title: Does expiratory muscle activity influence dynamic hyperinflation and exertional dyspnea in COPD?
abstract: Increased expiratory muscle activity is common during exercise in patients with COPD but its role in modulating operating lung volumes and dyspnea during incremental cycle ergometry is currently unknown. We compared gastric (Pga) and esophageal (Pes) pressures, operating lung volumes and qualitative descriptors of dyspnea during exercise in 12 COPD patients and 12 age- and sex-matched healthy controls. Pes- and Pga-derived measures of expiratory muscle activity were significantly (p<0.05) greater in COPD than in health during exercise. End-expiratory lung volume (EELV) increased by 0.8L, independent of increased expiratory muscle activity in COPD. Dynamic function of the diaphragm was not different in health and COPD throughout exercise. In both groups, dyspnea descriptors alluding to increased work and inspiratory difficulty predominated whereas expiratory difficulty was rarely reported, even at the limits of tolerance. In conclusion, increased expiratory muscle activity did not mitigate the rise in EELV, the relatively early respiratory mechanical constraints or the attendant perceived inspiratory difficulty during exercise in COPD.
authors.affiliation: Respiratory Investigation Unit, Department of Medicine, Queen's University & Kingston General Hospital, Kingston, ON, Canada; Sorbonne Universités, UPMC Université Paris 06, UMR_S 1158, Neurophysiologie Respiratoire Expérimentale et Clinique, Paris, France; INSERM, UMR_S 1158, Neurophysiologie Respiratoire Expérimentale et Clinique, Paris, France; AP-HP, Groupe Hospitalier Pitié-Salpêtrière Charles Foix, Service des Explorations Fonctionnelles de la Respiration, de l'Exercice et de la Dyspnée, Paris, France. Electronic address: pierantonio.laveneziana@psl.aphp.fr.
authors.forename: Pierantonio
authors.initials: P
authors.lastname: Laveneziana
authors.affiliation: Respiratory Investigation Unit, Department of Medicine, Queen's University & Kingston General Hospital, Kingston, ON, Canada.
authors.forename: Katherine A
authors.initials: KA
authors.lastname: Webb
authors.affiliation: Respiratory Investigation Unit, Department of Medicine, Queen's University & Kingston General Hospital, Kingston, ON, Canada.
authors.forename: Karin
authors.initials: K
authors.lastname: Wadell
authors.affiliation: Respiratory Investigation Unit, Department of Medicine, Queen's University & Kingston General Hospital, Kingston, ON, Canada.
authors.forename: J Alberto
authors.initials: JA
authors.lastname: Neder
authors.affiliation: Respiratory Investigation Unit, Department of Medicine, Queen's University & Kingston General Hospital, Kingston, ON, Canada. Electronic address: odonnell@queensu.ca.
authors.forename: Denis E
authors.initials: DE
authors.lastname: O'Donnell
mesh_terms: D000368:Aged; D003964:Diaphragm / Q000503:physiopathology; D004417:Dyspnea / Q000503:physiopathology*; D016552:Ergometry; D004947:Esophagus / Q000503:physiopathology; D015444:Exercise / Q000502:physiology*; D045853:Exhalation / Q000502:physiology*; D005260:Female; D006801:Humans; D001239:Inhalation / Q000502:physiology; D008297:Male; D008875:Middle Aged; D053580:Muscle Strength / Q000502:physiology; D005082:Physical Exertion / Q000502:physiology; D011312:Pressure; D029424:Pulmonary Disease, Chronic Obstructive / Q000503:physiopathology*; D012129:Respiratory Function Tests; D012132:Respiratory Muscles / Q000503:physiopathology*; D012720:Severity of Illness Index; D013270:Stomach / Q000503:physiopathology
keywords: COPD; Dyspnea; Exercise; Expiratory muscles; Respiratory mechanics