Air embolism is a very serious clinical event in which gas enters a vein and travels with the bloodstream to the right atrium, right ventricle, and thus to the pulmonary artery. If the amount of gas entering the bloodstream is relatively small, the gas is absorbed in the process and generally does not cause clinical symptoms. If more gas enters, it will cause symptoms such as breath-holding and dyspnea, and in serious cases, it will block the pulmonary artery, causing ischemia, hypoxia and respiratory failure of the lungs, thus causing death of the patient. Clinically, it is mostly seen in trauma of large veins, such as internal jugular vein injury, because the pressure inside the vein is negative, so air can easily enter, and it should be paid enough attention during the surgery.