Why patients on ventilators can take weeks to regain consciousness

by Cara Murez

Reporter of Health Day

TUESDAY Nov. 8, 2022 (HealthDay News) — While it can take some time for COVID patients taken off ventilators to regain consciousness, a new study suggests that’s not necessarily a bad omen.

Instead, it may be the body’s way of protecting the brain from lack of oxygen as the patient begins to recover.

Doctors should take this long recovery time into account when determining a patient’s prognosis, the researchers said.

“Delayed recovery in COVID-19 patients is very similar to the rare cases we have documented in previous studies,” said study co-author Dr. Nicholas Schiff, co-director of the Consortium for the Advanced Study of Brain Injury at Weill Cornell Medicine in New York City.

“In this new paper, we describe a mechanism to explain what we see in both types of patients,” he said in a Weill Cornell news release.

Schiff and his colleagues first noticed these delays more than a decade ago in comatose cardiac arrest patients. These patients received cooling therapy to reduce brain damage caused by loss of blood flow. One 71-year-old patient woke up after 37 days, but later recovered almost completely.

Schiff, a neurologist at New York-Presbyterian/Weill Cornell Medical Center, saw a similar delayed awakening when COVID-19 patients were taken off ventilators.

About a quarter of patients who survived breathing took 10 days or more to regain consciousness. It was longer if they had experienced more hypoxia while on a ventilator.

Evidence that the patients’ brains may be protecting themselves during these days or weeks can be found in animals that endure long periods without oxygen.

Schiff pointed out that this happens in painted turtles, which can go up to five months without oxygen under ice in the winter. They do this by activating the same inhibitory system in the brain that anesthetics target.

“These observations may provide new insights into how certain anesthetics induce unconsciousness and new strategies for sedation in the intensive care unit and to promote recovery from episodes of consciousness,” said study co-author Dr. Emery Brown, professor of anesthesia at Harvard Medical School.


Often, doctors may recommend reducing life support for patients who do not regain consciousness for a long time. It is usually set at 14 days or less for heart patients. There are no guidelines for COVID-19 patients.

The researchers said that as long as patients do not have brain damage, doctors should avoid making negative predictions about their chances of recovery.

The results were published in November. 7 in Proceedings of the Academy of Sciences.

More information

The US Centers for Disease Control and Prevention has more on ventilator use during the COVID-19 pandemic.

SOURCE: Weill Cornell Medicine, press release, Nov. 8, 2022

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