The typical symptom of air embolism is early loss of consciousness, which may or may not be accompanied by convulsions or other central nervous system symptoms. Mild signs and symptoms ranging from behavioral changes to mild hemiparesis may sometimes occur. Excessive pulmonary distension alone or with gas embolism may produce mediastinal and subcutaneous emphysema. Pneumothorax is rare but more severe. Hemoptysis or bloody foamy sputum suggests lung damage. Arterial gas embolism of medical origin is rare and should be suspected if there is a failure to regain consciousness after cardiac surgery. The common cause of arterial gas embolism, hyperinflation of the lungs, is mostly due to breath-holding during ascent from a dive equipped with an underwater inhaler. The escape of air during deep water can accelerate the event. If the swimmer enters the air source, the depth of the pool is sufficient to cause a gas embolism, even if only one breath is taken underwater. During ascent, the air absorbed at any depth can expand and, if not allowed to escape freely, can cause the lungs to expand and alveolar pressure to rise, possibly leading to gas entering the pulmonary veins. If the gas reaches the carotid artery, embolism of the cerebral vessels is almost inevitable. Air embolism prevention 1. Before infusion, make sure to check whether the connections of the infusion set are tightly connected and not easy to slip off, and the air must be led to ashes during infusion and replaced in time during infusion. Observe closely during pressure infusion and blood transfusion and do not leave the patient. 2.When connecting the drainage tube after chest injury or hepatobiliary surgery, be sure to seal the wound to avoid gas entering the artery.