The COVID-19 mystery of Ben O'Donnell, a 30-something Ironman athlete, remains as baffling today as it did March 10 — when Minnesotans learned the state's first coronavirus case needing intensive care was someone in his prime.

State health investigators were perplexed, given the virus' history of hitting the sick and elderly the hardest.

Minnesotans lost hope, because being young and healthy were not surefire shields against COVID-19.

"It made everything a lot more real," said Haley Kramer, an intensive care nurse who treated O'Donnell, "because he was me, he was my husband, he was a lot of my close friends and family. Just a young, healthy guy."

Odds of recovery were a coin flip after COVID-19 ravaged his lungs and forced doctors to place him on a ventilator and an ECMO heart-lung pump to keep oxygen-rich blood flowing in his body.

Today, he is home in Anoka County, still recovering but offering hope to a state awaiting the peak of this pandemic.

"I was close as you could be to checking out without checking out, and here I am," O'Donnell said. "I want to give hope to those that are going through it, those that have gone through it, and those that are not seeing the light at the end of the tunnel."

O'Donnell, 38, remains an anomaly in Minnesota, which on Saturday, had 2,213 COVID-19 cases and 121 deaths. The average age of confirmed cases is 54 years old and the average age of those hospitalized is 64.

Even among COVID-19 cases on ECMO, O'Donnell beat the odds. Only 21 of 65 patients globally have survived after ECMO.

"The reason you're putting people on it is there is nothing left to do for them," said Dr. Jeffrey Chipman, a critical-care leader for M Health Fairview and the University of Minnesota Medical Center, which has treated two of the world's 21 ECMO survivors.

Chipman felt relief watching O'Donnell's vital signs stabilize under ECMO. It bought time for doctors to figure out what to do next, albeit for a disease with no proven treatment.

Didn't look right

O'Donnell hadn't set out to make history when he arrived at the U emergency room March 9. He had been worn down from a business trip and stayed home sick for a week while his wife was on a getaway with her sister; their 3-year-old daughter stayed with grandparents.

O'Donnell didn't look right when he picked up his wife, Deanna, at the airport March 8 and asked her to drive.

"That was weird," she said.

They had been mindful of COVID-19 — staying separated when O'Donnell first got back from his work trip and keeping the house sanitized — but figured he would just go to the ER to receive fluids and rehydrate and then go home.

Instead, that was the last day for a month that husband and wife were together. Isolated because of his likely infection, O'Donnell signed "I love you" through a window to his wife before she left.

It was the U's first COVID-19 case, and Minnesota's third. O'Donnell's health cratered. The next morning, doctors snaked a tube down his throat and placed him on ventilation.

Hours later, they asked his wife by phone to OK the ECMO because O'Donnell's blood oxygen levels were critically low. His lungs were packed with fluid. He was going to die without swift action.

"His chest X-ray when he came in was abnormal," said Dr. Meghan Rothenberger, a U infectious-disease specialist. "Within two days of his hospitalization, it was terrible — the kind of terrible that when I looked at it, I was like, 'ohhh.' "

ECMO historically came with heavy sedation to keep patients from moving and injuring themselves. These days, doctors try to keep patients conscious and moving so they aren't "wet noodles" when they come off the machine, Chipman said.

Odds are better when people are young and strong, and O'Donnell had that going for him. He finished the 2017 Ironman in Madison, Wis., and was training for another one.

'Don't stop, don't quit'

O'Donnell's hallucinations as he faded in and out of consciousness were dark. His masked caregivers were evil captors to him. His vision was not of a hospital but of a den of human trafficking that was grooming him. He was in danger and needed to escape.

In hindsight, with counseling to deal with the trauma, O'Donnell came to see the positive interpretation. His brain was telling him he was in a bad place physically, and he needed to fight to get better.

"I was somewhere else mentally," he said. "It was a pretty terrible place, but I now know the entire time my mind was looking for a way for me to be able to escape."

O'Donnell woke one day to see his sister, Dawn Inman, a Mayo Clinic nurse, who was permitted to visit. Confused, he wrote her a note: "human tr?"

"No," he recalled her replying. "You've been here the entire time. You were really, really sick. You've started to get a little bit better."

It was March 17, the last day she was allowed in the hospital under new visitor prohibitions. The state now had 60 COVID-19 cases, and epidemiologists were two days from acknowledging that the virus had reached broad, community-transmission levels.

Inman ducked into the room one last time to hug her brother. Reality became clearer after that, O'Donnell said, and he believed he was going to be OK.

"Don't stop, don't quit, keep moving forward," he thought, repeating the mantra that fueled his Ironman finish.

The hospital had prepared for COVID-19 but was not expecting a first case so bad in someone so young. Rothenberger said some people feared walking by his room, but his nurses never hesitated to don protective gear and treat him.

Brain damage is a concern for ECMO patients, but O'Donnell's pupil responses and reflexes were good during initial sedation. Later, he amused caregivers with a middle-finger gesture when a nurse tried to put mitts that he didn't want over his hands. O'Donnell was still in there.

"It was amazing how much he remembered," Kramer said.

The dilemma was what to do with the time ECMO bought. Doctors tried an anti-malaria drug, hydroxychloroquine, based on reports that it worked against COVID-19.

Hospitals worldwide reported immune-system overreactions in some bad cases, and O'Donnell showed signs of a cytokine storm — an excessive release of cytokine proteins to fight the virus.

Hematologists at the U have treated that problem in cancer patients with tocilizumab, a drug that blocks the Il-6 cytokine, so the doctors tried it. Coincidentally, O'Donnell, a chemical company executive, had worked earlier in his career on a blood test for Il-6.

"We saw him really turn around," Rothenberger said, though the drug is only one possible reason.

O'Donnell was strong enough to stand while on ECMO, which was removed March 22, and he continued in therapy exercises until his discharge April 6.

O'Donnell wasn't the first U.S. COVID-19 case on ECMO, but he was the first survivor to get off it. Doctors flooded the U with questions about what worked. The case will soon be featured in a medical journal.

'Tiger germs' are gone

Back home, Deanna and their daughter grew hopeful. They had been quarantined for two weeks because of their potential exposure to the virus but never tested positive.

Daily video chats were limited to waves and hand signs at first, but soon O'Donnell was talking. To make the infection understandable, Deanna told their daughter that her father had "tiger germs" clawing him.

Some of the talks stung. O'Donnell recalled his daughter saying, " 'Daddy, I wish you never went to work to get those tiger germs.' "

Over time, the girl could see her father's progress — first his intubation was gone, then a large nasal cannula, and the feeding tube.

After discharge, O'Donnell's sister drove him home. Father, mother and daughter embraced for the first time in a long time on their driveway. The tiger germs were gone.

Treatment had been frightening and complicated. Twice, O'Donnell had to be reintubated — the first time when his breathing tube clogged, and the second when he coughed so hard he forced it out of his throat. He needed periodic dialysis for his kidneys, and suffered internal bleeding because of anti-clotting medication.

Full recovery remains possible, with patience. The Ironman lasted .4 miles on a treadmill this week, and needed supplemental oxygen for only half of a 15-minute walk.

Now, O'Donnell is looking to help. Researchers are studying his blood and genetics, trying to figure out what made him vulnerable to such an attack. He hopes to donate blood plasma to treat others with COVID-19.

"As terrible as it was," he said, "I would do it again if I could stop someone else from being sick."