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dc.contributor.authorFrisk, Benteen_US
dc.contributor.authorHardie, Jon Andrewen_US
dc.contributor.authorEspehaug, Birgitteen_US
dc.contributor.authorStrand, Liv Ingeren_US
dc.contributor.authorMoe-Nilssen, Rolfen_US
dc.contributor.authorEagan, Tomas Mikalen_US
dc.contributor.authorBakke, Peren_US
dc.contributor.authorThorsen, Einaren_US
dc.description.abstractBackground: 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. Methods: 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 V̇ O2peak 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∙V̇ E + 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. Results: Significant reductions in V̇ O2peak (p < 0.001) and V̇ Epeak (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 V̇ E and was related to the reduction in FEV1. Conclusion: 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.en_US
dc.publisherBioMed Centraleng
dc.relation.ispartof<a href="" target="blank">Exercise capacity and breathing pattern in patients with chronic obstructive pulmonary disease. Predictors and longitudinal changes</a>
dc.rightsAttribution CC BYeng
dc.titlePeak oxygen uptake and breathing pattern in COPD patients – a four-year longitudinal studyen_US
dc.typePeer reviewed
dc.typeJournal article
dc.rights.holderCopyright 2015 Frisk et al.
dc.source.journalBMC Pulmonary Medicine
dc.subject.nsiVDP::Medisinske Fag: 700::Klinisk medisinske fag: 750::Lungesykdommer: 777en_US

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