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Abstract:

Effects of bronchodilators on dynamic hyperinflation following hyperventilation in patients with COPD

FUJIMOTO K, YOSHIIKE F, YASUO M, KITAGUCHI Y, URUSHIHATA K, KUBO K, HONDA T. Respirology 2007; 12: 93-99 Background and objective:

The present study was performed to examine the occurrence of dynamic hyperinflation following hyperventilation in COPD patients and former smokers without COPD, and the efficacy of short-acting anticholinergic agents (SAAC) and β₂-agonists (SABA) for lung hyperinflation following metronome-paced hyperventilation in COPD. Methods:

Fifty-nine patients with COPD, 20 ex-smokers without COPD and 20 healthy subjects who had never smoked were examined for dynamic hyperinflation by metronome-paced hyperventilation with respiratory rate increasing from 20 to 30 and 40 tidal breaths/min. Dynamic hyperinflation was evaluated as the decrease in inspiratory capacity (IC) following hyperventilation, and the effects of SAAC and SABA on dynamic hyperinflation were assessed. Results:

COPD patients showed a significant increase in end-expiratory lung volume and a decrease in IC following hyperventilation, and ex-smokers without COPD also showed mild but significant dynamic hyperinflation. Multiple stepwise linear regression analysis revealed that the carbon monoxide transfer coefficient (DLco/V_A) and RV/TLC were significant and independent determinants of dynamic hyperinflation in COPD. Treatment with SAAC and SABA significantly increased IC at each respiratory rate, independently of the increases in FEV₁. Furthermore, SABA significantly inhibited the decrease in IC due to hyperventilation. Conclusions:

These findings suggest that lung hyperinflation following hyperventilation may be a useful method for detecting dynamic hyperinflation observed not only in patients with COPD but also in ex-smokers without COPD, and both SAAC and SABA are effective in reducing dynamic hyperinflation in COPD.

Keywords: air trapping; bronchodilator; COPD; hyperventilation; lung hyperinflation

Document Type: Research article

DOI: 10.1111/j.1440-1843.2006.00963.x

Affiliations: 1: Departments of Internal Medicine and 2: Laboratory Medicine, Shinshu University School of Medicine, Matsumoto, Japan

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