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CME Credit Offered
CME Credit Offered
Abstract Award
Abstract Award
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Poster Session 1

(297) Nitrous Oxide: Safe, Effective Labor Analgesia in Patients Treated with Medications for Opioid Use Disorder

Thursday, January 30, 2025
10:30 AM – 12:30 PM  

    Submitting Author and Presenting Author(s)

  • Molly R. Siegel, MD

    Massachusetts General Hospital, Division of Maternal Fetal Medicine
    Boston, Massachusetts, United States

    • Coauthor(s)

  • Leah N. Schwartz, MD, MSc (she/her/hers)

    Resident, Obstetrics and Gynecology
    Massachusetts General Hospital and Brigham and Women's Hospital
    Boston, Massachusetts, United States

  • DS

    Davida M. Schiff, MD, MSc

    Assistant Professor of Pediatrics
    Massachusetts General Hospital, Department of Pediatrics
    Boston, Massachusetts, United States

  • BK

    Brinda Kamdar, MD

    Massachusetts General Hospital, Department of Anesthesia
    Massachusetts General Hospital, Massachusetts, United States

  • Sarah N. Bernstein, MD (she/her/hers)

    Assistant Professor of Obstetrics, Gynecology, and Reproductive Biology
    Massachusetts General Hospital, Division of Maternal Fetal Medicine
    Boston, Massachusetts, United States

Objective: Nitrous oxide (NO) is an effective analgesic option for labor and postpartum laceration repair, but obstetric and anesthesia professional societies caution against its use in individuals treated with systemic opioids, including medications for opioid use disorder (MOUD), due to theoretical concerns about respiratory depression and sedation. We aimed to evaluate the safety of NO for labor analgesia in patients treated with MOUD.

Study Design: We evaluated a retrospective cohort of patients prescribed MOUD who received NO for labor analgesia utilizing an established dataset of opioid exposed pregnancies at an academic urban hospital from 2016-2023. Maternal demographic characteristics, respiratory status, delivery and neonatal outcomes were evaluated with univariate analyses.

Results: 26 patients treated with buprenorphine (17) or methadone (9) were included (Table) from a total of 361 opioid exposed pregnancies (7.2%). Safety data and maternal benefit are summarized in the Figure. There was no difference in maternal mean oxygen saturation before and after initiation of NO (p= 0.87). There was no maternal hypoxemia (lowest oxygen saturation 95%), respiratory depression (lowest respiratory rate 16), or documentation of maternal respiratory distress or somnolence related to NO therapy. Pain scores on 10-point scale significantly improved before and after NO (mean pain pre-NO 7 SD 2.2 vs post 3.5 SD 2.8, p < 0.005). Three (12.5%) had documented fetal intolerance of labor, all 4 or more hours after NO, which has a five-minute half-life. Six (25%) were admitted to the neonatal intensive care unit (NICU) and 13 (56.5%) to the special care nursery (SCN), most for neonatal abstinence syndrome (15/19, 78.9%). No NICU or SCN admissions were related to NO therapy.

Conclusion: Patients on MOUD are known to require higher doses of pain medication for adequate analgesia and have limited pain control options due to medication interactions. Our data suggests that NO is a safe and effective option for labor analgesia in patients treated with MOUD and should not be withheld.