Effects of inhaled furosemide on exercise capacity and on dyspnea in patients with COPD

This study investigated nebulized furosemide effects on dyspnea severity, exercise capacity and respiratory function variations in COPD (chronic obstructive pulmonary disease). We enrolled 12 patients with moderate-severe COPD. Patients received either 40 mg of isotonic inhaled furosemide or placebo on 2 separate days. Basal, post-aerosol, post-walk test and 90-minute post-inhalation values were recorded to assess respiratory function. Differently from placebo, FVC (forced vital capacity) and VC (vital capacity) increased both at the end of nebulization and 90 minutes later. FEV1 (forced expiratory volume in 1 second) diminished after physical exercise and returned to baseline only after 90 minutes with placebo: inhaled furosemide prevented FEV1 decrease both immediately and within 90 minutes. IVC (inspiratory vital capacity) decreased in all measurements, but much less in furosemide group. As for walk test, we considered covered meters, saturation at minutes 1, 3 and 4 and number of stops: such parameters were higher with aerosolized furosemide. VAS and modified Borg showed improved starting dispneic conditions. There were no changes in urine output between furosemide and placebo. Inhaled furosemide can reduce dynamic alveolar hyperinflation after physical exercise in COPD patients, thus bettering dyspnea. Changes in pulmonary function are minimal, but since COPD obstruction is partially fixed, it is difficult to imagine major changes in functional parameters. We also found that furosemide effectiveness lasts at least 90 minutes after nebulization, while up to now in literature it didn9t exceed 15 minutes. More research is needed.