Tracy,
Is your Dad still on pain meds? The constipation may be a combination of pain meds, liquid diet and hydration. If he hasn't had a movement in over a week, it's time to get serious about it. You would be surprised how many folks show up in ICU due to an impaction.(stool so solid the patient CAN'T move it out.) Not trying to alarm you, just a precaution to catch this sort of thing early and prevent a real problem later. Pain meds slow down the peristalsis or movement of the intestinal tract, liquid diets sometimes don't have the "bulk" the intestine needs to work things along, and hydration helps keep things soft. Plus, if he isn't up and about much, that's just another thing that will gum up the works.
Talk to the docs about these things and see what they suggest.

Andrea