Small airway pathology and bronchoreversibility in advanced emphysema.
BACKGROUND
Poorly reversible airflow obstruction is a hallmark feature of chronic obstructive pulmonary disease (COPD). However, some COPD patients demonstrate significant bronchodilator reversibility (BDR). The pathologic features associated with the presence or absence of this phenomenon are not known.


METHODS
We analyzed 67 patients with advanced upper lobe predominant emphysema who underwent lung volume reduction surgery and divided them into 2 groups: the reversible group [BD(+)] had a >12% and >200 mL increase in FEV(1) or FVC with bronchodilator; the irreversible group [BD(-)] had a <or=12% and <or=20 mL increase in FEV(1) and FVC. We measured the epithelial height (EH) and areas of epithelium (EA), subepithelium (SEA), smooth muscle (SMWA), and total wall (TWA) of the small airways (<2 mm in internal diameter) in the resected specimens, and adjusted these measurements for basement membrane area (BMA) or perimeter (BMP).


RESULTS
Despite similar baseline characteristics, the BD(+) group had a smaller EH (0.036 mm vs. 0.042 mm, p = 0.005) and EH/BMP (0.012 vs. 0.014, p = 0.007), and a greater SMWA/BMA (0.491 vs. 0.430, p = 0.034) compared to the BD(-) group. In addition, EA trended to be smaller in the BD(+) group when compared to the BD(-) group (0.160 mm(2) vs. 0.184 mm(2), p = 0.06). In a subset of patients with consistent patterns of BDR on serial testing, the BD(+) group had greater SMWA/BMA (0.518 vs. 0.433, p = 0.049) and TWA/BMA (1.405 vs. 1.266, p = 0.036) compared to the BD(-) group.


CONCLUSIONS
Small airway smooth muscle mass may play a role in determining BDR in severe emphysema.
Kim
Victor
V
Division of Pulmonary and Critical Care Medicine, Temple University School of Medicine, Philadelphia, Pennsylvania, United States. victor.kim@tuhs.temple.edu
Pechulis
Rita M
RM
Abuel-Haija
Mohammad
M
Solomides
Charalambos C
CC
Gaughan
John P
JP
Criner
Gerard J
GJ
D000368:Aged; D056151:Airway Remodeling; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D008297:Male; D008875:Middle Aged; D011013:Pneumonectomy; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications / Q000473:pathology / Q000503:physiopathology*; D011656:Pulmonary Emphysema / Q000150:complications / Q000473:pathology* / Q000601:surgery; D016896:Treatment Outcome; D014797:Vital Capacity