Correlation of a decline in aerobic capacity with development of emphysema in patients with chronic obstructive pulmonary disease: a prospective observational study.

Wakako Yamasawa,Sadatomo Tasaka,Kazuhiro Yamaguchi,Tomoko Betsuyaku,Marco Idzko

doi:10.1371/journal.pone.0125053

Wakako Yamasawa, Sadatomo Tasaka + Show 3 more

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https://doi.org/10.1371/journal.pone.0125053

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Abstract

In patients with COPD, CT assessment of emphysema and airway disease is known to be associated with lung function and 6-minute walk distance. However, it remains to be determined whether low attenuation area (LAA) on CT is associated with aerobic capacity assessed using cardiopulmonary exercise testing (CPET). In this prospective observational study, we repeatedly conducted high-resolution CT and CPET using a treadmill in 81 COPD patients over a median interval of 3.5 years. Two investigators independently scored LAA on images obtained at the aortic arch level, tracheal bifurcation level, and supradiaphragmatic level. Grades for the images of each lung were added to yield the total LAA score. Total LAA score was negatively correlated with peak aerobic capacity () (p<0.001, r = -0.485). LAA scores of the upper (aortic arch level) and the lower (supradiaphragmatic level) lungs were both significantly associated with peak . There was a significant correlation between total LAA score and peak CO2 output () (p<0.001, r = -0.433). Total LAA score was correlated with oxygen saturation at peak exercise (p<0.001, r = -0.634) and the estimated dead space fraction (p<0.001, r = 0.416). The mean annual change in total LAA score was significantly correlated with those in peak (p<0.001, r = -0.546) and peak (p<0.001, r = -0.488). The extent of emphysema measured by CT was associated with the results of CPET. The time-dependent changes in CPET data were also correlated with that in total LAA score. CT assessment could be a non-invasive tool to predict aerobic capacity in patients with COPD.

Highlights

Impaired exercise capacity is frequently observed in patients with chronic obstructive pulmonary disease (COPD) [1] and is traditionally associated with impaired lung function [2,3,4]
It was observed that cardiopulmonary exercise testing (CPET) parameters such as aerobic capacity and CO2 production were associated with emphysematous change evaluated by high-resolution CT (HRCT) as well as airflow limitation
Repeated assessment revealed that the longitudinal changes in CPET data were correlated with that in total low attenuation area (LAA) score on HRCT images

Summary

Introduction

Impaired exercise capacity is frequently observed in patients with chronic obstructive pulmonary disease (COPD) [1] and is traditionally associated with impaired lung function [2,3,4]. There have been few reports about the association between CT measures of emphysema and exercise capacity assessed by walking tests [7, 14]. No study has yet examined the predictive value of the extent of emphysema on CT images for the exercise capacity in COPD patients. We hypothesized that high-resolution CT (HRCT) measures of emphysema predict exercise capacity assessed by CPET independent of lung function. We first examined whether the extent of emphysema on HRCT is associated with exercise capacity and lung function. We evaluated the association between temporal changes in emphysema on HRCT images and those in exercise capacity and lung function

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