A 32-year-old man is admitted to the hospital after a motor vehicle collison that involved a bus and injured multiple passengers. The patient's injuries consist of transverse fractures of the right tibia and fibula and a comminuted fracture of the left femoral shaft. No other fractures or injuries were identified. Thirty-six hours after hospital admission the patient develops shortness of breath. Temperature is 37.9 C (100 F), blood pressure is 112/76 mm Hg, pulse is 95/min, and respirations are 34/min. Oxygen saturation on 3 L per nasal cannula is 88%. On physical examination, the patient appears confused. A petechial rash is present on the head, neck, anterior thorax, and axilla. Portable chest x-ray reveals a right lower lobe patchy consolidation. Emergency V/Q scan shows a mottled pattern of subsegmental perfusion defects with normal ventilation. Which of the following would most likely have prevented this complication in this patient?
Fat embolism syndrome | |
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This patient has worsening respiratory status (dyspnea, hypoxemia), neurologic dysfunction (confusion), and a petechial rash 36 hours after sustaining multiple long bone fractures. This presentation is most concerning for fat embolism syndrome (FES), a condition that occurs when the fracture of a bone (eg, femur) containing abundant marrow releases fat and hematopoietic cells into venous circulation. This release may lead to the mechanical disruption of capillary blood flow in pulmonary circulation and, often, systemic circulation, which fat emboli may enter as microemboli (small enough to pass through pulmonary circulation) or via a shunt (eg, patent foramen ovale).
When FES occurs, lung imaging studies (eg, chest x-ray, V/Q scan) are often obtained due to the patient's sudden clinical deterioration. Evidence of pulmonary microemboli may be present (eg, mottled pattern of subsegmental perfusion defects on V/Q scan), but findings are often nonspecific (eg, patchy consolidation on chest x-ray). Most commonly, an FES diagnosis is based on classic features (eg, hypoxia, confusion, petechial rash) occurring in the appropriate clinical setting. Management is primarily supportive (eg, oxygen supplementation, intravenous fluids).
The primary method for preventing FES is early fracture immobilization (eg, splinting) and operative fixation (possibly delayed in this patient due to the multiple passenger injuries). Limiting elevations in intraosseous pressure during orthopedic procedures may also reduce the release of intramedullary fat into venous circulation. Prophylactic corticosteroids have shown some potential in reducing the risk for FES, but their use remains controversial.
(Choices A and D) Breathing exercises and chest physiotherapy can help prevent atelectasis and pneumonia in postsurgical patients, and prophylactic antibiotics may reduce risk for postoperative wound infection. However, neither measure lowers the incidence of fat embolism.
(Choices C and E) Deep vein thrombosis (DVT) prophylaxis (eg, low molecular weight heparin) and sequential compression devices for the lower limbs are known to reduce the risk for venous thromboembolism (VTE) and are likely indicated in this trauma patient with an increased risk for DVT. However, neither measure has been shown to reduce the incidence of fat embolism. Although VTE can cause acute respiratory distress, confusion, and V/Q scan abnormalities, it would not explain this patient's petechial rash.
Educational objective:
Fat embolism syndrome (FES) is characterized by a classic triad of respiratory insufficiency, neurologic dysfunction, and a petechial rash. It most commonly occurs following fracture of bones (eg, femur) containing abundant marrow. Early fracture immobilization and operative fixation of these fractures reduce the risk for FES.