Anaesthesia for Caesarean section and neonatal acid-base status: a meta-analysis.
Spinal anaesthesia is generally preferred for Caesarean section. Its superiority for the baby is often assumed. Umbilical artery acid-base status provides a valid index of fetal welfare. Twenty-seven studies reporting neonatal acid-base data with different types of anaesthesia were used to compare umbilical artery or vein pH and base deficit, using random-effect meta-analysis. Cord pH was significantly lower with spinal than with both general (difference: -0.015; 95% CI -0.029 to -0.001; 13 studies, 1272 subjects) and epidural anaesthesia (difference -0.013; 95% CI -0.024 to -0.002; 11 studies, 828 subjects). Larger doses of ephedrine contributed to the latter effect (p = 0.023). Sixteen studies reported a base deficit, which was significantly higher for spinal than for general (difference 1.109; 95% CI 0.434-1.784 mEq.l(-1); seven studies, 695 subject) and epidural anaesthesia (difference 0.910; 95% CI 0.222-1.598 mEq.l(-1); seven studies, 497 subjects). Spinal anaesthesia cannot be considered safer than epidural or general anaesthesia for the fetus.
Reynolds
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Department of Anaesthesia, St Thomas' Hospital, London SE1 7EH, UK. felicity.reynolds@btinternet.com
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D000136:Acid-Base Equilibrium; D000138:Acidosis / Q000209:etiology*; D000767:Anesthesia, Epidural; D000768:Anesthesia, General; D000773:Anesthesia, Obstetrical / Q000009:adverse effects* / Q000379:methods; D000775:Anesthesia, Spinal / Q000009:adverse effects*; D002585:Cesarean Section; D005260:Female; D005315:Fetal Diseases / Q000209:etiology*; D006801:Humans; D008431:Maternal-Fetal Exchange; D011247:Pregnancy