Gas Exchange in the Normal Lung : Experimental studies on the effects of positive end-expiratory pressure and body position

Abstract

BACKGROUND:The principal function of the lung is gas exchange requiring adequate ventilation and perfusion at the level of the alveoli. The efficiency of gas exchange is depending on the distributions of regional ventilation (V) and pulmonary blood flow (Q) and their correlation. AIMS:To validate a high-resolution method to quantify regional V and to investigate the Radioactive microspheres, 15 m in diameter, were used for determining regional Q. Nitric oxide synthase (NOS) was inhibited with Nω-nitro-L-arginine methyl ester (L-NAME) to evaluate the role of NO on regional V/Q matching. The right lung was dried at total lung capacity and diced in approx. 1000 regions tracking the spatial location of each region. CONCLUSION: There were marked differences in redistribution of regional ventilation and regional pulmonary blood flow between prone and supine position when PEEP was applied. RESULTS:NO was not an active mechanism for V/Q matching in normal sheep lungs. VII List of original papershis thesis is based on the following four papers, which will be referred to by their Roman numerals: I.Positive end-expiratory pressure affects regional redistribution of ventilation differently in prone and supine sheep.