Impact of bronchodilator on pulmonary function and exercise tolerance in LAM
Rationale: Reduced exercise capacity in LAM patients is still slightly understood. As many patients have airflow obstruction and dynamic hyperinflation (DH) (abstract 4576, ATS 2010), bronchodilator (Bd) might be a plausible option. Objective: To evaluate the improvement with inhaled salbutamol in resting airflow obstruction, exercise tolerance and reversal of DH. Methods: 37 LAM patients (mean age 41±10 years; FEV1 79±24%pred; DLCO 68±24%pred) performed incremental CPET (incCPET) on cycle; decrease ≥ 10% in IC defined DH. So, a randomized double-blind crossover study (inhaled salbutamol x placebo) was done. After each intervention, they performed lung function (PFT) and endurance CPET (endCPET) (75% max work-rate). Exercise duration, Borg scale and IC were compared at isotime in endCPET after Bd and placebo. Results: 19 patients (51%) showed DH in incCPET, with max work-rate lower in DH group (93 × 115W, p=0.16) and higher values in Borg dyspnea (7 x 5, p=0.02). Compared to non-DH, DH group had lower DLCO (56 x 81%pred, p=0.001), lower FEV1 (76 x 89%pred, p=0.002) and greater RV/TLC (0.43 x 0.29, p Conclusion: DH during exercise is frequent in LAM and is associated with resting airflow obstruction, reduced exercise capacity and higher breathlessness. Short-term Bd may exert a potential beneficial effect in DH patients.