[Evaluation of the relations between exercise tolerance, dyspnea and pulmonary function in patients with chronic...

We studied 53 patients with severe COPD (FEV1 0.92 +/- 0.40 1, PaO2 61 +/- 9 mm Hg), aged 58 +/- 9 years, to assess the relationship between ability to exercise (6 MWD), dyspnea and baseline lung function parameters. Dyspnea at rest (D1) and during exercise (D2) was evaluated using VAS. During exercise dyspnea increased by 41 +/- 28, and oxygen saturation (StcO2) decreased from 92 +/- 3% to 84 +/- 9%. The fall in the StcO2 of more than 3% was observed in 42 patients (79%). We found that 6 MWD significantly correlated with the FEV1, VC and maximal dyspnea during exercise. There was no correlation between exercise tolerance and resting PaO2, PaCO2, severity of dyspnea at rest and the increase in dyspnea during exercise as well as with the resting and exercise StcO2 and the fall in StcO2 during walk. Dyspnea at rest and during exercise significantly correlated with air flow limitation and StcO2 at rest, during exercise and the exercise decrease in StcO2. There was a significant correlation between the fall in StcO2 during exercise and blood gases at rest. No relationship between the fall in StcO2 and the increase in dyspnea during exercise was found.