Effect of supplementing oxygen with positive end expiratory pressure during elective caesarean section under spinal anaesthesia on foetus

Background: It is known fact that pre-oxygenation with positive end-expiratory pressure (PEEP) improves the Partial pressure of oxygen (PO ₂). In this regard not many studies have been done in pregnant women to know its effect on foetus. In this randomised double blind controlled study, we analysed effect of pre-oxygenation with PEEP during caesarean section on foetal umbilical venous PO₂. Patients & Methods: 40 term pregnant women, ASA I or II, undergoing elective Caesarean section under spinal anaesthesia were randomly divided into PEEP and Non-PEEP groups of 20 each. PEEP group received oxygen flow of 6 L/minute with PEEP of 5 cmH2O using a modified Mapleson A circuit with fixed unidirectional PEEP valve at the expiratory port during pre-oxygenation and Non PEEP group received same fresh gas flow of oxygen using same breathing circuit without PEEP. Maternal arterial blood samples were collected before applying PEEP and at the end of 5 minutes of facemask application for oxygen analysis. Immediately after baby was delivered umbilical venous samples were taken for blood gas analysis. Results: Both groups were comparable in terms of maternal baseline oxygen saturation (Spo2) and base line Po2. After 5 minutes PO₂ was higher in PEEP Group than non PEEP group (491.65 + 49.96 vs. 452.08 + 77.61). Umbilical venous Po2 in PEEP group was higher than non PEEP group (34.22 + 6.50 vs. 28.29 + 6.10 mm of Hg). Conclusion: Application of PEEP during pre-oxygenation for spinal anaesthesia can increase foetal umbilical venous PO₂.