Structure of central airways in current smokers and ex-smokers with and without mucus hypersecretion: relationship to lung function.

Forty-five patients who underwent thoracotomy and lung resection for tumour were studied to compare the structure of the central airways in current smokers and ex-smokers. The patients were divided into four groups: current smokers with mucus hypersecretion (n = 15), current smokers without mucus hypersecretion (n = 14), ex-smokers with mucus hypersecretion (n = 5), and ex-smokers without mucus hypersecretion (n = 11). Quantitative histological studies of the airway wall showed no difference in gland size, smooth muscle, connective tissue, or Reid index between the groups. The central airways of patients with mucus hypersecretion showed increased mucosal inflammation. The five ex-smokers in whom mucus hypersecretion persisted after they had stopped smoking had both central and peripheral airways affected by the inflammatory response, and these patients also had an abnormal result in the nitrogen washout test.