Results of the CanCOLD study, conducted in AJRCCM published, show that decreased respiratory efficiency with exercise can cause dyspnoea and exercise limitation, even in mild COPD.
The participants were randomly recruited from the population and underwent clinical evaluation, lung function measurements, cardiopulmonary exercise testing and a chest CT. Decreased respiratory efficiency under exercise was defined by a nadir CO2 above the upper limit of normal (ULN).
Among the participants, 445 subjects had never smoked, 381 had ever smoked but no airway obstruction, 224 subjects COPD GOLD stage 1 and 200 GOLD stage 2-4. Participants with a CO2 above the ULN were more likely to have exertional dyspnea (Medical Research Council dyspnea scale ≥ 2; OR 1.77) and an abnormally low peak O2 below the lower limit of normal (OR 4.58). The Kco had a stronger correlation with nadir CO2 (r = -0,38; p < 0,001) dan andere relevante metingen van de longfunctie en de CT-scan.
The prevalence of a CO2 above the ULN was 24% in COPD. This percentage was similar in subjects with COPD GOLD 1 and 2-4. The prevalence in COPD patients was higher than in non-smokers (13%) and ever-smokers (12%).
Bron:
Phillips DB, Elbehairy AF, James MD, et al. Impaired Ventilatory Efficiency, Dyspnea, and Exercise Intolerance in Chronic Obstructive Pulmonary Disease: Results from the CanCOLD Study. Am J Respir Crit Care Med. 2022; 205: 1391-1402.
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