Intermittent positive-pressure breathing in chronic obstructive pulmonary disease.

Abstract

R. M. Cherniack and E. Svanhill in their recent article (REVIEW, June 1976) observed severe overdistention of the lungs in patients with chronic obstructive pulmonary disease (COPD) after 29 months of intermittent positive-pressure breathing (IPPB) therapy. They suggested that their own measurements of lung volumes done by helium-dilution should be controlled by body plethysmography. We have studied 51 patients with comparable degree of COPD on four times daily IPPB-therapy with inhalations with bronchodilators (salbutamol) over a period of up to 27 months (mean duration, 15 months). In addition to several other parameters we measured lung volumes by body plethvsmography (see table and figure). Residual volume (R V) did not increase, inspired vital capacity (VC) and total lung capacity (TLC) diminished slightly, but not significantly. We suggest that the overdisten tion in Cherniack and Svanhill's patients represents an artefact of the helium-dilution method which does not measure trapped air volume. By combining our data with theirs we conclude that IPPB-therapy with bronchodilators does not result in overdistention but rather in an increase of the fast space and a decrease of the slow space. Although our study does include only a small control group we are under the impression that IPPB-therapv has a beneficial effect in severe COPD.