Epidemiology

• Variable lag time of 24-48 hrs following the inciting event

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Etiology

• Long Bone Fracture: incidence increases with number of fractures
• Sickle Cell Disease (see Sickle Cell Disease, [[Sickle Cell Disease]]): due to bone marrow infarction
• Post-Orthopedic Surgery: subclinical fat emboli routinely occur during these procedures (documented by Echo and PA blood samples)
• Trauma to Fatty Liver:

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Physiology

• Two Mechanisms
  • Vascular obstruction by neutral fat particles: pulmonary hypertension due to vascular obstruction
  • Diffuse pulmonary/cerebral/other organ vasculitis: predominant mechanism of injury
• Lipases act on neutral fat to form FFA
• May produce capillary leak syndrome (in brain/lungs)

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Diagnosis

• CBC: thrombocytopenia
• CXR/Chest CT Patterns:
  • Infiltrates
  • ARDS:
• PFT’s: decreased DLCO
• Echo: CO is normal
• FOB: findings of fat droplets in BAL is neither sensitive nor specific for fat embolism
• Urine sudan fat stain: sensitive, but not specific
• V/Q Scan: useful to rule out acute PE

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Clinical Manifestations

General Comments

• Onset: symptoms occur 24-48 hrs after event

Dermatologic Manifestations

• Petechiae: occur in 20-50% of cases
  • Distribution: head, neck, anterior chest, axillae

Hematologic Manifestations

• Thrombocytopenia (see Thrombocytopenia, [[Thrombocytopenia]])

Neurologic Manifestations

• Altered Mental Status
  • Delirium
  • xxxx

Pulmonary Manifestations

• Acute Respiratory Distress Syndrome (ARDS) (see Acute Respiratory Distress Syndrome, [[Acute Respiratory Distress Syndrome]])
• Dyspnea (see Dyspnea, [[Dyspnea]])

Other Manifestations

• Fever (see Fever, [[Fever]])

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Prevention

Corticosteroids (see Corticosteroids, [[Corticosteroids]])

• Clinical Efficacy
  • Meta-Analysis of Corticosteroids in Long Bone Fracture (Can J Surg, 2009) [MEDLINE]: corticosteroids may be beneficial in preventing fat embolism and hypoxemia in long bone fracture -> however, data quality is poor
• Recommendations
  • Corticosteroid Use is Controversial

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Treatment

Supportive Care

• Treatments without Defined Clinical Benefit
  • Ethanol
  • Heparin

Surgical Care

• Early Fracture Fixation: decreases risk of fat embolism

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References

• Do corticosteroids reduce the risk of fat embolism syndrome in patients with long-bone fractures?  A meta-analysis. Can J Surg  2009; 52:386-393 [MEDLINE]
• Fat Embolism. Anesthesiol Clin  2009; 27:533-550 [MEDLINE]