Hyperoxygenation does not improve neonatal Apgar score among women with pathologic fetal heart rate (FHR) tracing, according to a recent study published in the American Journal of Obstetrics & Gynecology.
Takeaways
- Maternal hyperoxygenation, despite being a considered intervention for managing suspicious fetal heart rate tracings, did not result in improved neonatal Apgar scores in cases of pathologic tracings.
- This conclusion was drawn from a clinical trial that compared the outcomes of women receiving high fractional inspiration of oxygen (FiO2 of 80%) with those receiving standard care (FiO2 of 40%).
- While there were no significant differences in 5-minute Apgar scores between the intervention and usual care groups, the prevalence of 1-minute Apgar scores of 7 or less was lower in the intervention group.
- The study included 148 women with common comorbidities including thyroid disorders and diabetes mellitus, providing a comprehensive sample for analysis.
- Despite the lack of improvement in neonatal outcomes, no cases of perinatal death were reported, indicating the overall safety of both approaches.
An association has been reported between perinatal asphyxia and neonatal mortality, as well as increased risks of neurologic impairments. Fetal hypoxia and acidemia are often identified using fetal heart rate (FHR) tracing classifications from the International Federation of Gynecology and Obstetrics (FIGO) and other organizations.
Pathologic FHR tracing may be used because of impaired fetal oxygen delivery, which can lead to fetal growth restriction, clinical chorioamnionitis, preterm birth, postterm birth, and other adverse outcomes. Intrauterine resuscitation measures such as intravenous fluid bolus, amnioinfusion, maternal repositioning, and tocolytics are necessary to reduce risks.
Data has indicated efficacy from maternal hyperoxygenation in managing suspicious FHR tracings. However, a change in neonatal outcomes following hyperoxygenation use has not been established.
To evaluate the impact of maternal hyperoxygenation on neonatal outcomes using 5-minute Apgar score, investigators conducted a 2-arm parallel, outcome assessor-blinded clinical trial. Participants included women aged 18 years or older with a singleton pregnancy at term and in the active phase of labor with pathologic cardiotocography.
Exclusion criteria included fetal growth restriction, cord prolapse, multifetal pregnancy, placental abruption, prior cesarean delivery, fetal congenital malformation, heart disease, chorioamnionitis, and mechanically ventilated parturients. Screening was provided to all women in labor, with a partogram used to monitor progress of labor.
FIGO guidelines were followed during FHR tracing, and a cardiotocograph was used to measure FHR. Women with pathologic FHR tracings were randomized into 2 groups. Group A was the intervention arm, where patients received high fractional inspiration of oxygen (FiO2 of 80%).
In group B, patients received the standard care of FiO2 of 40%. Additionally, patients in group A received 10 L/min of oxygen through a nonrebreathing mask, while those in group B received 6 L/min of oxygen through a simple face or venturi mask.
Emergency cesarean delivery was performed following pathologic FHR tracing of more than 25 minutes. Patients with emergency cesarean delivery continued to receive FiO2 of 80%. FiO2 of 40% was administered after cord clamping, and other intrauterine resuscitation techniques were provided to patients in both groups.
Apgar scores at 1 minute and 5 minutes were recorded, as well as the requirements of neonatal resuscitation measures. Neonatal Apgar score was reported as the primary outcome of the analysis, while secondary neonatal outcomes included neonatal intensive care unit (NICU) admission, neonatal morbidity, and neonatal mortality.
