Pneumothorax occurs when air or gas enters the pleural cavity, the potential space between the visceral and parietal pleura, leading to partial lung collapse. Smoking is the most common risk factor for spontaneous pneumothorax.
Primary pneumothorax occurs in patients without known lung disease and secondary pneumothorax occurs in the presence of known lung disease, such as chronic obstructive pulmonary disease, asthma, cystic fibrosis, interstitial lung disease, infection, connective tissue disease, and cancer. Latrogenic pneumothorax occurs secondary to invasive procedures such as needle biopsy of the lung, placement of a subclavian line, nasogastric tube placement or positive pressure ventilation, Tension pneumothorax results from positive pressure in the pleural space leading to decreased venous return, hypotension, and hypoxia. Hemopneumothorax occurs in 2% to 7% of patients with spontaneous pneumothorax. Treating the underlying disease may help decrease the risk of pneumothorax.
Sudden-onset dyspnea and ipsilateral, pleuritic chest pain are the most common presenting symptoms. The physical examination findings are often subtle. Sinus tachycardia is the most common physical finding. In spontaneous pneumothorax the classic examination findings of ipsilateral decreased breath sounds, reduced chest expansion, and hyperresonance to percussion are often absent. However, in traumatic pneumothorax, the positive predictive value of ipsilateral decreased breath sounds is 86% to 97%. Clinical hallmarks of tension pneumothorax include severe progressive dyspnea, tachycardia (>140 bpm), hypoxia, and ipsilateral decreased breath sounds. Tracheal deviations away from the affected side, distended neck veins, and cardiac apical displacement are late and infrequent signs of progressive tension.
DIAGNOSIS AND DIFFERENTIAL
Pneumothorax is an important differential consideration in patients with pleuritic chest pain, especially in those with underlying lung disease. Patients with pulmonary embolism, pneumonia, pericarditis, pleural effusions, or shingles can present with pain similar to those with pneumothorax. As clinical signs and symptoms are often subtle and variable, the definitive diagnosis is usually established with appropriate imaging. In stable patients with suspected pneumothorax, an erect posteroanterior (PA) chest radiograph is usually the primary investigation. Characteristically this demonstrates a displaced pleural line with absent lung markings extending from the visceral pleura (lung edge) to the chest wall (parietal pleura). Routine expiratory radiographs do not significantly enhance diagnostic yield. The presence of cardiophrenic recess hyperlucency and costophrenic angle enlargement (deep sulcus sign) on a supine anteroposterior radiograph is suggestive of pneumothorax.
Large emphysematous bullae may mimic pneumothorax. To prevent the potentially disastrous consequence of inserting a chest drain into a lung bulla mistaken for a pneumothorax, thoracic computed tomography (CT) should be used to clarify the diagnosis. Bedside ultrasound is a rapid, noninvasive method to diagnose pneumothorax in young, healthy patients with no underlying lung disease.
In normal lung, the visceral and parietal pleura are in direct contact and ultrasound can be used to demonstrate the lung moving back and forth beneath the ribs during respiration (lung sliding), ...