The IVP med physically cannot go up many lines. If you look at your IV tubing, it should have an antireflux valve. What I'm saying is you should have a valve that PREVENTS the med from at least reaching the IVF bag. Even if it WERE to get all the way up to that valve, it would stop there. Once you stop pushing the med, if you have the IVF wide open then your med will eventually infuse with the wide open solution (that is, if it's actually infusing).
I *do* pinch the line, but that's because I NEVER run ANY IVF's free flow. I live in the ICU world, so NOT having a super accurate I&O is blasphemy for me
If you DON'T pinch the line and the IVF are on a pump, you'll set the pump off by saying, "Error occlusion" because you're putting back pressure in the system. If you pinch it, you don't have this problem.
Finally, in YOUR world, I would think this free flow/IVP system would work really well and have a nice controlled rate of getting a med. That being said, in YOUR world, I wouldn't think pinching would be needed. Also, you need to follow your formulary direction for IVP meds. If you're suppose to IVP Lopressor 5mg over 2minutes, stick with that. Some places do 2-5 minutes. Others do over 5minutes. Know your rules and push slow ... unless you're in a code situation, then GO GO GO!