Hmmmm, you might try another search . .
I tried to give links to literature, to support evidence-based practice.
My first-hand experience was using warm compresses (preceded by confirmation of a good IV and CAREFUL observation of the site during infusion, so you can halt the injection if you see swelling), thinking the warmth would dilate capillaries = increasing blood flow to the affected area, to aid in absorption of the contrast.
Others I've spoken with advocated cold compresses/ice packs, to decrease inflammation at the site.
I preferred the warm compresses because the pts reported the site felt better and the swelling diminished after 20-30 min of application.
I'm interested to hear any other opinions/experiences, or see any pertinent links.