title: Mechanical effects of obesity on airway responsiveness in otherwise healthy humans.
abstract: We investigated whether obesity is associated with airway hyperresponsiveness in otherwise healthy humans and, if so, whether this correlates with a restrictive lung function pattern or a decreased number of sighs at rest and/or during walking. Lung function was studied before and after inhaling methacholine (MCh) in 41 healthy subjects with body mass index ranging from 20 to 56. Breathing pattern was assessed during a 60-min rest period and a 30-min walk. The dose of MCh that produced a 50% decrease in the maximum expiratory flow measured in a body plethysmograph (PD50MCh) was inversely correlated with body mass index (r2=0.32, P<0.001) and waist circumference (r2=0.25, P<0.001). Significant correlations with body mass index were also found with the maximum changes in respiratory resistance (r2=0.19, P<0.001) and reactance (r2=0.40, P<0.001) measured at 5 Hz. PD50MCh was also positively correlated with functional residual capacity (r2=0.56, P<0.001) and total lung capacity (r2=0.59, P<0.001) in men, but not in women. Neither PD50MCh nor body mass index correlated with number of sighs, average tidal volume, ventilation, or breathing frequency. In this study, airway hyperresponsiveness was significantly associated with obesity in otherwise healthy subjects. In obese men, but not in women, airway hyperresponsiveness was associated with the decreases in lung volumes.
authors.affiliation: Pneumologia-Fisiopatologia Respiratoria , Azienda Ospedaliera S. Luigi, Torino, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Torchio
authors.forename: Alessandro
authors.initials: A
authors.lastname: Gobbi
authors.forename: Carlo
authors.initials: C
authors.lastname: Gulotta
authors.forename: Raffaele
authors.initials: R
authors.lastname: Dellacà
authors.forename: Marco
authors.initials: M
authors.lastname: Tinivella
authors.forename: Robert E
authors.initials: RE
authors.lastname: Hyatt
authors.forename: Vito
authors.initials: V
authors.lastname: Brusasco
authors.forename: Riccardo
authors.initials: R
authors.lastname: Pellegrino
mesh_terms: D000328:Adult; D000403:Airway Resistance; D015992:Body Mass Index; D016535:Bronchial Hyperreactivity; D001985:Bronchial Provocation Tests; D016085:Bronchoconstrictor Agents; D005260:Female; D005652:Functional Residual Capacity; D006801:Humans; D008168:Lung / Q000503:physiopathology*; D008176:Lung Volume Measurements; D008297:Male; D016210:Methacholine Chloride; D008875:Middle Aged; D009765:Obesity / Q000503:physiopathology*; D012123:Pulmonary Ventilation; D015656:Respiratory Mechanics; D012737:Sex Factors; D013990:Tidal Volume; D055105:Waist Circumference; D016138:Walking; D055815:Young Adult
chemical_list: D016085:Bronchoconstrictor Agents; D016210:Methacholine Chloride