Covid patients coming off ventilators may take weeks to regain consciousness

A new paper suggests that the combination of the virus and anesthesia puts the brain in a prolonged state of calm, like a freshwater turtle in winter.

In March 2020, New York hospitals filled with desperately ill Covid-19 patients. In many cases, when their fluid-filled lungs could no longer give them oxygen, doctors sedated them and put them on a ventilator.

The patients who recovered were removed from machines and anesthetized. In a day or two, their doctors expected them to wake up.

But that's when Dr Nicholas Schiff's phone , a neurologist at Weill Cornell Medicine, started to light up.

"We start having all these weird consultations," Dr. Schiff recalled. "People were released from anesthesia after surviving Covid, and they're not waking up."

Dr. Schiff, who had spent 25 years treating disorders of consciousness, was perplexed by the influx of unconscious Covid patients. They took weeks, if not months, to wake up. But then they usually regained full consciousness, with no signs of brain damage.

Dr. Since then, Schiff and his colleagues have been trying to make sense of this strange phenomenon. On Monday, he published an article that offers an answer. And the answer involves turtles.

The brains of unconscious Covid patients bear a striking resemblance to those of turtles that overwinter encased in ice, argued the Dr. Schiff and his collaborator, Dr. Emery Brown, a computational neuroscientist at M.I.T. Turtles survive by putting their neurons into an unusual state of calm that lasts for months. Dr Schiff and Dr Brown believe that the combination of Covid and sedatives causes a similar response in people.

If the theory holds water, it could point to new ways to save people from brain damage: by intentionally putting people in this state, rather than doing it by accident.

“If this is true, this can teach us how to better protect and preserve the brain,” said Dr. Schiff.

Dr. Schiff discovered that his experience was not unusual. Many other neurologists were seeing Covid patients take a very long time to wake up. In March of this year, Dr Schiff, Dr Brown and their colleagues published a study of 795 severe Covid patients with delayed recovery at three hospitals in New York and Boston. A quarter of patients took 10 or more days after getting off a ventilator to follow simple commands like squeezing a doctor's finger. After 23 days, 10% were still unconscious.

But the analysis did not provide easy answers as to why they were undergoing such a long time limit. Anesthetic drugs alone could not explain the long journey back to consciousness. "Time courses were absurd," said Dr. Schiff.

Brain damage can lead to months of minimal consciousness, but many Covid patients had healthy brains . "We didn't expect there to be a problem," said Dr. Schiff.

For years, Dr. Schiff and Dr. Brown have developed theories about what happens in the brain during comas, sleep, and anesthesia. Now they have turned their efforts to Covid. Their search for clues led them unexpectedly to turtle studies.

Across the north...