Peska Emil, Balki Mrinalini, Pfeifer Wesla, Maxwell Cynthia, Ye Xiang Y, Downey Kristi, Carvalho Jose C A
From the Departments of Anesthesiology and Pain Medicine.
Obstetrics and Gynecology, Mount Sinai Hospital, University of Toronto, Toronto, ON, Canada.
Anesth Analg. 2024 Apr 1;138(4):814-820. doi: 10.1213/ANE.0000000000006309. Epub 2022 Dec 8.
Multiple pregnancy is associated with higher risk of uterine atony, postpartum hemorrhage (PPH), blood transfusion, hysterectomy, and death. The optimal dose of oxytocin at cesarean delivery in people with twin pregnancy is unknown. We sought to determine the effective bolus dose of oxytocin required to initiate adequate uterine tone in 90% of people (ED90) with twin pregnancy undergoing elective cesarean delivery. Our hypothesis was that the dose of oxytocin would be higher than 0.5 international units (IU) but lower than 5 IU.
A double-blind dose-finding study using the biased coin up-down method was undertaken in people with twin pregnancy ≥36 weeks gestational age undergoing elective cesarean delivery under neuraxial anesthesia. Those with additional risk factors for PPH, apart from twin pregnancy, were excluded. Oxytocin was administered as an intravenous bolus over 1 minute on delivery of the second fetus. The first patient received 0.5 IU, and subsequent oxytocin doses were administered according to a sequential allocation scheme. The actual doses administered were 0.5, 1, 2, 3, 4, and 5 IU of oxytocin. The primary outcome was the response defined as the satisfactory uterine tone at 2 minutes after completion of administration of the oxytocin bolus, as assessed by the operating obstetrician. Secondary outcomes included need for rescue uterotonic drugs, adverse effects, and estimated blood loss. The ED90 was estimated using the Dixon-Mood and the isotonic regression methods.
Thirty patients were included in study. The estimated ED90 of oxytocin was 4.38 IU (95% confidence interval [CI], 3.68-4.86 IU) and 3.41 IU (95% CI, 2.83-3.98 IU) by the isotonic regression and Dixon-Mood methods, respectively. Seven patients had inadequate tone at the 2-minute evaluation point and required rescue uterotonic drugs. The median (interquartile range [IQR]) estimated blood loss was 1031 mL (732-1462 mL) calculated by the change in 24-hour hematocrit. Incidence of hypotension after oxytocin administration was 27%, nausea 30%, and vomiting 17%.
Our results demonstrated that people with twin pregnancy require a much higher dose of oxytocin than those with singleton pregnancies. We recommended people with twin pregnancies should receive an initial 5 IU bolus over at least 1 minute when undergoing elective cesarean delivery under neuraxial anesthesia.
多胎妊娠与子宫收缩乏力、产后出血（PPH）、输血、子宫切除术及死亡的风险较高相关。双胎妊娠患者剖宫产时缩宫素的最佳剂量尚不清楚。我们试图确定在接受择期剖宫产的双胎妊娠患者中，使90%的患者启动足够子宫张力所需的缩宫素有效推注剂量（ED90）。我们的假设是缩宫素剂量高于0.5国际单位（IU）但低于5 IU。
采用偏倚硬币上下法进行双盲剂量探索研究，纳入孕周≥36周、在神经轴索麻醉下接受择期剖宫产的双胎妊娠患者。排除除双胎妊娠外有PPH其他危险因素的患者。在娩出第二个胎儿时，缩宫素经静脉在1分钟内推注给药。首例患者接受0.5 IU，随后的缩宫素剂量根据序贯分配方案给药。实际给药剂量为0.5、1、2、3、4和5 IU缩宫素。主要结局为在缩宫素推注给药完成后2分钟时，由产科手术医生评估的定义为满意子宫张力的反应。次要结局包括是否需要抢救宫缩剂、不良反应及估计失血量。使用狄克逊-穆德法和等渗回归法估计ED90。
30例患者纳入研究。采用等渗回归法和狄克逊-穆德法估计的缩宫素ED90分别为4.38 IU（95%置信区间[CI]，3.68 - 4.86 IU）和3.41 IU（95%CI，2.83 - 3.98 IU）。7例患者在2分钟评估点子宫张力不足，需要抢救宫缩剂。根据24小时血细胞比容变化计算，估计失血量中位数（四分位间距[IQR]）为1031 mL（732 - 1462 mL）。缩宫素给药后低血压发生率为27%，恶心为30%，呕吐为17%。
我们的结果表明，双胎妊娠患者所需的缩宫素剂量比单胎妊娠患者高得多。我们建议双胎妊娠患者在神经轴索麻醉下接受择期剖宫产时，应至少在1分钟内初始推注5 IU缩宫素。
