By Sarah Toy & Mark Maremont

Several months into the coronavirus pandemic, hospital physicians are split on whether long-established treatment protocols for patients in respiratory distress are helping or harming patients with Covid-19.

In the intensive-care unit, doctors are trying to balance their own knowledge and past experiences treating respiratory illness with their current experiences treating the novel coronavirus and newly emerging data on Covid-19 therapies.

The result is there is little consensus among physicians about treatment, even as cases and hospitalizations surge in parts of the U.S. It also means the particular treatment a patient gets can vary widely from hospital to hospital, and even from doctor to doctor.

To begin with, physicians don’t agree on the type of lung injury the novel coronavirus causes. One camp says it leads to classic acute respiratory distress syndrome (ARDS), caused by widespread inflammation in the lungs where the tiny air sacs, the alveoli, thicken, fill with fluid and stiffen. The other camp says many Covid-19 patients are showing up with a different form of injury, marked by lungs that are stretchy and more elastic, not stiff—something not typically seen in classic ARDS—though their blood-oxygen levels are still low.

Although young patients make up more of the recent surge in cases at many hospitals, doctors say they don’t see age as a factor in the type of lung injury a patient might have.

In April, researchers published an article suggesting many Covid-19 patients with respiratory distress might require a different treatment approach than typically used for ARDS.

The disagreement has roiled the critical-care community, with those in favor of nontypical protocols accusing the other camp of being inflexible and tied to tradition at the expense of patient care during a pandemic. Those who favor sticking to longstanding approaches say the other side is playing fast and loose with treatment guidelines that have been proven to work.

The debate has crystallized around the best way to use ventilators to help Covid-19 patients breathe when they can’t on their own. Normally, for a patient with ARDS who required mechanical ventilation, the ventilator would be set to apply positive pressure—called positive end-expiratory pressure, or PEEP—to prevent the air sacs from collapsing at the end of each breath. The ventilator would also apply a low volume of air per breath, or tidal volume, to help minimize ventilator-induced lung injury.

But some doctors say these traditional settings are too extreme for Covid-19 patients who have good lung elasticity. The traditional PEEP settings could damage the lung and redirect blood flow away from parts of the lung that need it most, leading to poor patient outcomes, these doctors say. Instead, these patients should be placed on lower levels of PEEP and higher tidal volumes, they say.

Maurizio Cereda, an anesthesiologist and head of the surgical ICU at the Hospital of the University of Pennsylvania, said doctors normally use standardized tables to match the level of oxygen in the blood with the amount of PEEP needed. Penn tends to use a table with lower PEEP values, he said, but even those lower levels seem to damage the lungs of some of his Covid-19 patients. As a result, he disregards the table entirely at times, he said, even though some in his institution disagree with his approach.

“You can’t wait for somebody to make a giant study,” Dr. Cereda said. “You are alone with your clinical observation. A lot of people don’t feel comfortable with that because they want to have big guidelines. People seem to be afraid they’re going to do something wrong.”

John Marini, a professor of medicine at the University of Minnesota and one of the authors of the article, said patients with normal lung elasticity tend to present at the hospital earlier in their disease course. Some doctors have nicknamed them “happy hypoxemics.” Because their lungs aren’t as stiff, they breathe relatively normally when they show up at the hospital, despite having low blood-oxygen levels. They require different treatment than patients with classic ARDS, Dr. Marini said.

Robert Dickson, an assistant professor in the division of pulmonary and critical-care medicine at the University of Michigan, disagreed. He said most patients who come in don’t have good lung elasticity, and the PEEP levels recommended by Dr. Marini and others are too low. Allowing higher tidal volumes can be dangerous as that can overstretch the lungs, he added.

“By saying that this is not ARDS or some kind of atypical ARDS, we’re abandoning evidence-based practices and swapping them out for intuition, which has not served us well in the past,” Dr. Dickson said.

At Maimonides Medical Center in Brooklyn, critical-care and emergency-medicine doctor Cameron Kyle-Sidell said he was initially seeing much higher mortality rates from Covid19 patients on ventilators than he would have expected from classic ARDS, possibly because physicians were sticking to PEEP levels used to treat traditional ARDS.

“There are people who are treating this the way they would have treated any other ARDS,” he said. “Then there’re people on the flip side—and I am on that flip side—that think you should treat it as a different disease than we treated in the past.”

Some clinicians say the split could be due in part to how ARDS is defined. Past studies that formed the basis of how doctors treat ARDS today looked at patients who met a broad set of clinical criteria, but what was going on underneath varied widely, they note.

Dr. Marini, the co-author of the article, said patients presenting at the hospital at different stages of Covid-19 could also account in part for the differing views. Some hospitals might see more patients in the earlier stages of the disease; others might get patients further along, whose lungs more closely resemble what’s seen in classic ARDS. How a patient’s lungs look could also depend on the individual’s inflammatory response to the virus, he added.

Some in the critical-care community think there will be less divergence in opinion as time passes. Some doctors tend to lean on evidence from the population level, while others tend to treat patients on a more individual basis, said Marc Moss, head of the division of pulmonary sciences and critical-care medicine at the University of Colorado School of Medicine. Most use a mix, but some may be leaning more heavily on what they see at the bedside for their Covid-19 patients, as population-level evidence is still emerging, he said.

“As we learn more and as more evidence comes out, some of the variability that we’re seeing that’s based on people’s individual perceptions will probably go away,” Dr. Moss said.