FAT EMBOLISM

Introduction:

Fat embolism
It is a common pathological finding following long bone fracture especially with lower limb fractures e.g. Femur and Pelvis. It is common in fractures that have not been immobilized.
It can also occur after:
- Prosthetic joint replacement
- Cardiac massage
- Liver trauma
- Burns
- Marrow transplant
- Marrow biopsy
- Rapid high altitude decompression and liposuction
- Non traumatic etiology: Fatty liver, prolonged corticosteroid therapy, acute pancreatitis, osteomyelitis, conditions causing bone infarcts such as sickle cell disease.
It may occur in previously young and healthy individuals. More common 24 – 72 hours post fracture.

Pathology:

Marrow fat enters the circulation and lodges in the lungs causing mechanical obstruction.

Clinical features:
1. Hypoxia
2. Coagulopathy with transient petechial rash on neck, axilla and skin folds.
3. Neuro disturbance: confusion, disorientation, coma.
4. Clinically stable patients may deteriorate with low grade fever, petechial rash, hypoxia and confusion.
5. Jaundice and renal dysfunction are possible.

GURD’S criteria for diagnosis of Fat pulmonary embolism:
Major:
1. Axillary or subconjunctival petechial
2. Hypoxemia (PaO2<60 mm Hg, FiO2 110/min)
2. Pyrexia (Temperature >38.5 degree celcius)
3. Emboli present in retina on fundus examination
4. fat present in urine
5. Sudden unexplained drop in hemotocrit or platelet values
6. Fat globules present in sputum
7. Increasing sedimentation rate
Diagnosis requires at least 4 major and 1 minor criteria.


Diagnosis:
-Clinical suspicion in patients with lower limb fractures presenting with tachypnoea and hypoxia.
-Fat globules in urine.
Chest radiograph: Bilateral alveolar infiltrates. ARDS can develop.

CT Thorax: ground glass opacities / nodular opacities- centrilobular, subpleural
V/Q SCAN: perfusion scan shows multiple peripheral subsegmental defects.
Echocardiographic findings: Fat embolism can be identified in real time during orthopedic procedure.
Imaging recommendations:
Chest radiograph is usually adequate for detection of lung disease and monitoring disease course.


Differentials:
ARDS, Hydrostatic pulmonary edema, neurogenic pulmonary edema, Infection, Pulmonary hemorrhage, Acute venous thrombo embolic disease, Pulmonary contusion, Aspiration.



Treatment:
1. Immobilization of fracture site.
2. Fluid replacement
3. Oxygen
4. Supportive care.