Hundreds of centers across the nation currently offer nitrous oxide as an option in their labor and delivery units.
While nitrous oxide is still common in Europe and other parts of the world, some support the idea of a nitrous oxide “comeback” in the U.S. The Morton and Diane Stenchever Lecture, “Nitrous Oxide in Labor: The Good, The Bad, and The Ugly,” on Saturday morning featured a debate on whether the return of nitrous oxide is a good idea.
Arguing in favor of more widespread use of nitrous oxide was Laura Goetzl, MD, MPH, professor of obstetrics, gynecology and reproductive sciences and director of the Division of Maternal-Fetal Medicine at Temple University, Lewis Katz School of Medicine in Philadelphia. On the other side, Mark Zakowsky, MD, clinical director and chief of obstetric anesthesiology at Cedars-Sinai Medical Center in Los Angeles, warned of nitrous oxide’s “dark side.”
“Those who say nitrous oxide doesn’t do anything and is completely safe are totally incorrect —there are toxicity effects that we’ve learned about recently,” Dr. Zakowsky said. “On a metabolic basis, it inactivates an important enzyme, methionine synthase, which plays a key role in metabolism. So, there’s a question of mom and a question of baby, as nitrous oxide is insoluble and rapidly crosses the placenta. It has been shown that after only a one-hour exposure to 50 percent nitrous oxide, methionine synthase activity in the fetal liver was only 18 percent of baseline, so it doesn’t take much to inactivate this enzyme.”
Dr. Zakowsky pointed to a 2016 FDA statement that warned against the use of general anesthesia for pregnant women in their third trimester. He believes the use of nitrous oxide is an elective choice that should be avoided.
Dr. Goetzl, on the other hand, believes that the risks of nitrous oxide, when administered appropriately, are minimal and that it provides a good option for women who want an alternative to epidural anesthesia or who cannot have an epidural for medical reasons.
“Nitrous oxide can also be used as an adjunct to epidural anesthesia. There can often be a significant wait time to get an epidural and, in those instances, nitrous oxide can help relieve the patient’s anxiety while they wait for it,” she said. “It’s also good for people who have natural childbirth, but who then may need something after delivery if they have to have a tear repaired or their placenta is stuck and they have to have a manual extraction of the placenta.”
Prior to the advent of epidural anesthesia for labor pain control in the 1940s, it was not uncommon for nitrous oxide to be used in U.S. delivery rooms, but the use of nitrous oxide faded when the epidural became the gold standard. Dr. Goetzl said that the nitrous oxide comeback has started, with more than 300 centers across the country currently offering it as an option.
“Nitrous oxide is a win-win option,” Dr. Goetzl said. “It’s a win for American women who want to have more options for pain control in labor and it’s a win for hospitals that offer it because it gives them an additional therapy to offer women who are in pain that doesn’t cost as much as other pain medications, has better pain outcomes, and clears out of mom’s system quickly as needed.”