BOSTON (CBS/CNN) — Doctors are finding that placing the sickest coronavirus patients on their stomachs — called prone positioning – helps increase the amount of oxygen that’s getting to their lungs.

“Once you see it work, you want to do it more, and you see it work almost immediately,” said Dr. Kathryn Hibbert, director of the medical ICU at Massachusetts General Hospital.

Patients with coronavirus often die of ARDS, or acute respiratory distress syndrome. The same syndrome also kills patients who have influenza, pneumonia and other diseases.

Seven years ago, French doctors published an article in the New England Journal of Medicine showing that patients with ARDS who were on ventilators had a lower chance of dying if they were placed on their stomachs in the hospital.

Ever since, to varying degrees, doctors in the United States have been placing ventilated ARDS patients on their stomachs.

Critical care specialists say being on the belly seems help because it allows oxygen to more easily get to the lungs. While on the back, the weight of the body in effect squishes some sections of the lungs.

“By putting them on their stomachs, we’re opening up parts of the lung that weren’t open before,” Hibbert said.

In an interview with WBZ-TV, Hibbert said the hospital has been trying this tactic with patients on the medical floor before they need to be transferred to the ICU.

“It’s anecdotal so far, we have definitely seen some patients’ oxygen levels get significantly better when we put them in the prone position, when we place them on their stomachs,” she said.

Choosing belly or back

There is a downside to placing ventilated coronavirus patients on their stomachs.

Ventilated patients require more sedation when they’re on their stomachs, which could mean a longer stay in the ICU. About a third of Mass General coronavirus patients on ventilators get placed on their stomachs, usually the ones who are sickest and have the most to gain from being in that position.

At Mass General, a “proning team” of nurses visits patients outside the ICU to encourage them to turn onto their stomachs. Since it might be uncomfortable for a non-sedated patient to spend 16 hours on their stomachs, the nurses try to get them to spend at least four hours on the stomachs, split into two sessions.

“People who are stomach sleepers tolerate it a lot better than everybody else,” Hibbert said. “Some patients need help to be turned, some just need to be encouraged.”

The 2013 French study looked only at patients who were on ventilators, so it’s not entirely clear what effecting the stomach position has for patients who are not as severely ill.

Hibbert study said further study is needed, but more patients are willing to give it a try.

“It’s too soon to say whether that is durable or whether most of those patients may eventually need a breathing machine anyway, but we definitely do see some effect almost immediately in the oxygen levels,” she said.

(© Copyright 2020 CBS Broadcasting Inc. All Rights Reserved. CNN Senior Medical Correspondent Elizabeth Cohen contributed to this report.)