Effect of maternal oxygen inhalation on foetal free radical activity: a prospective, randomized trial.

BACKGROUND

Maternal inhalation of 35-40% oxygen concentration has no significant effect on foetal partial pressure of oxygen, and 60-100% produced maternal and foetal hyperoxia with increased free radical activity. The benefit of 50% maternal oxygen inhalation on foetal oxygenation, oxidant stress and total antioxidant status (TAS) during Caesarean section (CS) has not been simultaneously evaluated.

METHODS

In this prospective, randomized, controlled trial 120 ASA physical status I-II, term pregnant women were recruited to elective CS (n = 60) and emergency CS (n = 60) and received either 50% oxygen or air inhalation following subarachnoid block (SAB). Patients and investigators were blinded to the inhaled oxygen concentration. The primary outcome of the study was foetal umbilical artery (UA) malondialdehyde (MDA) at birth.

RESULTS

In both elective and emergency CS, there was no difference in foetal oxidative stress and TAS in spite of increase in maternal PaO2. In elective CS, maternal MDA was higher at delivery in mothers breathing 50% oxygen as compared to their own baseline values (P = 0.04). In emergency CS, maternal TAS at 10 min was lower in mothers inhaling 50% oxygen as compared to air (P = 0.01). The average duration of maternal oxygen supplementation was ~10.3 min in elective and ~7.4 min in emergency CS. Neonatal outcome, episodes of maternal hypotension and oxygen desaturation were similar in both the groups.

CONCLUSION

Brief duration of 50% oxygen maternal inhalation during elective or emergency CS did not significantly affect foetal MDA and TAS under SAB.