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)
    - Pancreatitis
    - Sickle Cell Disease

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.

Consider possibility of Fat Embolism Syndrome in patients with Sickle Cell Disease and [Bailey 2018]
- Acute Chest Syndrome
- Severe Vaso-occlusive Crisis unalleviated with increasing doses of analgesics.

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!