Post History
Every book is going to play around with reality to some degree, though some do it more than others. Every case is different. Is this a story that would end up on a "I can't believe they survived!...
Answer
#4: Attribution notice removed
Source: https://writers.stackexchange.com/a/46745 License name: CC BY-SA 3.0 License URL: https://creativecommons.org/licenses/by-sa/3.0/
#3: Attribution notice added
Source: https://writers.stackexchange.com/a/46745 License name: CC BY-SA 3.0 License URL: https://creativecommons.org/licenses/by-sa/3.0/
#2: Initial revision
Every book is going to play around with reality to some degree, though some do it more than others. Every case is different. Is this a story that would end up on a "I can't believe they survived!" style TV show? In my own book, I've included one of my favorite songs. But the song didn't exist in that time period. It's in Aramaic and Aramaic and Hebrew weren't languages yet; people spoke Canaanite, the precursor language to both. I am handwaving this away because it's a very old song and it's not inconceivable that a form of it existed even earlier. But I know that's a load of BS I'm telling myself so I can include it. And...so...I'm including it anyway. Because it's my book and that's what I want to happen. I'm also including things that didn't happen historically, at least not in the United States. They're things that could have happened, but they didn't. I have no idea if I'll have an afterword that talks about any of this, because that's more up to the publisher than anyone else. But [I do have a blog](https://writing.stackexchange.com/questions/42823/should-i-write-a-companion-book-blog). I can talk about all of these pressing issues as much as I want. And if _gasp_ some readers do not care as much as I do about linguistics and liturgical history as I do, they can just skip that post. In your situation, let your character survive and move on. If you need to, tweak the details just slightly as others have recommended, so survival is possible, even if improbable. As long as it's not too extreme (no one survives their head being cut off), readers can chalk it up to some amazing stroke of luck. You don't need to explain medical probability to the reader, just make it believable.