Effect of tiotropium compared to salmetrol on dynamic hyperinflation in patients with chronic obstructive pulmonary disease

Background: Dynamic hyperinflation now is increasingly recognized as the main factor in exercise limitation in patients with chronic obstructive pulmonary disease(COPD). Tiotropium is suggested to exert anti-inflammatory and bronchodilator effects in patients with COPD with increase in inspiratory capacity(IC), FEV₁ and decrease in RV/TLC. The aim of this study was compare the efficacy of Tiotrpium and Salmetrol in reducing in dynamic hyperinflation. Methods and material: seventy-five patients with COPD in the early stages (stages mild & moderate) selected based on ATS criteria and after excluding other cardiopulmonary or other interfering diseases and were randomly divided into two groups with Tiotropium (only Tiotropium with 18 microgram per day via inhalation ) and the classical treatment group (salmeterol 50 microgram twice daily via inhalation ). After complete history and physical exam spirometry and lung volume measurements were performed (using Jaeger body plethysmograph, Germany) before and at the end of treatment. The results of the change in various parameters of pulmonary function indicating hyperinflation were compared in the two groups. Results: Of parameters tested FEV₁ and IC increased and RV/TLC decreased significantly after treatment (P-Value=0.0001) in both groups. However in comparison of the two groups only FEV₁ and IC improvement were significantly higher in tiotropium group( P-Value =0,0001 and 0.02 respectively) compared to salmerterol group. Conclusion: These findings suggest that in patients with COPD, improvement in dynamic hyperinflation may be more prominent with tiotropium compared to salmeterol.