While Caring for a Patient Who Is on a Continuous

While caring for a patient who is on a continuous passive motion machine (CPM) after a total knee replacement, a nurse notices that the patient is grimacing. Pain medication is not due for 2 hours, but the CPM machine is supposed to continue for another 20 minutes. The best action by the nurse is to

A) Call the physician for additional pain medication.
B) Encourage the patient to bear it for 20 minutes longer.
C) Instruct the patient to tense and then relax his or her leg muscles.
D) Teach the patient relaxation techniques.