Efficacy of low-dose bupivacaine in spinal anaesthesia for Caesarean delivery: systematic review and meta-analysis

British Journal of Anesthesia, 07/18/2011

Arzola C et al.– The meta–analysis demonstrates that low–dose bupivacaine in spinal anaesthesia compromises anaesthetic efficacy (risk of analgesic supplementation: high grade of evidence), despite the benefit of lower maternal side–effects (hypotension, nausea/vomiting: moderate grade of evidence).

Methods

  • Spinal anaesthesia is the preferred anaesthetic technique for elective Caesarean deliveries.
  • Hypotension is the most common side-effect and has both maternal and neonatal consequences.
  • Different strategies have been attempted to prevent spinal-induced hypotension, including the use of low-dose bupivacaine.
  • The authors conducted a systematic search for randomized controlled trials comparing the efficacy of spinal bupivacaine in low dose (LD ≤8 mg) with conventional dose (CD >8 mg) for elective Caesarean delivery.
  • Thirty-five trials were identified for eligibility assessment, 15 were selected for data extraction, and 12 were finally included in the meta-analysis.
  • They investigated sources of heterogeneity, subgroup analysis, and meta-regression for confounding variables (baricity, intrathecal opioids, lateral vs sitting position, uterine exteriorization, and study population).
  • Sensitivity analysis was performed to test the robustness of the results.

Results

  • In the LD group, the need for analgesic supplementation during surgery was significantly higher [risk ratio (RR)=3.76, 95% confidence interval (95% CI)=2.38–5.92] and the number needed to treat for an additional harmful outcome (NNTH) was 4 (95% CI=2–7).
  • Furthermore, the LD group exhibited a lower risk of hypotension (RR=0.78, 95% CI=0.65–0.93) and nausea/vomiting (RR=0.71, 95% CI=0.55–0.93).
  • Conversion to general anaesthesia occurred only in the LD group (two events).
  • Neonatal outcomes (Apgar score, acid–base status) and clinical quality variables (patient satisfaction, surgical conditions) showed non-significant differences between LD and CD.

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