Nubain Problems in chronic pain pts

Hey there! I work in an interventional Cardiac unit where we regularly pull arterial lines post caths, and Nubain is frequently ordered for the line pull. However, I've had a couple of bad experiences with Nubain in pts that have been on a pain med at home for a long time; ie: Darvocet, Percocet, etc. where after I give the Nubain the pt goes absolutely nuts, acting very restless, c/o shaking and tingling feeling. We were told by a cardiac cath lab nurse that this was because Nubain competes for the pain receptor with the pain med and takes its place, effectively detoxing the pt very quickly. Has anyone come across this problem or heard about any research done on it? Thanks for reading!