Fat embolism syndrome (FES) usually results from trauma and typically presents between 30 minutes and 48 hours post injury. The following case demonstrates the similarity of fat embolism to the commoner pulmonary embolism where both present as acute respiratory distress.
A 12-year-old boy was brought to Red Zone on 31st January 2016; presented with dyspnoeic since morning. He had a history of left femur fracture put on implant twice in May and August last year. He also had a trauma to the left ankle a day before presentation. On arrival, he is alert but noted to be tachypneic and tachycardia. His blood pressure was normal. Lungs auscultation and other systemic examination were unremarkable except for swelling and tenderness over left ankle region. Petechial rashes were noted over the body. Saturation was 100% on high flow mask oxygenation. Bedside echo found an enlarged right ventricles with a plethoric inferior vena cava. Electrocardiogram showed sinus tachycardia with an S1Q3T3 presentation. Arterial blood gas showed metabolic acidosis, lactate of 14 and pO2 of 239. His full blood count was normal except total white cell of 23.5/uL. D-dimer recorded 6498ng/mL. Also sustained closed fracture distal third tibia. The patient was brought into ICU and intubated. Patient was thrombolysed with intravenous metalyse based on ECHO findings and D-dimer. However, CTPA done showed pulmonary fat embolism instead of pulmonary artery thromboembolism as no filling defect was seen.
There is no gold standard test for diagnosing FES; it is a clinical diagnosis. The Classical triad of respiratory symptoms, neurological abnormalities, and petechial rashes may not be all present. Gurd & Wilson criteria for diagnosis of fat embolism require 1 of 3 major criteria and four minor criteria. A chest x-ray is usually normal initially but may reveal increasing diffuse bilateral pulmonary infiltrates. ECG of S1Q3T3 does not confirm pulmonary embolism but rather acute pressure and volume overload of the right ventricle. The presence of fat globules, either in sputum, urine, wedged pulmonary catheter or even bronchoscopy to diagnose FES lack specificity and sensitivity.
In the patient presenting with a syndromic interpretation of acute respiratory distress, a high index of suspicion of fat embolism should be entertained especially if there was a recent trauma to the skeletal system. However, a non-traumatic situation like acute pancreatitis and sickle cell crisis may also cause fat embolism syndrome.