Follow the evidence to ensure laboring patients have access to all options.
- Nitrous oxide (N2O) in childbirth is widely used outside of the United States.
- As a relatively new modality in the United States, some misconceptions exist.
- The use of N2O supports women who want to preserve their mobility and don’t want regional anesthesia.
Nitrous oxide (N2O) has been used as an analgesic during childbirth since the late 1800s, almost exclusively outside of the United States, until it resurfaced around 2011. A resurgence in use, coupled with widespread lack of knowledge about the modality, has led to a bevy of misconceptions, which impedes the initiation of N2O services and leads to unnecessary interventions and cost.
Those caring for anyone in labor or birth (nurses, advanced practice providers, and physicians) should know this modality, its use, benefits and risks, and logistics. The Association of Women’s Health Obstetric and Neonatal Nurses (AWHONN) Practice Brief Number 6 serves as a viable resource for labor and delivery nurses to learn more about this analgesic option, including how to separate myth from fact.
Myth 1
N2O provides the same pain relief as an epidural
Although N2O’s pharmacologic mechanism of action is neither singular nor understood, it appears to affect analgesia via an opioid-like action. N2O has potent anxiolytic effects and also induces feelings of detachment from occurring events. The nickname for N2O—laughing gas—is a misnomer; it doesn’t typically induce laughter. However, users may experience sensations of heightened exhilaration and pleasure, as well as decreased feelings of anxiety.
Although N2O offers many positive pain-relieving attributes, it doesn’t compare to regional anesthesia solely in terms of pain relief. However, research notes that relief of pain, as a singular indicator of a woman’s satisfaction with labor and birth, isn’t the most important factor. As discussed by Camann, a significant body of literature documents that the satisfaction a woman feels with her birth experience includes many factors not centered on the degree of pain relief she obtains. Camann, an obstetric anesthesiologist, acknowledges Hodnett’s landmark review of maternal satisfaction in childbirth.
We can’t overstate that one’s satisfaction with the childbirth experience isn’t directly related to the degree of pain relief. Consider, for example, Richardson and colleagues’ study at a large academic medical center, which included 6,242 women who gave birth vaginally. Of the cohort, 19% used N2O during labor and birth (40% of that number converted to neuraxial anesthesia at some point after N2O initiation). Of the 6,242 participants, 81% used a form of neuraxial anesthesia. Regarding the degree of pain relief participants noted, those receiving neuraxial anesthesia reported a very high level of relief (>90%). By contrast, those using N2O alone reported varying levels of pain relief, which is typical; only 50% reported high levels of pain relief.
The crucial finding of this study is that of the women using either method (neuraxial anesthesia or N2O) who rated its effectiveness as poor, those who used only N2O reported high satisfaction with their birth experience more often than those who received neuraxial anesthesia. Of the participants who rated the pain relief of their chosen method as moderate, those using N2O reported high satisfaction more often than those in the neuraxial anesthesia group. Significantly, women in either group who rated pain relief as high didn’t differ in satisfaction ratings.
This study illustrates that, although N2O doesn’t provide the same level of pain relief as regional anesthesia, women using N2O still experience high rates of birth experience satisfaction. Everyone who works with laboring individuals must acknowledge that not every laboring person wants neuraxial anesthesia. We must offer a range of viable nonepidural options from which patients can choose.
Myth 2
Don’t use N2O before active labor begins
N2O has no negative effect on either uterine activity strength or frequency. However, fear and anxiety release adrenaline, which can negatively affect uterine activity. Anecdotally, some providers have noted enhanced uterine activity after initiating N2O (presumably via the anxiolysis produced).
Myth 3
Use N2O only for contractions
Many organizations have found N2O valuable in various situations, including insertion of I.V. lines and when drawing blood (especially for patients with needle phobias), insertion of the cervical ripening balloon, inspection of the perineum immediately post-birth and with subsequent injection of local anesthesia, and manual removal of the placenta. Providers also have used N2O during intrauterine device insertion, colposcopic examination, and external cephalic version.
Myth 4
Don’t use narcotics or regional anesthesia with N2O
The addition of a narcotic during N2O use increases the risk of respiratory depression. However, during childbirth, the synergistic effect of a narcotic with N2O may be desirable. During manual removal of the placenta, for example, N2O alone may not offer adequate pain relief.
Given the increased risk of respiratory depression when combining these two agents, individual organizations may require the presence of anesthesia personnel at the bedside. Organization policy also may require the nurse to initiate additional monitoring, including continuous pulse oximetry. Some organizations may call for the enactment of their conscious sedation policy and accompanying stipulation when combining N2O and a narcotic agent.
Myth 5
Women shouldn’t eat or drink when using N2O
For decades, obstetrics providers have debated oral intake during labor. The rationale for restricting oral intake has always been the theoretical risk of aspiration should the patient require induction of general anesthesia. However, no actual evidence exists to support this supposition. Additionally, most cesarean deliveries are performed under regional, not general, anesthesia. Palmer and Jiang cite a retrospective review in their work on nutrition during labor, which notes a rate of one case of aspiration per one million births, but admit that even that may be inaccurate because it’s such a rare event.
Women using N2O are awake, aware, and in control of the mask/mouthpiece through which they inhale the gas. Using N2O with a laboring patient isn’t comparable to an inhaled anesthetic as part of general anesthesia induction. Even in the latter circumstance, the incidence of aspiration remains rare.
Myth 6
N2O isn’t safe for women or their babies
A 2012 review of N2O by the Agency for Healthcare Research and Quality (AHRQ) noted that most harms described fall under the realm of side effects. According to a systematic review by Likis and colleagues, nausea (8% to 9%) and dizziness (3% to 29%) are the most frequently reported side effects.
No evidence exists to support that N2O causes maternal oxygen desaturation. Women organically experience oxygen desaturation as a physiologic function of labor. When administered at a ratio of 50% N2O to 50% oxygen, and not combined with any other pharmacologic agents, the N2O alone doesn’t cause respiratory depression. In addition, Zanardo and colleagues report a link between N2O and positive memories of the labor experience. The same study noted significantly higher breastfeeding rates for women who used N2O over matched controls receiving regional anesthesia when measured at 7 days, 1 month, and 3 months postpartum.
Apoptosis (cellular death in response to exposure to a particular stimuli) and N2O is a common topic related to fetal safety. Vallejo and Zakowski notes that the results of studies highlighted in discussions of neuroapoptosis can’t be applied generally to fetal indirect exposure during maternal use of N2O. According to Yon and colleagues, rat pups directly exposed to varying concentrations of N2O (50% and higher) for up to 6 hours exhibited no signs of neuroapoptosis. On the basis of these findings, we can reasonably conclude that secondary exposure via intermittent maternal use hasn’t been shown to cause apoptosis in a human fetus.
The literature remains consistent with regard to the absence of evidence of risk to the neonate as well. The AHRQ’s 2012 review found that Apgar scores demonstrated no difference between neonates exposed to N2O in utero and those who weren’t.
Myth 7
N2O use requires continuous pulse oximetry monitoring
Rollins and colleagues (the American Society of Anesthesiologists Committee on Obstetric Anesthesia Working Group) classify N2O as minimal sedation when used at a concentration of 50% or less and as a sole agent. As such, pulse oximetry isn’t required. While breathing room air, a laboring woman receives 21% oxygen concentration; when inhaling N2O in labor, the woman receives 50% oxygen concentration via supplemental oxygen.
Myth 8
Women must stay in bed while using N2O
Providers and nurses indiscreetly assign women using N2O to bedrest, as they (incorrectly) equate its use to regional anesthesia. When used at the recommended concentration for labor, N2O is classified as an analgesic; spinal, epidural, and combined spinal-epidural are modes of anesthesia.
One of the advantages of N2O is that it allows the patient to remain mobile. This attribute alone makes the modality attractive to many laboring women. In European hospitals and new U.S. obstetrical units, bathrooms, hallways, and virtually anywhere laboring women might ambulate have N2O ports so they can plug in their breathing apparatus as needed. Because a small number of women using N2O may experience dizziness, many organizations’ policies include having someone (not necessarily medical personnel) present in the room when the patient first ambulates.
Myth 9
Don’t use N2O while in the bathtub or shower
Hydrotherapy and N2O act synergistically to effect pain relief; women shouldn’t be excluded from using a tub or shower if they’re also using N2O. The ability of hydrotherapy to induce relaxation and decrease muscular tension complements N2O’s anxiolytic effect. U.S. providers should consider the European standard of practice as well as evidence for the safety of each modality when implementing restrictive practices.
Myth 10
Only anesthesia personnel can administer N2O
Administering N2O as an analgesic for labor and birth doesn’t require an anesthesia provider. The ideal member of the obstetrical care team to initiate N2O is the bedside nurse, as ordered by the patient’s midwife or physician. Organizations that require anesthesia personnel to initiate the gas frequently experience patient delays. For those without a 24/7 in-house anesthesia service, the anesthesia personnel requirement limits women’s options. The requirement also adds to patient costs; anesthesia personnel typically apply billing codes meant for the delivery of inhalation agents during surgery to laboring patients, whereas nurses can’t bill individually. Although the cost of medical N2O is estimated at just pennies per hour of use, labor units can recoup costs by charging patients for the disposable breathing units.
Many organizations offering N2O report increases in their patient population as a result of those seeking this option, which certainly offsets the modest cost of establishing an N2O service. In addition, organizations have initiated bedside nurse-driven programs across the country, which have proven efficient and cost-saving.
Follow the evidence
Although more U.S. healthcare organizations offer N2O as an option for labor and delivery, misinformation continues to circulate. N2O may not be the best option for some women, but for many it offers safe and effective pain relief. Patient satisfaction with and the safety of N2O—as documented by Alexander and colleagues, Bradfield and colleagues, and Richardson and colleagues—makes it an ideal analgesic option for inclusion in every birthing unit. In addition, Romanenko and colleagues note a decreased risk for postpartum depression compared to neuraxial analgesia.
Providers and organizations must base policies and procedures on current evidence to ensure the application of best practices. Actively working to debunk myths and misinformation enhances the quality of the experience for women who choose to use N2O for their labor and birth.
Michelle Collins is dean and professor at Loyola University New Orleans College of Nursing and Health in New Orleans, Louisiana.
References
Alexander A, Amor K, Vasher J, Coyazo N. Use of nitrous oxide in obstetrics. J Obst Gynecol Neonatal Nurs. 2022;
51(4):S41. doi:10.1016/j.jogn.2022.05.010
Bradfield Z, Rose MS, Freeman N, Leefhelm E, Wood J, Barnes C. Women’s perspectives of nitrous oxide for labour and procedural analgesia: A prospective clinical audit and cross-sectional study. “It’s the best thing.” Women Birth. 2023;36(6:529-37. doi:10.1016/j.wombi.2023.06.007
Camann W. Pain, pain relief, satisfaction and excellence in obstetric anesthesia: A surprisingly complex relationship. Anesth Analg. 2017;124(2):383-85. doi:10.1213/ANE.0000000000001676
Collins M. Use of nitrous oxide in maternity care: AWHONN practice brief number 6. Nurs Womens Health. 2018;22(2):195-8. doi:10.1016/S1751-4851(18)30070-9
Gao F, Wu Y. Procedural sedation in pediatric dentistry: A narrative review. Front Med. 2023;10:1186823. doi:10.3389/
fmed.2023.1186823
Hodnett, ED. Pain and women’s satisfaction with the experience of childbirth: A systematic review. Am J Obst Gynecol. 2002;186(5 Suppl Nature):S160-72. doi:10.1067/mob.2002.121141
Likis FE, Andrews JA, Collins MR, et al. Nitrous Oxide for the Management of Labor Pain. Agency for Healthcare Research and Quality. 2012. effectivehealthcare.ahrq.gov/sites/default/files/pdf/labor-nitrous-oxide_research.pdf
Miemi M. The problem of pain, the power of presence, and the appeal of nitrous. J Obstet Gynecol Neonatal Nursi. 2020;49(6):S65. doi:10.1016/j.jogn.2020.09.113
Palmer CM, Jiang Y. Limiting oral intake during labor: Do we have it right? Anesthesiology. 2022;136(4):528-30 doi:10.1097/ALN.0000000000004170
Richardson MG, Lopez BM, Baysinger CL, Shotwell MS, Chestnut DH. Nitrous oxide during labor: Maternal satisfaction does not depend exclusively on analgesic. effectiveness. Anesth Analg. 2017;124(2):548-53. doi:10.1213/ANE.0000000000001680
Rollins MD, Arendt KW, Carvalho B, Vallejo M, Zakowski. Nitrous oxide. American Society of Anesthesiologists. asahq.org/about-asa/governance-and-committees/asa-committees/committee-on-obstetric-anesthesia/nitrous-oxide
Romanenko A, Bielka K. Labour analgesia and the risk of postpartum depression. Wiad Lek. 2022;75(12):2948-52. doi:10.36740/WLek202212109
Vallejo MC, Zakowski MI. Pro-con debate: Nitrous oxide for labor analgesia. BioMed Res Int. 2019:4618798. doi:10.1155/2019/4618798
Yon JH, Daniel-Johnson J, Carter LB, Jevtovic-Todorovic V. Anesthesia induces neuronal cell death in the developing rat brain via the intrinsic and extrinsic apoptotic pathways. Neuroscience. 2005;135(3):815-27. doi:10.1016/j.neuroscience.2005.03.064
Zanardo V, Volpe F, Parotto M, Giiberti L, Selmin A, Straface G. Nitrous oxide labor analgesia and pain relief memory in breastfeeding women. J Matern Fetal Neonatal Med. 2018;31(24):3243-8. doi:10.1080/14767058.2017.1368077
Key words: nitrous oxide, labor, childbirth, analgesia, patient satisfaction
