title: Determinants of dynamic hyperinflation during metronome-paced tachypnea in COPD and normal subjects.
abstract: In COPD, dynamic hyperinflation (DH) occurs during exercise and during metronome-paced tachypnea (MPT). We investigated the relationship of DH with breathing pattern and ventilation (V˙E) in COPD and normal subjects (NS). In 35 subjects with moderate COPD and 17 younger healthy volunteers we measured inspiratory capacity (IC), breathing frequency (fR), expiratory time (TE), ventilation (V˙E) and end-tidal carbon dioxide tension (PETCO2) at baseline and after 30s of MPT at 40breaths/min with metronome-defined I:E ratios of 1:1 and 1:2. A reduction in IC (ΔIC) was taken to indicate DH. In COPD subjects, DH correlated with TE but not with V˙E or PETCO2, and was best predicted by total lung capacity. NS also showed DH (although less than in COPD), which correlated with PETCO2 but not with fR, TE or V˙E. We conclude that MPT evokes DH in both NS and patients with COPD. TE is the most important determinant of DH during MPT in patients with COPD.
authors.affiliation: Exercise Physiology Research Laboratory, David Geffen School of Medicine, University of California, Los Angeles, CA, USA; Division of Pulmonary and Critical Care Medicine, Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, USA. Electronic address: ccooper@mednet.ucla.edu.
authors.forename: C B
authors.initials: CB
authors.lastname: Cooper
authors.forename: G L
authors.initials: GL
authors.lastname: Calligaro
authors.forename: M M
authors.initials: MM
authors.lastname: Quinn
authors.forename: P
authors.initials: P
authors.lastname: Eshaghian
authors.forename: F
authors.initials: F
authors.lastname: Coskun
authors.forename: M
authors.initials: M
authors.lastname: Abrazado
authors.forename: E D
authors.initials: ED
authors.lastname: Bateman
authors.forename: R I
authors.initials: RI
authors.lastname: Raine
mesh_terms: D000328:Adult; D000368:Aged; D002245:Carbon Dioxide / Q000378:metabolism; D005080:Exercise Test; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D007320:Inspiratory Capacity / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D029424:Pulmonary Disease, Chronic Obstructive / Q000503:physiopathology*; D015656:Respiratory Mechanics; D013147:Spirometry; D059246:Tachypnea / Q000503:physiopathology*
chemical_list: D002245:Carbon Dioxide
keywords: Breathing pattern; COPD; Dynamic hyperinflation