Experimental Sutdies for Application of the Heterogeneous Lung as Oxygenator

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The following studies were carried out for the purpose of developing a natural ventilator which retains the merits of the in vivo lung,is more durable,and has no antigenicity. 1.The development of an apparatus for functional evaluation of the resected free lung: An apparatus to preserve the resected lung by perfusion with oxygenated blood with intermittent perfusion with venous blood was developed,and airway resistance,pulmonary artery pressure,and gas exchange ability were evaluated simultaneously at various time points. 2.functional evaluation of the preserved lung: The gas exchange ability of the preserved resected lung was serially monitored with the above apparatus,and optimal conditions of preservation were evaluated. The function of the rabbit lung preserved by simple immersion was well maintained for 48 hours but was significantly reduced after 72 hours. 3.Gas exchange ability of the fixed lung: The fixation method for maximum preservation of the lung function was evaluated. Am … More ong 10% formalin,0.625% glutaraldehyde,4% paraformaldehyde + 0.325% glutaraldehyde,the mixture of paraformaldehyde and glutaraldehyde was the best and showed a gas exchange ability comparable to the fresh lung. 4.Perfusion with heterogeneous blood and gas exchange ability: Whether the natural lung can be used as an oxygenator across the species was examined. The resected dog lung showed sufficient gas exchange ability for rabbit blood. 5.Imaging studies of the lung by ^1H-MRI: As a basic step for the development of a heterogeneous lung graft,the lung function was studied by MRI. The dynamics of the water in the lung,which determines its gas exchange ability,was evaluated according to MR images. The values of various parameters calculated in the preserved rabbit lung changed with the wet/dry weight ratio,which is an index of the water content of the lung.These findings suggest that the resected lung retains gas exchange ability comparable to that of the fresh lung if it has been fixed under appropriate conditions,that heterogeneous lungs show a gas exchange ability,that the gas exchange ability of the lung is reduced by thickening of the air-blood barrier due to edematous changes,and that MRI is useful for noninvasive detection of these changes. Improvements in the method for fixation of the lung are desired,and,for this purpose,the development of techniques that do not leave even a trace amount of the fixative or techniques for physical fixation is needed. Less