PfcAJ
Contributor
It takes a fairly long time for permanent tissue damage to happen.I think @CuzzA 's list looks pretty good. You need to know how/when to use what you're carrying and the list pretty much covers what most people can expect to deal with.
The tourniquet is a bit of a dilemma. Until a few years ago it was considered a "no-no" for most first aid kits. American forces experience in Afghanistan and Iraq changed that. However we still need to consider how appropriate it is in non-combat situations as it does cut off blood flow to the extremities, which can cause tissue to die.
TQ usage has really been positively demonstrated, and even the worst outcomes are better than a person bleeding out. In reality, definitive trauma care is very close time wise for most divers.
Major bleed is a real risk when diving (prop impact being the most likely scenario), but time after time again I see “first aid kits” that has no provisions to manage a major bleed. Not good.