I never apologize for calling a physician. It's BOTH of our jobs to care for the patient whether it be 10AM or 2AM. I will clearly state that A) I am concerned about a change in the patient's status, B) I have a direct order to notify the physician if X, Y, or Z occurs or C) I am required to notify a physician for critical labs, etc. If they don't want to be notified about a certain event, ask them if you can discontinue that order, otherwise they will continue to be notified. I've only been yelled at once in my 8 months so far *knocks on wood* but actually received a return phone call from that physician stating that I was right to call him, and he even apologized.
If you feel a physician is ignoring your concerns, file a complaint, notify your NM, get your charge nurse involved and call an RRT if you have that available at your facility. Better to be safe than sorry. Continue to be an advocate for your patient!!