[Answered]: An 81-year-old man was admitted to this hospital…

An 81-year-old man was admitted to this hospital with fever, cough, and shortness of breath. The patient had been in his usual state of health until 3 days before this admission, when fever and cough developed. On the morning of admission, he noted an abrupt onset of shortness of breath at rest and dyspnea on exertion. There was also substernal chest pain on the left side that worsened with deep breaths and when he lay down. The patient’s son called emergency medical services, and the patient was brought to the emergency department of this hospital for further evaluation. On arrival at the emergency department, the patient described ongoing chest pain and shortness of breath. The son reported that the patient had fallen at home 2 days before admission, but the patient did not remember falling and the son was not able to provide details about the nature or circumstances of the fall. The patient reported no pain in his abdomen, arms, legs, or groin and no headache. The patient had a history of hypertension. During a previous evaluation for cough, he was reportedly told that he had a lung disease that had “caused the lung tissue to harden.” Before the onset of his most recent symptoms, he had walked outside on a daily basis without limitation from shortness of breath. He took an unknown medication for hypertension. The patient did not smoke tobacco, use illicit drugs, or drink alcohol. He lived in an apartment with his wife. On examination, the temperature was 37.9deg C, the blood pressure 157/95 mm Hg, the pulse 112 beats per minute, the respiratory rate 30 breaths per minute, and the oxygen saturation 91% while the patient was breathing ambient air. The respiratory rate decreased to 28