Morphological changes in small pulmonary vessels are associated with severe acute exacerbation in chronic obstructive pulmonary disease

BACKGROUND Pulmonary vascular remodeling is essential for understanding the pathogenesis of chronic obstructive pulmonary disease (COPD). The total cross-sectional area (CSA) of small pulmonary vessels has been reported to correlate with the pulmonary artery pressure, and this technique has enabled the assessment of pulmonary vascular involvements. We investigated the contribution of morphological alterations in the pulmonary vessels to severe acute exacerbation of COPD (AE-COPD). METHODS This study enrolled 81 patients with COPD and 28 non-COPD subjects as control and assessed the percentage of CSA (%CSA) less than 5 mm(2) (%CSA<5) and %CSA in the range of 5-10 mm(2) (%CSA5-10) on high-resolution computed tomography images. RESULTS Compared with the non-COPD subjects, the COPD patients had lower %CSA<5. %CSA<5 was positively correlated with airflow limitation and negatively correlated with the extent of emphysema. COPD patients with lower %CSA<5 showed significantly increased incidences of severe AE-COPD (Gray's test; P=0.011). Furthermore, lower %CSA<5 was significantly associated with severe AE-COPD (hazard ratio, 2.668; 95% confidence interval, 1.225-5.636; P=0.010). CONCLUSION %CSA<5 was associated with an increased risk of severe AE-COPD. The distal pruning of the small pulmonary vessels is a part of the risk associated with AE-COPD, and %CSA<5 might be a surrogate marker for predicting AE-COPD.