ABSTRACT
Changes in the mechanical properties of the airways and airspaces are central to the disability in COPD. Increases in airway resistance, decreases in dynamic compliance and loss of lung recoil lead to hyperinflation of the lungs and chest wall and greatly increase the work of breathing. The unequal distribution of these changes leads to abnormal distribution of ventilation and is responsible for much of the inefficiency of the lungs as exchangers of O2 and CO2. In this chapter changes in lung mechanics in COPD will be considered at three stages: (i) mild disease as found in population studies of smokers; (ii) moderate to severe disease studied in the stable state; (iii) acute respiratory failure, defined as a significant deterioration of oxygenation from the chronic, stable state. A fuller bibliography of work on stable COPD up to 1985 is published elsewhere.1
