕吐发生率,新生儿Apgar评分和脐静脉血气组间差异无统计学意义（P〉0.05）.结论苯肾上腺素预注射100μg联合胶体快速输注有利于减少择期剖宫产脊麻后低血压发生次数,心动过缓发生率较低,能较好维持产妇血流动力学稳定.

Objective To investigate the appropriate pre-injection dosage of phenylephrine for hypotension after spinal anesthesia in selective cesarean delivery. Methods Eighty patients scheduled for elective cesarean section, ASAⅠor Ⅱ, were divided into 4 groups ( n=20 each):pre-injection of phenylephrine with 50 μg ( P1 group) , 100 μg ( P2 group) , 150 μg ( P3 group) group and control group ( C group, no pre-injection). Each subject received an IV rapid infusion of hydroxyethyl starch 130/0. 4 (approximately 15~20 mL/min) before delivery (target volume ≤500 ml). Intrathecal injection was performed at the L3,4 interspace with bupivacaine 9mg + morphine 0. 2mg(di-luted to 2ml with cerebrospinal fluid, injection time of 15s). The maternals were in the supine position and received the assigned doses of phenylephrine immediately after intrathecal injection. If maternal hypotension occurred before delivery, the appropriate dose phenylephrine (50 μg or 100μg) was administered. Results There were no between-group difference in the incidence of hypotension before delivery(P＞0. 05), but opposite in the incidence of bradycardia(P＜0. 05). With the increase in phenylephrine pre-administration dose the average low-est maternal systolic blood pressure(SBP) before delivery in each group increased(but no between-group difference(P＞0. 05);furthermore, the time from spinal administration to hypotension was increased, and the frequency of hypotension and the total intervention dose interference dose of phenylephrine (approximately 50~150 μg) was gradually reduced(P＜0. 05). There was no between-group difference in the inci-dence of nausea vomiting, neonatal Apgar score and umbilical vein blood gas analysis(P＞0. 05). Conclusion Pre-injection of phenyleph-rine 100 μg combined with rapid infusion of colloid facilitates the reduction of the frequency of spinal anesthesia-induced hypotension and the maintenance of hemodynamic stability for elective cesarean section.