After fracture, especially lower limb fracture or pelvic fracture, it is easy to lead to thrombosis. If the thrombus blocks the deep artery of the lower limb, it may cause poor blood circulation in the lower limb, resulting in frequent swelling of the lower limb, which can be relieved when the affected limb is elevated, but the symptoms will be aggravated when the affected limb drops. If the thrombus is free in the blood vessel and invades the important organs of the body, the most common is acute pulmonary embolism, resulting in acute respiratory distress and life-threatening cyanosis. If brain embolism occurs, acute stroke will appear, and if coronary artery embolism occurs, acute myocardial infarction will occur, and in serious cases, cardiac arrest and death will occur.