More than 70 unionized nurses at Tufts Medical Center have voted no confidence in the director of the operating room for failing to act on complaints of a nursing shortage.

On Thursday, a group of nurses delivered a letter to Anna DaSilva, executive director of perioperative services, saying they had “no confidence in [her] ability to manage Tufts OR Department safely and appropriately.”

Nursing leaders said the hospital has been consistently losing nurses over the last couple of years but has become untenable within the last six months.

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Nurses have also been meeting with DaSilva and the hospital’s chief nursing officer about staffing issues more frequently in the last couple months, but they say they’ve been met with inaction.

Izzy Stern, a nurse who’s worked at Tufts for 10 years, presented the letter to DaSilva last Thursday.

“It was definitely not something I wanted to do, but it was something that I felt I had no choice to do because we were at a point where it’s just so bad,” Stern said. “There was no other option.”

The union says it also filed complaints with the Massachusetts Department of Public Health, the American College of Surgeons, the Joint Commission and the Centers for Medicare and Medicaid Services.

Operating room nurses have held multiple meetings with the nursing administration at Tufts about the shortage, “with many promises made but no concrete action to address their concerns,” said David Schildmeier, a Massachusetts Nurses Association spokesperson.

Schildmeier also called the letter of no confidence “a last resort.”

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Operating room nurses call hospital management’s dependence on overtime and on-call hours to cover basic staffing “unsustainable” and “dangerous,” according to the letter.

Mary Havlicek Cornacchia, an operating room nurse who co-chairs the union’s bargaining committee at Tufts, said the situation has become unbearable.

“There’s one nurse in particular, he worked 40 hours of regularly scheduled shifts in a two-week period in the last two months,” she said. “Each week he worked 38 hours of overtime in addition.”

Stern, who makes the daily staffing schedule, said she’s noticed a lot of burnout among nurses and that overtime hours have led to more workplace injuries.

“We have multiple nurses out on leaves of absence because of workplace injury,” she said. “The amount of stress that people are under, no one is happy or even neutral when they’re coming in for the day. It’s just, it’s so rough for everyone.”

Stern said just in April, roughly 1,206 hours of overtime was posted for a four-week period. She says nurses were working 78 hours per week to fill in staffing gaps.

Cornacchia said they’ve lost roughly 10 nurses in the last year, partially because of the required amount on-call hours, and those positions have yet to be filled.

While she is unsure how many nurses the hospital needs to hire, she worried continued inaction will cause more nurses to leave.

“They’re exhausted, and you can’t keep up a pace like this without something happening,” she said. “You need to have a work-life balance where you can come and run your shift and then go home and recover and come back fresh the next day.”

Cornacchia said so far, DaSilva and hospital management haven’t acknowledged the letter.

A Tufts Medical Center spokesperson said in a statement that “patient safety, quality and caregiver wellbeing” are the hospital’s highest priorities.

“We remain confident in our staffing plan and nursing leadership and are committed to working collaboratively with our nursing colleagues to safely deliver outstanding care to our patients,” said spokesperson Jeremy Lechan.