Pathogenesis of hyperinflation in chronic obstructive pulmonary disease

Abstract

Chronic obstructive pulmonary disease (COPD) is a preventable and treatable lung disease characterized by airflow limitation that is not fully reversible. In a significant proportion of patients with COPD, reduced lung elastic recoil combined with expiratory flow limitation leads to lung hyperinflation during the course of the disease. Development of hyperinflation during the course of COPD is insidious. Dynamic hyperinflation is highly prevalent in the advanced stages of COPD, and new evidence suggests that it also occurs in many patients with mild disease, independently of the presence of resting hyperinflation. Hyperinflation is clinically relevant for patients with COPD mainly because it contributes to dyspnea, exercise intolerance, skeletal muscle limitations, morbidity, and reduced physical activity levels associated with the disease. Various pharmacological and nonpharmacological interventions have been shown to reduce hyperinflation and delay the onset of ventilatory limitation in patients with COPD. The aim of this review is to address the more recent literature regarding the pathogenesis, assessment, and management of both static and dynamic lung hyperinflation in patients with COPD. We also address the influence of biological sex and obesity and new developments in our understanding of hyperinflation in patients with mild COPD and its evolution during progression of the disease.

Keywords: chronic obstructive pulmonary disease; expiratory flow limitation; hyperinflation; operational lung volumes.

Figure 1

Lung volumes and capacities at rest and during exercise. Notes: Lung volumes and capacities in a healthy elderly control (A and C) and in an aged-matched COPD patient (B and D). Gray parts represents lung volumes during exercise. Abbreviations: COPD, chronic obstructive pulmonary disease; EELV, end-expiratory lung volume; EILV, end-inspiratory lung volume; ERV, expiratory reserve volume; FRC, functional residual capacity; FVC, forced vital capacity; IC, inspiratory capacity; IRV, inspiratory reserve volume; RV, residual volume; V_T, tidal volume.

Figure 2

Pressure–volume relationships of the total respiratory system. Notes: Pressure–volume relationships of the total respiratory system in healthy subjects (A) and in COPD (B). Tidal pressure–volume curves during rest (black) and exercise (gray) are shown. In COPD, the ability to further expand tidal volume is reduced. In contrast with health, the combined recoil pressure of the lungs and chest wall in hyperinflated patients with COPD is inwardly directed during both rest and exercise. Reproduced with permission of the European Respiratory Society. Eur Respir Rev December 2006 15:61–67; doi:10.1183/09059180.00010002. Copyright © remains with European Respiratory Society. Abbreviations: COPD, chronic obstructive pulmonary disease; EELV, end-expiratory lung volume; IRV, inspiratory reserve volume; P, pressure; RV, residual volume; TLC, total lung capacity; V, volume.

Figure 3

Acute effects of bronchodilation therapy on operational volume during constant work rate cycle ergometry in patients with COPD. Notes: Example of operating lung volumes during constant work rate cycle ergometry performed at 75% maximal workload after dosing of placebo (gray symbols) or bronchodilation therapy (black symbols). Adapted with permission from the American College of Chest Physicians. Maltais F, Hamilton A, Marciniuk D, et al. Improvements in symptom-limited exercise performance over 8 h with once-daily tiotropium in patients with COPD. Chest. 2005;128(3):1168–1178. Abbreviations: COPD, chronic obstructive pulmonary disease; EELV, end-expiratory lung volume; IC, inspiratory capacity; IRV, inspiratory reserve volume; TLC, total lung capacity; V_T, tidal volume.