title: Perceived inspiratory difficulty in neuromuscular patients with primary muscle disorders.
abstract: Intensity of perceived inspiratory difficulty was investigated in 17 patients with severe respiratory insufficiency due to muscle disease, compared with healthy matched controls. Subjects breathed through a threshold valve generating a constant inspiratory negative pressure proportional to their maximal inspiratory pressure. Four load levels ranging from 10 to 40% of the maximal inspiratory pressure were applied in random order. Patients had significantly less perceived inspiratory difficulty than controls at each load level expressed as a percentage of maximal inspiratory pressure P < 0.001. However, when the load was expressed as the absolute value, the slope of the Borg scale score versus mouth pressure was similar in the two groups (P = 0.11). The ventilatory pattern remained unchanged in each group as the load increased. We conclude that in patients with myopathy, loads leading to respiratory muscle fatigue (40% of maximal inspiratory pressure) may fail to produce perceived inspiratory difficulty.
authors.affiliation: Services de Réanimation Médicale, Physiologie-Explorations Fonctionnelles, et Centre d'Innovation Technologique Hôpital Raymond Poincaré, AP-HP, 92380 Garches, France.
authors.forename: Sandrine
authors.initials: S
authors.lastname: Hours
authors.forename: Michèle
authors.initials: M
authors.lastname: Lejaille
authors.forename: Delphine
authors.initials: D
authors.lastname: Pozzi
authors.forename: Line
authors.initials: L
authors.lastname: Falaize
authors.forename: Françoise
authors.initials: F
authors.lastname: Zerah-Lancner
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Raphael
authors.forename: Frédéric
authors.initials: F
authors.lastname: Lofaso
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D001239:Inhalation / Q000502:physiology*; D007320:Inspiratory Capacity; D008173:Lung Diseases, Obstructive / Q000209:etiology*; D008297:Male; D008451:Maximal Voluntary Ventilation / Q000502:physiology; D008875:Middle Aged; D009135:Muscular Diseases / Q000150:complications*; D011446:Prospective Studies; D012129:Respiratory Function Tests / Q000379:methods; D015656:Respiratory Mechanics / Q000502:physiology; D012132:Respiratory Muscles / Q000503:physiopathology*; D012684:Sensory Thresholds; D013990:Tidal Volume / Q000502:physiology; D013997:Time Factors