CONCORD, N.H. (AP) — Andy Hoang eagerly began her first nursing job this year in New Hampshire, with a desire to specialize in cardiac care.

She was excited about attending a November practice session on how to respond to someone in cardiac arrest. But as things were getting under way at Dartmouth-Hitchcock Medical Center, Hoang, 23, started to feel dizzy and nauseated. She felt she needed to sit down.

“That’s the last thing I remember,” she told The Associated Press in an interview. “I woke up to a room full of doctors and nurses.”

It turned out that she, herself, had gone into cardiac arrest and needed help immediately. Her colleagues sprung into action — instead of practicing chest compressions on a mannequin in a simulated environment, they went to work on her.

“One checked her carotid, one her femoral (arteries), and she did not have a pulse,” instructor Lisa Davenport said.

The nurses started CPR and a “code blue,” or medical emergency, team was called.

“What was really stressful about the situation was that we never had a real code blue in the center,” Davenport said. “We train for them all the time.”

Davenport shouted for help. Luckily, the Lebanon hospital’s critical care team was nearby, attending a separate session. More nurses came in, hooked Hoang up to defibrillator for monitoring, inserted an IV line and placed her on oxygen. A doctor and nurse from another department rushed in with crash carts.

Hoang was waking up by the time an emergency team arrived. Davenport estimated 15 minutes passed from the time Hoang slumped over to when they got her on a stretcher and sent her to the emergency department. But it felt longer.

“It worked out, but it was pretty frightening for all of us,” she said. “You just don’t expect that to happen with someone as young as Andy.”

Charmaine Martin, one of the nurses at the scene, agreed it was a scary moment, but also one “where I saw and felt supported and we all worked as a team,” she said in a statement.

Hoang, who recently returned to work, couldn’t believe what had happened either.

“I would say I’m your pretty average healthy 23-year-old,” she said. She goes to the gym four times a week, runs, and eats well. “I’m on my feet 12, 13 hours a day at work, so I want to make sure that I’m in shape for that.”

Cardiac arrest — the sudden loss of heart function — causes more than 436,000 deaths in the United States each year, according to the American Heart Association. It is different from a heart attack, which happens when blood flow to the heart is blocked.

A person can suffer cardiac arrest after having a heart attack, but the association says other conditions can also disrupt the heart’s rhythm and lead to cardiac arrest, including having a thickened heart muscle or cardiomyopathy, heart failure, arrhythmias and more.

According to information compiled by the National Heart, Lung and Blood Institute, a person’s risk of cardiac arrest increases with age. It is rare in someone younger than 30. Genetic arrhythmias, problems with the structure of the heart or coronary arteries, heart inflammation and substance abuse are the main risk factors in younger people. Most cardiac arrests also occur in men and women’s risk increases after menopause.

Hoang said before the day she suffered cardiac arrest, she had passed out twice before. The first time, she hadn’t eaten and her blood sugar was low. The second time was preceded by a sharp pain in her abdomen.

“So, nothing like this, nothing to this extent,” she said.

Hoang, who grew up in Vietnam and came to the United States in 2016 as a student, said her family has no history of heart problems. She had been living with a family in Montana before she got her nursing degree in Michigan, and then headed to New Hampshire.

While recovering, Hoang wore a patch that recorded the electrical activity of her heart. Doctors hope to learn more from the data.

The experience has strengthened her relationship with the other nurses — Hoang now regards them as best friends. “We basically went through this whole life-or-death experience,” she said.

“I am so grateful for Andy and her courage. She is an excellent nurse and someone I call friend,” Martin said.

Hoang said she feels like she’s part of a family at work, not just an employee. Her family told the AP they are extremely grateful that she was surrounded by medical personnel when she went into cardiac arrest.

It was care given by nurses to her grandfather, who died a couple of years ago, that made Hoang want to switch her career focus from graphic design to nursing. But she never expected she would become a patient.

“It really changed my perspective on how I view life, like ‘Hug your family a little longer,’” she said. “Tell them that you love them, because it might be the last time you get to say it to them. And just cherish life for what you’ve been given. It’s precious, and I didn’t realize how precious it was until I nearly lost it.”