A patient with long bone fractures develops tachycardia, hypoxia, and a petechial rash postoperatively. The most likely diagnosis is which of the following?

A patient with long bone fractures develops tachycardia, hypoxia, and a petechial rash postoperatively. The most likely diagnosis is which of the following?

• A. Pulmonary embolism
• B. Transfusion reaction from packed red blood cells
• C. Transfusion reaction from platelets
• D. Fat embolism

Answer: (D)

Fat embolism syndrome is the likely diagnosis. After long-bone fractures, fat from the bone marrow can enter the bloodstream and lodge in the pulmonary microvasculature, causing respiratory symptoms and hypoxemia, often with tachycardia. The process can also affect the brain and skin, producing neurologic symptoms and a petechial rash. This constellation typically appears within 24–72 hours after injury or surgery, matching the scenario described. Pulmonary embolism from a clot can cause similar breathing difficulty but usually lacks the characteristic petechial rash seen with fat embolism and doesn’t have the same temporal association with marrow injury. Transfusion reactions can cause dyspnea too, but the combination of long-bone fracture, hypoxemia with tachycardia, and a petechial rash is classic for fat embolism rather than a transfusion reaction.

Fat embolism syndrome is the likely diagnosis. After long-bone fractures, fat from the bone marrow can enter the bloodstream and lodge in the pulmonary microvasculature, causing respiratory symptoms and hypoxemia, often with tachycardia. The process can also affect the brain and skin, producing neurologic symptoms and a petechial rash. This constellation typically appears within 24–72 hours after injury or surgery, matching the scenario described.

Pulmonary embolism from a clot can cause similar breathing difficulty but usually lacks the characteristic petechial rash seen with fat embolism and doesn’t have the same temporal association with marrow injury. Transfusion reactions can cause dyspnea too, but the combination of long-bone fracture, hypoxemia with tachycardia, and a petechial rash is classic for fat embolism rather than a transfusion reaction.