title: Inhaled furosemide does not alleviate respiratory effort during flow-limited exercise in healthy subjects.
abstract: Expiratory muscle loading results in increased perception of respiratory effort; this response is mediated by non-vagal reflexes originating in the chest wall. Furosemide, due to its vagal effect, might not affect the perception of respiratory effort during expiratory flow-limited incremental exercise. In this study, we compared in nine healthy subjects the following determinants of exercise performance such as respiratory effort (Borg), workload (W'), ventilation (V'E), tidal volume (VT), respiratory frequency (f), and mean inspiratory flow (VT/TI), an index of central respiratory drive, during either standard incremental cycling exercise, or expiratory flow-limited incremental exercise. In addition we examined the effect of inhaled placebo, furosemide (40 or 80 mg) on the perception of respiratory effort following standard incremental cycling exercise and expiratory flow-limited incremental exercise. Compared with standard incremental cycling exercise, expiratory flow-limited incremental exercise increased the Borg score and VT/Ti, and decreased W',V'E ,VT, and f in all subjects at iso-workload. Neither placebo nor furosemide modified peak ventilatory variables, slopes, or intercepts of the relationships of the Borg score with W', V'E, VT/TI and VT during expiratory flow-limited incremental exercise. We conclude that (a) compared with standard incremental exercise, expiratory flow limited exercise increases central respiratory drive and perception of respiratory effort, and (b) furosemide does not affect the sensation of respiratory effort under the present conditions of increased drive to the respiratory muscles.
authors.affiliation: Dipartimento di Medicina Interna, Sezione di Immunologia e Malattie dell'Apparato Respiratorio, Università degli Studi di Firenze, Viale G.B. Morgagni 85, 50134 Firenze, Italy.
authors.forename: Pierantonio
authors.initials: P
authors.lastname: Laveneziana
authors.forename: Andrea
authors.initials: A
authors.lastname: Galarducci
authors.forename: Barbara
authors.initials: B
authors.lastname: Binazzi
authors.forename: Loredana
authors.initials: L
authors.lastname: Stendardi
authors.forename: Roberto
authors.initials: R
authors.lastname: Duranti
authors.forename: Giorgio
authors.initials: G
authors.lastname: Scano
mesh_terms: D000280:Administration, Inhalation; D000328:Adult; D018592:Cross-Over Studies; D004232:Diuretics / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D015444:Exercise; D005260:Female; D005665:Furosemide / Q000494:pharmacology*; D006801:Humans; D008297:Male; D012119:Respiration / Q000187:drug effects*; D012129:Respiratory Function Tests
chemical_list: D004232:Diuretics; D005665:Furosemide