title: 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 less than 0.01), exercise oxygen consumption (780 +/- 279 vs 638 +/- 200 ml/min, p less than 0.01) and exercise cardiac output (8.4 +/- 2.7 vs 7.3 +/- 2.0 liters/min, p less than 0.05), an increase in right ventricular ejection fraction (0.39 +/- 0.08 vs 0.43 +/- 0.08, p less than 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).
authors.affiliation: Department of Medicine (Cardiology), Denver Veterans Administration Medical Center, Colorado 80220.
authors.forename: D A
authors.initials: DA
authors.lastname: Morrison
authors.forename: M
authors.initials: M
authors.lastname: Collins
authors.forename: J R
authors.initials: JR
authors.lastname: Stovall
authors.forename: G
authors.initials: G
authors.lastname: Friefeld
mesh_terms: D000328:Adult; D000368:Aged; D000403:Airway Resistance / Q000502:physiology*; D001794:Blood Pressure / Q000502:physiology; D002302:Cardiac Output / Q000502:physiology; D015444:Exercise / Q000502:physiology*; D005541:Forced Expiratory Volume; D006801:Humans; D008173:Lung Diseases, Obstructive / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D009055:Mouth / Q000503:physiopathology*; D009064:Mouth Protectors; D009666:Nose / Q000503:physiopathology*; D010101:Oxygen Consumption / Q000502:physiology; D011446:Prospective Studies; D013147:Spirometry / Q000295:instrumentation; D013318:Stroke Volume / Q000502:physiology; D014797:Vital Capacity