An 18-year-old man comes to the emergency department with sudden-onset right-sided chest pain and dyspnea. The patient was at home watching a football game on television when his symptoms abruptly started. He now has pain with deep breaths. He has no other medical problems and takes no medications. The patient has smoked a pack of cigarettes daily for the past 2 years. His respirations are 24/min. Physical examination shows a thin, tall patient in acute distress. The right side of the chest is hyperresonant to percussion and lacks audible breath sounds. His chest x-ray is shown below.
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Which of the following conditions most likely led to this patient's presentation?
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This young male patient with sudden-onset unilateral chest pain, dyspnea, and absent breath sounds on examination likely has primary spontaneous pneumothorax (PSP). PSP is nontraumatic and is found in patients without preexisting pulmonary disease (eg, cystic fibrosis). It occurs when a large change in the alveolar or intrapleural pressure results in a break in the visceral pleura and subsequent trapping of air between the parietal and visceral spaces. The superficial alveoli in the apices experience greater pressure changes (due to the weight of the lungs pulling down on the apical tissue), predisposing them to the formation of subpleural blebs. The blebs then can spontaneously rupture through the visceral pleura, frequently while the patient is at rest.
Tall, thin males around the age of 20 are most commonly affected. Although the most important risk factor is smoking, taller individuals also appear to be at higher risk due to more negative intrapleural pressure in the lung apices.
(Choice B) Centriacinar emphysema occurs as the larger proximal bronchioles are destroyed, usually as a result of exposure to tobacco smoke in patients with chronic obstructive pulmonary disease. It predominantly affects the upper lung lobe and initially spares the superficial alveoli.
(Choice C) Compensatory hyperinflation results when normal lung parenchyma expands in response to loss of adjacent lung volume (eg, segmental/lobar collapse or surgical removal). PSP results in collapse of adjacent lung tissue due to extrinsic compression by intrapleural air and does not result in parenchymal expansion.
(Choice D) Obstructive hyperinflation occurs when a lung segment expands due to a partial obstruction (eg, bronchogenic carcinoma) of the airway supplying it. On inspiration, the airway expands, which allows the movement of air into the segment; however, as the airway closes on expiration, air is trapped behind the obstruction. In an otherwise healthy young patient, it is unlikely to be the cause of PSP.
(Choice E) Panacinar emphysema occurs more commonly in the lower zones and anterior margins of the lungs. It destroys the entire acinus uniformly and is associated with alpha-1 antitrypsin deficiency. Although pneumothorax can occur in these patients, it is usually preceded by symptoms of emphysema.
Educational objective:
Primary spontaneous pneumothorax occurs in patients without preexisting pulmonary disease when a large change in the alveolar or intrapleural pressure results in a break in the visceral (eg, ruptured superficial bleb) pleura and air trapping between the pleural spaces.