Updated: 12/17/2017

Fat Embolism Syndrome

Topic
Review Topic
0
0
Questions
5
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0
Evidence
9
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https://upload.orthobullets.com/topic/9055/images/bone marrow em_moved.jpg
https://upload.orthobullets.com/topic/9055/images/petechia.jpg
Introduction
  • A syndrome caused by an inflammatory response to embolized fat globules
    • characterized by
      • hypoxia
      • CNS depression
      • pulmonary edema
      • petechial rash
  • Epidemiology
    • incidence
      • 3-4% with isolated long bone trauma q
      • 10-15% with polytrauma
  • Pathophysiology
    • fat and marrow elements are embolized into the bloodstream during
      • acute long bone fractures
      • intramedullary instrumentation
        • intramedullary nailing
        • hip & knee arthroplasty q q q
    • pathophysiology
      • two theories regarding the causes of fat embolism include
        • mechanical theory
          • embolism is caused by droplets of bone marrow fat released into venous system
        • metabolic theory
          • stress from trauma causes changes in chylomicrons which result in formation of fat emboli
  • Prognosis
    • fatal in up to 15% of patients
Diagnosis Criteria
  • Major (1)
    • hypoxemia (PaO2 < 60)
    • CNS depression (changes in mental status)
    • petechial rash
    • pulmonary edema
  • Minor (4)
    • tachycardia
    • pyrexia
    • retinal emboli
    • fat in urine or sputum
    • thrombocytopenia
    • decreased HCT
  • Additional
    • PCO2 > 55
    • pH < 7.3
    • RR > 35
    • dyspnea
    • anxiety
Presentation
  • History
    • symptoms usually present within 24 hours of inciting event 
  • Symptoms
    • patient complains of feeling "short of breath"
    • patient appears confused
  • Physical exam
    • tachycardia
    • tachypnea
    • petechiae 
      • axillary region
      • conjunctivae
      • oral mucosa
Studies
  • ABG
    • hypoxemia (PaO2 < 60 mmHg)
Treatment
  • Nonoperative  
    • mechanical ventilation with high levels of PEEP (positive end expiratory pressure)
      • indications
        • acute fat emboli syndrome
  • Prevention
    • early fracture stabilization 
      • indications
        • early fracture stabilization (within 24 hours) of long bone fracture is most important factor in prevention of FES
      • techniques to reduce the risk of fat emboli
        • overreaming of the femoral canal during a TKA
        • use of reamers with decreased shaft width reduces the risk during femoral reaming for intramedullary fixation
        • use of external fixation for definitive fixation of long bone fractures in medically unstable patients decreases the risk  
 

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Questions (5)
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(OBQ06.62) A 79-year-old female falls onto her right hip at home and sustains the injury shown in Figure A. She undergoes an uncemented unipolar hemiarthroplasty. During insertion of the stem into the femoral canal, the patient becomes hypotensive and hypoxic. Which of the following has most likely occurred? Review Topic

QID: 173
FIGURES:
1

Femoral shaft fracture

0%

(4/2622)

2

Inadequate fluid resuscitation during surgery

1%

(18/2622)

3

Acute myocardial infarction

1%

(18/2622)

4

Pulmonary embolism caused by dislodging of deep venous thrombosis during hip exposure

2%

(51/2622)

5

Intramedullary fat and marrow embolization

96%

(2518/2622)

ML 1

Select Answer to see Preferred Response

PREFERRED RESPONSE 5

(OBQ04.147) A 20-year-old male sustains bilateral humeral shaft fractures and bilateral femoral shaft fractures from a motor vehicle collision. While awaiting surgery, the patient suddenly becomes tachycardic, hypoxemic and experiences mental status changes; physical exam demonstrates multiple petechiae in his bilateral axilla. CT angiography is ordered and is negative for pulmonary embolus. What is the most likely diagnosis? Review Topic

QID: 1252
1

hypovolemic shock

2%

(20/905)

2

stroke

0%

(2/905)

3

fat embolism syndrome

97%

(880/905)

4

sundown syndrome

0%

(1/905)

5

narcotic overdose

0%

(0/905)

ML 1

Select Answer to see Preferred Response

PREFERRED RESPONSE 3

(OBQ09.214) An 85-year-old woman undergoes the treatment seen in Figure A for a displaced left femoral neck fracture. During wound closure, the patient becomes hypoxic and hypotensive. Despite aggressive resuscitation efforts, she passes away three hours later in the intensive care unit. The autopsy findings seen in Figure B from the patient's lungs are most likely the result of which of the following Review Topic

QID: 3027
FIGURES:
1

Reaming for the femoral component

18%

(268/1468)

2

Insertion of a femoral component after cement pressurization

80%

(1170/1468)

3

Utilization of undersized broaches during canal preparation

1%

(18/1468)

4

Inadequate beta blockade

0%

(1/1468)

5

Use of spinal anesthesia

0%

(5/1468)

ML 2

Select Answer to see Preferred Response

PREFERRED RESPONSE 2

(OBQ05.194) In a patient undergoing total knee arthroplasty, the femoral and tibial bone resections can be done using intra-or extra-medullary alignment systems. Extra-medullary guidance systems have what benefit over intra-medullary guidance systems? Review Topic

QID: 1080
1

Decreased fracture risk

13%

(279/2133)

2

Decreased embolization risk

81%

(1736/2133)

3

Decreased surface area available for cement interdigitation

1%

(26/2133)

4

Increased risk of blood loss and/or transfusion requirement

4%

(85/2133)

5

Increased rates of cerebral ischemia

0%

(3/2133)

ML 2

Select Answer to see Preferred Response

PREFERRED RESPONSE 2
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