Question

Why does elastance increase after ventilator-induced lung injury? Provide specific structural changes that lead to increased elastance.

Answer 1

Lung elastance is a measure of the elastic stiffness of the lung parenchyma.

Elastance  varies as a function of both time and positive end-expiratory pressure (PEEP) reflects the nature and degree of lung injury, and infer the separate contributions of volutrauma and atelectrauma to ventilator induced lung injury.

There are a variety of microscale structures that contribute to the determination of lung elastance and that can become altered in acute lung injury. One is the network of extracellular matrix proteins (mostly collagen and elastin) depicted which provide the parenchyma with its structural integrity and which can become stiffened as a result of the fibro proliferation that is a common effect of ARDS .

This network occupies the interstitium of the blood-gas barrier, which is located between the endothelial and epithelial cell layers that provide most of the barrier function separating blood from the alveolar airspace. Also in this interstitial space are various cell types and fluid.

Expansion of the fluid volume is a common occurrence in the injured lung because blood plasma with associated plasma proteins, moves across the leaky endothelium to produce interstitial pulmonary edema .

The resulting congestion of the interstitial space can lead to a stiffening of the parenchyma, and thus results in the elevation in elastance.