Physiology and consequences of lung hyperinflation in COPD

• Published in: European respiratory review Vol. 15; no. 100; pp. 61 - 67
• Main Authors: O'Donnell, D. E, Laveneziana, P
• Format: Journal Article
• Language: English
• Published: Eur Respiratory Soc 01.12.2006; European Respiratory Society
• Subjects: Chronic obstructive pulmonary disease; dynamic hyperinflation; dyspnoea; exercise; lung volume; respiratory mechanics
• ISSN: 0905-9180; 1600-0617
• DOI: 10.1183/09059180.00010002

Division of Respiratory and Critical Care Medicine, Dept of Medicine, Queen's University, Kingston, ON, Canada. CORRESPONDENCE: D. E. O'Donnell, 102 Stuart Street, Kingston, ON, Canada K7L 2V6, Fax: 1 6135491459. E-mail: odonnell{at}post.queensu.ca Lung hyperinflation commonly accompanies expiratory flow limitation in patients with chronic obstructive pulmonary disease (COPD) and contributes importantly to morbidity and an impoverished quality of life. It is not surprising, therefore, that lung hyperinflation has become an important therapeutic target in symptomatic COPD patients. Acute dynamic increases in lung hyperinflation under conditions of worsening expiratory flow limitation and increased ventilatory demand (or both) can seriously stress cardiopulmonary reserves in patients with more advanced disease. The present understanding of the physiological mechanisms of dynamic hyperinflation during exacerbations of COPD and during physical activity continues to grow, together with an appreciation of its negative mechanical and sensory consequences. In this brief overview, definitions and measurement of lung hyperinflation during rest and exercise will be discussed and its potential clinical importance will be considered. The focus will mainly be on current concepts of the mechanisms of air trapping and its role in inducing respiratory discomfort and activity limitation in COPD. KEYWORDS: Chronic obstructive pulmonary disease, dynamic hyperinflation, dyspnoea, exercise, lung volume, respiratory mechanics