Question
What does the term "heterogeneous lung disease" mean in the context of ARDS?
Answer
Heterogeneous lung disease in ARDS (Acute Respiratory Distress Syndrome) refers to the fact that lung pathology is not consistent throughout the lungs. Different areas may have varying degrees of consolidation, obstruction, or dysfunction, leading to uneven gas exchange and challenges in ventilation. Mechanical ventilation introduces volume and pressure to the lungs. Alveoli that are functional may experience stress and strain due to the ventilator, and their behavior can influence nearby alveoli. Additionally, ventilator settings might not account for the complex interactions between alveoli.
The alveolar-capillary membrane is the thin barrier between the alveoli and the blood capillaries. It facilitates the exchange of gases between the air in the alveoli and the blood in the capillaries. When this membrane is compromised, as in cases of inflammation, gas exchange becomes less efficient. Inflammation triggers the release of cytokines, signaling molecules that can damage the alveolar-capillary membrane. This damage leads to the accumulation of proteinaceous fluid in the interstitium and alveoli, causing the collapse of alveoli and impairing gas exchange.
This Ask the Expert is an edited excerpt from the course, Mechanical Power at a Glance, presented by presenter, Keith Lamb, RRT, RRT-ACCS, FAARC, FCCM.
