A 59-year-old man comes to the emergency department due to sudden-onset, severe dyspnea and right-sided chest pain while driving to work. The patient has a history of chronic obstructive pulmonary disease, hypertension, gastroesophageal reflux, and chronic kidney disease. He has smoked a pack of cigarettes daily for 35 years. Blood pressure is 130/80 mm Hg and pulse is 102/min and regular. Pulse oximetry shows 89% on room air. On physical examination, the trachea is midline. Tactile fremitus and breath sounds are decreased on the right, and scattered wheezes are present on the left. No heart murmurs are heard. He has trace ankle edema. Which of the following is the most likely underlying mechanism of this patient's current condition?

Question

A 59-year-old man comes to the emergency department due to sudden-onset, severe dyspnea and right-sided chest pain while driving to work.  The patient has a history of chronic obstructive pulmonary disease, hypertension, gastroesophageal reflux, and chronic kidney disease.  He has smoked a pack of cigarettes daily for 35 years.  Blood pressure is 130/80 mm Hg and pulse is 102/min and regular.  Pulse oximetry shows 89% on room air.  On physical examination, the trachea is midline.  Tactile fremitus and breath sounds are decreased on the right, and scattered wheezes are present on the left.  No heart murmurs are heard.  He has trace ankle edema.  Which of the following is the most likely underlying mechanism of this patient's current condition?

Quizplus · Accepted Answer

This patient with chronic obstructive pulmonary disease (COPD) and acute-onset shortness of breath, hypoxia, and unilaterally decreased breath sounds likely has a secondary spontaneous pneumothorax (SSP). SSP occurs in patients with known lung disease (eg, COPD, cystic fibrosis). Other common manifestations include chest pain and hyper-resonance on percussion. Cigarette smoking markedly increases the risk of pneumothorax. Chronic destruction of alveolar sacs leads to the formation of large alveolar blebs, which can eventually rupture and leak air into the pleural space. blebs Diagnosis of pneumothorax is made by chest x-ray, which demonstrates a visceral pleural line beyond which no pulmonary markings are apparent. Tracheal deviation can occur but is rare (more commonly seen in patients with primary spontaneous pneumothorax). Management depends on the size of the lesion and the clinical status of the patient, and ranges from observation with supplemental oxygen to emergency tube thoracostomy. (Choice A) Although rapid bronchial occlusion resulting in extensive atelectasis can result in similar symptoms (eg, chest pain, dyspnea, hypoxia), this patient does not have risk factors for obstructive atelectasis such as a history of foreign body aspiration, malignancy, or severe pneumonia (mucus plug). Moreover, extensive atelectasis frequently causes tracheal deviation toward the collapsed lung. (Choice B) Diffuse bronchial obstruction is seen in an acute COPD exacerbation due to increased production of purulent sputum. Lung examination reveals diffuse rhonchi and wheezing, and symptoms tend to occur more gradually. (Choice C) Acute causes of pulmonary edema (eg, acute myocardial infarction, acute respiratory distress syndrome) most commonly result in symmetric examination findings (eg, bilateral coarse crackles). (Choice D) Transudation of pleural fluid can commonly occur in patients with heart, liver, or renal failure. The presence of fluid in the pleural space is characterized by dullness to percussion and decreased breath sounds over the effusion (usually in the lower lung fields), but the symptoms are typically slower to evolve. (Choice E) Patients with COPD are at increased risk for pneumonia due to chronic inflammation and chronic use of corticosteroids. However, patients with pneumonia typically present with fever and productive cough in addition to chest pain and breathlessness. Educational objective: Secondary spontaneous pneumothorax should be suspected in patients with underlying lung disease presenting with rapid worsening of respiratory symptoms. Rupture of alveolar blebs is the most common cause in patients with chronic obstructive lung disease. References: Pneumothorax risk factors in smokers with and without chronic obstructive pulmonary disease. (http://www.ncbi.nlm.nih.gov/pubmed/25295410)

A 59-Year-Old Man Comes to the Emergency Department Due to Sudden-Onset