What is Fat Embolism?
Fat embolism and fat embolism syndrome, commonly known as FES, are medical conditions where fat particles spread through the bloodstream. These fat particles can disrupt small blood vessels and affect the flow of blood in tiny vessels, leading to an inflammation response in the body. This inflammation response can affect various parts of the body, typically the skin, the brain, the lungs, and the eyes. It’s more common in patients with bone injuries, but it can also happen for non-accident-related reasons such as pancreatitis, bone marrow transplants, or liposuction.
In most situations, this condition is only confirmed when an autopsy is performed. A fat embolism refers to the direct appearance of fat globules in tiny vessels, while FES refers to the spread and effects of these fat particles. FES is like an advanced version of a fat embolism. The first record of FES was in 1863 when a patient had a severe injury, and the first clinical diagnosis was in 1873. Since then, many articles and studies have been done on this condition, particularly within the field of orthopedics as this is where most cases are seen.
The criteria to diagnose FES proposed by researchers Gurd and Wilson back in the 1970s is still the most widely used, but it’s essential to know that diagnosing FES remains a significant challenge for clinicians. In other words, it’s not easy to identify this condition.
What Causes Fat Embolism?
Some causes of Fat Embolism Syndrome (FES), a condition where fat particles block blood vessels, are linked to injuries, while others are not linked to injuries.
Injury-related causes are more common. FES can happen from fractures in long bones like the thigh or shin bone, or even the pelvis. Certain surgeries like those involving the pelvis or knee, or those placed a rod into a bone (intramedullary nailing), can also lead to FES.
Techniques during surgery that may increase the chance of FES include fast-paced drilling (reaming), excessive force when placing the medullary nail into the bone, and if there’s a big gap between the nail and the outer layer of the bone.
Some less common injury-related causes of FES are:
– Severe damage to soft tissue.
– Crush injuries.
– Long durations of cardiopulmonary resuscitation (CPR).
– Severe burns that cover more than half of the body.
– Bone marrow transplants.
– Liposuction.
– Surgery on the breastbone.
Non-injury related causes of FES are rare, but they can include:
– Fatty liver disease.
– Inflammation of the pancreas (either acute or chronic).
– Corticosteroid therapy (a type of medication).
– Infusion of fat emulsion (a type of medication).
– Lymphography, a type of medical imaging.
– Certain blood disorders like sickle cell disease and Thalassemia.
There are also certain risk factors that can increase the chance of developing FES. These include:
– Youth.
– Closed fractures, where the bone does not penetrate the skin.
– Multiple fractures.
– Extended non-surgical management of long bone fracture.
Risk Factors and Frequency for Fat Embolism
Fat embolism and Fat Embolism Syndrome (FES) are conditions where fat particles enter the bloodstream and can cause issues. The occurrence of these conditions varies greatly according to different reports. Small fat embolism incidents or mild cases of FES can often be missed and not diagnosed.
- In studies of patients who had been in orthopedic accidents, 67% had fat particles in their blood. This number rose to 95% when the blood sample was taken near the injury site.
- During surgery to repair long bone fractures, fat embolism and FES can occur. An imaging technique called a transesophageal echocardiogram showed fat embolism in nearly 41% of patients.
- Fat embolism is more common than FES. One pivotal study reported a 19% occurrence of FES in a group of trauma patients, using specific clinical criteria.
- Standard treatment procedures for repairing long bone fractures have helped reduce the occurrence of fat embolism and FES. Recent studies show a reduced occurrence, ranging from 1% to 11%.
Signs and Symptoms of Fat Embolism
A fat embolism is a condition where fat enters the bloodstream and can travel to various organs in the body such as the kidneys, heart, skin, brain, and lungs. This can cause damage and often occurs between 24 to 72 hours following a traumatic event.
The medical history of a patient suspected of having a fat embolism should cover the timing and onset of symptoms. Additionally, details about the related trauma, such as when and how it occurred, should be noted. A history of conditions like sickle cell disease or other forms of hemoglobinopathy can make the patient more prone to fat embolism. Asking the patient or their family about any history of sickle cell disease and its related complications is crucial. Questions should also cover any drug use or alcohol consumption that could lead to pancreatitis, another risk factor for this condition.
- Pain related to bone fracture
- Nausea
- General weakness
- Malaise or discomfort
- Difficulty breathing
- Headache
The signs and symptoms of fat embolism can involve a variety of bodily systems:
Respiratory symptoms can include:
- Fast breathing (tachypnea)
- Fast heart rate (tachycardia)
- Sweating (diaphoresis)
In the central nervous system, symptoms can occur such as:
- Agitation from lack of oxygen (hypoxia)
- Restlessness
- Change in mental status
- Seizure
- Coma
On the skin, a petechial rash may appear, and in the eyes, retinal hemorrhage may occur.
During a physical examination, doctors should thoroughly investigate the patient’s general appearance, respiratory system, cardiovascular system, central nervous system, skin, and eyes. Patients with fat embolism often appear anxious, agitated, and unwell. Examination of the respiratory system should focus on any abnormal breathing sounds or signs of respiratory distress. Heart rate and blood pressure should be checked, as these may start high, but eventually lead to a drop in blood pressure. If the patient’s Glasgow Coma Scale score is less than 8, indicating potential issues with their central nervous system, the patient may need ventilation aid. The presence of a petechial rash on the skin along with the above factors can indicate a fat embolism. A thorough eye exam should also be done to look for any retinal hemorrhage.
Testing for Fat Embolism
Fat Embolism Syndrome (FES) can be difficult to diagnose because the symptoms can be unclear. At the moment, there’s not an accepted set of criteria to diagnose FES. Over the years, experts have suggested different criteria to diagnose FES. This is based on their experiences and research.
Gurd and Wilson suggested the following criteria for diagnosis:
Major Criteria:
* A rash of tiny red spots (called a petechial rash)
* Breathing difficulties (respiratory insufficiency)
* Signs of brain involvement in patients who haven’t had a head injury
Minor Criteria:
* High fever over 38.5 C
* Fast heart rate, over 110 beats per minute
* Changes in the retina of the eye
* Yellowing of the skin (jaundice)
* Signs of kidney issues
* Anaemia
* Low platelet count (thrombocytopenia)
* Elevated erythrocyte sedimentation rate
* Presence of fat proteins in the blood (fat macroglobulinemia)
Schoenfeld proposed another way to diagnose FES, based on a scoring system. A score over 5 indicates FES.
* 5 points for a petechial rash
* 4 points for widespread signs of fluid in the lungs on an x-ray
* 3 points for low oxygen levels in the blood
* 1 point each for fever, fast heart rate, and confusion
Lindeque suggested diagnosing FES based only on breathing symptoms, but this idea hasn’t become widely accepted.
Other tests that can help diagnose FES include:
* Complete blood count: Anaemia and a low platelet count are common in FES.
* Comprehensive metabolic panel: These tests can show metabolic acidosis, increased BUN and creatinine levels which are indicators of FES.
* Arterial blood gas: This test can show if there’s a mismatch between ventilation and blood flow in the lungs, a hallmark of FES.
An advanced test called bronchoalveolar lavage can also help diagnose FES. This test looks for fat cells in samples from the lungs. However, the test isn’t specific to FES and can be time-consuming and invasive.
Imaging tests can also help in diagnosing FES. These include:
* Chest X-ray: To look for fluid in the lungs or lung infections
* CAT scan of the chest: To look for areas of increased blood flow or fluid in the lungs
* Imaging of the brain: A CT scan can rule out other causes of altered mental states, like bleeding in the brain. An MRI can show changes in the brain related to FES.
Research into biological markers for FES hasn’t been promising so far because of low specificity. Tests to look for fat globules in the blood, urine, or sputum aren’t specific to FES.
Treatment Options for Fat Embolism
Fat embolism syndrome (FES) is a medical condition that doesn’t have a specific treatment yet. Past attempts have been made to decrease the mobilization of free fatty acids (building blocks of fat) in the body using treatments like dextrose infusion and ethanol, but these didn’t show proven benefits. While heparin, a type of medication, showed benefits in animal studies, it’s not used clinically because of the risk of bleeding it poses.
Treatment with corticosteroids, a type of medication that lowers inflammation in the body, has also been suggested for FES. Some reasons for this include the drugs’ ability to inhibit the aggregation of white blood cells, limit the levels of free fatty acids, and stabilize cell membranes. Yet, the use of corticosteroids remains controversial, as a large study of 7 trials found a reduction in the risk of FES, but no change in mortality, infection, or avascular necrosis (bone death caused by poor blood supply) between the treatment group and the control group.
It’s also been proposed to use an inferior vena cava filter to prevent the dispersal of fat emboli (clumps of fat in the bloodstream). This hasn’t been sufficiently studied, so it’s not a commonly used treatment for FES.
In terms of surgical measures, it’s strongly recommended to quickly address fractures of long bones. FES occurs more frequently in patients who’ve fractures of long bones and are managed without surgery. Managing these fractures with internal fixation devices substantially reduces the incidence of FES.
If a patient develops FES, the main treatment becomes supportive care, which means helping the body heal as much as possible and managing symptoms. This includes providing adequate oxygen/ventilation, maintaining stability in the body’s basic functions, blood transfusion if necessary, prevention of deep vein thrombosis (blood clots), and ensuring proper nutrition and hydration. If the patient’s oxygen levels severely drop, intubation (inserting a tube into the airway) and mechanical ventilation may be needed.
Albumin, a protein in blood, is often used as part of the treatment for low blood volume. It restores the amount of blood in the body and helps to bind free fatty acids, preventing the widespread spreading of fat globules.
Intubation may be required if the patient’s mental status changes significantly or if there’s a lot of difficulty breathing that isn’t improving with noninvasive support. If the patient develops pulmonary hypertension (high blood pressure affecting the arteries in the lungs and right side of the heart) with right ventricular failure, medication to support the heart may be necessary. If brain swelling is present, treatments like mannitol, hypertonic saline, or intracranial pressure monitors might be needed.
What else can Fat Embolism be?
When trying to identify fat embolism syndrome (FES), doctors should also consider ruling out other conditions that show similar symptoms. These conditions may affect the respiratory system, the central nervous system, or cause skin rashes.
For the respiratory system, FES should be distinguished from conditions like pulmonary contusion, pulmonary edema, aspiration pneumonia, and pulmonary thromboembolism. These conditions might show similar symptoms but can be differentiated with the help of a CT scan of the chest. For example, a pulmonary contusion generally occurs within 6 to 10 hours of chest injury and is visible as an area of foggy opacity on the lung in a CT scan.
The central nervous system disorders that could be mistaken for FES include conditions like:
- Meningitis
- Encephalitis
- Brain tumor
- Epidural, Subdural, or Subarachnoid bleed
All these conditions can also lead to altered mental status, similar to FES. A CAT scan of the brain can help identify a bleed or tumor while Meningitis and Encephalitis can be ruled out with a lumbar puncture and analyses of cerebrospinal fluid.
Lastly, if the patient presents with petechial skin rashes, conditions like:
- Idiopathic thrombocytopenic purpura
- Thrombotic thrombocytopenic purpura
- Leukemia
should also be considered. As these are blood disorders, their presence can be determined by examining other clinical signs and symptoms, and with the consultation of specialists like a hematologist/oncologist and a dermatologist.
What to expect with Fat Embolism
If you have experienced a traumatic fat embolism syndrome (FES) – a serious condition where fat particles enter the blood stream and block blood vessels – the chances of recovery largely depend on how quickly a surgery is performed to fix a fractured long bone. Receiving appropriate support therapy also plays a crucial role in recovery. It helps patients get over the changes in their nervous systems, breathing, and vision that are typically associated with fat embolisms.
Recent research shows that the mortality rate for FES ranges from 7% to 10%. The most common causes of serious health conditions or death are due to sudden, severe lung disease (acute respiratory distress syndrome or ARDS) and swelling of the brain (cerebral edema).
