Reduced exercise capacity of chronic obstructive pulmonary disease patients exercising with noseclip/mouthpiece

Abstract

A noseclip and low resistance mouthpiece are often used to monitor exhaled gases during exercise. Because otolaryngologic studies suggest that 50% of airway resistance is in the nose and mouth, it was hypothesized that patients with advanced chronic obstructive pulmonary disease might be artifactually limited by exercise testing with a noseclip and mouthpiece. Accordingly, 12 patients with stable chronic obstructive pulmonary disease performed identical symptom-limited supine bicycle exercise tests with and without noseclip and mouthpiece. Right-sided cardiac hemodynamic measurements, radionuclide ventriculography and arterial and mixed venous gas sampling were performed during each exercise test. Exhaled gases were analyzed during the noseclip/mouthpiece exercise. The order of exercise tests was alternated. Comparing exercises with and without a noseclip, there were significant reductions in exercise duration (397 ± 270 vs 300 ± 230 seconds, p < 0.01), exercise oxygen consumption (780 ± 279 vs 638 ± 200 ml/min, p < 0.01) and exercise cardiac output (8.4 ± 2.7 vs 7.3 ± 2.0 liters/min, p < 0.05), an increase in right ventricular ejection fraction (0.39 ± 0.08 vs 0.43 ± 0.08, p < 0.01) and no change in exercise heart rate (106 ± 14 vs 106 ± 14), right-sided cardiac pressures or arterial and mixed venous blood gases. These data suggest that a noseclip/mouthpiece can limit exercise tolerance in advanced chronic obstructive pulmonary disease patients. This limitation may result from decreased right-sided cardiac preload (venous return).