A 16-year-old boy is rushed to the emergency room after sustaining a stab wound to the chest during a fight. Physical examination reveals a 1-cm entry wound at the right 5th intercostal space in the midclavicular line. His temperature is 37degC (98.6degF), respirations are 35 per minute, and blood pressure is 90/50 mm Hg. A chest X-ray shows air in the right pleural space. Which of the following pulmonary conditions is the expected complication of pneumothorax arising in this patient?

Atelectasis. Pneumothorax, which is defined as the presence of air in the pleural cavity, may be due to traumatic perforation of the pleura or may be spontaneous. Traumatic causes include penetrating wounds of the chest wall (e.g., stab wound or a rib fracture). Traumatic pneumothorax is most commonly iatrogenic and is seen after aspiration of fluid from the pleura (thoracentesis), pleural or lung biopsies, transbronchial biopsies, and positive pressure-assisted ventilation. Pneumothorax causes collapse of a previously expanded lung, a condition that is termed atelectasis. Additional causes of atelectasis include deficiency of surfactant, compression of the lungs, and bronchial obstruction. Chylothorax (choice B) is the accumulation of lymphatic fluid within the pleural space and is a rare complication of trauma.Diagnosis: Atelectasis