Aha, got it. Alright.
Yes, saline can be applied while you and the patient are at the tent in TAKISTAN. PAK only in medical hum or ambulance.
In CHERNARUS, everything works everywhere.
Expressing my feelings:
1. Well, If i am not wrong, in modern wars, combat medics can apply saline, plasma and blood, just attaching it to the soldiers helm or somewhere in the gear. The soldier will have free movement if stable and not harmed in legs or arms, and the needle goes somewhere better then the elbow area, like: hand or neck. I heard this from a Doctor from Brazillian Army: if the soldier is combat effective, plug the needle to his hand or neck and he is god to shoot his way with the doctor back to medevac.
2. And, since we are speaking realistic situations, if you get shot in the leg, is not a bandage that will fix your bones back together and stitch your wounds.

Don't want to be a pain in the ass, but, it doesn't make sens for the saline not to work in the field and one bandage "unbreak" a bone and stitch the wound and it never reopens. At least until you get a surgical kit or PAK.