In yet another sign that severe COVID-19 is tough to recover from, a new study shows that some survivors who required mechanical ventilation take days or even weeks to regain consciousness after sedation is halted and their breathing tube is removed.

For the study, the researchers analyzed data on 795 patients with severe COVID-19 who were treated with mechanical ventilators in the intensive care units of three medical centers for at least six days.

Of the 72% who survived and recovered consciousness before hospital discharge, 25% took 10 or more days to regain consciousness after being taken off the ventilator, and 10% took more than three weeks to regain consciousness.

“When we examined the potential causes of delayed recovery of consciousness, we found that low blood oxygen levels correlated with the time to recovery, even after accounting for other factors such as exposure to sedatives,” said study co-senior author Dr. Brian Edlow. He is associate director of the Center for Neurotechnology and Neurorecovery at Massachusetts General Hospital (MGH), in Boston.

“This relationship was dose-dependent — the more episodes of low blood oxygen that a patient experienced, the longer it took them to wake up,” Edlow said in a hospital news release.

Most of the patients had normal brain scans, which suggests that the long time it took for them to recover consciousness was not due to stroke, swelling or bleeding in the brain, according to the authors of the study published online recently in the Annals of Neurology.

“These observations were consistent across all three medical centers and during the first and second surges of the COVID-19 pandemic,” noted study co-leader Dr. Jan Claassen, an associate professor of neurology at Columbia University Vagelos College of Surgeons and Physicians, in New York City.

Importantly, Edlow said, “These findings provide us with more accurate information to guide families who are deciding whether to continue life-sustaining therapy in unconscious COVID-19 patients. The fact that delayed recovery of consciousness was consistently seen at three different medical centers, across two surges of COVID-19, suggests that we should consider the possibility of delayed recovery when making life-or-death decisions for these patients in the intensive care unit.”

The findings may also apply to critically ill patients with other medical conditions, according to the researchers.

Study co-author Dr. Emery Brown, a professor of anesthesia at Harvard Medical School and an anesthesiologist at MGH, said, “We are trying to determine whether the lessons learned from patients with severe COVID-19 can inform our approach to oxygenation targets and sedation management in the intensive care unit for the broad spectrum of patients who require mechanical ventilation.”

More information

There’s more on COVID-19 at the U.S. Centers for Disease Control and Prevention.

SOURCE: Massachusetts General Hospital, news release, March 15, 2022

Source: HealthDay