Progressive Care Nursing Certification (PCCN) Practice Exam

What major physiologic derangements occur in acute respiratory distress syndrome (ARDS)?

1. Movement of fluid out of the capillary bed

2. Histamine release and vasodilation

3. All of the above

4. Decreased oxygen saturation only

The correct answer is: All of the above

In acute respiratory distress syndrome (ARDS), significant physiological derangements involve multiple mechanisms. One primary feature of ARDS is increased permeability of the pulmonary capillaries, leading to the movement of fluid out of the capillary bed and into the alveolar spaces. This results in pulmonary edema, which severely hampers gas exchange and contributes to hypoxemia. The condition frequently involves inflammatory processes and mediators, such as histamines, which can lead to vasodilation and increased capillary permeability. The inflammatory response can also cause further lung injury and exacerbate the existing fluid accumulation in the alveoli. Recognizing the interconnectedness of these physiological changes is crucial. The combined effects lead to not only impaired oxygenation, as indicated by decreased oxygen saturation, but also the overall clinical picture seen in ARDS. Therefore, acknowledging the multiple derangements, including fluid movement and inflammatory responses, is essential in understanding the pathophysiology of ARDS.