Inhaled furosemide greatly alleviates the sensation of experimentally induced dyspnea

Furosemide is known to influence the activity of vagally mediated mechanore ceptors in the airways. because vagal afferent fibers may play an important role in modulation of the sensation of dyspnea, it is possible that inhale d furosemide may modify the sensation of dyspnea. In a double-blind, random ized, crossover study, we compared the effect of inhaled furosemide on dysp neic sensation with that of placebo. Severe dyspneic sensation was induced in 12 healthy subjects in two ways: (1) breathholding and (2) loaded breath ing with a combination of inspiratory resistive load (240 cm H2O/L/s) and h ypercapnia induced by extra mechanical dead space (0.26 L). Subjects were a sked to rate their sensation of respiratory discomfort using a visual analo gue scale (dyspneic VAS). Breathholding times and changes in dyspneic VAS s core during a 5-min period of loaded breathing were measured after inhalati on of placebo and furosemide (40 mg). Total breathholding time after inhala tion of furosemide (median, 93 [interquartile range, 78 to 112]s) was prolo nged compared with the total breathholding time after placebo inhalation (6 7 [47-74]s). We also found that respiratory discomfort during loaded breath ing after inhalation of furosemide develops more slowly and is less than th at observed after inhalation of placebo. Our findings indicate that inhaled furosemide greatly alleviates the sensation of dyspnea induced experimenta lly by breathholding and by a combination of resistive loading and hypercap nia.