[Is oxygen therapy truly useful and necessary during elective cesarean section under spinal anesthesia?].
To analyze maternal and fetal well-being with and without the application of oxygen therapy.
                Randomized trial of full-term parturients who had received prenatal care during pregnancy. The women were healthy and classified as ASA 1. They were scheduled for delivery by cesarean section under spinal anesthesia and randomized to 2 groups to breathe room air or air providing an inspired oxygen fraction of 40% through a face mask. We assessed the well-being of the neonate immediately after birth with the Apgar test and by measuring umbilical cord blood gases.
                One hundred thirty women were enrolled. Both groups were similar, with no differences in demographic or hemodynamic variables, time from uterine incision to fetal extraction, neonatal birth weight, presence of umbilical cord abnormalities, type of resuscitation required by the neonate, or Apgar score in the first or fifth minute. Oxygen saturation in maternal blood by pulse oximetry was higher after 10 minutes in the group of women who received supplemental oxygen through face masks. We also observed significant differences in umbilical cord arterial blood between the room air and supplemental oxygen groups, respectively, as follows: PaCO2, 51.14 mm Hg vs 54.33 mm Hg (P=.016); bicarbonate, 22.19 mEq L(-1) vs 23.23 mEq L(-1) (P=.012); lactate, 1.85 mmol L(-1) vs 1.64 mmol L(-1) (P=.038). The PO2 in venous blood also differed significantly: 25.53 mm Hg vs 28.13 mm Hg, respectively (P=033).
                Breathing supplemental oxygen or not during elective cesarean delivery of healthy parturients under spinal anesthesia does not have a significant effect on neonatal well-being.
Implications for practice

There is not enough evidence to support the use of prophylactic oxygen therapy for women in labour, nor to evaluate its effectiveness for fetal distress.


Implications for research

In view of the widespread use of oxygen administration during labour and the possibility that it may be ineffective or harmful, there is an urgent need for randomized trials to assess its effects.