Jordan A. Guenette

Does dynamic hyperinflation contribute to dyspnoea during exercise in patients with COPD

Dynamic hyperinflation (DH) during exercise occurs in most but not all patients with advanced chronic obstructive pulmonary disease (COPD). It is not known whether the presence or absence of DH has implications for dyspnoea and exercise tolerance. Therefore, we compared detailed ventilatory and sensory responses to exercise in hyperinflators and nonhyperinflators with moderate-to-severe COPD. Nonhyperinflators (n=65) were retrospectively identified from a sample of 427 patients and case-matched to a group of hyperinflators (n=65) based on sex, age, body mass index and % predicted forced expiratory volume in 1 s. Resting pulmonary function and constant work rate cycle exercise responses were compared. Hyperinflators decreased inspiratory capacity (IC) from rest to peak exercise by 0.46±0.24 L whereas the nonhyperinflators increased IC by 0.10±0.15 L (p<0.0001). There were no significant group differences in endurance time (9.11±5.98 versus 8.87±5.24 min) or dyspnoea intensity for any given time or ventilation. An inflection in tidal volume versus ventilation occurred in the majority of nonhyperinflators (n=61) and hyperinflators (n=62) at a similar time and ventilation. Mechanical constraints on tidal volume expansion and the attendant rise in dyspnoea intensity were similar in both groups. Dyspnoea intensity during exercise was associated with progressive mechanical constraints on tidal volume expansion regardless of the presence of DH.

Decline of Resting Inspiratory Capacity in COPD: The Impact on Breathing Pattern, Dyspnea, and Ventilatory Capacity During Exercise

BACKGROUND To better understand the interrelationships among disease severity, inspiratory capacity (IC), breathing pattern, and dyspnea, we studied responses to symptom-limited cycle exercise in a large cohort with COPD. METHODS Analysis was conducted on data from two previously published replicate clinical trials in 427 hyperinflated patients with COPD. Patients were divided into disease severity quartiles based on FEV(1) % predicted. Spirometry, plethysmographic lung volumes, and physiologic and perceptual responses to constant work rate (CWR) cycle exercise at 75% of the peak incremental work rate were compared. RESULTS Age, body size, and COPD duration were similar across quartiles. As the FEV(1) quartile worsened (mean, 62%, 49%, 39%, and 27% predicted), functional residual capacity increased (144%, 151%, 164%, and 185% predicted), IC decreased (86%, 81%, 69%, and 60% predicted), and peak incremental cycle work rate decreased (66%, 55%, 50%, and 44% predicted); CWR endurance time was 9.7, 9.3, 8.2, and 7.3 min, respectively. During CWR exercise, as FEV(1) quartile worsened, peak minute ventilation (

Does the Respiratory System Limit Exercise in Mild Chronic Obstructive Pulmonary Disease

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HUMAN RESPIRATORY MUSCLE BLOOD FLOW MEASURED BY NEAR-INFRARED SPECTROSCOPY AND INDOCYANINE GREEN

e) and tidal volume (Vt) decreased, whereas an inflection or plateau of the Vt response occurred at a progressively lower

Pulmonary Gas Exchange Abnormalities in Mild Chronic Obstructive Pulmonary Disease. Implications for Dyspnea and Exercise Intolerance.

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Mechanisms of exercise intolerance in Global Initiative for Chronic Obstructive Lung Disease grade 1 COPD

e (P < .0005), similar percentage of peak