Intraoperative fetal oxygen saturation during Caesarean section: general anaesthesia using sevoflurane with either 100% oxygen or 50% nitrous oxide in oxygen.

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.