Effect of ventilation on surface forces in excised dogs' lungs.

Abstract

Air volumes remaining at given transpulmonary pressures were used as quantitative indicators of pulmonary surface forces in excised lobes of dogs'' lungs. Ventilation in vitro appeared to increase the surface forces by an amount which depended on the gas used for ventilation, was directly related to the tidal volume and the duration of ventilation, and was inversely related to the end-expiratory pressure. If, following ventilation, the lobes were kept at constant volume for 3 hrs., the effects of ventilation were reversed. Recovery when the lobes were held at constant volume was irreversibly depressed by anoxia and reversibly depressed by low temperature, leading us to postulate that recovery involved production of new surfactant by metabolic processes.