...if you are regularly going against enemies that use the kind of heat necessary to instntly cauterize wounds, I wish both yourself and your students luck. I'm afraid I cannot add much more information without knowing the specific kinds of attacks these people are using - Burning Palms or some kind of fire projectile is the only thing I can think of off the top of my head.

In such a case, all I can really suggest is dealing with the enemy as fast as possible and hope that they do not hit anything vital in your students. Burned major organs are not pretty and damn hard to heal, even for an experienced medic.