Fat embolism

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A fat embolism (which via major trauma may progress to fat embolism syndrome) is a type of embolism in which the embolus consists of fatty material. They are often caused by physical trauma such as fracture of soft tissue trauma, and burns.Fat embolism syndrome is distinct from the presence of fat emboli, symptoms usually occur 1-3 days after a traumatic injury and are predominantly pulmonary (shortness of breath, hypoxemia), neurological (agitation, delirium, or coma), dermatological (petechial rash), and haematological (anaemia, low platelets). The syndrome manifests more frequently in closed fractures of the pelvis or long bones.

Video Fat embolism

Signs and symptoms

In terms of signs and symptoms the severe form of this condition presents as acute pulmonary heart disease and respiratory failure. This may lead to death within a few hours of injury.Clinical fat embolism syndrome presents with tachycardia, tachypnea, elevated temperature, hypoxemia, hypercapnia, thrombocytopenia, and occasionally mild neurological symptoms.A petechial rash also called purpura that appears on the upper anterior portion of the body, including the chest, neck, upper arm, axilla, shoulder, oral mucosa and conjunctivae is considered to be a pathognomonic sign of fat embolism syndrome, however it appears late and often disappears within hours. It results from occlusion of dermal capillaries by fat, and increased capillary fragility.Central nervous system signs, including a change in level of consciousness, are not uncommon. They are usually nonspecific and have the features of diffuse encephalopathy: acute confusion, stupor, coma, rigidity (neurology), or convulsions. Cerebral edema contributes to the neurologic deterioration. Unlike emboli that arise from blood clots, fat emboli are small and multiple, and thus have widespread effects.

Complications

Embolized fat travels through the venous system to the lungs and can occlude pulmonary capillaries, fat emboli may cause cor pulmonale if adequate compensatory pulmonary vasodilation does not occur.Circulating free fatty acids are directly toxic to pneumocytes and capillary endothelium in the lung, causing interstitial hemorrhage, edema and chemical pneumonitis.Complications from a fat embolism can be serious such as:

1. Pulmonary fat embolism: Obstruction causes sudden death.
2. Systemic fat embolism: These may get lodged in capillaries of organs like the brain, kidneys, or skin, causing minute hemorrhage and microinfarcts.

Maps Fat embolism

Cause

Fat emboli occur in almost 90% of all people with severe injuries to bones, although only 10% of these are symptomatic. The risk of fat embolism syndrome is thought to be reduced by early immobilization of fractures and especially by early operative correction. There is also some evidence that steroid prophylaxis of high-risk individuals reduces the incidence. The mortality rate of fat-embolism syndrome is approximately 10-20%.

Fat emboli can be either traumatic (resulting from fracture of long bones, accidents, or trauma to soft tissue) or non-traumatic (resulting from burns or fatty liver).

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Pathogenesis

The pathogenesis of fat embolus occurs in long bone fractures, though intramedullary procedures also show some incidence (0.8%). In the event of an accident where bone fractures occur , a large movement of fat droplets occurs in the human body, this can elevate the vascular resistance and therefore cause, potentially, right ventricular failure to happen. Possible mechanisms are:

1. Mechanical. Mobilisation of fluid fat following trauma to bone and soft tissue.
2. Biochemical theory. Indicates that inflammation due to trauma, in turn cause the bone marrow to liberate fatty acids, increasing levels of these, as well as inflammatory mediators, damage capillary beds.

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Diagnosis

The diagnosis of an individual suspected of having fat embolism syndrome can be done via the following:

• Transesophageal echocardiography (TEE)
• Cytologic examination of urine,and blood
• Decreased hematocrit occurs within 1 to 2 days
• MRI (brain)
• chest X-ray may show pulmonary shadows
• Hypoxemia may occur in an individual with FES(PaO2 <60 mmHg)
• Doppler ultrasonography

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Treatment

Treatment for this condition entails the maintenance of intravascular volume. Additionally, the following can be done as a means of managing FES in an individual:

• Albumin can be used for volume resuscitation
• Long bone fractures should be attended to immediately (surgery)
• Mechanical ventilation

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See also

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References

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Further reading

Source of the article : Wikipedia