Fat Embolism

PATHOPHYSIOLOGY:

  • It is a common phenomenon.
  • It is most commonly seen in patients with multiple fractures and in fractures involving lower limb especially femur.
  • Fat originates from the site of trauma, particularly from the injured marrow of the fractures bone and the suggestion that the fat arises from the plasma as a result of agglutination of chylomicrons is not supported by the vivo experiments.
  • Circulating fat globules >10 mm in diameters occurs in most adults after close fracture of long bones and histological traces of fat can be found in the lungs and other internal organs. Few of these patients develop clinical features similar to ARDS and are known as fat embolic syndrome.

CLINICAL PRESENTATION:

  • The patient is usually a young adult with a lower limb fracture (especially of femur), more commonly after closed fracture of long bone (especially of femur) and more so when fractures are multiple.
  • It usually manifests itself within 24-48 hrs, but occasionally the onset may be delayed for several days.
  • Early warning signs (within 72 hrs of injury) periumbilical rash,slight rise in temperature (pyrexia) and pulse rate (tachycardia).
  • In more pronounced cases there is breathlessness, mild restlessness, petechiae on the chest,axillae, retina and conjunctival folds, progressing to marked respiratory distress and coma in severe cases. Classical triad of fat embolism syndrome is -

Respiratory symptoms Dysnea,  Tachpnea, or even ARDS.
Neurological symptoms → Confusion, disorientation.
Petechial rash              → In axilla, neck
LAB FINDINGS:

  • Thrombocytopenia
  • Hypocalcemia
  • Fat microglobulinemia (not macroglobulinemia)
  • T ESR
  • Anemia
  • Hypoalbuminemia
  • Fat globules in urine
  • Hypoxemia
  • chest X-ray shows widespread mottling throughout the lung field like a snowstorm

MANAGEMENT:

  • Prevention:


  1. Rough handling, inadequate immobilization and long journey to reach trauma centre are predisposing factors that must be avoided in long bone fractures. Fracture stabilization by IM nail.Stopping the emboli from reaching main circulation by tieing profunda vein (this is of doubtful value)
  2. Removing fat emboli from circulation by lipolytic agents as heparin 9 serum lipase activity)
  3. Hypertonic glucose (decrease FFA production)


  • Offset its effect by:


  1. Vasodilation e.g. phenoxybenzamine
  2. Prompt correction of hypovolemia
  3. Prophylactic use of O2
  4. Dextran (expand plasma volume, reduce RBC aggregation and platelet adherence)
  5. Aprotinin (protease inhibitor) decrease platelet aggregation and serotonin release.
  6. Alcohol has vasodilator and lipolytic effect


  • Treatment of established case:


  1. Aim of treatment is maintaining adequate O2 level in the ventilation.
  2. Oxygen is the only therapeutic tool of proven use. It should be administered in sufficient amount to maintain arterial PO2 > 80 mmhg.
  3. O2 toxicity (pneumonia) is avoided by using O2 conc. below 40%
  4. Steroids are given to avoid chemical pneumonia resulting from breakdown of pneumonia fat emboli in to FFA.
  5. Surface cooling will diminish O2 demand.

Exam Question
  • Multiple injuries develops fever, restlessness, tachycardia, tachypnea and periumbilical rash is diagnosed with Fat embolism
  • Fracture femur followed by breathlessness is seen in fat embolism
  • Fracture mobility is a risk factor, Thrombocytopenia & On ABG PaO2 is seen in fat embolism
  • Tachypnea,Systemic hypoxia, Fat globules in urine,Petechiae in anterior chest wal & Manifestation after several days of traumais the features of fat embolism
  • The management of fat embolism includes Oxygen, Heparinization, Low Molecular weight dextran 
  • Tachypnoeic, and conjunctival petechiae seen after femur fracture may be due to fat embolism
  • After an operation on femur bone, chest X-ray shows widespread mottling throughout the lung field like a snowstorm. It is diagnostic of Fat embolism
  • Fat embolism is characterized by Petecheal haemorrhages, Closed fractures of femur & Aggregation of chylomicrons
  • Laboratory findings in fat embolism consist of Thrombocytoenia, Fat globules in urine &Anemia
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