Background and objective: The study was designed to evaluate whether the administration of sevoflurane in 100% oxygen for anaesthesia during Caesarean section would improve fetal and neonatal oxygenation compared with the administration of sevoflurane with 50% nitrous oxide in oxygen.

Methods: The randomized, single-blind controlled study examined 24 mothers, ASA I-II, at term undergoing Caesarean section who were allocated to receive sevoflurane in either 100% oxygen (n = 13) or 50% nitrous oxide in oxygen (n = 11). General anaesthesia was induced in both groups with thiopental 4–5 mg kg−1 followed by succinylcholine 1.5 mg kg−1 to facilitate tracheal intubation. Parturients received sevoflurane given either in 100% O2 or in a 50 : 50 nitrous oxide and oxygen mixture, using 0.5-1.0% progressive incremental dosing up to 1.5–2.0 MAC. Non-invasive fetal oxygen saturation was measured between induction to delivery, and umbilical artery and vein PaO2 were evaluated at birth.

Results: Intraoperative fetal oxygen saturation increased in all patients after maternal 100% oxygen administration (P < 0.01). Maternal hyperoxygenation significantly increased the umbilical vein and umbilical artery PaO2 and the umbilical artery SaO2 at birth (P < 0.0001).

Conclusions: Maternal hyperoxygenation significantly improves fetal as well as neonatal oxygenation.