The authors declare that they have no competing interests.
Concept and design (BF, ET, JAH, TMLE, PSB). Data collection (BF, JAH, TMLE, PSB, ET). Data analyses and interpretation (BF, BE, RMN, JAH, LIS, ET). Drafting the manuscript (BF, ET, BS, LIS, JAH, RMN). All the authors have revised and approved the final manuscript.
Activities of daily living in patients with chronic obstructive pulmonary disease (COPD) are limited by exertional dyspnea and reduced exercise capacity. The aims of the study were to examine longitudinal changes in peak oxygen uptake (V̇O2peak), peak minute ventilation (V̇Epeak) and breathing pattern over four years in a group of COPD patients, and to examine potential explanatory variables of change.
This longitudinal study included 63 COPD patients, aged 44-75 years, with a mean forced expiratory volume in one second (FEV1) at baseline of 51 % of predicted (SD = 14). The patients performed two cardiopulmonary exercise tests (CPETs) on treadmill 4.5 years apart. The relationship between changes in V̇O2peak and V̇Epeak and possible explanatory variables, including dynamic lung volumes and inspiratory capacity (IC), were analysed by multivariate linear regression analysis. The breathing pattern in terms of the relationship between minute ventilation (V̇E) and tidal volume (VT) was described by a quadratic equation, VT = a + b∙V̇E + c∙V̇E2, for each test. The VTmax was calculated from the individual quadratic relationships, and was the point where the first derivative of the quadratic equation was zero. The mean changes in the curve parameters (CPET2 minus CPET1) and VTmax were analysed by bivariate and multivariate linear regression analyses with age, sex, height, changes in weight, lung function, IC and inspiratory reserve volume as possible explanatory variables.
Significant reductions in V̇O2peak (p < 0.001) and V̇Epeak (p < 0.001) were related to a decrease in resting IC and in FEV1. Persistent smoking contributed to the reduction in V̇O2peak. The breathing pattern changed towards a lower VT at a given V̇E and was related to the reduction in FEV1.
Increasing static hyperinflation and increasing airway obstruction were related to a reduction in exercise capacity. The breathing pattern changed towards more shallow breathing, and was related to increasing airway obstruction.
Hyatt RE. Expiratory flow limitation. J Appl Physiol. 1983;55:1–7. PubMed
Gallagher CG, Brown E, Younes M. Breathing pattern during maximal exercise and during submaximal exercise with hypercapnia. J Appl Physiol. 1987;63:238–44. PubMed
Bruce RA. Exercise testing of patients with coronary heart disease. Principles and normal standards for evaluation. Ann Clin Res. 1971;3:323–32. PubMed
Borg G. Borg's Perceived exertion and pain scales, vol. viii. Champaign, IL: Human Kinetics; 1998. p. 104.
Stubbing DG, Pengelly LD, Morse JL, Jones NL. Pulmonary mechanics during exercise in subjects with chronic airflow obstruction. J Appl Physiol. 1980;49:511–5. PubMed
- Peak oxygen uptake and breathing pattern in COPD patients – a four-year longitudinal study
Jon A. Hardie
Liv I. Strand
Tomas M. L. Eagan
Per S. Bakke
- BioMed Central
Neu im Fachgebiet Innere Medizin
Meistgelesene Bücher aus der Inneren Medizin
Mail Icon II