Sub is a partial opiate that hogs your entire opiate receptor. So it will try and keep the Dilaudid out. But it has the potential to make you very sick if you get precipitated withdrawal.
You definately need to talk to both your Sub doctor and your surgeon, at least a week before surgery. Probably best to talk to them now, so they can a game plan figured out. If the surgeon is not aware that you are on Sub and they give you Dilaudid or any other opiate, it won't work properly and may cause you to become very, very sick.
Don't mess with this....talk to your doctors.
Let the surgeon know your taking it. I would talk to him at least a week before surgery .
Dilaudid is a narcotic....I would talk to your doctor about it. He may adjust your dose