Case and content by Shannon McConnaughey, MD
Edited by Brandon Fainstad, MD
- Identify diffuse lung disease and review the differential for acute causes
A 50 year old woman with a history of post-operative deep vein thrombosis presents with acute onset hypoxemia with a dry cough 5 days after a revision of her R total hip. Only new medications is prophylactic heparin. Has not received peri-operative transfusions.
What is your differential based on these findings?
- Fat embolism
- Pulmonary edema- less likely with normal LV size and function (pulmonary hypertension may be due to acute fat emboli)
- Drug toxicity – no new exposures
- TRALI/TACO – no recent transfusions
- Diffuse alveolar hemorrhage – no hemoptysis, but remains a possibility
DIAGNOSIS AND TAKE HOME POINTS
Fat embolism syndrome
- Classically occurs 2 days after traumatic long bone fractures. However, this is also often seen 3-5 days following large surgical screw placement. The delayed presentation is due to immobilization after surgery and the embolization does not occur until the patient starts walking, which places stress on the screws and mobilizes the bone marrow fat.
- The pathology is not simply obstructive embolization, but more significantly, an inflammatory response to fatty acids that leads to pulmonary edema or inflammatory changes in any involved end-organ.
- It is a clinical diagnosis and managed with supportive care. Consider giving steroids in severe cases to decrease inflammation caused by fatty acid metabolites.