Inhalation of high concentlation of oxygen during Cesarean section: its effect on umbilical vessel blood gas

Abstract

We give high concentration of oxygen during Cesarean section in the hope of giving the fetus more oxygen.
In order to assess the validity of the practice, we measured the umbilical arterial and venous blood O₂ tention.
The study was performed in 32 healthy pregnant women undergoing Cesarean section with spinal anesthesia by making them inhale 21%, 50%, or 90% O₂. The maternal PaO₂ (MAPO₂) was compared with the umbilical artery PO₂ (UAPO₂) and umbilical vein PO₂ (UVPO₂) obtained immediately after delivery.
The results showed that UVPO₂ change little with MAPO₂ up to 250mmHg, while UVPO₂ increased linearly with MAPO₂ between 250 and 400mmHg, but some cases showed declining UVPO₂ with MAPO₂ above 400mmHg.