MIAMI — Newly minted nurse Katie O’Bryan was determined to stay at her first job at least a year, even if she did leave the hospital every day wanting to quit.

She lasted nine months. The stress of trying to keep her patients from getting much worse as they waited, sometimes for 12 hours, in an overwhelmed Dallas emergency room was just too much. The breaking point came after paramedics brought in a child who’d had seizures. She was told he was stable and to check him in a few minutes, but O’Bryan decided not to wait. She found he had stopped breathing and was turning blue.

“If I hadn’t gone right away, he probably would have died,” O’Bryan said. “I couldn’t do it anymore.”

Many novice nurses like O’Bryan are thrown into hospitals with little direct supervision, quickly forced to juggle multiple patients and make critical decisions for the first time in their careers. About 1 in 5 newly licensed nurses quits within a year, according to one national study.

That turnover rate is a major contributor to the nation’s growing shortage of nurses. But there are expanding efforts to give new nursing grads better support. Many hospitals are trying to create safety nets with residency training programs.

“It really was, ‘Throw them out there and let them learn,”’ said University of Portland nursing professor Diane Vines. The university now helps run a yearlong program for new nurses.

“This time around, we’re a little more humane in our treatment of first-year grads, knowing they might not stay if we don’t do better,” she said.

The national nursing shortage could reach 500,000 by 2025, as many nurses retire and the demand for nurses balloons with the aging of baby boomers, according to Peter Buerhaus of Vanderbilt University Medical Center. The nursing professor is author of a book about the future of the nursing work force.

Nursing schools have been unable to churn out graduates fast enough to keep up with the demand, which is why hospitals are trying harder to retain them.

Medical school grads get on-the-job training during formal residencies ranging from three to seven years. Many newly licensed nurses do not have a similar protected period as they build their skills and get used to a demanding environment.

Some hospitals have set up their own programs to help new nurses make the transition. Often, they assign novices to more experienced nurses, whom they shadow for a few weeks or months while they learn the ropes. That’s what O’Bryan’s hospital did, but for her, it wasn’t enough.

So more hospitals are investing in longer, more thorough residencies. These can cost roughly $5,000 per resident. But the cost of recruiting and training a replacement for a nurse who washed out is about $50,000, personnel experts estimate.

One national program is the Versant RN Residency, which was developed at Childrens Hospital Los Angeles and since 2004 has spread to 70 other hospitals nationwide. One of those, Baptist Health South Florida in the Miami area, reports cutting its turnover rate from 22 percent to 10 percent in the 18 months since it started its program.

The Versant plan pairs new nurses with more experienced nurses and they share patients. At first, the veterans do the bulk of the work as the rookies watch; by the end of the 18-week training program, those roles are reversed.

The new nurses must complete a 60-item checklist. They must learn how to put in an IV line and urinary catheter; interpret different heart rhythms and know how to treat them; monitor patients on suicide watch and do hourly checkups on very critically ill patients; know how to do a head-to-toe physical assessment on a patient, as well as how to inform families about the condition of their loved one.

For Yaima Milian, who’s currently in the program at Baptist, this is markedly different from the preparation she got at her first hospital in New Jersey. She left after a six-week orientation because she didn’t feel ready to work solo.

While Milian was paired with a more experienced nurse at the New Jersey hospital, they didn’t see patients together; they split the workload. Her first week on the job, Milian was charged with caring for several patients with complicated issues — those on ventilators and with chest tubes — and she felt thoroughly unprepared.

“It just didn’t feel right, it felt very unsafe,” Milian said.

Besides the residency’s professional guidance, which includes classroom instruction, new nurses also get personal support from mentors — people they can call after a bad day or to get career advice. The new nurses also gather with their peers for regular debriefing, or “venting” sessions.

“Here you have this group that is pretty much experiencing the same things you’re experiencing,” Milian said, “and it makes you feel better.”