Chest
Original ResearchCOPDDecline of Resting Inspiratory Capacity in COPD: The Impact on Breathing Pattern, Dyspnea, and Ventilatory Capacity During Exercise
Section snippets
Materials and Methods
The data from two randomized, double-blind, placebo-controlled clinical trials that evaluated the effects of daily tiotropium on exercise tolerance, hyperinflation, and dyspnea in patients with COPD were retrospectively combined for this analysis.7, 8 There is no overlap between this independent analysis of the pretreatment data and previous analyses of the same data set.7, 8, 9, 10 The Queen's University and Affiliated Teaching Hospitals Research Ethics Board approved the use of these data and
Subjects
Characteristics of the 427 evaluable subjects are shown in Table 1. Age, height, BMI, and COPD duration were similar across the FEV1 quartiles. There was a larger percentage of current smokers in Q1 than in the other three quartiles. Pulmonary function data showed that lung hyperinflation worsened progressively as disease severity increased. Peak incremental cycle work rate and oxygen consumption (o2) also decreased progressively from Q1 to Q4.
Physiologic Responses to Symptom-Limited CWR Exercise
Measurements at the peak of CWR exercise are
Discussion
The novel findings of this study were as follows: (1) the progressive erosion of resting IC with worsening airflow obstruction and hyperinflation was associated with the development of an increasingly shallow, rapid breathing pattern and worsening dyspnea at progressively lower levels of ventilation during exercise, and (2) despite significant interquartile differences in resting airflow obstruction, lung hyperinflation, and ventilatory capacity, exertional dyspnea intensity consistently
Conclusions
The resting IC importantly influences ventilatory capacity, breathing pattern responses, and the evolution of exertional dyspnea across the range of disease severity in patients with COPD who hyperinflate during exercise. Progressive reduction of the resting IC with increasing disease severity was associated with the appearance of critical constraints on Vt expansion and attendant increase in dyspnea at a progressively lower ventilation during exercise. Regardless of baseline differences in
Acknowledgments
Author contributions: Dr O'Donnell had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.
Dr O'Donnell: contributed to the study design and conduct as principal investigator of the original multicenter trials, the original idea for the current analysis and interpretation of the results, and the writing of the manuscript.
Dr Guenette: contributed to the data analysis and preparation for presentation and writing
References (22)
- et al.
Improvements in symptom-limited exercise performance over 8 h with once-daily tiotropium in patients with COPD
Chest
(2005) - et al.
Fifteen-year interval spirometric evaluation of the Oregon predictive equations
Chest
(1988) - et al.
Effects of various respiratory stimuli on the depth and frequency of breathing in man
Respir Physiol
(1966) - et al.
Dynamic hyperinflation and exercise intolerance in COPD
Am J Respir Crit Care Med
(2001) - et al.
Qualitative aspects of exertional breathlessness in chronic airflow limitation: pathophysiologic mechanisms
Am J Respir Crit Care Med
(1997) - et al.
Sensory-mechanical relationships during high-intensity, constant-work-rate exercise in COPD
J Appl Physiol
(2006) - et al.
Effect of salmeterol on the ventilatory response to exercise in chronic obstructive pulmonary disease
Eur Respir J
(2004) - et al.
Role of inspiratory capacity on exercise tolerance in COPD patients with and without tidal expiratory flow limitation at rest
Eur Respir J
(2000) - et al.
Inspiratory fraction and exercise impairment in COPD patients GOLD stages II-III
Eur Respir J
(2006) - et al.
Effects of tiotropium on lung hyperinflation, dyspnoea and exercise tolerance in COPD
Eur Respir J
(2004)
Performance during constant workrate cycling exercise in women with COPD and hyperinflation
COPD
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Funding/Support: Funding received from Boehringer-Ingelheim GmbH (to Dr Guenette).
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