What is a Fat Embolism?
A fat embolism is a common problem for patients following trauma or surgery to the lower limbs. Under these conditions fat from bone marrow is able to escape into the bloodstream and form emboli (collection of fat droplets). Many patients who have fat emboli are not even aware as the symptoms may be minor. For a small number of patients however these emboli block small blood vessels in the lungs, skin or brain triggering a cascade of events leading to the illness known as ‘fat embolism syndrome'. The most severe problem of fat embolism syndrome is acute respiratory distress syndrome (ARDS) where the lungs are unable to absorb oxygen properly and patients become severely hypoxic (lacking in oxygen). It is this group of patients who will be admitted to the ICU.
What are the causes of fat embolism?
Fat embolism is most commonly associated with trauma or surgery of the pelvis or long bones of the legs. However it can also occur in illnesses or treatments where fat droplets are able to enter the bloodstream. Some of the causes include:
- Long bone and pelvic fractures
- Rib factures
- Severe burns
- Massive soft tissue injury
- Bone marrow biopsy
- Diabetes mellitus
- High dose steroid therapy
What are the symptoms?
Symptoms of fat embolism syndrome are usually evident 24 to 72 hours after an injury, and involve the lungs, the brain and the skin. Symptoms include:
- An altered mental state with symptoms including irritability, agitation, headache, confusion, seizures or coma
- Lung problems including rapid breathing, shortness of breath (dyspnoea), difficulty breathing and a low oxygen level
- A rash on the skin (petechiae) - blockages in small blood vessels leading the small pin-point haemorrhages, usually in the upper torso. These haemorrhages also occur in the eye.
Diagnosis is made on the basis of a patient's presenting condition and symptoms, as well as excluding other possible problems. It is likely most patients will have chest xrays, blood tests and CT scans as well as cardiac investigations such as an ECG and echo cardiography to exclude a cardiac cause of symptoms.
What is the treatment?
There is no specific therapy for fat embolism syndrome because it is a self-limiting illness. The treatment is therefore supportive, with the aim being to provide adequate oxygen to all of the tissues of the body. In minor cases oxygen therapy with an face mask may be adequate however in severe cases where the ALI is severe patients will require admission to ICU and full breathing (respiratory) support using a breathing machine (ventilator). The best way to prevent fat embolism when patients have fractures is to immobilise these fractures early.
What happens in the ICU?
- Monitoring of the heart rate, blood pressure, oxygen saturation and temperature. This will be seen on a bedside monitor.
- An arterial line may be inserted to monitor blood pressure and to take blood samples.
- Medication and intravenous fluids may be given via a central venous catheter including sedatives (to assist in sleep), analgesics (pain killers) and antibiotics (for infections). These medications will be given via infusion pumps.
- Oxygen may be delivered via a face mask however if the lung problems are severe patients will require assistance with breathing using a breathing machine (ventilator) where a breathing tube(endotracheal tube) is inserted into the windpipe (trachea). The ventilated patient will require suctioning to remove secretions from the lungs and airways.
- If the patient is unable to eat, nutrition may be given via a nasogastric tube. This is a tube that is placed in the nose and goes down the throat into the stomach. Fluid can also be removed from the stomach via the nasogastric tube.
- Insertion of an indwelling catheter to drain and measure urine output.
- Chest x rays and other tests such as blood tests.
- Sequential compression devices may be put on the legs to prevent the formation of blood clots.
- An air mattress may be used to prevent pressure areas developing.
- Care of the eyes is very important, as sometimes even blinking the eyes may be affected.
How long will the patient remain in the intensive care?
The patient will remain in the intensive care unit until they no longer require respiratory support and are recovering. The prognosis for patients who survive fat embolism is good, and recovery usually takes 2-4 weeks. In some cases however, visual disturbances may remain.
References & Links
- Freebairn, FC (1997) Fat embolism syndrome (chapter 31) Intensive care manual TE Oh 4th edition, Butterworth Heinemann
- Gore, T and Lacey S (2005) Bone up on fat embolism syndrome Nursing 2005, August
- Fat embolism Version 1
- Published January 2009
- Authors: Kathleen Ryan & Kaye Rolls CNC ICCMU
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