Effect of Venous Air Embolization on Pulmonary Microvascular Protein Permeability

Abstract

Objective: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 (σ_f). Methods: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_Pwas 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. Results:Q_Lincreased and C_L/C_Pdecreased 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 σ_fchanged following pulmonary air embolization. Conclusions:Utilizing the washdown technique, the authors could not find any evidence that pulmonary microvascular protein permeability is altered by air embolization. Microcirculation(2004) 11,409–414. doi:10.1080/10739680490457773

• lymph-to-plasma protein concentration ratio
• microvascular protein permeability
• pulmonary air embolism
• reflection coefficient