Effect of venous air embolization on pulmonary microvascular protein permeability

An increase in pulmonary lymph flow and lymph protein clearance following pulmonary air embolization has been interpreted as evidence of increased pulmonary microvascular permeability. The authors hypothesized that air embolization does not alter the pulmonary microvascular permeability to protein and that this could be demonstrated by determining the effect of air embolization on the pulmonary solvent drag reflection coefficient (sigma(f)).

Anesthetized dogs were instrumented with left atrial balloon-tipped catheters, pulmonary lymphatic cannulae, and inferior vena caval catheters. Values were determined for pulmonary lymph flow (Q(L)) and the lymph-to-plasma protein concentration ratio (C(L)/C(P)) at baseline, after C(L)/C(P) was decreased to a filtration independent value by raising left atrial pressure via progressive balloon inflation and after 2 h of air embolization into the inferior vena cava with continued left atrial hypertension.

Q(L) increased and C(L)/C(P) decreased to a filtration-independent value following induction of left atrial hypertension. Air embolization induced during left atrial hypertension resulted in no significant change in C(L)/C(P). The authors were unable to demonstrate that sigma(f) changed following pulmonary air embolization.

Utilizing the washdown technique, the authors could not find any evidence that pulmonary microvascular protein permeability is altered by air embolization.