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

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]])

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]