Review Question - QID 105863

This patient with shortness of breath, pleuritic chest pain, tachycardia, tachypnea, hypoxemia, and clinical signs of lower extremity deep venous thrombosis (DVT) likely has developed a pulmonary embolism (PE). For the majority of patient's with PE, chest radiograph is normal with no acute findings.

Pulmonary emboli most often originate from DVTs in leg veins, and the classic patient is often described as either pregnant/postpartum, a current smoker or OCP user, or someone on long distance travels. Virchow's triad is the classic description of three broad categories that are thought to play a role in DVT formation: stasis, endothelial damage, and hypercoagulable states. Well known acquired risk factors include recent surgery, immobility and cancer. Chest radiographs in PE are most often normal, but may show a pleural effusion, Hampton's hump (a wedge shaped infarct), or a Westermark's sign (oligemia in the embolized lung zone). Treatment for all patients includes anticoagulation with heparin and warfarin, unless otherwise contraindicated.

Wilbur et al. discuss the diagnoses of DVTs and PEs. When the likelihood of DVT is low, a negative D-dimer can help exclude a DVT. If the likelihood of DVT is intermediate or high, ultrasound should be performed. PEs, which are associated with greater mortality, are often found as a consequence of DVTs. Helical computed tomography is considered to be the diagnostic test of choice for someone with a suspected PE.

Lavorini et al. report on the diagnosis and treatment of PEs. Because PEs present in such a non-specific manner and the risks of anticoagulant treatment are so great, there is great effort to either refute or establish the diagnosis so that the proper care of the patient can be undertaken. When diagnostic tests are combined with clinical assessments of patients experiencing PE-like symptoms, the overall accuracy of tests are higher.

Illustration A depicts a helical CT noting saddle emboli in the pulmonary arteries. Illustration B is a chest radiograph demonstrating a Hampton's hump in a patient with a RLL PE. Illustration C is a picture of an IVC filter, which is used in patients that have a contraindication to anticoagulation.

Incorrect Answers:
Answer 1: Hyperinflated lungs with flattening of the diaphragm would be suggestive of chronic obstructive pulmonary disease (COPD). While COPD certainly causes shortness of breath, it is not sudden onset. It is often accompanied by cough, and develops over the course of years.

Answer 2: Lobar infiltrate on chest radiograph would be suggestive of a lobar pneumonia. While shortness of breath is often present, cough would also be expected as well as fever.

Answer 4: Unilateral absence of lung markings on chest radiograph would suggest the presence of a large pneumothorax. While a pneumothorax could cause sudden onset shortness of breath and pleuritic chest pain, this patient's history and exam are more suggestive of pulmonary embolism.

Answer 5: A wedge shaped infarct may be visualized on chest radiograph in some patients with pulmonary embolism. However, this is not a reliable finding and is only present in the minority of patients with PE. More often, lung infarcts are visualized on CT imaging.

Bullet Summary:
Most patients with pulmonary embolism have no acute findings visualized on chest radiographs.