Small airways disease in patients without chronic air-flow limitation

We measured airway diameter and quantitated airway pathology scores in respiratory bronchioles (RB) and membranous bronchioles (MB) in 37 patients undergoing resection for solitary pulmonary nodules. The patients had FEV1 greater than 75% of the predicted. Measurements of FEV1, nitrogen washout curve (delta N2/L), closing volume as a percentage of vital capacity (CV/VC%), and maximal flow at 50% of VC (V50) were made prior to surgery. There were 22 smokers and 15 nonsmokers. There were more MB per cm2 of tissue than RB (0.74 versus 1.02). The mean internal diameter for MB was 0.55 +/- 0.27 mm; for RB it was 0.47 +/- 0.15 mm. There were more MB greater than 1.0 mm in internal diameter than RB greater than 1.0 mm, and the mean diameter of MB was less than that noted in autopsy specimens. The total pathology scores for all airways were less than those found in Caucasian populations. Pathology scores were higher for MB than for RB, except for pigment deposition. Inflammation scores were higher in patients with FEV1 less than 100% predicted both for RB (p less than 0.05) and for MB (p less than 0.05). FEV1 values correlated with goblet cell metaplasia scores (p less than 0.05) for MB and with fibrosis (p less than 0.05), pigment deposition (p less than 0.05), and intraluminal macrophages (p less than 0.05) for RB. Tests specific for small airways (delta N2/L, V50, CV/VC%) did not correlate with the pathology scores.