Lumbar epidural is the gold standard for labour analgesia. Low concentrations of local anaesthetic are recommended. This network meta-analysis investigated whether further reducing the concentration of local anaesthetic can improve maternal and neonatal outcomes without compromising analgesia. We conducted a systematic search of relevant databases for randomised controlled trials comparing high (>0.1%), low (>0.08% to ≤0.1%) or ultra-low (≤0.08%) concentration local anaesthetic (bupivacaine or equivalent) for labour epidural. Outcomes included mode of delivery, duration of labour and maternal/neonatal outcomes. Bayesian network meta-analysis with random-effects modelling was used to calculate odds ratios or weighted mean differences and 95% credible intervals. A total of 32 studies met inclusion criteria (3665 women). The total dose of local anaesthetic received increased as the concentration increased; ultra-low compared with low (weighted mean difference −14.96 mg, 95% credible interval [−28.38 to −1.00]) and low compared with high groups (weighted mean difference −14.99 [−28.79 to −2.04]), though there was no difference in the number of rescue top-ups administered between the groups. Compared with high concentration, ultra-low concentration local anaesthetic was associated with increased likelihood of spontaneous vaginal delivery (OR 1.46 [1.18 to 1.86]), reduced motor block (Bromage score >0; OR 0.32 [0.18 to 0.54]) and reduced duration of second stage of labour (weighted mean difference −13.02 min [−21.54 to −4.77]). Compared with low, ultra-low concentration local anaesthetic had similar estimates for duration of second stage of labour (weighted mean difference −1.92 min [−14.35 to 10.20]); spontaneous vaginal delivery (OR 1.07 [0.75 to 1.56]; assisted vaginal delivery (OR 1.35 [0.75 to 2.26]); caesarean section (OR 0.76 [0.49 to 1.22]); pain (scale 1–100, weighted mean difference −5.44 [−16.75 to 5.93]); and maternal satisfaction. Although a lower risk of an Apgar score < 7 at 1 min (OR 0.43 [0.15 to 0.79]) was reported for ultra-low compared with low concentration, this was not sustained at 5 min (OR 0.12 [0.00 to 2.10]). Ultra-low concentration local anaesthetic for labour epidural achieves similar or better maternal and neonatal outcomes as low and high concentration, but with reduced local anaesthetic consumption.

中文翻译：

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超低浓度、低浓度和高浓度局麻药在分娩硬膜外镇痛中的比较：系统评价和网络荟萃分析

腰椎硬膜外麻醉是分娩镇痛的金标准。建议使用低浓度的局部麻醉剂。这项网络荟萃分析调查了进一步降低局麻药浓度是否可以在不影响镇痛作用的情况下改善孕产妇和新生儿结局。我们对相关数据库进行了系统搜索，用于比较高浓度（>0.1%）、低浓度（>0.08% 至 ≤0.1%）或超低浓度（≤0.08%）局部麻醉剂（布比卡因或等效物）用于硬膜外分娩的随机对照试验. 结果包括分娩方式、分娩持续时间和孕产妇/新生儿结局。使用随机效应建模的贝叶斯网络荟萃分析来计算优势比或加权平均差和 95% 可信区间。共有 32 项研究符合纳入标准（3665 名女性）。局麻药总剂量随浓度增加而增加；超低与低组相比（加权平均差 -14.96 mg，95% 可信区间 [-28.38 至 -1.00]）和低组与高组相比（加权平均差 -14.99 [-28.79 至 -2.04]），尽管有两组之间进行的救援充值次数没有差异。与高浓度相比，超低浓度局麻药与自然阴道分娩的可能性增加（OR 1.46 [1.18 至 1.86]）、运动阻滞减少（Bromage 评分 >0；OR 0.32 [0.18 至 0.54]）和持续时间缩短相关第二产程（加权平均差 -13.02 分钟 [-21.54 至 -4.77]）。相比低，超低浓度局麻药对第二产程持续时间的估计相似（加权平均差 -1.92 分钟 [-14.35 至 10.20]）；自发阴道分娩（OR 1.07 [0.75 至 1.56]；辅助阴道分娩（OR 1.35 [0.75 至 2.26]）；剖宫产（OR 0.76 [0.49 至 1.22]）；疼痛（量表 1-100，加权平均差 -5.44 [ -16.75 至 5.93]）；和产妇满意度。尽管据报道，与低浓度相比，超低的 Apgar 评分 < 7 的风险较低（OR 0.43 [0.15 至 0.79]），但在 5 min (OR 0.12 [0.00 to 2.10]). 用于硬膜外分娩的超低浓度局麻药在低浓度和高浓度下达到相似或更好的母婴结局，但局麻药用量减少。和母亲的满意度。尽管据报道，与低浓度相比，超低浓度在 1 分钟时 Apgar 评分 < 7 的风险较低（OR 0.43 [0.15 至 0.79]），但这在 5 分钟时并未持续（OR 0.12 [0.00 至 2.10]）。用于分娩硬膜外的超低浓度局麻药可实现与低浓度和高浓度相似或更好的母婴结局，但局麻药用量减少。和母亲的满意度。尽管据报道，与低浓度相比，超低浓度在 1 分钟时 Apgar 评分 < 7 的风险较低（OR 0.43 [0.15 至 0.79]），但这在 5 分钟时并未持续（OR 0.12 [0.00 至 2.10]）。用于分娩硬膜外的超低浓度局麻药可实现与低浓度和高浓度相似或更好的母婴结局，但局麻药用量减少。