What type of emboli injure blood vessels and cause acute respiratory distress syndrome (ARDS)?

Fat emboli are responsible for injuring blood vessels and can lead to acute respiratory distress syndrome (ARDS). When fat globules enter the bloodstream—often as a result of trauma, such as from a fracture of long bones or orthopedic surgery—they can travel to the lungs. In the pulmonary circulation, these fat globules can obstruct small blood vessels, leading to increased vascular permeability and inflammatory responses. This can result in fluid accumulation in the alveoli, profoundly impairing gas exchange and causing the hallmark symptoms of ARDS, such as severe respiratory distress and hypoxemia.

The mechanism by which fat emboli evoke these responses is primarily through the release of inflammatory mediators and the direct mechanical obstruction of blood flow, compromising the oxygenation process in the lungs. Understanding this pathophysiology is crucial for recognizing and managing ARDS in clinical practice, as the presence of fat globules can trigger significant respiratory compromise and necessitate immediate medical intervention.