Fat embolism syndrome after humerus and pelvis fracture complicated by acute kidney injury requiring blood purification: a case report and literature review

Abstract Background Fat embolism syndrome (FES) is a rare syndrome that typically occurs 12–72 h after long bone or pelvic fractures with a classic triad of respiratory distress, neurologic changes, and petechial rash. Although Gurd’s criteria for FES include anuria or oliguria, the mechanism of acute kidney injury (AKI) remain unknown. Here, we present a case of FES complicated by AKI that required blood purification. Case presentation A 79-year-old woman was admitted to our hospital because of a right humerus and pelvic fracture caused by a traffic accident. On the second day of hospitalization, she developed impaired consciousness, respiratory failure, and disseminated intravascular coagulation (DIC). Chest radiography revealed bilateral diffuse alveolar infiltration. Brain magnetic resonance imaging revealed diffuse high signal intensity on diffusion-weighted imaging and diffuse low signal intensity on susceptibility-weighted imaging in the cerebral and cerebellar regions. The diagnosis of FES was confirmed and the patient was treated with methylprednisolone (40 mg/day) and ulinastatin. On the third day of hospitalization, she was admitted to our department because of AKI with oliguria. Although echocardiography showed an elevated right ventricular artery systolic pressure suggestive of pulmonary hypertension (PH), pulmonary congestion was initially considered on chest imaging, and hemodialysis and rapid ultrafiltration were initiated. However, she developed hypovolemic shock and treatment was switched to continuous hemodiafiltration and slow ultrafiltration. Thereafter, her consciousness, hypoxemia, DIC and PH completely improved. She was weaned from blood purification therapy on the 29th day of hospitalization. She had hemolytic anemia that might have been caused by thrombotic microangiopathy (TMA), but it resolved without plasmapheresis. On the 51st day of hospitalization, the patient was transferred to another hospital for rehabilitation. Conclusions FES can be complicated by AKI. In this case, DIC, which was difficult to differentiate from TMA, and/or renal congestion were considered to be a cause of AKI. Chest radiographs of FES may be indistinguishable from pulmonary congestion. In our case, chest radiography showed bilateral diffuse alveolar infiltrates which was not indicative of pulmonary congestion but pulmonary involvement of FES. FES is associated with PH, which may lead to right heart failure. Therefore, the patient could have developed hypovolemic shock due to hemodialysis and rapid ultrafiltration. Clinicians should pay attention to the hemodynamics when blood purification for FES is performed.