The Vd/Vt ratio may be increased at end-exercise due to either parenchymal or pulmonary vascular disease. Although Jones and Goodwin have reported abnormal increases in the Vd/Vt ratio during exercise in patients with pulmonary vascular disease, D’Alonzo et al found that the typical response observed in nine of 11 patients with pulmonary hypertension was a fall in the Vd/Vt ratio during exercise. We failed to observe a consistent response in the patients with pulmonary hypertension in the present study and their Vd/Vt ratio at end-exercise was not significantly different from that of the patients without pulmonary hypertension.
The majority, nine of 11 patients, stopped exercising because of peripheral muscle fatigue. Two stopped at a low work load with a subnormal heart rate response, suggesting that peripheral muscle weakness limited their exercise tolerance. However, five patients had a heart rate response exceeding 80 percent of their predicted target heart rate and a low 02 pulse, suggesting a cardiac limitation to exercise. In contrast, none of the patients had evidence of a ventilatory limit to their exercise capacity. buy asthma inhaler
In summary, we found that symptomatic impairments in pulmonary function are uncommon in patients with polymyositis. Unsuspected pulmonary hypertension is extremely common in polymyositis patients and the reduced 02 pulse during exercise suggests that cardiac performance also may be impaired in these patients. The clinical significance of these findings cannot be determined from this study. In the majority of patients, peripheral muscle fatigue appears to be a major factor contributing to the impairment in exercise performance.