Hiker who went missing in mountain in whiteout conditions 'grateful' to doctors who revived him

The hiker rescued after going missing during a mountain hike praised the team of doctors who revived him after his heart stopped for nearly 45 minutes.

Michael Knapinski, 45, told "Good Morning America" that he's grateful for the staff at Harborview Medical Center who saved his life after he was caught in a whiteout situation while hiking in Mount Rainier National Park in Washington state last week. Doctors said Knapinski's heart stopped when he arrived at the hospital, and for over 45 minutes, they used CPR and other methods to get it pumping again.

"I mean, there were hundreds of people looking for me and a humongous team of doctors working for me. I'm already a pretty grateful person, but this is just life-changing," Knapinski told "GMA" from his hospital bed.

Knapinski said he went hiking with his friend on Nov. 7; along the way, they decided to split up and explore different parts of the mountain. Knapinski, who had gone on a 15-mile hike the day before, said the weather picked up as he hiked alone and his surroundings began to get into whiteout conditions as night fell.

"I couldn't see anything down there, zero visibility, even with a headlight or anything," he said, adding that he has no memory between getting lost and waking up in the hospital. "I don't know what happened."

National Park crews searched the park until early into the next morning, and temperatures had already dipped to below freezing, according to park officials. A Navy search and rescue team used a helicopter the next morning to find Knapinski.

Dr. Nick Johnson, the emergency medicine and critical care specialist at Harborview Medical Center, told ABC News that when Knapinski arrived at the hospital, his body was 70 degrees Fahrenheit and his heart went into an "abnormal rhythm where it stopped pumping blood to the rest of the body."

"I would say the odds were against him," Johnson said. "We certainly see a lot of people who spend nights in a cold, but he was one of the coldest people that I've seen arrive at the hospital, lose their pulse, have a cardiac arrest and survive."

The hospital activated its extracorporeal membrane oxygenation or ECMO team to treat Knapinski and revive him, according to Johnson. The team put tubes into the hiker's major blood vessels, took the blood out of his body, warmed it up, provided it with oxygen and put it back in, according to the hospital staff.

"I mean, essentially, we're just we're faced with a patient whose brain has been shut down by the cold. And we're hoping that we'll be able to buy enough time to reboot the most complicated computer in the world, essentially," Dr. Jenelle Badulak, a member of the ECMO team at Harborview Medical Center, told ABC News.

Knapinski woke up two days later, much to the relief of the hospital staff, Johnson said.

"We had a little telephone celebration first and then all of us have taken turns doing a socially distant mass visit just to say hello, and actually get to talk to them in person," he said.

Knapinski said he was still regaining his cognitive abilities when he woke, but was in awe when the medical professionals told him what happened and how they saved his life.

"I was like, 'Holy moly,'" he said.

"A lot of the people that worked on me didn't really expect me to recover from this," he added. "They came through my room, introduced themselves, said, 'Hi, I'm so-and-so, I did this for you and I did that for you.' I'm really glad they did that because it got me a chance to thank a lot of people in person."

Doctors said Knapinski will have a long road to recovery, including therapy to restore his memory and cognitive ability. Knapinski said he has some frostbite, stitches and bruises throughout his body.

The hiker said he plans to give back to the hospital and the community through volunteer work. As for his future in hiking, Knapinski said he'd consider hiking the mountain again under better weather conditions.

"I'll be safer next time," he said. "I won't split up with anybody and definitely learn from my mistake."