A Study of Respiratory Factor Influing Excercise Limitation in Chronic Pulmonary Disease Patients

To clarify the cause of dyspnea on exercise, 29 COPD patients were studied by stepwise incremental exercise test by ergometer. The main cause of exercise limitation was ventilatory limitation. VO_2 max correlatecl with FEV_<1・0>, % RV, RV/TLC, SGaw, VEmax and ΔPaCo_2. Therefore, the ventilatory limitation seems to be to （1） decreased ventilatory capacity caused by intrinsic airway obstruction, extrinsic dynamic compression of airway and respiratory muscle fatigue, and （2） increased ventilatory requirement caused by low DLco and high O_2 equivalent. Concerning to circulating factors, COPD patients showed low DLco, low O_2 pulse and rapid increase of hight of PII on ECG. I think that low DLco and low O_2 pulse indicate low cardiac output and rapid increase of hight of PII indicate the elenation of pulmonary resistance. Therefore, circulating factors also seem to be one of the limiting factors. In conclusion, the main cause of exercise limitation on COPD patients was ventilatory limitation, but circulating factors also seemed to be related to exercise limitation. And the decrease of PaO_2 by exercise correlated with DLco at rest, especially in CPE patients, it should be considered in case of introduce of home oxygen therapy