Fat embolism syndrom (FES) is one of the more serious complications of orthopedic surgery, mostly seen in long bone fractures and pelvic fractures, which has attracted widespread attention at home and abroad because of the lack of early diagnostic criteria and the tendency to delay early treatment, which can lead to death in serious cases. Since 1882, when Zenker first discovered fatty droplets in the pulmonary vascular bed of a severe trauma death case and 1887, when Bergmann first clinically diagnosed fat embolism, although it has been a century and many people have studied it from different angles, its clinical manifestations vary greatly because some cases are aggressive and have a rapid onset, and even die quickly before the appearance of typical symptoms, and some There can be no obvious clinical symptoms, but only found in post-mortem examination, so only in the last 20 years has there been further understanding of its pathophysiology. As a specialized orthopedic hospital, we perform surgery or manipulation on nearly 10,000 orthopedic patients each year, so every clinician should be aware of the etiology, clinical manifestations and early treatment of fat embolism syndrome.
What are the conditions that must be present to cause embolism?
(1) Rupture of the adipocyte membrane, producing free lipids.
(2) An injured and open vein.
(3) Localized injury or fracture with hematoma formation and elevated local pressure, which drives fat into the ruptured vein.
How can we quickly determine that a patient has developed FES?
There are 3 major criteria, 2 minor criteria and 7 reference criteria that are recognized by most scholars. 3 major criteria include
①Pulmonary symptoms (characterized by shortness of breath, dyspnea, and cyanosis with PaO2 ↓ and PCO2 ↑).
② neurological symptoms (confusion, drowsiness, convulsions, coma) without head trauma.
③ bleeding spots on the skin mucosa.
The diagnosis is confirmed by meeting the 2 main criteria.
In clinical work, it is found that most patients with long bone fractures have varying degrees of pulmonary dysfunction, of which 10-15% present with severe FES, showing respiratory insufficiency (in mild cases, dyspnea and shortness of breath, in severe cases, it is difficult to distinguish from ARDS), neurological manifestations (such as delirium, drowsiness, confusion, or even coma, which can be fully recovered in most patients if treated promptly, but due to If treated promptly, most of the patients can recover completely, but due to the hypersensitivity of the cerebral cortex, the sequelae can be left in different degrees), skin and mucous membrane bleeding spots, fever, etc. Laboratory tests and imaging lack specificity, while clinical diagnosis of FES is the key. However, the incubation period of FES is 4~72h, and early diagnosis is more difficult, reminding clinicians that
Once hypoxemia and impaired consciousness that are difficult to explain by the primary disease appear must be thought of the possibility of fat embolism syndrome.
How to give proper early management to FES patients?
FES is a self-limiting disease, and there is no specific treatment yet. Targeted or supportive treatment measures are mainly used, such as respiratory support therapy, appropriate sedation, glucocorticoid application, hyperbaric oxygen therapy, dehydration, lipid-lowering drugs, antibiotics and other symptomatic treatment. Early management of lipoembolism (subclinical type) with milder symptoms has a better prognosis, while fulminant cases have a poor prognosis. Patients who enter coma after a very short period of consciousness indicate a very dangerous condition. The mortality rate of symptomatic fat embolism is about 10% to 20%, and the cause of death is mostly the breakdown of the fat embolus, which releases free lipic acid and leads to hemorrhagic pneumonia. After treatment of fat embolism, some cases may have sequelae such as epileptic psychiatric symptoms, temperament changes, decortication ankylosis, uveitis, visual impairment, myocardial damage, and renal dysfunction, but the incidence is not high.
How to avoid the occurrence of FES?
The pathophysiological pathways of FES are still not well understood and complete avoidance is not yet possible; preventive measures need to be given sufficient attention.
1. The fractured limb should be fixed in a timely and proper manner. When examining, dressing and fixing the fracture site and traction treatment, the operation should be gentle. For patients who are fixed too tightly with intraoperative tourniquet or cast, the process of relaxing the tourniquet or removing the cast should be slow to prevent fat embolism induced due to hemodynamic changes. Continuous elevation of the affected limb to promote venous reflux is an effective preventive measure for fat embolism syndrome.
2.Early appropriate pain relief can reduce the sympathomimetic response to trauma and help reduce the level of free fatty acids in the blood.
3.When traction treatment and manual repositioning are performed after fracture, the pressure in the medullary cavity is obviously increased. Repeated repositioning can lead to continuous bleeding, aggravate swelling and promote the release of bone marrow fat into the venous circulation, avoiding repeated manual repositioning can effectively reduce the incidence of FES.
4. As far as possible, patients with fractures should undergo surgical incision and internal fixation as early as possible, so that the fat droplets at the fracture end can be excluded with the hematoma, preventing tissue re-injury and fracture end activity, limiting the continued release of fat from the medullary cavity, reducing fat emboli into the venous circulation, and reducing the incidence of fat embolism syndrome.
5, the operation should be light and fast, and the intramedullary nail should be inserted during the operation, and as far as possible, the appropriate one should be chosen to achieve the treatment purpose without expanding the marrow with locking intramedullary nail; if the marrow must be expanded, a sharp marrow expander should be used as far as possible, and the expander should not be pushed in too fast to control the sudden increase of the intramedullary pressure and induce the occurrence of fat embolism syndrome.
In conclusion, laboratory tests and imaging tests are not specific for the diagnosis of FES. Early clinical diagnosis, respiratory support, adequate sedation and comprehensive treatment are important to reduce the mortality of FES patients.