Pathophysiology of Acute Lung Injury

Abstract

Nearly all types of pulmonary edema reduce to two main forms; increased pressure edema and increased permeability edema, as specified by the Starling equation:

$$ \dot Q = K\left[ {\left( {Pmv - Ppmv} \right) - \sigma \left( {\Pi mv - \Pi pmv} \right)} \right], $$

where $\dot Q$ is the net transvascular liquid filtration rate; K is the liquid conductance of the microvascular barrier; P is the hydrostatic pressure in the microvascular (mv) lumen and in the perimicrovascular (pmv) interstitial liquid space, respectively; σ is the reflection coefficient (a number between 0 and 1 representing the resistance of the microvascular barrier to protein leakage); and Π is the protein osmotic pressure in the microvascular and perimicrovascular liquid, respectively.