Increased residual volume is associated with a larger pulmonary artery in patients with chronic obstructive pulmonary disease (COPD), according to a study published in PLoS One. The results suggest that gas trapping may contribute to pulmonary hypertension among patients with COPD.
R. Graham Barr, MD, MPH, from the Columbia University Medical Center in New York, and colleagues conducted the MESA COPD Study, a cross-sectional study of smokers from the Multi-Ethnic Study of Atherosclerosis (MESA) and the Emphysema and Cancer Action Project (EMCAP), to determine whether pulmonary hyperinflation is associated with the cross-sectional area of the pulmonary artery in COPD.
The study included 106 participants with COPD and controls from 2 population-based cohort studies. Participants were between 50 and 79 years of age with at least 10 pack-years and who were free of clinical cardiovascular disease.
The participants underwent body plethysmography, and a cardiac MRI was performed to measure the cross-sectional area of the main pulmonary artery. The investigators assessed percent emphysema, which was defined as “the percentage of lung voxels less than -950 Hounsfield units as assessed via X-ray computed tomography.”
The researchers found that the mean residual volume was 1.98 ± 0.71 L and the mean pulmonary artery cross-sectional area was 7.23 ± 1.72 cm2. They noted that one standard deviation increase in residual volume was associated with an increase in main pulmonary artery cross-sectional area of 0.55 cm2. However, there was no evidence of an association with percent emphysema or total lung capacity.
“Pulmonary hyperinflation and specifically gas trapping, as assessed by increased residual volume and residual volume to TLC [total lung capacity] ratio, was associated with a larger main PA [pulmonary artery] cross-sectional area on MRI,” the study authors concluded.
“In contrast, there was no evidence that the extent of emphysema as measured by CT or measures of hyperexpansion (increased [functional residual capacity] and TLC) were associated with PA dimensions. These findings suggest that gas trapping, but not emphysema, are associated with pulmonary vascular remodeling in current and former smokers.”
- Poor HD, Kawut SM, Liu CY, et al. Pulmonary hyperinflation due to gas trapping and pulmonary artery size: The MESA COPD Study. PLoS One. 2017. doi:10.1371/journal.pone.0176812