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Nic Brown is lucky, and he knows it.

The 38-year-old father of three is recovering from the coronavirus after spending 10 days in Cleveland Clinic's intensive care unit. He was kept mostly sedated while hooked up to a ventilator to help him breathe.

"There was a time during this process where the hospital reached out to my wife to have the discussion about end-of-life options," Brown, of Tuscarawas County, Ohio, said. "It was very emotional for all of us."

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While a majority of patients who become infected with the coronavirus appear to have mild symptoms, or no symptoms at all, it's becoming clear that those with the most severe complications must spend a significant amount of time in the ICU.

"We have people on ventilators for 20 to 30 days," New York Gov. Andrew Cuomo said during a news conference this week.

It's a similar situation at the Tulane Medical Center in New Orleans, which has become another hot spot in the coronavirus outbreak. Doctors there say COVID-19 patients rarely get better within two or three days, instead remaining on mechanical oxygen for one to two weeks.

Critical care doctors know that the longer patients remain in the ICU, the more likely they are to suffer long-term physical, cognitive and emotional effects of being sedated.

In fact, those effects have a name: "post-intensive care syndrome." Some physicians call it post-ICU delirium.

"The longer somebody is in the ICU, the more they're at risk," Dr. Amy Bellinghausen, a pulmonary, critical care and sleep medicine fellow at the University of California, San Diego, said. She estimates that up to two-thirds of ventilated patients may be affected.

The longer somebody is in the ICU, the more they're at risk.

Patients may be physically weak and experience a type of post-traumatic stress. The exact cause of post-intensive care syndrome is unclear. It could be the result of patients not getting enough oxygen or blood to the brain. Or, it could be sedative medications — critical for what physicians must do in acute care, but with potentially long-lasting ramifications.

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"I had one patient who came to our ICU recovery clinic, who told me that he was kind of at half conscious state the whole time," Bellinghausen said, "He thought the nurses were hooking up poisonous snakes to his arms."

Of course, the nurses were simply putting IVs in, but the patient experienced it as trauma.

When patients recover to the point of being discharged, cognitive difficulties may follow.

"Often when patients come out of the ICU, they really struggle to think as clearly as they did before," Bellinghausen said. "Sometimes it's as simple as not being able to figure out how to find the shared drive at work anymore, or what's on the schedule for the next day."

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Bellinghausen works with post-ICU patients at UCSD on their cognitive rehabilitation, which is a bit like physical therapy for the brain.

Rehab can take as long as six months, and very often, doctors say the best way to help patients avoid such post-ICU stress in the first place is through contact with loved ones. That's a problem for people with the coronavirus.

ICU patients need "to have humans around to orient them, to calibrate them, to touch them, to look in their eyes, and make them understand what's happening," Dr. E. Wesley Ely, a professor of medicine and critical care at Vanderbilt University, said.

"But that's exactly what the COVID patients won't get because they're all being isolated."

Ely said physicians are learning about the specific impact of COVID-19 on post-ICU syndrome from countries that have already had large numbers of cases.

"We've had reports from places where COVID cases are high, like China and Italy, that there is a boatload of delirium experienced by these patients," Ely said.

Beyond the potential for cognitive problems, there's early evidence that some patients may continue to struggle getting enough air into their lungs.

According to the South China Morning Post, doctors at Hong Kong's Hospital Authority have noted some COVID-19 patients experience drops of 20 to 30 percent in lung function. Other studies have hinted that COVID-19 infection could lead to heart injury, which is damage that can occur when blood flow to the heart is reduced.

Nic Brown, 38, couldn't get out of bed to write his message of gratitude himself, so he dictated to one of his nurses at the Cleveland Clinic. Photos of Brown's message went viral after the Cleveland Clinic posted them on Twitter. Courtesy Cleveland Clinic

Worldwide, physicians have only just started to learn about this new virus that in three months' time has sickened nearly 600,000 people, including more than 100,000 people in the U.S.

"We are just learning how these patients recover," Dr. Eduardo Mireles, director of the medical ICU at Cleveland Clinic, said.

Brown, the Ohio man who has now been discharged from the Cleveland Clinic ICU, appears so far not to have suffered lasting trauma from his time there.

In fact, he was so moved by the selfless acts of his medical staff while the in ICU, that he asked a nurse to write a message of gratitude on the window of his hospital room.

Photos of the message, which Brown dictated, were posted on Twitter and have since gone viral.

Technology is the way isolated COVID-19 patients can stay in touch with loved ones. Nic Brown

"Today I leave this ICU a changed person, hopefully for the better," Brown had his nurse write, "not only because of your medical healing, God's direction and guidance, but with the fact of knowing that there are such wonderful people dedicated to the care and concern of others."

Technology may have also helped, as Brown was able to remain in contact with his loved ones. That, perhaps, has helped him avoid post-intensive care syndrome.

"You really don’t understand the vulnerability of the human body, and you really don’t understand the impact of your connections, of your family and your loved ones," Brown said during an interview with staff at the Cleveland Clinic.

"This virus will forever impact this world," he added. "If nothing else comes out of it but people getting closer to each other," Brown said, "then, how much better is this world going to be?"

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