Authors: Lei G et al.
Source: International Journal of Obstetric Anesthesia. Published May 17, 2026.
Summary:
This randomized clinical trial studied whether high-flow nasal oxygen improves fetal acid-base status during elective cesarean delivery under combined spinal-epidural anesthesia.
The concern behind the study is that oxygen is commonly given to mothers during cesarean delivery, but the fetal benefits and possible risks are still debated. High-flow nasal oxygen may improve maternal oxygenation, but its effect on the baby’s acid-base status had not been well studied.
The trial included patients undergoing elective cesarean delivery at 37 weeks or later. Patients were randomly assigned to either high-flow nasal oxygen at 40 L/min with 100% oxygen or room air at 2 L/min. Oxygen or room air was started after epidural catheter placement and continued until delivery.
The primary outcome was umbilical artery lactate. The high-flow nasal oxygen group had significantly lower umbilical artery lactate levels compared with the room air group. The high-flow group also had a slightly higher umbilical artery pH, higher umbilical artery oxygen partial pressure, and lower carbon dioxide partial pressure.
Importantly, there were no significant differences in Apgar scores, oxidative stress markers, or other short-term neonatal outcomes. This suggests that short-term high-flow oxygen before delivery improved fetal acid-base measurements without showing evidence of increased newborn oxidative stress.
Clinical importance:
This study suggests that high-flow nasal oxygen during elective cesarean delivery may improve fetal oxygenation and acid-base status. The findings are reassuring because the intervention did not appear to worsen oxidative stress markers or short-term neonatal outcomes.
For anesthesia providers, this may be relevant when managing elective cesarean deliveries under neuraxial anesthesia, especially when trying to optimize fetal oxygenation. However, this was a low-risk elective cesarean population, so the findings should not automatically be applied to emergency cesarean deliveries or high-risk pregnancies without further study.
Bottom line:
High-flow nasal oxygen during elective cesarean delivery under combined spinal-epidural anesthesia improved fetal acid-base markers and oxygenation compared with room air, without increasing newborn oxidative stress markers. The results support its short-term safety in low-risk elective cesarean deliveries and justify further study in higher-risk maternal and fetal populations.
Thank you to the International Journal of Obstetric Anesthesia for publishing this important study on high-flow nasal oxygen during elective cesarean delivery and its effects on fetal acid-base status.