The nurse is caring for a client in the post-anesthesia care unit (PACU) who underwent a thoracotomy two hours ago. The nurse observes the following vital sign: heart rate 140 beats/minute, respirations 26 breaths/minute, and blood pressure 140/90 mmHg. Which intervention is most important for the nurse to implement?
A. Administering pain medication as prescribed
B. Notifying the surgeon of the vital sign changes
C. Administering oxygen therapy to maintain saturation
D. Encouraging the client to cough and deep breathe