The holidays are approaching and many friends are ready to go on a trip. A considerable part of middle-aged and elderly friends may take a long-distance flight to the warm south, and here we remind you: long-distance travel must pay attention to pulmonary embolism! Pulmonary embolism is a disease with a very high mortality rate. It occurs because of the formation of thrombus in the venous (especially lower limb veins and pelvic veins) system, in which more than half of the emboli will be dislodged and reach the pulmonary circulation with the blood flow, and finally block the pulmonary artery and its branches. After pulmonary embolism occurs, the ventilation of the lungs is severely restricted and blood oxygenation decreases, accompanied by an increase in pressure in the right heart system. Patients may experience pallor, cold sweat, dyspnea, chest pain, cough, and even syncope and hemoptysis. Some patients may have symptoms of cerebral hypoxia such as convulsions and coma. If a large arterial embolism occurs, the patient may die suddenly. And why does long-distance travel lead to pulmonary embolism? People who fly in airplane, especially in economy class, have little space to move around, and the blood is pooled in the venous system of lower limbs. Coupled with the fact that he feels inconvenient to go to the toilet, he will deliberately reduce drinking water, which makes the blood concentrated and the viscosity increase, all of which will increase the formation of venous thrombosis in the lower limbs. If the patient suddenly stands or walks, this thrombus may dislodge and lead to pulmonary embolism, which is life-threatening. The same goes for long bus rides and long train rides, both of which increase the chances of pulmonary embolism. Whenever a pulmonary embolism occurs, it must be treated in a hospital because the mortality rate of pulmonary embolism is relatively high. High-risk patients should be treated with thrombolysis or even surgical removal of the embolus. Patients with milder symptoms also need oral drug anticoagulation therapy, which needs to be taken for at least 3 months. We remind you that if you travel long distance recently, especially by long-distance airplane, you must pay attention to increase the time and frequency of activity, suggesting at least half an hour of activity, massage the calf appropriately, and drink a little more water as much as possible. If once you have chest tightness, shortness of breath discomfort symptoms, immediately contact the flight attendant, as soon as possible to seek medical attention.