What is acute respiratory distress syndrome (ARDS) defined by?

Acute Respiratory Distress Syndrome (ARDS) is characterized by the body's inability to maintain adequate gas exchange due to severe lung inflammation and damage. This condition often arises from factors such as pneumonia, sepsis, or trauma, leading to fluid accumulation in the alveoli and resulting in hypoxemia and difficulty in breathing. In ARDS, the lungs are unable to provide the necessary oxygen to the bloodstream, severely impairing the body’s ability to breathe independently without medical intervention, which may include mechanical ventilation.

Although other options refer to symptoms related to respiratory problems, they do not define ARDS specifically. For instance, inability to perform normal physical activities could indicate a range of conditions affecting physical fitness, not solely reflecting the critical and acute nature of ARDS. Similarly, a chronic cough with phlegm is more associated with chronic respiratory conditions like chronic obstructive pulmonary disease (COPD) or bronchitis, rather than the acute and immediate respiratory failure seen in ARDS. Persistent shortness of breath while resting can also occur in various conditions and does not capture the severe acute onset and the underlying physiological changes associated with ARDS. Therefore, the correct choice highlights the critical nature of ARDS as a state where the individual cannot breathe adequately without assistance.