Emphysema with bullae is a common feature of patients with chronic obstructive pulmonary disease. Central to the pathophysiology of emphysema is the presence of airflow obstruction and lung and chest hyperinflation. Because of the increased ventilatory demand and the need to maintain gas exchange, patients with emphysema increase their work of breathing. This article reviews the adaptive and maladaptive consequences of these changes. A rationale is given as to the possible mechanism by which surgery aimed at resecting hyperinflated portions of the lungs may be effective.