Pneumothorax incidence status Between 1991 and 1995, the annual number of pneumothorax visits in the United Kingdom was 24/100,000 for men and 9.8/100,000 for women, and the hospitalization rate was 16.7/100,000 for men and 5.8/100,000 for women. The overall incidence rate refers to the rate of new pneumothorax in a given population over a period of time. According to this calculation, there are 8,000 hospitalizations for pneumothorax in the UK each year, and the average hospital stay per person for pneumothorax is about 1 week, so pneumothorax consumes about 50,000 bed-days of medical resources in the whole country, and the economic burden caused by hospitalized patients amounts to £13.65 million, and the annual cost of pneumothorax treatment in the US is as high as $130 million. Types of pneumothorax Depending on the cause, pneumothorax can be classified as primary spontaneous pneumothorax, secondary spontaneous pneumothorax, or traumatic (medical or other) pneumothorax. Traumatic pneumothorax is not included in the scope of this review. Based on the presence or absence of underlying lung disease, spontaneous pneumothorax can be divided into primary and secondary, with significant differences in morbidity, mortality, severity of symptoms (degree of hypoxia during the attack), and management strategies. Although primary pneumothorax occurs mostly in healthy individuals without significant underlying lung disease, most of such patients will have some unspecified abnormal lung lesions. In a small case-control study, emphysema-like changes were seen on CT in 81% of 27 non-smoking patients with primary pneumothorax, whereas none of the 10 non-smoking healthy volunteers showed such changes. Complication rates and mortality rates are higher in secondary pneumothorax than in primary pneumothorax because of the reduced cardiopulmonary reserve function due to the presence of underlying lung disease. Tension pneumothorax is often life-threatening and must be treated as a matter of urgency. In patients with tension pneumothorax, the rupture of the dirty pleura is a one-way valve, so the air enters the pleural cavity when inhaling and cannot be exhaled when exhaling, resulting in the accumulation of more and more air in the pleural cavity and the continuous increase of internal pressure, which compresses the vena cava and makes the return flow obstructed, and also affects the output function of the heart. Clinically, high concentration of oxygen, emergency puncture and decompression of the second intercostal space in the midclavicular line are often required, and further placement of closed drainage of the chest cavity. Because tension pneumothorax affects hemodynamic stability and can be life-threatening, it usually requires urgent management before imaging can confirm the diagnosis. Imaging of tension pneumothorax is characterized by a mediastinal deviation to the healthy side, and in some patients, subluxation of the affected diaphragm and widening of the rib cage due to increased intrapleural pressure on the affected side. Diagnosis Most patients with pneumothorax can be diagnosed by typical clinical features, while a small proportion of patients with pneumothorax have insignificant symptoms and need to rely on imaging for diagnosis. Most pneumothoraces have an acute onset and often present with sudden onset chest pain, chest tightness and shortness of breath, but some patients are symptom-deficient. Secondary pneumothorax is more obvious or severe than primary pneumothorax due to the presence of underlying lung disease. Signs of pneumothorax mainly include decreased respiratory motion, percussion drum sounds, and decreased or absent breath sounds on the affected side on auscultation. Hypotension and tachycardia suggest the possible presence of a tension pneumothorax. Most patients can be diagnosed by standard inspiratory-phase chest radiographs. Because chest radiography cannot improve the diagnostic accuracy of pneumothorax, the routine use of chest radiography is not recommended. The typical presentation of a pneumothorax is an outwardly convex arc of thin linear shadows, called pneumothorax lines, with increased translucency and loss of lung texture outside the lines and compressed lung tissue inside the lines.