The following are multiple choice questions (with answers) about medical knowledge.   **Question:** A 55-year-old man recovering from knee replacement surgery complains of breathlessness in the postoperative ward. He has been confined to bed for the past 5 days and is under observation. He felt a sudden difficulty in breathing and called for the ward nurse. He says that he is unable to take deep breaths and has a sharp pain on the right side of his chest with each inspiration. His temperature is 37.5°C (99.8°F), the pulse is 111/min, the respirations are 31/min, and the blood pressure is 85/55 mm Hg. He experiences pain in his right calf on dorsiflexion. There are no other prominent findings on physical examination. His chest X-ray does not show anything significant. The ECG reveals sinus tachycardia. Which of the following is the best course of management at this time?   (A) Subcutaneous fondaparinux   (B) Inferior vena cava filter   (C) Ventilation-perfusion scan   (D) Lower extremity doppler
['(A) Subcutaneous fondaparinux <> answer', 'The following are multiple choice questions (with answers) about medical knowledge. <> instruction', '(A) Subcutaneous fondaparinux \n (B) Inferior vena cava filter \n (C) Ventilation-perfusion scan \n (D) Lower extremity doppler <> possible answers', '  A 55-year-old man recovering from knee replacement surgery complains of breathlessness in the postoperative ward. He has been confined to bed for the past 5 days and is under observation. He felt a sudden difficulty in breathing and called for the ward nurse. He says that he is unable to take deep breaths and has a sharp pain on the right side of his chest with each inspiration. His temperature is 37.5°C (99.8°F), the pulse is 111/min, the respirations are 31/min, and the blood pressure is 85/55 mm Hg. He experiences pain in his right calf on dorsiflexion. There are no other prominent findings on physical examination. His chest X-ray does not show anything significant. The ECG reveals sinus tachycardia. Which of the following is the best course of management at this time? <> context@']