What Is Fat Embolism Syndrome?

Fat Embolism Syndrome (FES) is when there is creation of fat emboli (fat particles) throughout the body, which enter the microcirculation and can have whole-body effects. Symptoms vary in severity, ranging from a rash, to a change in mental function.¹

FES is a rare medical condition which can lead to a range of dysfunctions in the body. It is particularly common in patients with long-bone fractures. Whilst it is rare, the development of FES amongst these patients varies between 1-29%.² To put it in context, the incidence rate for nut allergies in the UK is 2% ³, therefore a rate of up to 29% is significant. But what is FES and how can we treat it?

Overview

Zenker recorded the first instance of fat embolism syndrome (FES) in a patient with a crush injury more than 150 years ago. FES is a relatively rare, but potentially fatal illness marked by the systemic release of fat globules into the circulation system, resulting in multi-organ failure. It often occurs following long bone fractures, particularly femur (the thigh bone) fractures, but it can also be related to other traumatic injuries, orthopaedic procedures, or medical diseases like pancreatitis. FES is most common between the ages of 10 and 40, and it affects those assigned male at birth (AMAB) more frequently than those assigned female at birth (AFAB).¹ The vast range of incidence is most likely due to the diversity of diagnostic criteria. The National Hospital Discharge Survey recently discovered a 0.17% FES frequency in individuals with single or multiple orthopaedic fractures. When solitary femoral fractures were present, the frequency climbed to 0.54%, and it climbed further to 1.29% when multiple fractures of the femur were reported. Although FES is still an uncommon condition, undetected FES in the trauma population is common, with an autopsy series revealing fat embolism in the pulmonary circulation in 82% of trauma patients, and 88% of patients who had cardiopulmonary resuscitation (CPR).²

Causes of fat embolism syndrome

FES is usually caused by severe injuries, notably fractures of long bones such as the femur. However, it can also occur following orthopaedic surgery, particularly when intramedullary treatments (using the bone marrow space) are undertaken. Pancreatitis, sickle cell crises, alcoholic liver illness, bone marrow harvest or a transplant, and liposuction are examples of non-orthopaedic causes of FES.¹

During fractures, or other traumatic damage, fat globules are released from damaged fat tissue or bone marrow and enter the circulation. These fat globules can then block tiny blood vessels, meaning that downstream organs are starved of blood and oxygen, causing tissue damage. The inflammatory reaction to fat emboli leads to the development of FES.³

Signs and symptoms of fat embolism syndrome

FES is a rarely seen, but potentially fatal illness. The signs and symptoms of FES usually appear within 24 to 72 hours following the initial damage; however, this might vary. The typical triad of FES symptoms includes:⁴

• Respiratory distress - these are frequently the first to appear. Tachypnea (rapid breathing), tachycardia (fast heart rate), and low oxygen saturation are all possible symptoms
• Neurologic abnormalities - including altered mental states, disorientation, restlessness, agitation, and even coma. The occlusion of blood arteries in the brain is considered to cause neurological symptoms
• Petechial rash - characterised by the appearance of small red or purple patches (petechiae) on the skin, most notably on the chest, abdomen, and neck. The fat emboli can burst tiny blood arteries, resulting in these patches

FES can also cause an increase in body temperature, which might be due to an inflammatory reaction caused by fat globules. Some people may have tachycardia, low blood pressure, or other cardiac problems. Some people also have abdominal discomfort, nausea, vomiting, and diarrhoea.⁵

Management and treatment for fat embolism syndrome

FES management is supportive, with the primary goal of providing adequate blood oxygenation. Patients suffering from FES frequently require prompt medical care and stabilisation. This includes maintaining optimal blood pressure and fluid balance, as well as providing proper oxygenation and treating breathing issues.⁶

Treatment may include:

• High flow rate oxygen to keep the arterial oxygen concentration in the normal range
• Fluid restriction and the use of diuretics can reduce fluid buildup in the lungs as long as circulation is maintained
• Early corticosteroid therapy may help decrease inflammation and relieve symptoms in FES
• Anticoagulants in FES might be considered in some circumstances, although it should be done with caution, due to the increased bleeding risk
• In the case of significant blood artery blockage or signs of compartment syndrome (increased pressure inside a muscle compartment), surgical intervention might be needed to decrease pressure and restore blood flow.

Diagnosis

FES can be challenging to diagnose since its symptoms are non-specific and might overlap with other illnesses. FES is normally diagnosed using a combination of clinical examination, imaging investigations, and laboratory testing. The most common trio of symptoms linked with FES is respiratory distress, neurological problems, and a petechial rash, however, not all patients may have all three.⁷

The medical history and physical examination are critical in diagnosing FES. Long bone fractures (particularly in the lower extremities), severe trauma, or orthopaedic surgeries all increase the likelihood of FES. FES can be characterised by respiratory distress, hypoxemia (low oxygen levels), and an accelerated respiratory rate. An arterial blood gas (ABG) study may reveal low oxygen levels and elevated carbon dioxide levels. Patients may have changed mental states, experienced disorientation or agitation, or even gone into a coma. Mild cognitive impairment, seizures, and localised neurological symptoms are examples of neurological impairments. The occurrence of petechial rash, which manifests as minute, red, or purple patches on the skin owing to microscopic blood vessel ruptures, is a distinguishing feature of FES. The rash usually develops on the upper chest, axilla (armpits), and neck, although it can present elsewhere in the body.

A chest X-ray may reveal distinguishing features, including bilateral patchy infiltrates (white patches) in the lungs, which might suggest pulmonary oedema or inflammation. Transesophageal echocardiography (TEE) can assist in identifying fat globules in the heart and major vessels, especially if FES is suspected but not yet proven.⁸ Brain imaging, such as a computed tomography (CT) scan or magnetic resonance imaging (MRI), may be conducted to examine any neurological issues linked with FES.

There is no particular laboratory testing for FES, however, some results may help to confirm the diagnosis. These include increased blood lipid levels, a reduction in platelet count, and higher levels of lactate dehydrogenase (LDH) and creatinine phosphokinase (CPK). These tests, however, are not limited to FES and may be raised in other circumstances as well.⁹

FAQs

How can I prevent fat embolism syndrome?

FES can be avoided by identifying and treating long bone fractures and other traumatic injuries as soon as possible. In high-risk patients, such as those undergoing major orthopaedic surgeries, vigilance is essential. Thromboprophylaxis (prevention of blood clots) and meticulous surgical methods can also aid in the prevention of fat embolism. Educating healthcare providers about FES risk factors and symptoms assists in early detection and management. Timely steps to stabilise patients, ensuring appropriate oxygenation, and giving supportive care are critical in avoiding serious consequences from FES.¹⁰

How common is fat embolism syndrome?

Although FES is relatively rare, it can develop in individuals with long bone fractures or severe traumas. The reported incidence varies greatly, although it is expected to impact 1% to 10% of those who have long bone fractures. The syndrome is more common in younger people who have had serious traumas. Despite its rarity, FES necessitates quick diagnosis and treatment owing to the possibility of life-threatening consequences and a major influence on patient outcomes.⁹

Who is at risk of fat embolism syndrome?

FES is most common in people who have long bone fractures, such as femur or tibia fractures, as a result of major trauma, such as a car accident or a fall. Orthopaedic treatments, particularly those requiring bone marrow manipulation, such as joint replacement surgeries, are also risk factors. Younger patients, particularly those AMAB, are more vulnerable. Furthermore, people who have undergone specific medical procedures, such as liposuction or bone marrow transplantation, may be at a higher risk. Fat embolism can cause life-threatening consequences such as respiratory distress, cognitive impairments, and multiorgan malfunction, necessitating rapid medical intervention in high-risk situations.¹¹

When should I see a doctor?

Seek emergency medical assistance if you have signs of fat embolism syndrome, such as respiratory difficulty, disorientation, petechial rash, or neurological abnormalities following trauma or fractures.¹¹

Summary

Fat Embolism Syndrome (FES) is an uncommon but deadly illness that can develop following a long bone fracture or other trauma. Fat globules from the bone marrow or fat tissue enter the circulation and obstruct tiny blood arteries, resulting in a variety of symptoms and problems. Respiratory distress, neurological problems, and petechial rash (little red or purple patches on the skin) are the characteristic trio of FES. However, not every patient will display the entire trifecta.

Because of its non-specific symptoms, FES can be difficult to diagnose, but a combination of clinical assessment, imaging procedures (chest X-ray, brain imaging), and laboratory testing (elevated blood lipids, reduced platelet count) may assist in diagnosis. Treatment focuses on patient stabilisation, sufficient oxygenation, and supportive care. Oxygen treatment, hydration control, and corticosteroids may be employed in some cases. To lower the incidence of fat embolism, preventive interventions are needed, especially in high-risk individuals. The importance of early detection and action in enhancing patient outcomes cannot be overstated. FES is a complicated illness whose treatment should be adapted to each unique instance.