Supplemental oxygen in elective cesarean section under spinal anesthesia: Handle the sword with care.

Background And Objectives: We aimed to investigate the effect of 21% and 40% oxygen supplementation on maternal and neonatal oxidative stress in elective cesarean section (CS) under spinal anesthesia.

Methods: Eighty term parturients undergoing elective CS under spinal anesthesia were enrolled in the study. We allocated patients randomly to breathe 21% (air group) or 40% (oxygen group) oxygen from the time of skin incision until the end of the operation. We collected maternal pre- and post-operative and umbilical artery (UA) blood samples. Total antioxidant capacity (TAC), total oxidant status (TOS) and the oxidative stress index (OSI) were measured.

Results: Age, weight, height, parity, gestation week, spinal-skin incision time, skin incision-delivery time, delivery time, operation time, 1(st) and 5(th) minutes Apgar scores, and birth weight were similar between the groups (p > 0.05 for all comparisons). There were no differences in preoperative TAC, TOS, or OSI levels between the groups (p > 0.05 for all comparisons). Postoperative maternal TAC, TOS and OSI levels significantly increased in the oxygen group (p = 0.047, < 0.001 and 0.038, respectively); umbilical artery TAC levels significantly increased in the oxygen group (p = 0.003); and umbilical artery TOS and OSI levels significantly increased in the air group (p = 0.02 and < 0.001, respectively).

Conclusions: The difference in impact on maternal and fetal oxidative stress of supplemental 40% compared to 21% oxygen mandates further large-scale studies that investigate the role of oxygen supplementation during elective CS under spinal anesthesia.