FAT EMBOLISM



I. Pathophysiology and epidemiology
  1. Results from fat globule deposition in microcirculation
  2. Typically associated with traumatic fractures may also occur with orthopedic surgery
  3. Unclear to what degree the clinical manifestations are due to mechanical obstruction of blood vessels vs. biochemical changes e.g. release of inflammatory mediators
  4. Risk factors:
    1. Traumatic fractures involving pelvis or long bones (most cases)
      1. Closed fractures (as opposed to open)
      2. Multiple fractures (as opposed to single)
      3. Fractures treated non-surgically (as opposed to surgically)
    2. Orthopedic procedures
    3. Liposuction
    4. Bone marrow harvesting or transplant
    5. Severe burns
    6. Soft tissue injuries
    7. Pancreatitis
    8. Osteomyelitis
    9. Panniculitis
    10. Bone tumor lysis
    11. Corticosteroid therapy
    12. Sickle cell disease
    13. Alcoholic fatty liver disease
    14. Cardiopulmonary bypass
    15. Diabetes mellitus
    16. Young age
II. Clinical features
  1. Usually sudden-onset of the following (not all are always present)
    1. Hypoxemia
    2. Central neurologic symptoms (particularly CNS depression disproportionate to degree of hypoxemia)
    3. Petechial rash, particularly on thorax ("vest" distribution)
    4. Pulmonary edema
  2. May also  have fever, tachycardia, anemia, thrombocytopenia, and/or elevated ESR
  3. Symptoms may start immediately after precipitating event or up to 72h after (presents within 48h of inciting event in 85%) of cases
  4. Mortality may be up to 15%
  5. CXR may show "snowstorm" pattern of fleck-like radiodensities in lung fields
  6. Head CT may show petechial hemorrhages of the white matter
  7. Fat in urine, blood, sputum, or in bronchial macrophages from bronchial lavage (fat in blood, urine, or sputum may also occur with dyslipidemias, lipid infusion, or sepsis)
III. Prevention
  1. IV corticosteroids perioperatively may reduce incidence in patients with multiple fractures of pelvis and/or long bones
  2. Early immobilization of fractures and relief of intraosseous pressure during fracture fixation

IV. Management
  1. Mostly supportive: volume replacement, O2, etc.
  2. Anticoagulation to prevent venous thrombosis is often used
(Sources include Core Content Review of Family Medicine, 2012)