A 65-year-old man with a long history of smoking comes to the emergency department with shortness of breath and a chronic mild cough. His symptoms progressed gradually over the last week and today have become suddenly worse. The patient has hypertension that is controlled with hydrochlorothiazide. On examination, his temperature is 36.7 C (98 F), blood pressure is 135/85 mm Hg, pulse is 94/min, and respirations are 24/min. Pulse oximetry shows 86% on room air. He has decreased breath sounds over the right chest. His chest x-ray is shown in the image below. Which of the following is the most likely cause of this patient's radiographic findings?

Question

A 65-year-old man with a long history of smoking comes to the emergency department with shortness of breath and a chronic mild cough.  His symptoms progressed gradually over the last week and today have become suddenly worse.  The patient has hypertension that is controlled with hydrochlorothiazide.  On examination, his temperature is 36.7 C (98 F), blood pressure is 135/85 mm Hg, pulse is 94/min, and respirations are 24/min.  Pulse oximetry shows 86% on room air.  He has decreased breath sounds over the right chest.  His chest x-ray is shown in the image below.  Which of the following is the most likely cause of this patient's radiographic findings?

Quizplus · Accepted Answer

11ec160b_3a08_3391_9249_e9d34264b559_MD0001_00 This patient's decreased breath sounds, hemithorax opacification on the right, and deviation of the trachea toward the opacified side are suggestive of a collapsed lung due to bronchial obstruction. Complete collapse of a lung usually occurs following obstruction of a mainstem bronchus (eg, central lung tumors in chronic smokers). As the air trapped in the lung gradually gets absorbed into the blood, there is loss of lung volume due to alveolar collapse (ie, atelectasis), which causes the trachea to deviate toward the affected side. Other mediastinal structures (eg, heart, esophagus, great vessels) may also shift in the same direction. The loss of radiolucent air, combined with shifting of organs into the hemithorax, appears as a completely opacified hemithorax on chest x-ray. (Choice A) Fluid in the alveolar spaces can occur with pulmonary edema. This typically manifests as bilateral fluffy-appearing infiltrates, not unilateral lung opacification. (Choice B) Interstitial lung disease, such as pulmonary fibrosis, would cause reticular markings in both lungs on chest x-ray rather than complete opacification. (Choice C) Intrapleural air accumulation (pneumothorax) would show increased lucency on the affected side, whereas a large pleural effusion can cause complete hemithorax opacification. Tension pneumothorax or a large pleural effusion will cause tracheal deviation away from the affected lung because the excess air or fluid pushes against the mediastinal structures. (Choice D) Pulmonary embolism is a form of pulmonary vascular disease that usually presents with a normal chest x-ray. Characteristic findings such as Westermark sign (area of lucency due to reduced perfusion) or Hampton's hump (wedge-shaped opacity adjacent to the pleura) occur less frequently. Educational objective: An obstructive lesion in a mainstem bronchus can prevent ventilation of an entire lung, leading to obstructive atelectasis and complete lung collapse. Characteristic findings on chest x-ray include unilateral pulmonary opacification and deviation of the mediastinum toward the opacified lung. __________ References: Black, white, and shades of gray: common abnormalities in chest radiographs. (http://www.ncbi.nlm.nih.gov/pubmed/11759553)

A 65-Year-Old Man with a Long History of Smoking Comes