A pilot study assessing the effect of bronchodilator on dynamic hyperinflation in LAM.

Introduction: Positive responses to bronchodilators (BDs) on spirometry can be found in up to 30% of patients with lymphangioleiomyomatosis (LAM). However, no previous studies have investigated the impact of BDs on exercise outcomes, including dynamic hyperinflation (DH).

Methods: A randomised, double-blind, placebo-controlled, crossover trial was conducted on 38 patients with LAM, comparing inhaled placebo versus salbutamol. Pulmonary function tests and a cycle endurance test at 75% of the maximal work capacity, with evaluation of DH by serial measurement of inspiratory capacity (IC), which was the primary endpoint, were performed after each intervention.

Results: Although salbutamol produced a slight improvement in airway obstruction, compared with placebo, there was no significant variation in resting IC or air trapping. A total of 18% of the patients met the criteria for a positive response to BD. During submaximal exercise, BD did not reduce DH or dyspnoea nor did it improve exercise tolerance in the entire population. In addition, BD produced only slight improvement in FEV1 and air trapping in patients who had DH during incremental cardiopulmonary exercise testing, without the beneficial effects on exercise outcomes.

Conclusions: Although salbutamol produced a slight improvement in airway obstruction, it did not lead to a reduction in DH or increase in exercise tolerance in patients with LAM.

Clinical Trial Registration: Brazilian Registry of Clinical Trials (ReBEC); www.ensaiosclinicos.gov.br; registration number: RBR-49sk2j.