Just a few points of this topic, since it has come up a couple times in emails from fans of Arduin Eternal.
First off, Medical skill, First Aid has a chart on pg 327 that shows that to stop bleeding or render care takes a TD 50. Against Critical wounds its a TD 150 and requires a complications check. Critical wounds equal internal or organ damage; serious stuff, let me tell you!
Medical skill aside, other healing, such as that from potions, prayers, rituals and like cannot handle critical wound damage unless specifically set for it, such as the OP 5 ritual of healing critical wounds. Normal healing may counter the HP damage but will not lift the status or reattach a limb if severed. It would also not stop bleeding though it may temporarily heal the HP damage.
Regeneration can counter Critical effects but it takes longer. It treats an effect as attribute damage for healing purposes, converting things like X #HP bleeding to an equivalent amount of attribute damage for the purpose of determining how long or when its healed. Status effects, like Unsettled or Shaken are considered equivalent 5 characteristic damage for the purpose of how fast healed.
Example: A being that had regenerate
at the rate of 3 HP/1 attribute/1 characteristic per melee round. Would heal damage in that order, at that rate. So, if they took 28 HP damage, 3 STR impairment, 12 BODY damage and had a Staggered Status, they would heal the HP damage, the attributes next, then the characteristic (BODY) and the status last. It would take 10 melee rounds for the HP, 3 m/r for the STR 12 for the BODY and 5 for the Staggered status. In total, 30 m/r or 10 minutes to heal it all.