2024 FSA Podium and Poster Abstracts

P087: INFLUENCE OF NITROUS OXIDE USE ON SURGICAL ANESTHESIA METHOD FOR CESAREAN DELIVERY
Jin Choi, BS; Omowonuola Ogundele, BS; Grace DeSana, BS; Meghan Brennan, MD; Adam Wendling, MD; University of Florida

Introduction: The use of self-administered nitrous oxide during labor is associated with a high degree of maternal satisfaction but is frequently not the sole method of pharmacologic analgesia used. The purpose of our study is to determine the method of surgical anesthesia for patients who used nitrous oxide then underwent cesarean delivery, and whether nitrous oxide use is associated with increased rates of general anesthesia during cesarean delivery. 

Methods: In this interim analysis of data from a single-center, retrospective study, we analyzed 175 patients above the age of 18 who utilized nitrous oxide as labor anesthesia between August 30, 2018 and December 31, 2022. Three trained reviewers abstracted data from the electronic medical record, including type of labor, times of analgesia, and estimated blood loss during cesarean delivery. A senior reviewer adjudicated conflicts and verified results. Complete chart review of 1130 charts and addition of a comparison group who did not use nitrous oxide is pending.

Results: Of the 175 patients who received nitrous oxide, 136 (77.7%) converted to an alternate form of analgesia prior to delivery. Of the 136, 29 patients also required cesarean deliveries. 27 (93.1%) of these patients converted to neuraxial analgesia (24 epidural, 1 spinal, and 2 combined spinal-epidural) prior to cesarean delivery, while 2 (6.9%) patients received general anesthesia for their cesarean deliveries. Patients who received neuraxial anesthesia had a mean estimated blood loss of 1124mL (range 359-2722mL), while the patients who received general anesthesia had estimated blood loss of 1613mL (range 1425-1800mL). The patients who had general anesthesia did not have a difficult or failed intubation. There was no incidence of postpartum wound infection in any patient. 

Discussion: The use of nitrous oxide likely delays the use of neuraxial analgesia, which may increase rates of general anesthesia in patients who use nitrous oxide and subsequently need cesarean section. In our study, general anesthesia was used in only 6.9% of the patients who received nitrous oxide then subsequently underwent cesarean deliveries, while 93.1% used a form of neuraxial analgesia. Thus far, our study has found no association between the use of nitrous oxide during labor and general anesthesia during subsequent cesarean delivery. In addition, the use of general anesthesia during cesarean deliveries has been associated with increased risk of complications including postpartum hemorrhage (blood loss > 1,000 mL). Postpartum hemorrhage was seen in 2 (100%) patients who underwent cesarean delivery with general anesthesia, and in 13 (48.1%) of those who underwent cesarean delivery with neuraxial anesthesia. Next steps in our project include the addition of a comparison group who initiated analgesia with labor epidural and had an intrapartum cesarean delivery without utilizing N2O labor analgesia.