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Research Article Free access | 10.1172/JCI106563
1Mayo Clinic, the Mayo Foundation, and the Mayo Graduate School of Medicine, Rochester, Minnesota 55901
Find articles by Potter, W. in: JCI | PubMed | Google Scholar
1Mayo Clinic, the Mayo Foundation, and the Mayo Graduate School of Medicine, Rochester, Minnesota 55901
Find articles by Olafsson, S. in: JCI | PubMed | Google Scholar
1Mayo Clinic, the Mayo Foundation, and the Mayo Graduate School of Medicine, Rochester, Minnesota 55901
Find articles by Hyatt, R. in: JCI | PubMed | Google Scholar
Published April 1, 1971 - More info
The interrelationships among transpulmonary pressure, flow, and volume during exhausting exercise were studied in 12 males with chronic obstructive lung disease. Expiratory pressure during exercise was compared with flow-limiting pressure (Pmax) measured at rest. In 11 patients, expiratory pressure during exercise exceeded Pmax, indicating that ventilation became mechanically inefficient. Pmax values of the patients were lower than those of normal subjects. Evidence of expiratory flow augmentation during exercise was noted in two subjects. Since 10 subjects achieved maximal expiratory flow predicted from flow-volume curves when heart rate was not maximal, we conclude that exercise capacity in most subjects was clearly limited by the deranged ventilatory apparatus. Elevations in mean intrathoracic pressure during exercise also may interfere with venous return and impose an additional limitation.