Tyagi Asha, Mathur Monika, Salhotra Rashmi, Rautela Rajesh S
Department of Anaesthesiology and Critical Care, University College of Medical Sciences and GTB Hospital, Delhi, India.
J Anaesthesiol Clin Pharmacol. 2024 Jul-Sep;40(3):491-497. doi: 10.4103/joacp.joacp_189_23. Epub 2024 Mar 28.
Vasopressor usage can affect the rostral spread of intrathecal drug and, hence, its requirement during cesarean delivery. Although a decreased spread is evidenced with phenylephrine, there is no data for norepinephrine usage. The present study aimed to evaluate the minimum effective dose of intrathecal hyperbaric bupivacaine for cesarean section with and without prophylactic norepinephrine infusion.
Patients scheduled for elective cesarean section under combined spinal-epidural block were randomized to receive intravenous infusion of norepinephrine (0.05 μg/kg/min) or normal saline (placebo), initiated immediately after intrathecal injection. Postspinal hypotension in either group (systolic arterial pressure ≤0.8 baseline) was treated with norepinephrine 4 μg rescue. Dose of intrathecal hyperbaric bupivacaine (0.5%) was decided for individual patients using up-and-down sequential allocation method. Primary outcome measure was the minimum effective dose of intrathecal hyperbaric bupivacaine (0.5%) defined as ED50, while secondary observations included spinal block characteristics and neonatal outcomes.
Demographic parameters were statistically similar between both groups ( > 0.05). ED50 of intrathecal hyperbaric bupivacaine was 7.8 mg (95% confidence interval [CI]: 6.7-8.8) and 7.4 mg (95% CI: 6.1-8.7) for normal saline and norepinephrine group respectively ( = 0.810). Block characteristics were similar between both groups as was neonatal APGAR score, but umbilical artery base excess was greater for norepinephrine versus normal saline group (-4.4 ± 3.6 vs. -6.5 ± 2.4, = 0.038).
Use of prophylactic norepinephrine (0.05 μg/kg/min) during cesarean delivery does not require adjustment of intrathecal hyperbaric bupivacaine.
血管升压药的使用会影响鞘内药物的头端扩散，从而影响剖宫产时药物的用量。虽然去氧肾上腺素可减少药物扩散，但尚无关于去甲肾上腺素使用情况的数据。本研究旨在评估在剖宫产中使用和不使用预防性去甲肾上腺素输注时，鞘内高压布比卡因的最低有效剂量。
计划在腰麻-硬膜外联合阻滞下行择期剖宫产的患者，随机分为接受静脉输注去甲肾上腺素（0.05μg/kg/min）或生理盐水（安慰剂）组，在鞘内注射后立即开始输注。两组中任何一组出现脊髓麻醉后低血压（收缩压≤基线值的0.8）时，均用4μg去甲肾上腺素进行抢救。鞘内高压布比卡因（0.5%）的剂量采用序贯上下法为个体患者确定。主要观察指标是鞘内高压布比卡因（0.5%）的最低有效剂量，定义为半数有效量（ED50），次要观察指标包括脊髓阻滞特征和新生儿结局。
两组的人口统计学参数在统计学上相似（P>0.05）。生理盐水组和去甲肾上腺素组鞘内高压布比卡因的ED50分别为7.8mg（95%置信区间[CI]：6.7 - 8.8）和7.4mg（95%CI：6.1 - 8.7）（P = 0.810）。两组的阻滞特征相似，新生儿阿氏评分也相似，但去甲肾上腺素组的脐动脉碱剩余高于生理盐水组（-4.4±3.6 vs. -6.5±2.4，P = 0.038）。
剖宫产时使用预防性去甲肾上腺素（0.05μg/kg/min）不需要调整鞘内高压布比卡因的剂量。
