292: Does intrapartum maternal oxygen supplementation improve category II fetal heart tracings?

Abstract

Maternal oxygen (O2) administration for Category II electronic fetal monitoring (EFM) is a widely used intrauterine resuscitation technique, despite paucity of evidence on its ability to improve EFM patterns. We investigated the effect of intrapartum O2 administration on Category II EFM patterns. This is a secondary analysis of a randomized trial conducted from 2016-2017, in which patients ≥ 37 weeks in active labor with Category II EFM were assigned to 10L/min O2 by facemask or room air (RA) until delivery. Trained obstetric research nurses, blinded to allocation, extracted EFM data. The primary outcome was resolution of recurrent decelerations (lates and/or variables) within 60 minutes of randomization. Secondary outcomes were presence of recurrent variables, recurrent lates, tachycardia or minimal variability. Outcomes were compared between RA and O2 groups using univariable statistics. Time-to-event analysis was used to compare time to resolution of recurrent decelerations between groups. Paired analysis was used to compare pre- and post- randomization outcomes within each group. All 114 randomized patients (57 RA, 57 O2) were included in this analysis. There was no difference in resolution of recurrent decelerations within 60 minutes between O2 and RA groups (O2 75.4% vs RA 86.0%, p=0.15). Time to resolution of recurrent decelerations was similar between RA and O2 groups (Figure). RA and O2 groups had similar rates of recurrent variables, recurrent lates, tachycardia, and minimal variability 30 and 60 minutes after randomization (Table). There was no difference in EFM features pre- and post- randomization in both groups. Use of additional intrauterine resuscitation measures was similar in the two groups. Intrapartum maternal O2 administration for Category II EFM did not resolve or hasten the resolution of recurrent decelerations. These results suggest that O2 administration has no impact on Category II EFM patterns.View Large Image Figure ViewerDownload Hi-res image Download (PPT)