Hi there! I have a character who gets stabbed in the side and into one of her lungs. The wound is deep enough for air to start seeping out and collapse it. I have a fairly decent idea of how it’s going to be treated, but I’m also wondering about blood entering the lung and how to treat that. Google didn’t help much there, I’m afraid. For the record, this takes place during medieval times and I’m aware I’m going to have to use some plot armor for the character to survive.
That’s not plot armor, your character needs magic, superpowers, or modern medical treatment to avoid a rather unpleasant death. If your character is lucky, they die from an infection, if they’re not, then it’s going to be pneumonia.
Okay, if you’re wandering around today, get run through by an especially strange individual wielding a large knife, and your lung is punctured and collapses, that’s bad. However, it is survivable, if you get medical treatment. The lung can be surgically repaired, you can be put on antibiotics, as needed, and your lung can be re-inflated. I’m not sure on all the options for this, but I know one common example is to simply force air into the lung via a plastic tube inserted down the throat.
I’m not 100% certain what getting blood in your lungs will do, but I am sure having blood in your lungs is a potentially lethal situation (even today). In particular, blood quickly coagulates into a solid clot when exposed to oxygen. In your lungs, this means you cannot extract oxygen from the atmosphere, and it’s not going anywhere. Over time clots break down, but the results are not something you really want to deal with internally.
If you’re getting foreign matter of any kind into your lungs, that’s a vector for infection. Lung infections are extremely dangerous and can easily kill you. Symptoms include a fever, increased respiration rate (with an increased heart rate), chest pains, and increased mucus production (which, incidentally is what’s actually causing the problems in the first place, because that stuff is interfering with your ability to breathe in the first place.) If I understand correctly, getting blood in your lungs basically guarantees an infection, or infection like symptoms.
So, in short, without modern medicine, there’s no way to properly treat the collapsed lung. And, assuming the blade wasn’t clean (which, it wasn’t), any medical treatment your character did receive wouldn’t account for concepts like bacterial infection (because that wouldn’t be discovered for centuries), so your character would get sick, and die.
I realize I haven’t written a hard shutdown like this in awhile, but, yeah, this injury, with that level of medical technology is a textbook example of how to kill a character in an extremely painful, and agonizing way.