Would a sternotomy being used to treat massive internal bleeding be plausible? Hypothetical question regarding a character from a book I'm writing.

Hi there!

So, I'm writing a book featuring a character who has some rather prominent scars he's insecure about. Namely a sternotomy scar. I wanted to see if the way he acquired this scar was medically sound, in theory?

To make a long story short, the character is a roughly 20 year old male with an otherwise clean bill of health who was attacked and beaten nearly to death. My thinking is that his chest was cracked as a measure to access massive internal bleeding. I want to know if this is a plausible method of treatment.

Additional question: I've written that as a result of the attack he was left with a TBI which led to nerve damage manifesting as a severe cold intolerance, essentially just becoming painfully cold very easily.

I have no real medical knowledge myself, so I wanted to get a better informed take on the realism of what I've described above.

Thanks!