Doctors are still figuring out the best ways to care for patients with COVID-19, the illness caused by the novel coronavirus.

Over the past few weeks, as the virus has spread in New York City, one hospital has started keeping patients off ventilators longer, hoping that they'll be able to recover faster than if they were intubated.

Others are trying tactics like placing patients on their stomachs to help their lungs better circulate oxygen.

Still others are noticing that patients seem to be surviving on lower levels of oxygen in the blood than usual.

Critical-care doctors treating the sickest patients are rapidly working to figure out the best way to care for them at a time when science-backed evidence is scarce.

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Over a week, Maimonides Medical Center made an unexpected change to how it treated coronavirus patients.

Initially, the Brooklyn hospital was racing to put patients on ventilators early on. Now it's relying more on high-flow oxygen therapy, in which oxygen is delivered into the lungs of patients through the nose.

The hope is that by keeping patients breathing on their own and able to move longer, doctors will be able to open up their lungs more than if they were sedated and on a ventilator.

Maimonides' decision is at the center of a growing debate in medicine about the best way to treat patients with the most severe form of COVID-19, the illness caused by the coronavirus — those who are struggling to breathe. Some doctors are putting them on ventilators as early as possible, before their condition deteriorates to the point where they're less stable and there are more risks involved. Others say patients should be kept off the machines as long as possible because of the complications and side effects of going through the invasive ventilation process.

"We started treating this as a knee-jerk intubation-ventilation process because that's what we've done with people who have such profoundly low oxygen levels," Dr. Trevor Pour, an emergency-medicine physician at Mount Sinai Health System, told Business Insider. Now, he said, COVID-19 patients seem to be doing well on less oxygen.

To follow the debate, it's helpful to understand acute respiratory distress syndrome, or ARDS, a condition in which fluid builds up in the lungs and keeps them from getting the air they need. That's what happens to patients with the most severe form of COVID-19. The lack of oxygen in the bloodstream leads to a condition called hypoxia.

While ARDS is a condition that doctors are used to treating, the coronavirus has been around for only a few months. That's leaving those tasked with caring for the sickest patients with tough treatment decisions, and approaches have evolved over the pandemic.

It's an "evidence-free environment," Dr. Greg Martin, a professor of pulmonary critical care at Emory University and president-elect of the Society of Critical Care Medicine, told Business Insider. "That's the real challenge."

'In uncharted territory'

Dr. Mitchell Levy, the medical director of the medical intensive-care unit at Rhode Island Hospital and a professor of medicine at Brown University, helped write the guidelines for how ICU doctors should care for critically ill patients with COVID-19.

The guidelines suggest some basics clinicians should have in mind, like managing the breathing machine, being conservative with fluids, and wearing the right protective gear.

"Normally, guidelines are based on science," he said. With how fast the novel coronavirus has spread, that's not really an option.

"We're in uncharted territory," Levy said.

A healthcare worker assists a person with COVID-19 at a library that was turned into an intensive-care unit in Badalona, Spain. AP Photo/Felipe Dana

Keeping patients off ventilators

New York City has emerged as a center of the outbreak following Seattle, but other places in the country stand to be hit hard as well as the virus spreads.

"Our knowledge of this virus is about three months old," Dr. Patrick Borgen, the chair of surgery at Maimonides, said in an interview at the end of March. "We're learning as we go the quirks and the eccentricities and the scary things that this virus can do."

What Maimonides has learned has led doctors there to rely more on high-flow oxygen therapy — ideally, keeping patients off ventilators. That's not because the organization is running low on ventilators, but because high-flow oxygen is seen as a better treatment.

Martin said his hospital was still putting patients on ventilators early, adding that doing so while they're more stable is less risky than waiting for them to get sicker.

"We still tend to transition those patients to earlier intubation to avoid anything that's an emergency," Martin said.

Using high-flow oxygen as an alternative to ventilation had been gaining popularity before the coronavirus outbreak, Levy said. The problem is that pumping a lot of oxygen can help the coronavirus spread more readily in patient rooms.

While his hospital has enough ventilators, Levy said he was being cautious and putting patients on ventilators early. That calculation could change should the hospital run low on the breathing machines; in that case, it could opt to use high-flow oxygen in its place, though it might not benefit patients, he said.

"It's definitely not going to support patients better," Levy said.

Placing patients on their stomachs

Increasingly, healthcare workers are placing patients who are having trouble breathing on their stomachs, in a prone position, rather than on their backs. They're finding that this position, a common protocol for treating patients with ARDS, is particularly helpful for coronavirus patients.

It works by redistributing the blood flow through the lungs, helping better match the airflow to the blood supply and getting patients back up to better oxygen levels.

"We've known for some time that some of those people will do quite well if you place them on their stomach," Martin said.

Doctors are using the position beyond the ICU. Pour, the ER physician at Mount Sinai, said he did it on Wednesday during his shift and saw his patients improve. But it's not a perfect solution.

"It's just buying you time before you have to decide what to do next," Pour said.

When are oxygen saturation levels too low?

Pour said coronavirus patients had an unusual response to the low levels of oxygen in their blood. He said he'd left patients in the ER who had oxygen levels in the 80s who were breathing fine — but typically they'd be "hungry for breath" or breathing heavily to try to get their oxygen levels back up to 100%.

"The problem is we're not used to seeing this volume of patients with ARDS that are profoundly hypoxic and yet aren't looking sick," Pour said. "It's confusing to us."

That might give staff in the ER more time to talk with patients about what going on a ventilator could mean before intubating them.

The debate about oxygen saturation levels in the blood existed before COVID-19, Levy said. It's unclear what the best oxygenation level is with ARDS and whether or not you need high oxygen saturation.

The anecdotal reports of patients doing fine even with low oxygen saturation are confusing ICU experts too.

"It's hard to pick that apart and understand why that is," Martin said. Often it'll happen in people with chronic lung diseases whose bodies have adapted to not having 100% oxygen all the time. But it's unclear whether that's the case with COVID-19 patients.

"We don't really understand in COVID-19 if it's something that's unique," Martin said.

'The consequences of being sick for that long'

While getting patients on ventilators before their condition deteriorates too much is key, the volume of patients who reach that point is high, and it's raising the question of how well they'll do once they're on a ventilator.

Being put on a ventilator requires patients to be sedated. Often, they can be asleep for weeks as they recover from COVID-19.

The Associated Press reported on Wednesday that New York City officials said 80% of patients on ventilators there had died.

If the patient is unlikely to recover after being put on a ventilator, Pour will have a conversation with the family and patient about what they'd prefer to do, such as if the patient would rather spend that time awake with family.

Ventilators are a necessity for treating COVID-19, but the ventilators are not a cure, Pour said.

"I do worry about all the consequences of being sick for that long," he said.

Once on a ventilator, patients can't communicate or move around, and thus can't perform basic daily functions like eating and going to the bathroom on their own. And a side effect of being put on a ventilator is delirium, Martin said. It's not easy to be sedated for that long.

Ideally, the sooner patients are off the ventilator, the better they'll do, Martin said.

With COVID-19, doctors are also seeing blood clots occurring in the lungs and bodies of patients on ventilators, and doctors have said that their kidneys have started shutting down.

Eventually, healthcare workers will have more evidence to help them decide how to treat patients with severe cases of COVID-19. But the science-backed answers might still be months away.

"The problem right now is there's no evidence for anything. We have to rely on poor-quality evidence to make decisions," Pour said. "We're probably all doing things we find out later are wrong. And that's incredibly humbling."