Fat Embolism Criteria

Schonfeld’s FES criteria

The seven criteria from the Schonfeld model created in 1983 are:

1. Petechiae (5 points);

2. X-ray chest diffuse infiltrates (4 points);

3. Hypoxemia (3 points);

4. Fever (1 point);

5. Tachycardia (1 point);

6. Tachypnea (1 point);

7. Confusion (1 point).

Positive diagnosis of FES by Schonfeld criteria is given to scores of at least 5 points.

Gurd's and Wilson's criteria

This diagnosis rule was developed in 1974 by Gurd and Wilson. It consists of four major and seven minor criteria.

Major criteria:

■ Axillary or subconjunctival petechiae;

■ Hypoxaemia (PaO₂ = 0.4);

■ Central nervous system depression disproportionate to hypoxaemia;

■ Pulmonary oedema.

Minor criteria:

■ Tachycardia >110 bpm;

■ Pyrexia >38.5°C;

■ Emboli present in the retina on fundoscopy;

■ Fat present in urine;

■ A sudden inexplicable drop in haematocrit or platelet values;

■ Increasing ESR;

■ Fat globules present in the sputum.

Positive diagnosis by Gurd's and Wilson's criteria is obtained when at least one major and four minor criteria result from the patient examination.

About fat embolism syndrome

FES is a condition with 15% mortality (if left untreated) that is most often caused by trauma and orthopedic injuries (within 24 hours of injury) but may also be related to internal medicine comorbities, such as diabetes and pancreatitis.

There is a 3 to 4% incidence of FE in isolated bone trauma and a 10 to 15% incidence in polytrauma. Incidence also tends to be higher in men (greater proneness of being involved in high velocity trauma).

The condition is characterized by the presence of fat droplets in the lung microcirculation which lead to:

■ Hypoxia;

■ Bilateral pulmonary infiltrates;

■ Altered mental status.

The syndrome represents the inflammatory response of the body to the presence of circulating embolized fat globules. There are two theories in regard to the origin of the embolized fat:

■ Bone marrow fat released through mechanical trauma;

■ Fat from chylomicron exchanges due to cellular stress caused by trauma.

FES manifests through clinical signs such as petechial rash or progressive respiratory insufficiency.

There are no dedicated tests, thus FE diagnosis is based on non-specific tests and on universal criteria. Some of the laboratory tests routinely performed are:

■ Complete blood count (haematocrit, platelet count, fribrinogen);

■ Microglobulinemia (for Gurd and Wilson’s criteria);

■ ABG (to check the alveolar to arterial oxygen difference).

Chest radiography is used to reveal the bilateral pulmonary infiltrates whilst computed tomography may be employed to check for petechial hemorrhages indicating microvascular injury.

Original sources

1. Schonfeld SA, Ploysongsang Y, DiLisio R, Crissman JD, Miller E, Hammerschmidt DE, Jacob HS. Fat embolism prophylaxis with corticosteroids. A prospective study in high-risk patients. Ann Intern Med. 1983; 99(4):438-43.

2. Gurd AR, Wilson RI. The fat embolism syndrome. J Bone Joint Surg Br. 1974; 56B(3):408-16.

Other references

1. Nandi R, Krishna HM, Shetty N. Fat Embolism Syndrome Presenting as Sudden Loss of Consciousness. J Anaesthesiol Clin Pharmacol. 2010; 26(4): 549–550.

2. Glazer JL, Onion DK. Fat embolism syndrome in a surgical patient. J Am Board Fam Pract. 2001; 14(4):310-3.

3. Kwiatt ME, Seamon MJ. Fat embolism syndrome. Int J Crit Illn Inj Sci. 2013; 3(1): 64–68.