Fat Embolism Syndrome in Children

Ok, so maybe Homer has the wrong idea about “Fat Embolism”… I think he should be more worried about a devastating Food Impaction… but, with the Holidays upon us and the prevalence of fatty foods surrounding, me I began to ponder fat embolism and children. (Yes, this is how my warped mind works. When I am at a pool and see a tall, lanky kid, I think of Marfan Syndrome and when I am getting ready to enjoy a little vacation, I think about Fat Emboli.) So for this 525th Ped EM Morsel (THANK YOU ALL FOR THE SUPPORT!), let us consider a critical topic that can lead to sudden devastation and one we should all remain vigilant for: Fat Embolism Syndrome in Children

Fat Embolism in Children: Basics

  • Fat Embolism = circulating macroglobules of yellow fat in the systemic and pulmonary microvasculature. [Huffman, 2020]
  • Fat Embolism is not uncommon. [Huffman, 2020; Eriksson, 2015]
    • Often seen with:
      • Orthopedic trauma / procedures (estimated to occur in >90% of patients with the following):
        • All long bone fractures
        • Multiple fractures
        • Intramedullary reaming and nailing
        • Hip arthroplasty
      • Cosmetic procedures (ex, liposuction)
      • Medical conditions (much less often)
  • Fat Embolism is not the same as Fat Embolism Syndrome [Huffman, 2020; Bailey 2018]
    • Most patients with Fat Emboli do not exhibit significant symptoms.
    • Only a small percentage will go on to have severe symptoms.
    • Fat Embolism Syndrome is the systemic effects due to having Fat Emboli.

Fat Embolism Syndrome

  • While most often Fat Emboli are well tolerated, occasionally severe symptoms can occur. [Huffman, 2020; Bailey 2018]
    • Symptoms usually develop within 12-72 hours of insulting event.
    • Can progress rapidly.
  • Fat Embolism Syndrome can affect all organ systems: [Bailey 2018]
    • Respiratory (ex, distress, overt failure)
    • Neurologic (ex, confusion, seizures, coma)
    • Hematologic (ex, anemia, thrombocytopenia)
    • Cutaneous (ex, petechiae)
    • Renal (ex, acute renal failure)
    • Ocular (ex, conjunctival petechiae, retinopathy)
    • ** Hallmarks are typically Respiratory Distress with Altered Mental Status and Petechiae! (clearly a number of other items exist on this Ddx list).
  • The exact pathophysiology is not clear, but believed to have 3 inter-related mechanisms: [Huffman, 2020; Bailey 2018]
    • Mechanical Theory: fat emboli lead to thrombotic, obstructive mass (similar to pulmonary embolism)
    • Biochemical Theory: degradation of fat emboli leads to free fatty acids and subsequent inflammatory cascade and results in injury to pneumocystis and small capillaries (similar to ARDS)
    • Coagulation Theory: released thromboplastin and marrow activate complement cascade and eventual intravascular coagulation with platelets adhering to fatty emboli.
  • Recognition of Fat Embolism Syndrome is challenging. [Huffman, 2020; Bailey 2018]
    • Diagnosis is really one of exclusion.
    • There are several scoring criteria, but none have been validated and all utilize nonspecific findings.
    • Examples:
      • Gurd and Wilson’s Criteria: (1 Major + 4 Minor)
        • Major Criteria
          • Petechial Rash
          • Respiratory insufficiency
          • Cerebral involvement (altered mental status)
        • Minor Criteria
          • Tachycardia, Fever,
          • Jaundice, Retinal changes, Renal signs
        • Lab Values
          • Thrombocytopenia
          • Anemia
          • High ESR
          • Fat Macroglobulinemia
      • Schonfeld’s Critieria: (Score >5)
        • Petechiae = 5 pts
        • CXR with diffuse infiltrates = 4 pts
        • Hypoxemia = 3 pts
        • Fever, Tachycardia, Tachypnea, Confusion all get 1 pt respectively
    • These obviously do not work for a patient who is intubated (as the respiratory distress and altered mental status are difficult to discern). [Huffman, 2020]
      • Huffman et al. recommend using Oxygenation Index (OI)
        • OI= (Mean Airway Pressure x FIO2 x 100) / PaO2.
        • Normal OI = 0.
        • OI > 0 indicates some level of pulmonary / respiratory dysfunction
      • Once again, this clearly does not define the condition on its own.
    • Imaging: [Bailey 2018]
      • CXR and CT will show bilateral infiltrates.
      • May appear similar to ARDS.

Fat Embolism Syndrome & Sickle Cell Disease

  • Fat Embolism Syndrome is a potential complication seen with Sickle Cell Disease. [Bailey 2018]
    • Believed to be due to the acute infarction and necrosis of bone.
    • Along with infection, this is one of the identifiable causes of Acute Chest Syndrome.
    • Contributes significant mortality!
      • May have up to 38% mortality in first 24 hours.
      • Leads to rapid deterioration.

Fat Embolism Syndrome: Management

  • There is no specific treatment for Fat Embolism Syndrome. [Bailey 2018]
  • Supportive care is the main strategy. [Bailey 2018]
    • Pulmonary toilet and respiratory support
    • Vasopressor support when needed
      • May present with Obstructive Shock
      • Excessive volume resuscitation should be avoided
      • May want to use Echocardiogram to help guide fluid management.
    • May need to consider ECMO.
  • Heparin has been debated, but not currently recommended… of course it may be started as the clinical picture may be unclear.

Moral of the Morsel

  • Balls of Fat are Bad. Sure fat may make your steak taste delicious, but a bolus of free fatty acids in small capillaries can be deadly!
  • Keep asking “why?” Why is the patient not improving? Why did this patient have such terrible respiratory distress after a straight forward femur fracture? The question may lead to Fat Embolism Syndrome as an answer.
  • Sickle Cell Disease is TERRIBLE! Infarction of the bone by your own blood is cruel… and apparently can lead to Fat Emboli!

References

Author

Sean M. Fox
Sean M. Fox
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