Nitrous Oxide During Labor: Maternal Satisfaction Does Not Depend Exclusively on Analgesic Effectiveness.

BACKGROUND Evidence on the analgesic effectiveness of nitrous oxide for labor pain is limited. Even fewer studies have looked at patient satisfaction. Although nitrous oxide appears less effective than neuraxial analgesia, it is unclear whether labor analgesic effectiveness is the most important factor in patient satisfaction. We sought to compare the relationship between analgesic effectiveness and patient satisfaction with analgesia in women who delivered vaginally using nitrous oxide, neuraxial analgesia (epidural or combined spinal-epidural [CSE]), or both (neuraxial after a trial of nitrous oxide). METHODS A standardized survey was recorded on the first postpartum day for all women who received anesthetic care for labor and delivery. Data were queried for women who delivered vaginally with nitrous oxide and/or neuraxial labor analgesia over a 34-month period in 2011 to 2014. Parturients with complete data for analgesia quality and patient satisfaction were included. Analgesia and satisfaction scores were grouped into 8 to 10 high, 5 to 7 intermediate, and 0 to 4 low. These scores were compared with the use of ordinal logistic regression across 3 groups: nitrous oxide alone, epidural or CSE alone, or nitrous oxide followed by neuraxial (epidural or CSE) analgesia. RESULTS A total of 6507 women received anesthesia care and delivered vaginally. Complete data were available for 6242 (96%) women; 5261 (81%) chose neuraxial analgesia and 1246 (19%) chose nitrous oxide. Of the latter, 753 (60%) went on to deliver with nitrous oxide alone, and 493 (40%) switched to neuraxial analgesia. Most parturients who received neuraxial analgesia (>90%) reported high analgesic effectiveness. Those who used nitrous oxide alone experienced variable analgesic effectiveness, with only one-half reporting high effectiveness. Among all women who reported poor analgesia effectiveness (0-4; n = 257), those who received nitrous oxide alone were more likely to report high satisfaction (8-10) than women who received epidural analgesia alone (OR 2.5; 95% CI 1.4-4.5; P = .002). Women who reported moderate analgesia (5-7) and received nitrous oxide only were more likely to report high satisfaction compared with the other groups. Among women who reported a high level of analgesic effectiveness, satisfaction with anesthesia was high and not different among groups. CONCLUSIONS Patients who received nitrous oxide alone were as likely to express satisfaction with anesthesia care as those who received neuraxial analgesia, even though they were less likely to report excellent analgesia. Although pain relief contributes to the satisfaction with labor analgesia care, our results suggest that analgesia is not the only contributor to maternal satisfaction.