Diagnosis and Discussion

Diagnosis

Systemic fat emboli

Discussion

Fat emboli are defined as fat globules within the circulatory system. The majority of the cases occur after a traumatic injury or after surgical procedures involving manipulation of the bone marrow, where an increase in intramedullary pressure allows fat globules to gain access to the systemic venous system and eventually lodge in the capillaries. Fat Embolism Syndrome (FES) is a clinical entity that when the fat globules disseminate throughout the body causing respiratory failure, neurologic deficits, and ultimately can result in death. Clinical identification of fat emboli and FES remain a diagnostic challenge.

Patients with FES often present with a triad of respiratory abnormalities, neurologic alteration and diffuse petechial rash. The most common early presentations are respiratory abnormalities, including hypoxia, dyspnea, and tachypnea. As the presentation is often indistinguishable from other entities that cause acute respiratory distress syndrome, several diagnostic criteria have been proposed to aid the diagnosis of FES, such as Gurd and Wilson Criteria and Fat Embolism Index. However, diagnosis of fat emboli can only be confirmed by pathology with a conventional Oil Red O stain on fresh frozen tissue, which directly highlights fat globules as red-orange staining within the pulmonary capillaries.

Many studies have confirmed that early immobilization of long bone fractures decreases the mortality rate from FES, however the majority of treatment options for FES are mostly supportive. When supportive therapy, the mortality rate of FES declines to approximately 5-15%.

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References

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Franks TJ. Thurlbeck's Pathology of the Lung. NEJM. 2006. 354(13): p. 1435-1436.

Fulde GW and P. Harrison. Fat embolism--a review. Arch Emerg Med. 1991. 8(4): p. 233.

Koessler MJ, et al. The clinical relevance of embolic events detected by transesophageal echocardiography during cemented total hip arthroplasty: A randomized clinical trial. Anesth Analg. 2001. 92(1): p. 49-55.

Weinhouse G. Fat embolism syndrome, in UpToDate, P.F. Parsons, G, Editor. 2019: UpToDate, Waltham, MA (Accessed on September 17, 2019).