Maternal Inspired Oxygen Concentration and Neonatal Status for Caesarean Section Under General Anaesthesia

Abstract

The relationship between maternal FIO2 and umbilical venous PO2, PCO2, pH and neonatal Apgar and TSR (time to sustained respiration) scores was studied in 35 patients undergoing Caesarean section under general anaesthesia. Patients were allocated randomly to breathe an FIO2 of either 0.5 or 0.33. Umbilical venous blood was collected at the time of delivery, and TSR and 1- and 5-min Apgar scores recorded. Mean values for umbilical venous blood were: PO2 3.9 kPa and 3.7 kPa; PCO2 6.2 kPa and 6.2 kPa; pH 7.30 and 7.31 (50% and 33% groups, respectively (P greater than 0.05]. No differences were found between groups for 1- or 5-min Apgar scores or TSR values. It is concluded that no difference in fetal outcome or acid-base status can be detected when maternal FIO2 is decreased from 0.5 to 0.33, and that the use of 33% oxygen in 66% nitrous oxide appears to be safe for neonates who have not suffered fetal distress before delivery.

Maternal oxygen administration for fetal distress

“…Four studies (Jozwik 2000;Lawes 1988;Simpson 2005;Nesterenko 2012) were excluded from the review (see table of 'Characteristics of excluded studies'). Lawes 1988 investigated the e ect of maternal oxygen concentration (50% versus 33%) on neonatal status in women who had caesarean section under general anaesthesia.…”

Maternal hemodynamic influence on uteroplacental oxygen distribution during cesarean section

“…Their values performing general anesthesia with 50% FiO 2 and sevoflurane 1 vol% were very close to the present results (umbilical vein PaO 2 4.7 kPa and umbilical artery blood PaO 2 2.9 kPa). Lawes et al [21] found a main value of neonatal umbilical vein PaO 2 of 3.9 kPa. In the present study, the main value of umbilical artery PaCO 2 was 6.55 ± 1.10 kPa in the SA group, compared with 6.16 ± 1.25 kPa in the GBA group (p > 0.05).…”