Effects of Inhaled Furosemide on Breathlessness During Exercise in the Presence of External Thoracic Restriction: A Dose-Reponse Study

Breathlessness on exertion is a common and troublesome complaint of individuals with restrictive lung disorders. In these adults, breathlessness contributes to physical activity-limitation and avoidance and an adverse health-related quality-of-life, often in a self-perpetuating cycle. It follows that alleviating dyspnea and improving exercise tolerance are among the principal goals in the management of adults with restrictive lung disorders. Nevertheless, effective management of breathlessness and physical activity-limitation remains an elusive goal for many healthcare providers and current therapies (e.g., antifibrotic agents, oxygen, exercise training) are only partially successful in this regard. Thus, research aimed at identifying breathlessness-specific medications to complement existing therapies for the management of physical activity-related breathlessness in restrictive lung disorders is timely and both clinically and physiologically relevant. The purpose of this randomized crossover study study is to examine the acute effects of two doses of inhaled nebulized furosemide (a loop diuretic) on the perception of breathlessness during laboratory-based cycle exercise in healthy, young men in the presence of an external thoracic restriction to mimic a 'mild' restrictive lung deficit. To this end, the investigators will compare the effects of inhaled 0.9% saline placebo and inhaled furosemide (40 mg and 120 mg) on detailed assessments of breathlessness (sensory intensity and affective responses) and its physiological determinants (ventilation, breathing pattern, dynamic operating lung volumes, cardio-metabolic function) symptom-limited, high-intensity, constant-work-rate cycle exercise testing with external thoracic restriction sufficient to mimic a 'mild' restrictive pulmonary deficit in healthy, men aged 18-40 years.