SEATTLE — Medical leaders in Washington State, which has the highest number of coronavirus deaths in the country, have quietly begun preparing a bleak triage strategy to determine which patients may have to be denied complete medical care in the event that the health system becomes overwhelmed by the coronavirus in the coming weeks.

Fearing a critical shortage of supplies, including the ventilators needed to help the most seriously ill patients breathe, state officials and hospital leaders held a conference call on Wednesday night to discuss the plans, according to several people involved in the talks. The triage document, still under consideration, will assess factors such as age, health and likelihood of survival in determining who will get access to full care and who will merely be provided comfort care, with the expectation that they will die.

The effort is statewide so individual doctors and hospitals will not be left to make such decisions, said Cassie Sauer, chief executive of the Washington State Hospital Association, one of the groups convening the call.

“It’s protecting the clinicians so you don’t have one person who’s kind of playing God,” she said, adding, “It is chilling, and it should not happen in America.”

The state has been urgently seeking ventilators for patients and protective masks for health care workers, including from the Strategic National Stockpile, a repository of critical medical supplies for public health emergencies. Officials have also been looking to have the U.S. Navy hospital ship Mercy, which has 80 intensive care beds, dock near Seattle to handle seriously ill patients other than those who have contracted Covid-19, the disease caused by the virus.

Dr. Chris Spitters, the interim health officer for the Snohomish Health District, where the nation’s first coronavirus case was diagnosed, was part of the group that discussed the rationing proposals this week. He said that while the crisis strategies were not something anyone wants to anticipate, it would be worse not to be ready in the event they were needed.

“I would love to learn a month from now that the social distancing measures we adopted did indeed curb the outbreak enough to avoid going into that crisis zone of activity,” Dr. Spitters said. “But that would be poor planning — to simply hope.”

Dr. Spitters said hospitals are also strategizing how to repurpose space, staff members and resources to help deal with an expected surge in patients.

Those involved in the discussions said the goal for developing criteria for prioritizing care is to provide fair and evenly applied practices across the region and eliminate the possibility that the care a patient receives might depend on which hospital he or she goes to. They said they also hope to avoid placing the responsibility and anguish of denying lifesaving aid on any individual doctor or nurse.

“They look at the criteria — in this case it would likely be age and underlying disease conditions — and then determine that this person, though this person has a chance of survival with a ventilator, does not get one,” Ms. Sauer said.

“This is a shift to caring for the population, where you look at the whole population of people who need care and make a determination about who is most likely to survive, and you provide care to them,” she said. “Those that have a less good chance of survival — but still have a chance — you do not provide care to them, which guarantees their death.”

In Washington State, the crisis care planning is being led by the Northwest Healthcare Response Network, a coalition of hospitals assembled to handle disaster response, in conjunction with the Washington State Department of Health.

The group pulls on expertise in many disciplines, including specialists in pulmonary care, emergency medicine, infectious diseases, pediatrics and medical ethics.

“Now we are getting down to the point of how you would deploy it, when would you deploy it, who needs to know about it,” said Dr. Cameron Buck, president of the Washington chapter of the American College of Emergency Physicians.

“In my career, I can’t think of any other example where we have come this far, and had to make these preparations and develop these frameworks in real time with a moderate probability of having to use this work,” Dr. Buck said.

Dr. Kathy Lofy, the state health officer, said the guidelines under discussion have come from a group of clinical experts who have in recent years worked on the issue of providing health care in challenging circumstances. “We are doing everything possible to slow the spread of the virus and increase resources within the health care system so that resources will be available for everyone who needs them,” Dr. Lofy said in a statement.

Roughly 280 people were on Wednesday’s three-hour conference call, including the chief medical officials and nursing representatives for most of the state’s hospitals and hospital systems, Ms. Sauer said. There was an overwhelming sense of shock, she said, as clinicians realized that the time to begin discussing such dire plans had arrived.

“It just takes a lot of time for people whose lives are about saving lives to process that they may have to make these decisions,” she said.

Hospitals in the greater Seattle region already have been working to distribute patients evenly so no single hospital truly reaches its capacity. Seattle Children’s Hospital has taken pediatric patients from other facilities and begun admitting people up to 21 years old to free up more beds in adult hospitals.

Teams from regional health departments and hospitals would be responsible for triaging patients and potentially making these decisions, and the crisis-based decision-making criteria could be turned off and on as the situation evolved, Dr. Buck said.

The group plans additional calls twice a week, to get updates on the capacity challenges and to share proposed changes to the criteria that are still under consideration.

Dr. Buck said the health care rationing that occurred recently in Italy in response to the coronavirus outbreak weighed heavily on doctors as they discussed how their own work might have to proceed. “This is something that is obviously very serious and that we take very seriously.”