Is It Advisable To Apply Warm Compresses At Injection Site?

I had a ct scan with contrat today. However the power injector caused the contrast to leak outside the vein into other tissue, severe pain occurred but later subsided. The iv remained in my arm and the nurse extracted about 4 viles of bloody fluid from the site. Instructions were to apply a couple of warm compresses. Other things I read suggest cold not hot. First, is cold or warm correct? Other concerns that I should look for?