Early cardiovascular findings include non-specific tachycardia, ventricular ectopy and right heart EKG changes such as right axis deviation and ST-T wave changes. A hyperdynamic state is likely, until there is compromise of the cardiac output. If there is hypoxemia and cyanosis, concurrent hypotension is likely from decreased left-sided cardiac output. CNS signs of FES include anxiety disorientation, lethargy and unconsciousness. Seizure activity can evolve, with grave prognosis. Coma can evolve from cerebral ischemia, hypoxia, or embolization to key areas in the brain stem. Elevated temperature is a non- specific CNS sign of FES. DIC can result from the activation
to hypoxemia. Fat metabolism within the capillary-alveolar bed will lead to further inflammation. The activity of lipase will also lead to destruction of type II pneumocytes by the cytotoxicity of accumulated free fatty acids. The presence of greatly increased levels of free fatty acids is cytotoxic to pulmonary capillaries. This will induce micro thrombi involving lipids, platelets and fibrin, with subsequent chemotaxis. Progressive pulmonary accumulation of clotting factors can lead to depletion of intravascular clotting materials and further mechanical obstruction of the pulmonary. In extreme cases, disseminated intravascular coagulation (DIC) can occur. The most common cause of death related to FES is respiratory failure.
DIAGNOSIS Clinical recognition of FES is facilitated by a high index of suspicion in patients undergoing procedures. Early identification of signs during anesthesia that indicate
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that fat is embolizing can lead to technical changes that may alter the evolution of FES in a favorable manner. Early clinical changes indicative of
fat embolism syndrome (FES) include altered level of consciousness, tachycardia, tachypnea, dyspnea. Desaturation via pulse oximetry is an early warning sign. An arterial oxygen tension of less than 60 mmHg by itself suggests possible FES. Early changes in the respiratory system include wheezing, pleuritic chest pain, hemoptysis, or copious secretions consistent with non-cardiogenic pulmonary edema. At this point, the PaO2 is usually below 70 mmHg. Later diagnostic signs include wheezing to auscultation and bilateral infiltrates on chest radiograph, a relatively late sign. Other early signs of possible FES can
be found with examination of the skin. Identification small, confluent petechiae on the chest, neck and axilla is highly suggestive of FES. Further confirmation can be found with retinal fundiscopic exam if ‘cotton-wool’ exudates are found.
of microscopic coagulation from the interaction of free fatty acids with cell membranes and the adherence of platelets and fibrin within the pulmonary circulation. An early sign of DIC is an unexplained drop in the platelet count or the fibrin level. There are no specific laboratory tests that absolutely confirm the diagnosis of FES. Unexplained PaO2 below 60 mm Hg is highly suggestive of FES. Serial blood gas results that demonstrate progressive hypoxemia is further confirmation. Progressive decrease in the platelet and/ or red cell count is also a sign of FES. Fat globules in the sputum, serum or urine can be found in all cases of FES, but are also found in sub-acute cases. A majority of patients with FES develop diffuse, bilateral infiltrates on chest x-ray, but this is usually found after other clinical signs have confirmed the diagnosis. Elevate serum lipase levels occur in a majority of cases of severe FES, although this is another non-specific late finding. Right axis deviation and ST-segment changes are very non-specific signs of FES. Finding an A-a O2 gradients greater than 100 mm Hg is a highly associated FES. Bronchial lavage has been reported as diagnostic and therapeutic in severe cases.
HIGH RISK PROCEDURES The obvious high risk case is the acute care of patients with multiple trauma. Lower extremity joint replacement is also high risk for FES. Fat embolism associated with femoral stem insertion, and the use of methyl methacrylate can trigger FES. Although the incidence is lower due to
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