Why patients on ventilators can take weeks to regain consciousness

By Cara Murez

Health Day Reporter

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

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

Physicians should consider these long recovery times when determining a patient’s prognosis, the researchers said.

“The delayed recovery in COVID-19 patients is very similar to the rare cases we have documented in previous research,” said study co-senior 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 article, we describe a mechanism to explain what we see in both types of patients,” he said in a Weill Cornell press release.

Schiff and his colleagues first observed these delays more than a decade ago in patients in comatose cardiac arrest. These patients received cold therapy to reduce brain damage caused by a loss of blood flow. A 71-year-old patient awoke after 37 days but later made an almost complete recovery.

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

About a quarter of the patients who survived ventilation took 10 days or more to regain consciousness. This was longer when they experienced more oxygen deprivation while on the ventilator.

Evidence that patients’ brains protect themselves during these days or weeks can be found in animals that can tolerate prolonged periods without oxygen.

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

“These observations could provide new insights into the mechanisms by which certain anesthetics induce loss of consciousness and new approaches to ICU sedation and promoting recovery from impaired consciousness,” said study co-author Dr. Emery Brown, Professor of Anesthesiology at Harvard Medical University School.

For patients who do not regain consciousness for a long time, doctors can often recommend stopping life support. This is typically 14 days or less in cardiac patients. There are no guidelines for COVID-19 patients.

The researchers said as long as patients don’t have brain injuries, doctors should avoid making negative predictions about their potential for recovery.

The results were published on November 7th in the Proceedings of the National 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, November 8, 2022