鞘内注射硫酸镁对腰麻剖宫产时布比卡因半数有效剂量的影响

Effects of adding intrathecal magnesium sulphate on median effective dose of bupivacaine for spinal anesthesia in patients undergoing cesarean section

目的 探讨鞘内添加硫酸镁对布比卡因腰麻剖宫产半数有效剂量（ED50）的影响。方法 采用前瞻性、随机对照的方法进行试验。选择60例择期行剖宫产的初产妇,ASA分级Ⅰ级或Ⅱ级,随机分为两组,每组30例,均于L3～4行腰硬联合穿刺。硫酸镁组腰麻药物为硫酸镁50 mg＋舒芬太尼5μg＋布比卡因,对照组为舒芬太尼5μg＋布比卡因。两组布比卡因的起始剂量均为8 mg,剂量梯度为1 mg,根据麻醉是否有效确定下一例患者剂量。采用Dixon-Massey序贯法计算布比卡因的ED50,并观察感觉及运动阻滞的起效时间和维持时间,镇痛持续时间以及术中并发症、术后镇痛药的使用情况等。结果 硫酸镁组布比卡因ED50为4.9 mg（95%CI：4.7～5.1 mg）,对照组为4.7 mg（95%CI：4.5～4.9 mg）,组间比较无显著差异（P〉0.05）。硫酸镁组患者感觉及运动阻滞的起效时间和维持时间、镇痛持续时间与对照组比较均延长,术后24 h芬太尼的使用量较对照组减少[（343±41）μg vs.（550±48）μg],差异均有非常显著意义（P〈0.01）。两组均无低氧血症发生,低血压、恶心和呕吐、瘙痒发生率均无显著差异（P〉0.05）。结论鞘内添加硫酸镁50 mg不能降低布比卡因腰麻剖宫产的剂量,但是可以延长麻醉镇痛持续时间,减少患者对术后镇痛药的需求量且不增加不良反应。

AIM To observe the effects of adding intrathecal magnesium sulfate （MgSO4） on the median effective dose （EDso） of bupivacaine for spinal anesthesia in patients undergoing caesarean section. METHODS Sixty women, with ASA statues Ⅰ or Ⅱ , undergoing caesarean section were included in a prospective, placebo- controlled trial. The combined spinal epidural anesthesia technique was finished at L3-4 interspace. The patients were randomly assigned to receive spinal anesthesia with bupivacaine and sufentanil 5 μg with either sodium chloride injection 0.2 mL （group C） or 25% magnesium sulfate injection （50 mg） 0.2 mL （group M）. The dose of intrathecal hyperbaric bupivacaine was decided by using the up- and- down method with an initial dose of 8 mg and dosing change of 1 mg. The ED50 was calculated according to Dixon- Massey up-and-down method. Onset and duration of sensory and motor block, duration of spinal analgesia and postoperative analgesia requirements were observed. RESULTS The EDs0 of bupivacaine in the group C and group M was 4.7 mg （95%CI： 4.5-4.9 mg） and 4.9 mg （95%CI： 4.7-5.1 mg） respectively （P 〉 0.05）. Compared with those in the group C, the duration of spinal analgesia and the onset and duration of sensory and motor block were significantly longer in the magnesium group （P 〈 0.01）. Fentanyl requirement for 24 h following surgery was significantly lower in the group M than that in the group C （（343 ± 41） μg vs. （550 ± 48） μg, P 〈 0.01）. No hyoxemia occurred in both groups and the incidence rate of hypotension, nausea, vomiting and pruritus were similar between two groups （P 〉 0.05）. CONCLUSION MgS04 50 mg adding to spinal bupivacaine-sufentanil can＇t reduce intrathecal dose requirement of bupivacaine, but it can increase duration of analgesia and decrease the consumption of postoperative anesthetics without additional adverse reactions.