WEDNESDAY, Oct. 26 (HealthDay News) -- The number of airways with a diameter of 2 to 2.5 mm is significantly reduced in patients with chronic obstructive pulmonary disease (COPD), and the narrowing and disappearance of small-airways precedes emphysematous destruction, according to a study published in the Oct. 27 issue of the New England Journal of Medicine.
John E. McDonough, from St. Paul's Hospital in Vancouver, Canada, and colleagues investigated the association between small-airway obstruction and emphysematous destruction in 78 patients with various stages of COPD based on the Global Initiative for Chronic Obstructive Lung Disease (GOLD) scale. Multidetector computed tomography (CT) was used to compare the number of airways in isolated emphysematous lungs from patients undergoing lung transplantation and donor (control) lungs. The extent of emphysema, the number of terminal bronchioles per milliliter of lung volume, and the minimum diameters and cross-sectional areas of terminal bronchioles were measured using microCT.
The investigators found that the number of 2.0- to 2.5-mm-diameter airways was significantly reduced for patients with GOLD stages 1, 2, 3, or 4 compared to the control samples. The total cross-sectional area and number of terminal bronchioles were reduced by 81 to 99.7 percent and by 72 to 89 percent, respectively, in patients with GOLD stage 4 disease. A comparison of the number and dimensions of terminal bronchioles at varying stages of emphysema indicated loss and narrowing of terminal bronchioles before emphysematous destruction onset in COPD.
"These results show that narrowing and disappearance of small conducting airways before the onset of emphysematous destruction can explain the increased peripheral airway resistance reported in COPD," the authors write.
The study was partially funded by GlaxoSmithKline; several authors disclosed financial relationships with pharmaceutical companies, including GSK.