Aerosol furosemide for dyspnea: High-dose controlled delivery does not improve effectiveness

Published studies have shown great variability in response when aerosolized furosemide has been tested as a palliative treatment for dyspnea. We hypothesized that a higher furosemide dose with controlled aerosol administration would produce consistent dyspnea relief. We optimized deposition by controlling inspiratory flow (300-500 mL/s) and tidal volume (15% predicted vital capacity) while delivering 3.4 mu m aerosol from either saline or 80 mg of furosemide. We induced dyspnea in healthy subjects by varying inspired PCO2 while restricting minute ventilation. Subjects rated Breathing Discomfort on a Visual Analog Scale (BDVAS, 100% Full Scale equivalent to intolerable). At the PETCO2 producing 60% BDVAS pre:treatment, furosemide produced a clinically meaningful reduction of BDVAS (i.e., > 20% FS) in 5/11 subjects; saline reduced dyspnea in 3/11 subjects; neither treatment worsened dyspnea in any subject. Furosemide and saline treatment effects were not statistically different. There were no significant adverse events. Higher furosemide dose and controlled delivery did not improve consistency of treatment effect compared with prior studies.