I would call dispatch and ask their opinion.... Whoops.... Wrong thread.
I take it we are asking this about situations where implied consent does not apply.
If a patient refuses an IV, with out being through more advanced ethics class then my EMT book offers, I would explain to them the situation, the benefits of the IV procedure, and what is associated with it. If they still refuse, of course you would want it documented. I may even go as far as having the patient sign that portion of my PCR affirming they denied the treatment.
My question, if they deny it while conscious, and then they lose consciousness, does implied consent take over?