Pneumothorax occurs when air enters the potential space between the visceral and parietal pleura, leading to lung collapse on the affected side. Pneumothoraces may occur spontaneously, especially in the setting of lung disease, or they may result from accidental or iatrogenic trauma. A tension pneumothorax is a life-threatening condition that occurs when the air in the pleural space is under pressure, displacing mediastinal structures and compromising cardiopulmonary function.
Tension pneumothoraces result from injuries to the lung parenchyma or bronchial tree and can act as one-way valves such that air enters the pleural space but cannot escape. The trapped air in a tension pneumothorax causes increased intrathoracic pressure, pushing mediastinal structures contralaterally and reducing venous return and cardiac output. These patients are hypoxic and become difficult to ventilate, with potentially rapid progress to cardiorespiratory collapse and death. If sufficient clues are evident (eg, tracheal deviation, hypotension, decreased breath sounds, hyperresonance), chest decompression should begin without a delay for imaging.
Hemothorax is defined by blood in the pleural space and occurs when the lung parenchyma and the intercostal or mammary vessels are injured. Massive hemothoraces arise with hilar injuries, aortic ruptures, or myocardial ruptures. A tension hemopneumothorax develops when both blood and air are under tension in the pleural space.
A pneumothorax in any patient who has sustained thoracic trauma should arouse suspicion. The patient may complain of an acute onset of sharp pleuritic chest pain, with radiation to the ipsilateral shoulder and associated dyspnea and anxiety. Typical physical findings in pneumothorax include unilaterally decreased breath sounds, hyperresonance to percussion over the affected lung, and asymmetric chest rise. In tension pneumothorax, the patient displays respiratory distress, tachypnea, and tachycardia, and the patient may also experience cyanosis, jugular venous distention, tracheal deviation away from the affected lung, and a pulsus paradoxus.
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Cite this: Sara W. Nelson, Daniel M. Lindberg. A 26-Year-Old Man Who Has Been in a Motor Vehicle Collision - Medscape - Aug 31, 2016.