Ah, yes, the 'common sense' doctrine. A close cousin to the 'personal resposibility' doctrine. Otherwise known as the 'if you didn't do what I think I would have done in that situation, you're an idiot and you deserved whatever happened to you' clause.
The struggle for air thing, though - it's not that simple. Someone who's dangerous ill from cardiac and respiratory problems isn't neccessarily struggling for breath and obviously in distress, particularly if they're stoic by personality. Most of the damage that will kill them is being done silently and invisibly, to their heart.