Alterations in lung mechanics and gas exchange following training in chronic obstructive lung disease.

Fourteen patients with advanced chronic obstructive lung disease participated in an in-patient exercise training program to investigate possible correlations between improved exercise tolerance and changes in certain pulmonary and metabolic parameters. The patients were all clinically stable and no changes in medication were made. Daily increasing periods of treadmill walking were performed breathing room air in six patients, and initially breathing 60 per cent oxygen in eight patients. All achieved 30 minutes of continuous treadmill walking, breathing room air (12 patients at one mile per hour and 4 per cent grade, and two patients at two miles per hour and S per cent grade). There was a change of breathing pattern towards slower and deeper breathing. Improved ventilation-perfusion relationships were suggested by a smaller alveolar-arterial oxygen gradient and improvement in venous admixture, as well as a shorter 90 per cent desaturation time. Dynamic compliance increased and work of breathing during exertion decreased. Blood lactate levels decreased following the training period.