Regional and total lung function studies in patients with hemidiaphragmatic paralysis.

Global and regional lung function were studied in 17 subjects with hemidiaphragmatic paralysis. Global lung function (VC, MVV, and FEV1) in the sitting postion was reduced by an average of about 25%. Regional lung function data in the same position showed a considerable decrease in perfusion (19%), ventilation (20%), and lung volume (7%) of the diseased side as compared to reference values obtained in healthy volunteers. Compared to the partition of function in the supine, the perfusion of the affected lung increased when it was lowermost in the lateral decubitus postion, while regional FRC decreased and ventilation changed little. When uppermost, perfusion and ventilation of the affected lung decreased while FRCr increased somewhat. The arterial oxygen tension was significantly below normal in the supine position but in the normal range in the sitting position. It increased further during exercise. Bronchography showed compression of the basal lung segments on the affected side in the erect, and kinking and obliteration of lower lobe bronchi in the supine position and still more when the lung was lowermost in the lateral decubitus position.