PS from a professional in the field of EMS.
Cell phone reception may alter your interpretation of the following; someday I may actually be able to get reception on the trail. So far I have not. Ever. You may be luckier than I.
A person is injured? Stop where you are. Sit, evaluate and treat. Here are some thoughts:
General thoughts on leaving the injured for help: You may if essential leave an injured individual if there is no risk of the person going into shock and the individual is calm and rational. If the person is in shock or in risk of going into shock do not leave them. You must shelter in place until the risk of shock is past. Treat for shock where you are. Exude confidence.
Head injuries and leaving for help: Do not leave a person if there is any risk of the person becoming irrational. This includes any kind of blow to the head. Even a very mild concussion (which does NOT require loss of consciousness) can result in progressive retrograde amnesia (the person seems OK after the blow, but a short time later cannot remember what happened previously). This is a potentially fatal issue if the person develops amnesia and suddenly finds himself alone in the wilderness, confused and irrational. Even an apparently mild blow to the head can result in a concussion that yields this scenario. If you know how to do a neurological exam, it would be helpful. It would not help to discuss it here; you need experience and instruction to interpret what you see, beyond what can be conveyed in a post. One further note on head injuries: injuries resulting in persistent unconsciousness, delirium or a depressed area of the skull are extremely emergent. None of these can be successfully treated outside a hospital.
Bleeding: Everything depends on how serious the cut and how seriously the patients ability to move has been compromised. If the patient can walk and the risk of new bleeding is not great you are good. If the person cannot walk without risk, this may help: If shock does not threaten, there is no risk of arterial involvement and the patient has NO SIGNIFICANT BLEEDING it is probably safe to go for help. Remember though, blood loss can cause shock as can even the sight of blood from a comparatively minor cut. I once saw a patient go into shock for the loss of maybe an ounce and half of blood; it was fear, "I can see the bone! I can see the bone!" If the person can walk, you may see dizziness, nausea, dehydration, and possibly terror en route. Exercise and weight carrying will cause a rise in blood pressure and the bleeding may resume.
The real issue perhaps is when do you leave for help and when do you stay put. If the patient can walk without risk, you and he are good.
If not, is the trail heavily traveled? Are you miles from the roadhead? There is no ready answer to these questions. I am often a half days walk from a road and often in difficult terrain. Remember, you not only need to get to the trailhead, but get to somewhere where help can be summoned. An experienced wilderness rescue team will need to be assembled (often from their day jobs) and you then have to return and guide them to the patient. An hour walk to the trailhead, an hour to summon help, an hour to assemble the team, an hour to get equipment to the trail, an hour to walk in. You see the mathematics. What is the math like if it is four hours to the nearest road?

Edited by EMT Dave (12/19/17 06:58 PM)