For anyone who is seriously hurt first aid is simply keeping them alive till they can reach a hospital and be treated there.
Cuts, scratches, stunned by a chair to the head. These are first aid cases. Once you hit that second stat to zero then first aid is purely about keeping you alive till the low berth or autodoc is reached.
Sucking chest would from a gauss hit, hey its only -2 DM. I have medic one, I'll deal with it :lol:
A first aid roll in the field should stop the problem getting any worse and in the case of minor injuries the first few minutes can be important. That ice pack or anti inflammatory drug, a quick shot of anti histamine or asthma treatment applied quickly prevent the problem getting worse and as such would make healing quicker. Waiting half an hour till that knee injury is blown up like a balloon and then going for an ice pack is a bit late. Having done the knee thing myself on a motor bike several times an icepack had me up and walking in days where as taking over an hour to get an anti inflammatory after the crash left me limping for a week.
Simple first aid is unlikely to cause that much harm but once you start using the drugs and tools in a med kit to treat injuries you are in a whole new area of risk. A quick aspirin for that heart attack is a life saver, if however you have mistaken the diagnosis and the problem is a hemorrhagic stroke then pumping them full of aspirin could be making everything worse.
A character that has two stats above zero is, in my opinion, bruised and battered but not seriously hurt. Yes taking a hit from a laser rifle is not going to leave a bruise only but since you are functional I see it more as a graze that leaves you with first and second degree burns or a close hit that hit you with shrapnel. A square hit from a laser rifle explosively vaporises large bits of a person, that is what needs an Autodoc and in this sort of case first aid is plugging the hole and stopping them bleeding out.
The RAW description of seriously wounded is not something I use. You could take enough damage to reduce END then take one attack that does a point of DEX and another attack that does a point of STR meaning you are then seriously hurt whereas Having no END and then taking enough damage to reduce your STR OR DEX to 1 leaves you only wounded. Seriously wounded to me is two stats down or one stat down and the other two stats both below half.