It is not possible for a brain to go 45 minutes without oxygen and have that person live by any definition.
Indeed. The doctors worked on him for 45 minutes
, and pronounced him dead at the end of that time. Notably, air can get trapped in the lungs by resuscitation efforts, and when they stop, it lets the air get to the heart again. Heart activity started five to seven minutes later, at which point the doctors started working on him again. Also, his body was cooled by them, which increased the amount of time his brain could survive without oxygen. In other words, if it hadn't been for the doctors and everything they did to keep him alive, he wouldn't be.
Something to point out to your former friends, median, is that they, in their ignorance, would ignore what these doctors actually did that kept this man alive, instead giving the credit to God.