BRONCHOVASCULAR CUFF FORMATION AND LUNG LYMPH FLOW IN EDEMA FORMATION OF ANESTHETIZED SHEEP

Abstract

The relationship between bronchovascularcuff formation and lung lymph flow in hydrostaticedema was evaluated. After a balloonwas inserted into the left atrium to increaseleft atrial pressure for 5 hrs, peripheral lungtissues were resected for analysis of the wetdryratio and cuff formation. The degree ofcuff formation was expressed as the cuff ratio(outer diameter of cuff / outer diameter ofmicrovessel or airway) in three size categories:80-200, 200-400, and 400-750 μm in diameter.The amount of excess lung lymph (Ex LL) for5 hrs was calculated from the recorded datafor the whole lymph flow wave. The wet-dryratio showed a significant correlation withΔLAP and lung lymph flow increased significantly(flow rate, 0.67 ± 0.46 ml/min (mean ±SD); Ex LL, 56.4 ± 47.6 ml). Cuff formationwas found at all levels of the bronchovasculartree, with a larger cuff ratio (>1.3) observed atarteries and veins of 80-200 &m in diameter,but a significant correlation with Ex LL wasfound only for arteries of 80-200 μm. Fluidaccumulation in lung interstitium firstoccurred at smaller extra-alveolar arterieseven under mild hydrostatic pressure elevationwith a significant increase in lymph flow.