Effect of posture on static lung volumes and pulmonary mechanics in pneumonectomized rabbits

Static lung volumes, lung (CL) and respiratory system compliance (Crs), and the slope of phase III of the single-breath O2 test (slope III) were measured in rabbits in the prone, supine, and right and left lateral positions. Control rabbits, rabbits that had the left lung removed (Px), and rabbits that had the left lung removed and replaced with wax (Px + W) were studied. Surgeries were performed > or = 7 wk before study. Lung volumes, Crs, and slope III were not different among groups. Total lung capacity, vital capacity, residual volume, Crs, and slope III were smallest in all rabbits in the prone position. Functional residual capacity and expiratory reserve volume were unaffected by posture in control rabbits but were larger in Px and Px + W rabbits in the left lateral position. CL was unaffected by posture but was smaller in Px and Px + W rabbits than in control rabbits. Pneumonectomy-induced changes in lung shape altered the effect of posture on functional residual capacity but not on regional lung function, as assessed by the single-breath O2 test.