Ventilation and tissue oxygenation patterns induced by LABA and LAMA in COPD patients

Introduction: Different profiles of proximal and peripheral bronchodilation induced by salbutamol have been documented in asthma and COPD using the ventilation distribution test (SBWO) but the impact on gas exchange is controversial. Objectives: To compare proximal and peripheral bronchodilation patterns and their impact on gas exchange of long-acting ß2-adrenergics (LABA-olodaterol) and muscarinic antagonists (LAMA-tiotropium), the mainstay of treatment in COPD. Methods: FEV1, the slope (S) of He and SF6 of SBWO, NO and CO lung transfers (TLNO/TLCO ratio) and transcutaneous oxygen tension (TcO2) were measured before and 2 hours after LABA (day 1) and LAMA (day 3) in 21 COPD patients (63±12years; 38%F; FEV1 55±21%pred; GOLD: A 28%, B 48%, C 5%, D 19%), after 5 days of washout for LABA and 7 days for LAMA. The decrease in SHe and SSF6 reflect the opening of the pre- and intraacinar obstruction, respectively. Results: Results are presented in table 1 as mean percentage± standard deviation change from baseline. Conclusions: In our cohort of COPD patients, LABA induced greater proximal bronchodilation than LAMA. Despite the opposite gradient of their documented receptor density, both drugs caused a similar peripheral obstruction relief which resulted in an increased tissue oxygenation after LAMA only. Our data suggest that this could be associated to an improvement in the pulmonary capillary vascularization induced by LAMA.