Hospitals are holding back from ordering more medical ventilators because of the high cost for what may be only a short-term spike in demand from the coronavirus epidemic, supply chain experts and health researchers say, intensifying an anticipated shortage of lifesaving equipment for patients who become critically ill.

The lack of ventilators — and growing calls for a more aggressive government role to fill the gap — was a subject of tense exchanges this week between President Trump and state officials. The issue also revealed a disconnect between different parts of the health-care industry, with the main hospital association disputing the accounts about the adequacy of supply of the lifesaving equipment.

Mechanical ventilators, which help patients breathe or breathe for them, are considered critical to the nation’s effort to contain the worst effects of the pandemic and avoid a crisis like the one Italy is facing. Depending on how bad the coronavirus pandemic gets in the United States, individual cities could come up thousands of ventilators short as patients flood hospitals, researchers say.

“It’s a challenge for states, local governments and hospital administrators to allocate tens of millions of dollars to something when they don’t know if they need it or not," said Chris Kiple, chief executive of Ventec Life Systems, a small ventilator manufacturer in Washington state. “But if they don’t do it, they are going to be caught flat-footed, and facilities are going to be faced with not enough ventilators to meet demand."

Ventilator manufacturers could achieve, within a few months, a significant boost in production from about 50,000 units a year currently, said Julie Letwat, a health-care lawyer with McGuireWoods in Chicago who is monitoring the industry. Orders have not flooded in, she said, because most hospitals can’t afford to increase inventory of expensive equipment for what could turn out to be a short-term event.

“The risk is that they’ll never be used, and hospitals can’t eat the cost," she said. “Most hospitals in this country are not profitable."

Ventilators range from $25,000 for a basic model to $50,000 for a machine used in the most advanced intensive care units. Buying them also requires additional large investments in staff and training. Letwat said federal government investment would be the surest way to boost supply.

Governors and local health authorities worry about an insufficient supply of ventilators and have been calling on the Trump administration to move aggressively to solve the problem. The president indicated Wednesday he has a plan to boost ventilator supplies but did not provide specifics. “We are ordering thousands and thousands of ventilators and they are complex,” Trump said at a White House press briefing.

Other governments have rushed to stock up on ventilators. The United Kingdom has asked Rolls-Royce Holdings, which makes jet engines, and other heavy manufacturers to make ventilators. Germany ordered 10,000 ventilators with Dragerwerk AG, which Dow Jones said was the company’s largest order ever.

In the United States, Trump told state officials on a conference call that states and local governments should procure their own equipment. “Respirators, ventilators, all of the equipment — try getting it yourselves,” Trump told the governors, according to the New York Times, which first reported the call.

The Trump administration has barely begun to release up to 13,000 older ventilator models cached around the country in the federal Strategic National Stockpile, saying state officials have not requested them. On Tuesday, the Defense Department said it will contribute an additional 2,000 ventilators to the effort.

Maryland Gov. Larry Hogan (R), chairman of the National Governors Association, said leaders nationwide are scrambling to secure ventilators to prepare hospitals for a surge of coronavirus patients, but there are not enough available.

“There is a problem with supplies and ventilators,” Hogan said Monday. “There’s not enough supplies. The states don’t have enough. The federal government doesn’t have enough. They’re not getting distributed fast enough. And that’s a problem for all of us.”

Hospital officials do not know how many patients will need ventilator care in the United States or whether the system will be overwhelmed. They say they are in a race against the spread of the virus, hoping measures to keep people in their homes will reduce the size of the short-term spike in those seeking care.

Nancy Foster, vice president for quality and patient safety policy at the American Hospital Association, said hospitals are canceling elective surgeries to try to free up ventilators. “Knowing exactly what is enough is hard at the moment,” said Foster, whose organization was one of three that asked Congress for more resources in a letter Monday.

Foster also said hospitals are preparing to move ventilators to hot spots of infection within multi-hospital systems and planning to bring older models back into use.

“We do have the capacity in an emergency to turn the switch on a lot of different things. We could change in a very short time,” said Brahim Ardolic, executive director of Staten Island University Hospital, which is part of a 22-hospital chain.

Foster said she has not heard any American Hospital Association member hospital say it was not purchasing ventilators because of cost. “They want to be fully prepared to serve the needs of their community and to do so intelligently,” she said.

Hospitals meanwhile are scrambling to buy as much personal protective equipment as they can for medical staff before the coming wave of infection, including disposable protective masks called N95 respirators, which are in short supply nationwide.

On the front lines of one of the nation’s earliest outbreaks, J. Randall Curtis, a doctor in Seattle, has treated six coronavirus patients in the intensive care unit at Harborview Medical Center, three of them requiring ventilators (including one who died). He cited as unique in those patients’ care both the intense focus on infection control and also the heavy use of personal protective equipment for medical staff.

The team managed the patients with the state-of-the-art ventilators, and he said more are available.

“Right now, we are mobilizing additional staff and cordoning off ICUs to take care of these patients, canceling surgeries, but we’re not exceeding capacity,” he said.

Nationally, the gap between demand and supply of ventilators could run into the tens of thousands, according to estimates. An analysis by the Society for Critical Care Medicine, citing figures developed for the American Hospital Association, said U.S. hospitals have 62,000 full-featured ventilators for advanced intensive care units with nearly 100,000 more with lesser capabilities.

Contrast supply with potential demand: More than 900,000 patients may need ventilator care during the coronavirus pandemic, the analysis concluded.

Keeping backup ventilators is impractical for most hospitals because of the need to service and maintain them and train additional staff during rare events when they are needed, said Lewis Kaplan, a trauma surgeon at the University of Pennsylvania and president of the Society of Critical Care Medicine.

“It’s like taking military planes out of your boneyard,” he said. “There can be a variety of economic disincentives to be prepared for the worst thing that can happen."

Not all patients would be sick at once, so the shortfall may not be as dire as it may seem, Kaplan added. And many coronavirus patients can be adequately treated with older models of ventilators or less invasive modes of respiratory help, he said.

Medtronic, GE Healthcare, Becton Dickinson and Philips are among the largest producers of ventilators for the global market. Several large manufacturers said they are increasing manufacturing of medical supplies, including ventilators, but would not provide specific numbers.

“We are taking steps to increase our manufacturing capacity and output of equipment that is important in the diagnosis and treatment of covid-19 patients,” a spokeswoman for GE Healthcare said in a statement.

Competition for supply could become an issue. With Europe’s governments placing massive orders, manufacturers also could face delays in obtaining spare parts because of supply-chain disruptions.

“A lot of these components for these ventilators are coming from other countries overseas, and some of the parts they need are creating a little bit of a backlog,” said Timothy R. Myers, chief business officer for the American Association for Respiratory Care, which represents health-care workers who specialize in ventilator treatment.

Anthony S. Fauci, director of the National Institute of Allergy and Infectious Diseases, confirmed Sunday the federal government’s emergency stockpile of medical supplies contains nearly 13,000 ventilators. To access those, hospitals are required to ask their state and local governments, which then ask the federal government to release supplies.

Secretary of Health and Human Services Alex Azar said Sunday at a news briefing at the White House that the government has barely heard from states about tapping the stockpile.

“We have received, so far, only, I think, one request for just several ventilators,” he said. In contrast to Fauci’s disclosure that the stockpile contains nearly 13,000, Azar said the number was not disclosed for national security reasons.

Pressed by Sen. Patty Murray (D-Wash.) at a congressional hearing this month about the adequacy of supplies, Azar suggested a key reason for passage of an $8.3 billion emergency spending bill was to procure more equipment, including ventilators and personal protective equipment for health-care workers.

Foster, of the American Hospital Association, said requests to obtain ventilators from the Strategic National Stockpile have not begun because the location of potential shortfalls is not yet known.

“It is a wait-until-it’s-needed situation,” she said. “We don’t know which communities are going to be hard hit at any given time."

Erin Cox contributed to this report.