Fat Embolism

 

Fat embolism can occur when fat globules are released from the bone, usually during long bone fractures. These fat globules can travel to the lungs and obstruct the pulmonary vessels. Release of these fat globules can also occur during reaming of the intramedullary canal. These fat globules also cause the release of inflammatory mediators which cause endothelial lung damage and hypoxemia. Fat embolism usually occurs in trauma patients with multiple fractures, especially the fractures which involve the pelvis and long bones. Fat embolism occurs more with closed fractures. The fat globules may also travel to the brain; this is called cerebral embolism. The fat globules may also travel to the skin capillaries. The classic triad for fat embolism includes respiratory changes, neurologic signs, and petectial rash. The fat globules affect the pulmonary vessels, and the patient will have difficulty in breathing (dyspnea, hypoxia). You see this from the history, the physical examination of the patient, the patient’s vital signs and blood gases. The fat globules may travel to the brain. The patient may have confusion or alteration of the mental status. In severe cases, the patient may have seizures. The fat globules can affect the dermal capillaries. Patient history is important in diagnosis. The mortality rate involving fat embolism is about 10%. Fat embolism usually occurs earlier than deep venous thrombosis (DVT). Patients with femur fractures, nonoperative treatment, overreaming of the fracture, or pathologic fractures are at risk for fat embolism. Patients with pathological fractures are especially at risk in bilateral femur fractures; try not to fix bilateral pathological femur fractures in the same sitting. Multiple trauma patients are always at risk of fat embolism. There are diagnostic signs. Major respiratory signs include shortness of breath- hypoxemia (oxygen saturation less than 60mmHg) or pulmonary edema. Major neurological signs confusion, agitation, altered mental status, or drowsiness. Major petectial rash signs include axillae, conjunctiva, or palate. Rash occurs in about 20-50% of cases and usually appears within 36 hours. Rash is usually self-limiting and usually disappears in about 7 days. Minor signs include tachycardia, pyrexia, anemia, thrombocytopenia, or fat in the urine. Early stabilization of long bone fractures will reduce risk of fat embolism. High index of suspicion is needed for diagnosis. Treatment of fat embolism is supportive treatment such as oxygen or In severe cases, mechanical ventilation with high levels of PEEP. The outcome of the patient post fat embolism depends on the pre-injury condition of the heart and the lungs.