[Comparative study of ventilatory functions of smokers with MTTp and F-V curve configuration]

To assess the clinical significance of partial mean transit time(MTTp) and F-V curve configuration for testing small airway functions in smokers, routine ventilatory functions, MTTp and F-V curve configuration were studied in 116 passive and active light, heavy smokers. Routine ventilatory functions and F-V curve configuration were determined with routine methods. MTTp were calculated with "convenient calculation". The results showed that the distribution of convex type of F-V curve rose with the degree of smoking. The decrease of V50, V25 and prologation of MTT45%-55%, MTT70%-80% in convex type were just correspondent with heavy smokers. The range of prolongation of MTT45%-55% and MTT70%-80% was 110%-120% of predicted value both in heavy smokers and convex type. These showed there were light disturbances in small airways. Therefore, the convex type, the prolongation of MTT45%-55% and MTT70%-80%, and the decrease of V50 and V25 should all be used as sensitive indices for testing small airway functions. The value of MTTp calculated with "convenient calculation" is accurate and easy-to-do so the method is appropriate for clinical application.