Static and dynamic hyperinflation during severe acute exacerbations of chronic obstructive pulmonary disease

Background: Static hyperinflation is known to be increased during moderate acute exacerbations of chronic obstructive pulmonary disease (COPD) (AECOPD), but few data exist in patients with severe exacerbations of COPD. The role of dynamic hyperinflation during exacerbations is unclear. Methods: In a prospective, observational cohort study, we recruited patients admitted to hospital for AECOPD. The following measurements were performed upon admission and again after resolution (stable state) at least 42 days later: inspiratory capacity (IC), body plethysmography, dynamic hyperinflation by metronome-paced IC measurement, health-related quality of life and dyspnea. Results: Forty COPD patients were included of whom 28 attended follow-up. The IC was low at admission (2.05±0.11 L) and increased again during resolution by 15.6%±23.1% or 0.28±0.08 L (mean ± standard error of the mean, p <0.01). Testing of metronome-paced changes in IC was feasible, and it decreased by 0.74±0.06 L at admission, similarly to at stable state. Clinical COPD Questionnaire score was 3.7±0.2 at admission and improved by 1.7±0.2 points ( p <0.01), and the Borg dyspnea score improved by 2.2±0.5 points from 4.4±0.4 at admission ( p <0.01). Conclusion: Static hyperinflation is increased during severe AECOPD requiring hospitalization compared with stable state. We could measure metronome-paced dynamic hyperinflation during severe AECOPD but found no increase.