右美托咪定用于剖宫产术中镇静时产妇意识消失的半数有效量

Median effective dose of dexmedetomidine for maternal loss of consciousness during intraoperative sedation for cesarean section

目的探讨腰硬联合麻醉下右美托咪定用于剖宫产产妇术中镇静时意识消失的半数有效量(ED_(50))。方法选择29例腰硬联合麻醉下行剖宫产术的产妇,年龄18~40岁,孕35~42周,美国麻醉医师协会(ASA)分级Ⅰ、Ⅱ级。胎儿、胎盘娩出后,给予产妇静脉泵注右美托咪定行术中镇静,给药剂量使用二阶段改良序贯法决定,初始负荷剂量1.4μg/kg,15 min恒速泵注完毕,第26分钟使用警觉/镇静(OAA/S)评分评估产妇的镇静深度,记录右美托咪定给药前(T_(0))、给药后5 min(T_(1))、给药后10 min(T_(2))、给药后15 min(T_(3))、给药后20 min(T_(4))、给药后25 min(T_(5))和给药后30 min(T_(6))的心率和平均动脉压(MAP),同时记录产妇的不良反应。通过计算改良序贯法第二阶段4个转折点中点的平均值得到右美托咪定诱导产妇意识消失(OAA/S评分≤2分)的ED_(50),使用Probit回归分析计算出其95%有效量(ED_(95))。结果右美托咪定诱导产妇意识消失的ED_(50)为1.94μg/kg,ED_(95)为2.11μg/kg。与T_(0)时比较,所有产妇T_(1)~T_(6)时心率均降低(均P<0.05),MAP均升高(均P<0.05)。术中3例产妇出现心动过缓,3例产妇在给药前诉腹痛,1例产妇伴有恶心、胸闷,给药后症状均缓解或消失,无一例产妇出现寒战。结论右美托咪定用于剖宫产产妇术中镇静时诱导产妇意识消失所需剂量较大,血流动力学波动明显,临床应用需严密观察。

Objective To investigate the median effective dose(ED_(50))of dexmedetomidine for maternal loss of consciousness during intraoperative sedation of cesarean delivery under combined spinal and epidural anesthesia.Methods A total of 29 pregnant women,aged 18-40 years old,at 35-42 weeks of gestation,with American Society of Anesthesiologists(ASA)gradeⅠorⅡ,who underwent cesarean section under combined spinal and epidural anesthesia were selected.After delivery of the fetus and placenta,the women were intravenously injected by pump with dexmedetomidine for intraoperative sedation.The dose was determined using the two-stage modified sequential method,with an initial loading dose of 1.4μg/kg,and the pumping was completed at a constant rate for 15 min.The depth of maternal sedation was assessed by the Observer's Assessment Alert/Sedation(OAA/S)score at the 26th min.The heart rate and mean arterial pressure(MAP)were recorded before administration(T_(0)),5 min after administration(T_(1)),10 min after administration(T_(2)),15 min after administration(T_(3)),20 min after administration(T_(4)),25 min after administration(T_(5)),and 30 min after administration(T_(6)).Maternal adverse reactions were also recorded.The ED_(50) of dexmedetomidine-induced maternal loss of consciousness(OAA/S score≤2)was obtained by calculating the mean of the midpoints of the four turning points in the second stage of the modified sequential method,and the ED_(95) was calculated by probit regression analysis.Results The ED_(50) of dexmedetomidine-induced maternal loss of consciousness was 1.94μg/kg,and the ED_(95) was 2.11μg/kg.Compared with those at T_(0),all women showed decreases in heart rate(all P<0.05)and increases in MAP(all P<0.05)from T_(1) to T_(6).There were three cases of bradycardia,three cases of abdominal pain before administration,one case of nausea and chest tightness,which disappeared or were relieved after the administration of dexmedetomidine.No women reported chills or discomfort.Conclusions The dose of dexmedetomidine is high,when the agent is used for intraoperative sedation of maternal loss of consciousness for cesarean section,with obvious hemodynamic fluctuation.Therefore,its clinical application needs to be closely observed.