The coronavirus pandemic could cause a dramatic upsurge of hospital patients in the U.S., creating unprecedented demand for ventilators. And its not clear hospitals have enough of them .

Ventilators are the machines that push and pull air through a tube connected to the lungs, allowing people with compromised pulmonary capacity to breathe. For people with severe infections from this coronavirus, which attacks respiratory cells, these machines can literally be the difference between life and death.

Nobody is quite sure how many of the devices are available in the U.S. because theres no central system of accounting for them. And nobody knows how many will be required because that depends on the course of the pandemic and whether efforts to slow its spread are successful.

The consequences of a shortage would be dire. Doctors would have to make harrowing decisions about who gets the ventilators and who doesnt, decisions that doctors in coronavirus-ravaged China, Iran and Italy say they are making already .

Public officials like New York Gov. Andrew Cuomo (D) have been warning about this possibility with increasing urgency and begging the federal government for help. We are looking for ventilators desperately, Cuomo said in a press conference on Tuesday.

President Donald Trump and his advisers say they are on the case. At their own daily briefing, hours after Cuomos, they said they were taking a complete inventory of available ventilators while also ordering more. A day earlier, Trump had told governors to obtain them on their own, as The New York Times reported. The president on Tuesday said he never intended to suggest that federal authorities wouldnt also take action.

Whatever the Trump administration is or isnt doing already, its clear that the availability of ventilators depends in part on what steps the federal government takes and when it takes them.

Over the past week, HuffPost talked to about a dozen engineers, current and former executives in the medical device industry, and critical care physicians about how to make the most of the countrys existing ventilator stock and how to increase the supply as quickly as possible. Several asked that HuffPost not use their names because they still work in the industry.

None felt comfortable making firm pronouncements about what was possible. They cited the many unknowns, from the availability of electronic components to the severity and timing of the pandemic itself.

But they all said the federal government could make a big difference by making advance purchases, rushing the regulatory process, financing or even providing transportation, and making sure ventilators get to the places that need them most. Factories are already speeding up, they said, but theres a chance to do even more.

The industry has shifted into overtime to produce much-needed medical supplies, devices and equipment, such as ventilators, Mark Van Sumeren , a device industry veteran who is managing director of the firm Health Industry Advisor, told HuffPost. Theres a limit, however, to how much capacity it can ramp up on its own. Government can be a key partner here.

Assessing The Current Ventilator Supply Is Difficult

Precise, reliable counts of available ventilators do not exist yet. The estimate most people cite comes from a 2009 survey that said 62,000 units were scattered across hospitals and clinics around the country. The number today is probably at least a few thousand higher, if only because that figure is a decade old and the population has grown significantly since then.

So that sounds like a lot. But its not as if those machines are just sitting there waiting for somebody to use them. On a normal day, the majority of working ventilators are already in use for patients with everything from cancer to heart disease. Usage rises even more during flu season.

The need for ventilation services during a severe pandemic could quickly overwhelm these day-to-day operational capabilities, a February report from the Johns Hopkins University Center for Health Security warned.

Hospitals can free up ventilators by cutting back on certain elective surgeries, as they are already, and by switching patients to alternative forms of breathing assistance that would not be appropriate for COVID-19, the illness caused by the coronavirus. (Some breathing devices can disperse droplets from the patients airway, potentially spreading infection.)

And there are other ventilators, possibly quite a lot of them, that could be put to use. The federal government keeps an emergency stockpile and officials have indicated its about 10,000 units, although the precise number and location are classified because it is part of the governments defense plans against bioterrorism and biological warfare.

On Tuesday, the Defense Department announced it was releasing 2,000 ventilators to the Department of Health and Human Services.