Acute respiratory distress syndrome (ARDS) is a medical condition occurring in critically ill or critically wounded patients characterized by widespread inflammation in the lungs. ARDS is not a particular disease; rather, it is a clinical condition triggered by various pathologies such as trauma, pneumonia, and sepsis.
The hallmark of ARDS is diffuse injury to cells which form the barrier of the microscopic air sacs of the lungs, surfactant dysfunction, activation of the innate immune system response, and dysfunction of the body's regulation of clotting and bleeding. In effect, ARDS impairs the lungs' ability to exchange oxygen and carbon dioxide with the blood across a thin layer of the lungs' microscopic air sacs known as alveoli.
The syndrome is associated with a death rate between 20 and 50%.
The risk of death varies based on severity, the person's age, and the presence of other underlying medical conditions.
Although the terminology of “adult respiratory distress syndrome” has at times been used to differentiate ARDS from “infant respiratory distress syndrome” in newborns, the international consensus is that “acute respiratory distress syndrome” is the best term because ARDS can affect people of all ages.