Fat embolismsyndrome is one of the early and critical complications of severe trauma and fracture. It is a clinical condition with respiratory distress and central nervous system disorders caused by fat and lipid substances from bone marrow and other tissues that accumulate in large volumes in the blood with reduced emulsification capacity and abnormal physicochemical properties and embolize in the blood vessels of lungs, brain, skin and other organs. Traditionally, fat embolism syndrome (FES) is defined as dyspnea, impaired consciousness and petechiae 24 to 48 h after pelvic or long bone fracture. Zenker first described the process of fat embolism in 1862, and Bergman made the first clinical report of FES in 1873. Reports on the incidence of FES vary widely, but in general are proportional to the severity of the trauma and the number of long bone fractures. It rarely occurs in patients with upper extremity fractures, and the incidence in children is only 1% of that in adults. With aggressive open surgical treatment of the fracture, its incidence has decreased substantially. However, FES remains a serious life-threatening complication after traumatic fracture. Diagnostic criteria for fat embolism syndrome (FES): The currently applied diagnostic criteria are based on those proposed by Gurd and Wilson (1974) with modifications for clinical use. The main criteria are ① subcutaneous bleeding spots, commonly found in the skin and mucous membrane areas of the head, neck and upper chest; ② respiratory symptoms, manifested as shortness of breath (>35 times/min) and blizzard-like shadow of both lungs on chest X-ray; ③ brain symptoms not due to cranial injury. Secondary criteria ① decreased partial pressure of blood oxygen (<8?0kPa); ② decreased hemoglobin (<100g/L). Reference criteria ① increased pulse rate (>120 beats/min); ② fat droplets in urine; ③ fever (>38℃); ④ blood sedimentation (>70mm/h); ⑤ free fat droplets in blood; ⑥ decreased platelets; ⑦ increased lipase in blood; ⑧ emboli in retina by fundoscopy. Among the above criteria, 2 of the major criteria or 1 of the major criteria and 4 or more of the minor or reference criteria can determine the clinical diagnosis. If there is no major criterion, only 1 secondary criterion and 4 reference criteria are considered as occult FES. Drug treatment is based on hormone therapy, hypertonic glucose, albumin and peptidase inhibition. Diuretics are used in the presence of pulmonary edema. Cerebral fat embolism causes cerebral edema and mostly scattered perivascular punctate hemorrhage.