Here's my take on it all (with design notes):
Medical House Rules
A seriously wounded character loses his current Endurance DM in characteristic points each hour until he is treated with a successful Medic check to stabilize serious wounds. This check does not heal damage like a normal First Aid check, but prevents the character from worsening every hour. A First Aid check may be made immediately before or after a stabilize serious wounds check.
A patient who is unable to rest while seriously wounded will exacerbate his seriously wounded condition and take 1d6-Endurance DM damage at the end of the day, which may quickly put him into a mortally wounded state.
Medic Task: Stabilize serious wounds: Dexterity, 1-6 minutes, Average (+0). The patient will now be able to heal naturally (which may still result in death).
Add to last paragraph, page 74:
A character is considered mortally wounded if he has lost more than half of all of his physical characteristics. As soon as one of his physical characteristics is restored above half damage, no matter how, he is no longer mortally wounded.
Note: This may appear to unfairly penalize tough characters who spread their damage around, however, seriously wounded already does that, and this is just a worse form of being seriously wounded. And any difficulty in stabilizing heavily damaged tough guys compared to weenies is completely outweighed by the fact that you have to compare totally different levels of damage. The weenie who takes 15 damage total and is mortally wounded can’t be compared to the tough guy who has taken 15 damage and isn’t even seriously wounded. If one wanted to adjust for this, apply the victim’s undamaged Endurance DM to the Medic’s task check.
Add after first paragraph, pg 75:
Mortally wounded characters who are somehow not unconscious are unable to significantly move and lose their significant action in combat. Additionally, mortally wounded characters lose an additional physical characteristic point (determined randomly if necessary) every minute until they die or receive medical treatment. Mortally wounded characters never heal naturally.
Add to Medical Treatment, First Aid section, pg 75:
Mortally wounded characters die quickly without receiving first aid. To effectively staunch a mortal wound, a medic must bring the mortally wounded character to the seriously wounded or wounded state using the First Aid task under Medic. Otherwise, the mortally wounded character continues to lose characteristic points every minute. Note that the first aid check result takes effect after the time required, which is normally 1-6 minutes. Thus, it may be necessary to rush the process, taking the -1 DM for moving up on the Timing Table. Mortally wounded characters will never survive surgery—it is necessary to stabilize them to the seriously wounded state first. Certain types of technology, including Fast Drug or most kinds of cryoberths, will automatically stabilize the character, but do not heal the damage—the character simply gains time. Attempting to staunch mortal damage without the proper equipment is at least a Difficult (-2 DM) task.
Optional: Instead of an EDU based Medic check, make Staunch mortal damage a Dexterity based Medic check, but otherwise the same. This means that someone with artificial Medic skill from a computer is able to learn how to fix up a wounded character, but when presented with a traumatic wound, is completely flabbergasted. (After all, it’s basically quick field surgery.)
Clarification: Surgery requires 1-6 hours per check and is a Dexterity-based Medic skill check. Emergency surgery in the field is usually a Difficult task (-2 DM). Surgery without the proper tools is often impossible.