Q. A 65-year-old female underwent surgery for a total hip replacement 3 days ago. The procedure was uneventful and the patient has recovered as expected. You are called to evaluate the patient because she has developed acute cyanosis, shortness of breath (dyspnea), and substernal chest pain. On physical examination, the patient is diaphoretic and in obvious acute respiratory distress. She has no rashes or lesions. The patient is on a cardiac monitor and appears to be in normal sinus rhythm. Her respiratory rate is 40/min and her breathing is labored. Her blood pressure is 100/70 mm Hg. Cyanosis is present, and chest auscultation demonstrates decreased breath sounds in the lower lobe of the right lung, as well as adventitious breath sounds in all lobes. Based on the information provided, what is the most likely diagnosis in this patient?