Abstract
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.
Footnotes
For editorial comments, see page 283.
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Support Statement
This study was supported by Boehringer Ingelheim Pharma GmbH & Co. KG (Ingelheim, Germany). J. Guenette was supported by postdoctoral fellowships from the Natural Sciences and Engineering Research Council of Canada, the Canadian Thoracic Society and the Canadian Lung Association.
Statement of Interest
Statements of interest for D.E. O’Donnell, and for the study itself, can be found at www.erj.ersjournals.com/site/misc/statements.xhtml
- Received September 12, 2011.
- Accepted December 9, 2011.
- ©ERS 2012