The typical symptoms are sudden onset of chest pain, followed by chest tightness or dyspnea, and an irritating dry cough. There are also patients with slow onset and even no conscious symptoms. Some patients have triggers such as coughing hard, holding heavy objects, breath-holding or strenuous activities before the onset of the disease, while many patients develop the disease during normal activities or quiet rest. The severity of symptoms depends on the urgency of onset, the degree of lung atrophy, the primary lung disease, and the status of pre-existing cardiopulmonary function. Many patients (especially those with primary pneumothorax) have a pneumothorax already present a few days before the onset of symptoms, and, the longer this phase is, the more likely it is that recurrent pulmonary edema will occur. In general, patients with secondary pneumothorax have more severe symptoms than patients with primary pneumothorax, and the degree of respiratory distress is not proportional to the degree of pneumothorax. The presence of a tension pneumothorax should be considered when a patient presents with hemodynamic disturbances. Pneumothorax signs depend on the amount of air accumulation. A small amount of pneumothorax may have no obvious signs. When the amount of gas is large, the affected side of the chest is full, the respiratory motion is diminished, the palpable fibrillation is diminished or absent, the percussion is bulging, and the auscultatory breath sounds are diminished or absent. In patients with emphysema complicated by pneumothorax, although the respiratory sounds are weakened on both sides, the weakening on the pneumothorax side is more obvious, even if the amount of pneumothorax is not much, so attention should be paid to the left-right comparison and the up-down comparison during percussion and auscultation. The mediastinum is shifted to the healthy side when there is a large amount of pneumothorax. In the case of right-sided massive pneumothorax, the hepatic turbid boundary is shifted downward, and in the case of left-sided pneumothorax or mediastinal emphysema, a click sound or high-pitched metallic sound consistent with the heartbeat is heard at the left sternal border (Ham-man sign). The presence of tension pneumothorax should be considered when the patient presents with cyanosis, profuse sweating, severe shortness of breath, tachycardia, and hypotension.