Fat Embolism

Epidemiology

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

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:

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)

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

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

Neurologic Manifestations

  • Altered Mental Status
    • Delirium
    • xxxx

Pulmonary Manifestations

Other Manifestations

  • Fever (see Fever, [[Fever]])

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

Treatment

Supportive Care

  • Treatments without Defined Clinical Benefit
    • Ethanol
    • Heparin

Surgical Care

  • Early Fracture Fixation: decreases risk of fat embolism

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]