Taking these questions in reverse order: Yeah, kinda,
sometimes, and it varies wildly, based on the injuries sustained. Also, it’s
not the adrenaline crash that kills you.
Adrenaline rushes mean that you’re often unaware of injuries
sustained in the moment. I’ve never been fully certain if adrenaline actually
dulls the pain response, or if it simply causes your brain to ignore it. Either
way, while you’re under an adrenaline rush you can suffer injuries and be
unaware of them. It’s why you’ll sometimes see characters (and, for that
matter, real people, with prior experience) checking themselves for injuries
after combat (or any other traumatic event). It is entirely possible to be wounded
and have no idea it’s happened until you’re trying to figure out where all that
blood is coming from.
Depending on what you’ve just been through, coming down off
an adrenaline rush can be deeply unpleasant. Your brain is sure something’s
fucked up, but it can’t pin down exactly what or where, so it’s going to take
that out on you, and everything aches. Adrenaline crashes won’t kill you. (There
may be some weird outliers here for people with heart conditions, but, in
general.) A crash may make you wish you were dead, or make you want to throw up on
people, but it’s not lethal.
In the moment an
adrenaline means that you can suffer (fairly severe) injuries and keep on
fighting. If the injury doesn’t outright disable a limb, you can keep using it,
even if that’s a very bad idea. Getting stabbed or shot is no guarantee that
someone will sit down and peacefully bleed to death. Actually, shooting someone
is a pretty good way to ensure they won’t sit down and bleed to death without
When you’re trying to figure out how long it will take
someone to die, you’re actually asking about how fast someone bleeds out. This
relates directly to the injuries sustained. Someone who’s had a knife driven
into their neck isn’t going to keep fighting. Someone who had it run through
their bicep or buried in their shoulder blade, probably can.
We’ve covered blood loss before (and I strongly recommend you take a look at that tag, if you haven’t), but that’s the real factor
here that controls if someone can fight. If they still have enough blood in
their body to function. Lose too much, your ability to fight is impaired, and
you’ll eventually fall unconscious and die.
Blood loss is why concepts like, “first blood,” are important
in duels. Once that happens, the clock is ticking for that
character; the longer the fight goes, the more their ability will decay, and
unless they find a way to turn it around, they will die. (Even if they manage to prevail, they may still die without medical attention.)
Fighting through a stab wound is a fantastically bad idea.
Engaging in any physically strenuous activity that raises your heart rate, (for
example: fighting someone, or running away), will speed up blood loss, meaning impairment
kicks in sooner. Still, the point of adrenaline is to keep you functional after
sustaining an injury, so that you can survive.
If someone suffers an injury which disables them in some way,
such as breaking an arm, there’s no powering through that. Adrenaline won’t let
you override shattered bones. The biomechanical pulley system of muscles and
tendons simply doesn’t work with broken bones.
So, the short answer is, “yeah, kinda.” You can keep fighting
after being attacked. So far as it goes, there’s plenty of cases where someone
took a stray bullet and kept on fighting, only to bleed to death later.