Fat embolism syndrome

Background

• Caused by fat globules in pulmonary microcirculation
• Fat is prothrombotic and pro-inflammatory
• Commonly associated with orthopedic fractures, especially long bone fractures of lower extremities (eg. femur)
• Occurance in Men > women, highest rates: ages 10-40 y/o

Clinical Features

• multi-system dysfunction
• Classic triad: hypoxemia, neurological abnormalities and petechiae
• neuro findings included: focal deficits, AMS, coma
• thrombocytopenia and anemia common
• can progress to DIC
• Fulminant cases: RV dysfunction, biventricular failure, ARDS, shock, death
• Other etiologies (uncommon): pancreatitis, sickle cell crisis, alcoholic liver ds, bone marrow harvest/transplant/liposuction

Differential Diagnosis

• pulmonary embolism
• ARDS
• pulmonary edema
• alveolar hemorrhage
• other causes of [[hypoxemia]
• other causes of shock

Workup

• Clinical diagnosis, no gold standard

Gurd's Criteria

• Most frequently cited diagnostic criteria
• Need 1 major, 4 minor

Major

• Petechial rash
• Resp symptoms w XR changes
• CNS signs unrelated to another condition

Minor

• Tachycardia
• Pyrexia
• retinal changes (fat or petechiae)
• renal abnormalities (oliguria, anuria or lipiduria)
• thrombocytopenia
• acute anemia
• elevated ESR
• fat globules in sputum

• Chest Xray/CT scan chest
  • Bilateral patchy infiltrates
• MRI brain: star-field pattern of diffuse, punctate, hyperintense lesions on DWI
• Bronchoalveolar lavage
  • 30% of alveolar cells staining for fat strongly asso w diagnosis

Management

• Supportive care
• Heparin and steroids have not shown improvement
• Supplemental O2, mechanical ventilation if needed
• Frequent neurochecks, consider ICP monitoring
• Vasopressors as needed
• Refractory hypotension/shock: consider ECMO

Disposition

• ICU

Prevention

• Decreased incidence with orthopedic repair w/i 24h
• Consider prophylactic corticosteroids in pts w/ long bone fractures
  • decreased hypoxemia, no difference in mortality