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Fat Embolism

  • Author: Constantine S Bulauitan, MD; Chief Editor: Vincent Lopez Rowe, MD  more...
 
Updated: Apr 06, 2015
 

Background

For those who manage major trauma victims, the topic of fat embolism weighs heavily on the mind. The incidence of this problem can approach 90% in patients who have sustained major injuries. If it progresses to the rare clinical entity known as fat embolism syndrome (FES), a systemic inflammatory cascade affecting multiple organ systems, morbidity and mortality are high. Accordingly, swift diagnosis and treatment of fat embolism are paramount for ensuring the survival of this patient population.[14]

Ernst Von Bergmann, in 1873, was the first person credited with making a clinical diagnosis of fat embolism. He did this on the basis of knowledge gathered from experiments with cats 10 years previously, in which he injected them with intravenous oils. Von Bergmann later described a patient who fell off a roof and sustained a comminuted fracture of the distal femur; 60 hours after the injury, the patient developed dyspnea, cyanosis, and coma.[14]

The diagnosis of FES is mainly a clinical one. It is dependent on clinical identification of dyspnea, petechiae, and cognitive dysfunction in the first few days following trauma, long bone fracture, or intramedullary surgery. Various laboratory studies and imaging modalities exist to aid in its discovery (see Presentation and Workup). Supportive measures are the mainstay of treatment; thus, efforts are targeted at prevention, early diagnosis, and symptom management (see Treatment).

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Pathophysiology

The exact mechanism of fat embolism and its evolution to the entity known as FES has not been fully elucidated, but a number of experimental models have been proposed. Asymptomatic fat embolism to the pulmonary circulation almost always occurs with major trauma, including elective surgical procedures such as intramedullary nailing of long bones, which has been demonstrated with echocardiography. The development of FES is rare, occurring in 0.5-11% of cases.[15, 16]

Although poorly understood, the development of FES is attributed to a series of biochemical cascades resulting from the mechanical insult sustained in major trauma. Release of fat emboli leads to occlusion of the microvasculature, triggering an inflammatory response that is clinically manifested by dermatologic, pulmonary, and neurologic dysfunction.[17, 1] (See the images below.)

Frozen section of lung stained with oil red O show Frozen section of lung stained with oil red O showing multiple orange red fat globules of varying sizes in septal vasculature. Image courtesy of Dr AVC Rao, Senior Lecturer in Pathology, The University of the West Indies at St Augustine, Trinidad and Tobago. Originally published in Journal of Orthopaedics (http://www.jortho.org/2008/5/4/e8/).
Hematoxylin-eosin stain of section of lungs showin Hematoxylin-eosin stain of section of lungs showing blood vessel with fibrinoid material and optical empty space indicative of presence of lipid dissolved during staining process. This 55-year-old woman died of massive fat embolism after developing pancreatitis due to endoscopic retrograde cholangiopancreatography. Image courtesy of Wikimedia Commons. Originally published in Kanen BL, Loffeld RJLF. Pancreatitis with an unusual fatal complication following endoscopic retrograde cholangiopancreaticography: a case report. Journal of Medical Case Reports. 2008;2:215.

Pulmonary consequences of FES are clinically similar to those of acute respiratory distress syndrome (ARDS) and almost always occur. They are usually the initial manifestation of FES, typically appearing within 24 hours after the traumatic insult. They result from injury to the pulmonary capillary endothelium caused by free fatty acids that were hydrolyzed by lipoprotein lipase, releasing local toxic mediators. These mediators cause increased vascular permeability, resulting in alveolar hemorrhage and edema and causing respiratory failure and ARDS.[18, 19]

Approximately 20-30% of the population have a patent foramen ovale; this may explain how fat emboli that pass through the pulmonary circulation end up with systemic manifestations of FES, particularly involving the brain and kidneys. As a result of the occluded cerebral vasculature, patients exhibit gross encephalopathy, localized cerebral edema, and white-matter changes.[18, 20, 21]

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Etiology

Causes of FES include the following:

  • Blunt trauma (associated with 90% of all cases) [22]
  • Acute pancreatitis
  • Burns
  • Joint reconstruction
  • Liposuction
  • Cardiopulmonary bypass
  • Decompression sickness
  • Parenteral lipid infusion
  • Sickle cell crisis [2, 3, 13]
  • Pathologic fractures
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Epidemiology and Prognosis

Fat embolism occurs in 90% of all trauma patients.[23] FES accounts for only 2-5% of patients who have long-bone fractures.[20]

The duration of FES is difficult to predict because the syndrome is often subclinical or overshadowed by other illnesses or injuries. Increased alveolar-to-arterial oxygen gradient and neurologic deficits, including coma, may last days or weeks. Hematologic aberrations due to FES frequently are indistinguishable from those due to other causes common in these patients.

As in ARDS, pulmonary sequelae usually resolve almost completely within 1 year. Residual subclinical diffusion capacity deficits may exist. FES alone has not been reported to cause global anoxic injury, but it may contribute in conjunction with other cerebral insults. Residual neurologic deficits may range from nonexistent to subtle personality changes to memory and cognitive dysfunction to long-term focal deficits.

Outcomes in patients who develop FES are bleak if the syndrome is not identified early and aggressive supportive measures are not initiated. When action is taken early in the disease course, the prognosis is generally favorable, with a mortality of less than 10%.[14]

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Contributor Information and Disclosures
Author

Constantine S Bulauitan, MD Surgical Critical Care Fellow, Division of Acute Care Surgery, Rutgers Biomedical and Health Sciences, Rutgers Robert Wood Johnson Medical School

Constantine S Bulauitan, MD is a member of the following medical societies: American College of Surgeons, Society of Critical Care Medicine, Philippine Medical Association of America, World Surgical Foundation

Disclosure: Nothing to disclose.

Coauthor(s)

Rajan Gupta, MD, FACS, FCCP Associate Professor of Surgery, Chief, Division of Acute Care Surgery, Rutgers Robert Wood Johnson Medical School

Rajan Gupta, MD, FACS, FCCP is a member of the following medical societies: American Association for the Surgery of Trauma, American College of Chest Physicians, American College of Surgeons, Association for Academic Surgery, New Hampshire Medical Society, Shock Society, Society of Critical Care Medicine, Eastern Association for the Surgery of Trauma, European Society for Trauma and Emergency Surgery, Western Trauma Association, International Society of Surgery, International Association for Trauma Surgery and Intensive Care, New England Surgical Society

Disclosure: Nothing to disclose.

Chief Editor

Vincent Lopez Rowe, MD Professor of Surgery, Program Director, Vascular Surgery Residency, Department of Surgery, Division of Vascular Surgery, Keck School of Medicine of the University of Southern California

Vincent Lopez Rowe, MD is a member of the following medical societies: American College of Surgeons, American Heart Association, Society for Vascular Surgery, Vascular and Endovascular Surgery Society, Society for Clinical Vascular Surgery, Pacific Coast Surgical Association, Western Vascular Society

Disclosure: Nothing to disclose.

Acknowledgements

Lisa Kirkland, MD, FACP, CNSP, MSHA Assistant Professor, Department of Internal Medicine, Division of Hospital Medicine, Mayo Clinic; ANW Intensivists, Abbott Northwestern Hospital

Lisa Kirkland, MD, FACP, CNSP, MSHA is a member of the following medical societies: American College of Physicians, Society of Critical Care Medicine, and Society of Hospital Medicine

Disclosure: Nothing to disclose.

Francisco Talavera, PharmD, PhD Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Medscape Salary Employment

References
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Hematoxylin-eosin stain of section of lungs showing blood vessel with fibrinoid material and optical empty space indicative of presence of lipid dissolved during staining process. This 55-year-old woman died of massive fat embolism after developing pancreatitis due to endoscopic retrograde cholangiopancreatography. Image courtesy of Wikimedia Commons. Originally published in Kanen BL, Loffeld RJLF. Pancreatitis with an unusual fatal complication following endoscopic retrograde cholangiopancreaticography: a case report. Journal of Medical Case Reports. 2008;2:215.
Frozen section of lung stained with oil red O showing multiple orange red fat globules of varying sizes in septal vasculature. Image courtesy of Dr AVC Rao, Senior Lecturer in Pathology, The University of the West Indies at St Augustine, Trinidad and Tobago. Originally published in Journal of Orthopaedics (http://www.jortho.org/2008/5/4/e8/).
 
 
 
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