In the second season of the BBC television show “Call the Midwife,” a laboring woman who demands laughing gas is disappointed to learn that she’ll have to go to a hospital if she wants pain relief.

For British women, who’ve had access to nitrous oxide during labor for decades, the scene was just another historical anecdote in the post-World War II period drama. But for U.S. women, it was a revelation.

You mean laughing gas is an option? At a growing number of U.S. hospitals, the answer is, ‘Yes.’

Oregon Health & Science University Hospital in Portland will make nitrous available by this fall. Legacy Emanuel Medical Center, also in Portland, is considering it too. Nitrous advocates say it’s a useful form of pain relief, but it has been controversial because high-quality scientific research on safety and effectiveness is lacking.

“However, we do have decades of observational experience,” said Cathy Emeis, program director of nurse-midwifery education at OHSU. A practicing nurse-midwife, she spearheaded the process of getting the hospital’s approval. “We don’t see any concerning effects on infants.”

How it works

Nitrous oxide is used differently in labor than in dentist’s offices. The mix of nitrogen is fixed at 50 percent, as opposed to a concentration of up to 70 percent, and the woman self-administers the gas.

Self-administration is what makes nitrous oxide so attractive, Emeis said. “Women really do desire some control in their labor process.”

That is also what ensures that nitrous oxide is used safely, said Michelle Collins, program director of nurse-midwifery at Vanderbilt University.

“The risk of ‘overdose’ is not a real reality,” Collins said in an email.

If the woman becomes too sedated, she won’t be able to hold the mask to get more, Collins said. That’s because the equipment contains a demand valve, which requires the patient to make a good seal around the mask, and then inhale, she explained. When the patient exhales, the valve closes and the gas is no longer free-flowing.

Nitrous clears the system quickly, so even if a woman were to pass out, she would come around with a few breaths of air, Collins said.

The exhaled gas is “scavenged,” or removed from the environment, to avoid health risks to nurses and others who work around it.

While those delivering babies appreciate having nitrous as an alternative form of pain relief to offer women, nitrous has its drawbacks. Side effects can include dizziness, nausea and vomiting. Because it takes effect 30 to 50 seconds after inhalation, women have to figure out how to inhale the gas in concert with their contractions, according to an article that Collins co-authored for Nursing for Women’s Health.

Experts emphasize that nitrous offers mild pain relief, which is not comparable to the total pain elimination of epidural anesthesia. One study that compared the effects of nitrous and a placebo found no significant difference in pain scores, according to a 2012 review by the Agency for Healthcare Research and Quality.

The gas is most effective against anxiety, which tends to reach a peak as women are transitioning to the pushing stage of labor, Emeis said. “Pain is such a complex thing. That anxiety piece can really alter a woman’s perception of pain.”

The movement for nitrous at OHSU and other hospitals has come from women who hope to avoid epidurals, which means they’ll be confined to bed with a catheter, IV and continuous fetal monitoring. About 25 percent of women are using nitrous at Vanderbilt University Medical Center, which rolled it out four years ago, Collins said.

At least 35 percent of those women end up having an epidural, but Collins doesn’t see that as a failing. Nitrous can help women delay the epidural until their labor reaches a point where it’s less likely to be stalled by the anesthesia, she said.

Likewise, Emeis thinks nitrous will become a versatile tool at OHSU. “It could be on a continuum from water tub to nitrous to epidural to baby, or it could be the only thing a mother chooses to use in her labor,” she said.

Four years ago Vanderbilt and the University of California San Francisco were among the very few U.S. hospitals that offered nitrous, Collins said. Now, she’s aware of 100 hospitals that are at least considering it. Around 50 birth centers operated by lay midwives are using it as well, she said.

St. Charles Health System is not considering nitrous, nor have any patients requested it, spokeswoman Lisa Goodman said.

It’s also not on the radar of local women who are planning out-of-hospital births, so there are no plans to bring it to Bend Birth Center, licensed midwife Yesenia Guzman said. “I’ve heard of one person here talk about it, and she spent some time in Europe,” she said.

If nitrous becomes popular at OHSU, the local hospital might follow suit, Guzman said. “They’re open. They’re not completely opposed to change,” she said of St. Charles.

Proceeding with caution

Bringing a new form of pain relief into labor and delivery is typically a long process. Hospital personnel want to know that it’s safe for mother and baby, and how do they make sure the laboring woman’s friends and family members aren’t using the laughing gas?

Those questions come from all corners of hospital administration, said Collins, at Vanderbilt in Nashville, but anesthesiologists tend to be the most concerned.

“People will contact me almost every day,” Collins said. “‘We want to do this at our hospital, and anesthesia says, ‘Over my dead body.’”

While pointing out the dearth of data around nitrous oxide for labor, the American Society of Anesthesiologists hasn’t opposed its use. “We’re not against or for it,” said Ted Yaghmour, chairman of the ASA’s obstetric committee. “We just believe like any intervention, we want it to be safe,” he said. “We want people watching the process to be capable of protecting the woman and child from any untoward effects.”

While Portland hospitals have given nitrous serious consideration, it’s still controversial among Oregon anesthesiologists. Dr. Mark Norling, president of the Oregon Society of Anesthesiologists, said none of his colleagues who work in obstetrics were willing to discuss it with The Bulletin.

Lay midwives, who work outside of hospitals, have been able to bring nitrous into their practices much more quickly than hospitals. Currently there are no state regulations on the use of nitrous oxide in birthing centers.

That’s alarming to Sharron Fuchs, a Portland resident who advocates for more oversight of out-of-hospital births. She said the state should make sure the gas is handled by qualified people and monitored so it’s not misused. “If women get pain relief from it, and they want it, I’m all for it,” she said. “But I want the safety, too.”

Andaluz, a Portland birthing center, was the first place in Oregon to offer nitrous oxide, and owner Jennifer Gallardo believes it has led to fewer women being transferred to hospitals for epidural relief.

Gallardo alleges that nitrous hasn’t come to more hospitals because it threatens the anesthesiology business model. Her theory: “They’re not going to make money on nitrous, so why are they going to be excited about bringing that in?”

Yaghmour dismissed that notion. Nitrous appeals to women who hope to avoid an epidural in the first place, he said, so it’s not likely to cut into an anesthesiology practice.

At OHSU, anesthesiologists will be in charge of the nitrous, and nurses will simply monitor the patient’s use of it, Emeis said. That means an anesthesiologist will be the one to bring the equipment into the room and talk to the patient about an array of pain-relief options.

“The anesthesiologists at Oregon Health & Science University fully support the introduction of nitrous oxide,” Dr. Karen Hand said in an email. “Our interest is in providing high-quality analgesia for laboring women who want it, and we welcome this addition to women’s choices.”

Most of the hospitals offering nitrous are teaching institutions with large midwifery practices, but Emeis said laughing gas could some day become as ubiquitous as in-room bath tubs.

“I think it will be up to women,” Emeis said. “If you think about the childbirth education movement in the 1960s, the desire for water, those things have been pretty patient driven.”

— Reporter: 541-617-7860 kmclaughlin@bendbulltin.com