title: Acute effects of inspiratory pressure threshold loading upon airway resistance in people with asthma.
abstract: Large inspiratory pressures may impart stretch to airway smooth muscle and modify the response to deep inspiration (DI) in asthmatics. Respiratory system resistance (Rrs) was assessed in response to 5 inspiratory manoeuvres using the forced oscillation technique: (a) single unloaded DI; (b) single DI at 25 cmH(2)O; (c) single DI at 50% maximum inspiratory mouth pressure [MIP]; (d) 30 DIs at 50% MIP; and (e) 30 DIs at 50% MIP with maintenance of normocapnia. Rrs increased after the unloaded DI and the DI at 25 cmH(2)O but not after a DI at 50% MIP (3.6+/-1.6 hPa Ls(-1) vs. 3.6+/-1.5 hPa Ls(-1); p=0.95), 30 DIs at 50% MIP (3.9+/-1.5 hPa Ls(-1) vs. 4.2+/-2.0 hPa Ls(-1); p=0.16) or 30 DIs at 50% MIP under normocapnic conditions (3.9+/-1.5 hPa Ls(-1) vs. 3.9+/-1.5 hPa Ls(-1); p=0.55). Increases in Rrs in response to DI were attenuated after single and multiple loaded breaths at 50% MIP.
authors.affiliation: Department of Sport & Exercise Sciences, University of Gloucestershire, Oxstalls Lane, Gloucester GL2 9HW, UK. show@glos.ac.uk
authors.forename: Stephen C
authors.initials: SC
authors.lastname: How
authors.forename: Lee M
authors.initials: LM
authors.lastname: Romer
authors.forename: Alison K
authors.initials: AK
authors.lastname: McConnell
mesh_terms: D000280:Administration, Inhalation; D000328:Adult; D000403:Airway Resistance / Q000187:drug effects / Q000502:physiology*; D000704:Analysis of Variance; D001247:Asthenia / Q000503:physiopathology*; D001993:Bronchodilator Agents / Q000494:pharmacology; D005260:Female; D005541:Forced Expiratory Volume / Q000187:drug effects / Q000502:physiology; D006801:Humans; D008168:Lung / Q000187:drug effects / Q000473:pathology / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D011312:Pressure; D012119:Respiration; D012132:Respiratory Muscles / Q000187:drug effects / Q000503:physiopathology*; D055815:Young Adult
chemical_list: D001993:Bronchodilator Agents