(295) Adverse Outcomes Associated with Time from Neuraxial Anesthesia to Delivery: a retrospective cohort study

Objective: Although studies have shown an inverse association between time from spinal anesthesia to delivery and umbilical artery pH, these studies have been relatively small or excluded patients receiving other neuraxial anesthesia.

Study Design: Retrospective cohort study from 2013-2019 of singleton, term, non-anomalous births via planned cesarean delivery with neuraxial anesthesia. We assessed rates of adverse pregnancy outcomes associated with different time intervals from neuraxial placement to delivery: 1) < 20 minutes, 2) 20-39 minutes, 3) 40-59 minutes, and 4) ≥ 60 minutes. We further analyzed the time intervals for key portions of the surgical procedure among neonatal umbilical artery pH cohorts: 1) pH ≤ 7.00, 2) pH 7.01-7.10, 3) pH 7.11-7.20, 4) pH 7.21-7.30; and 5) pH ≥ 7.30. All statistical analyses were performed on STATA IC 15.1 and a p-value < 0.05 was considered statistically significant.

Results: Of the 5255 planned cesarean deliveries, 645 (12.3%), 4067 (77.4%), 468 (8.9%), and 75 (1.4%) delivered within 20 minutes, 20-39 minutes, 40-59 minutes, and ≥ 60 minutes from neuraxial anesthesia, respectively. As delivery time interval increased, there was positive association with number of prior cesarean delivery, BMI, and rates of multiparity, chronic hypertension, and diabetes. Increased time from neuraxial placement to delivery was associated with umbilical artery pH ≤ 7.1 and ≤ 7.2, umbilical artery base deficit > 8, and meconium-stained amniotic fluid (all p < 0.05). After adjusting for confounders and using > 20-minutes as a base comparator, increased time from neuraxial placement to delivery remained associated only with umbilical artery pH ≤ 7.2 (adjusted OR 1.83; 95% CI 1.01-3.28). In our secondary analysis, as the pH cohort decreased, there was association with increased time from neuraxial placement to delivery, skin incision to uterine incision, and uterine incision to delivery (all p < 0.01).

Conclusion: Findings suggest that during scheduled cesarean delivery, increased time from neuraxial anesthesia to delivery was associated with lower umbilical artery pH.