The last thing Dan Bass remembers about his flight from Duluth, Minnesota, on Feb. 2, 2017, is turning on the autopilot for his piston-powered, single-engine plane and being cleared for his destination — Winona, Minnesota.
Shortly into the flight, he knew something was wrong. He experienced a strong headache and a butterfly feeling in his stomach. He began to feel anxious. Dan strongly considered calling air traffic control to ask if he could land. Just 10 minutes after take-off, Dan lost consciousness. His plane continued on autopilot, traveling south from Duluth at 13,000 feet for an hour and a half until it ran out of gas and crashed in a field 45 miles from Rochester, Minnesota, shortly before 8 p.m.
Miraculously, he survived. Injuries from the crash landed Dan in the hospital at Mayo Clinic, where his care team discovered that his symptoms and loss of consciousness during the flight were a result of carbon monoxide poisoning. Fortunately for Dan, his treatment at Mayo Clinic's Rochester campus — including hyperbaric oxygen therapy — helped him recover and become well enough to return to the skies.
When Dan regained consciousness after the plane crash and realized what had happened, he tried to find his flashlight and his cell phone. He couldn't locate either one. Then he tried to get out of the plane.
"I couldn't move my legs and thought initially that I was paralyzed. Then I was able to move my toes and realized my feet were pinned," Dan says. "After I got free and got out of the plane, I started to walk toward the road. I couldn't walk more than a couple steps before falling down. I crawled some and tried to walk again, but I was physically exhausted."
While lying on the ground, Dan noticed buildings in the distance. He got up and started walking in that direction. It was around 9 p.m., and it was 5 degrees outside.
Dan found a house and could see a woman sitting in her living room through the window. As he made his way up the driveway, he started yelling for help. When she opened the door, Dan told her he'd crashed his plane, and asked her to call 911 and call his wife. Soon after, Dan was taken by ambulance to a helicopter that was waiting to fly him to Mayo Clinic Hospital — Rochester. That was one aspect of the situation that made Dan feel lucky.
"I passed out going in a direction that flew me to Mayo Clinic," Dan says. "The trauma staff has this innate ability to calm you down. They worked really fast and all of them were personable."
In the Emergency Department at the hospital, Dan learned he had a spine compression fracture, a puncture wound on his knee, a laceration on his upper lip, and a broken upper jaw. He also found out why he'd passed out at the start of his flight.
A crack in the exhaust of the plane had been leaking fumes into the cabin through the plane's heating system during the flight. Blood work showed that the level of carbon monoxide in Dan's bloodstream was high at 13.8 percent.
People who lose consciousness due to carbon monoxide are at significant risk of neurologic injuries that can develop days or weeks after the poisoning. Those injuries can lead to memory loss, confusion, personality changes, altered mood, hallucinations and Parkinson-like movement disorders.
Hyperbaric oxygen therapy helps clear carbon monoxide by dramatically increasing blood oxygen levels. Patients breathe 100 percent oxygen while under three times normal air pressure in a sealed room. The delivery of oxygen at that increased pressure is 15 times more than what is possible at normal air pressure.
"This therapy limits further ischemic brain cell injury by reducing swelling, delivering high levels of dissolved oxygen, and limiting the toxic effects of carbon monoxide on those cells," says Paul Claus, M.D., medical director of the Mayo Clinic Hyperbaric and Altitude Medicine Program.
A respiratory therapist recommended the oxygen therapy for Dan. Although he was a bit skeptical at first, Dan had the treatment at noon the next day.
"They took me to three atmospheres, which is about 100 feet below sea level," Dan says. "My first treatment was three hours long."
Dan had two more treatments the following day.
Since his treatment, Dan hasn't experienced any symptoms from his exposure to carbon monoxide, and recovery from his other injuries has gone smoothly.
The Winona native, who's been flying since he was 17, is now out of the brace that immobilized his back for three months while his body healed, and he's ready to get back in the pilot seat. Although being involved in a plane crash is not something he would choose to experience, Dan is grateful he came down where he did.
"There isn't another place in the world I would rather crash," Dan says. "All the nurses, all the staff, everybody I dealt with was great."