You are covering a busy hospital service at night when you are paged to evaluate a 78-year-old man with sudden onset of dyspnea. A quick review of the patient’s chart reveals that he was diagnosed with small cell lung cancer 2 months earlier. In spite of a regimen of radiation and chemotherapy, he was admitted to the hospital 3 days earlier with a suspected pathologic fracture to the right femur. He has no other known metastases. Thirty minutes ago he became acutely short of breath. Current vital signs include a heart rate of 115 beats/minute, blood pressure of 92/69, and respiratory rate of 32. Oxygen saturation is 94% on 4 L of oxygen via nasal cannula. He is anxious and tachypneic, but lung sounds are clear and symmetric. The heart rhythm is regular and no murmurs are appreciated. What is the best next step in the management of this patient?
A. Immediately administer empiric antibiotics for coverage of hospital-acquired pneumoniaAlthough there are many causes of acute dyspnea in the hospitalized patient, the most likely etiology in this patient is pulmonary embolism. In addition to the rapid onset of symptoms, the patient’s risk factors for development of a venous thromboembolism (malignancy, bone fracture, immobility, and advanced age) are suggestive of a PE. Virchow triad predisposing to clot formation includes hypercoagulability, blood stasis, and endothelial injury. Specific risk factors for venous thromboembolism include recent surgery, trauma or pregnancy, prior thromboembolic event, obesity, and hypercoagulable state. Potential etiologies of the hypercoagulable state include prothrombin gene mutation, antiphospholipid antibody, activated protein C resistance, hyperhomocysteinemia, and deficiencies in protein C, S, or antithrombin III. Assuming no absolute contraindication, the first-line therapy for a PE is immediate anticoagulation. Because the majority of deaths from PE occur within 1 hour of onset of symptoms, it would be inappropriate to withhold treatment until confirmatory testing (CT or V/Q scan) is completed. Evaluation of a V/Q scan (answer d) may be complicated by the likelihood that he has an abnormal chest x-ray given his history of lung cancer and thoracic radiation. In this circumstance, a CT pulmonary angiogram would be the preferred test. Although a diagnosis of pneumonia could be considered (answer a) the rapidity of onset of symptoms, the lack of purulent sputum and the clear lung fields make this diagnosis less likely than PE. There should be time to evaluate for pneumonia once the patient is stabilized. Answer c is incorrect because the patient likely has sinus tachycardia as a result the PE; sinus tachycardia will improve with treatment of the underlying cause. Although the patient may symptomatically improve in the short term with anxiolytic therapy (answer e), his low blood pressure may limit the use of benzodiazepines. If the patient were having an “anxiety attack” rather than a PE, the blood pressure would usually be elevated rather than depressed.