Chapter 7

### Key Concepts

• Epidemiology

• It is estimated that two to three million patients suffer from emphysema.

• Pathophysiology

• Except for rare cases caused by enzyme deficiency, smoking is the cause of diffuse emphysema. The smoke destroys lung tissue in an irreversible fashion leading to bullous formation. The bullae may be relatively small or quite large.

• Clinical features

• Patients are hypoxic and dyspneic. The dyspnea ranges from mild to the need for home oxygen supplementation with subsequent diminishment in the quality of life.

• Diagnostics

• Clinically, emphysema is a subset of chronic obstructive pulmonary disease (COPD). The other causes of COPD including chronic bronchitis and hyperreactive airways can coexist. Emphysema is diagnosed by pulmonary function testing that shows a decrease in forced expiratory volume in 1 second (FEV1) and increase in total lung capacity and residual volume.

• Treatment

• Medical: Cessation of smoking eliminates progression of the disease but the tissue loss is irreversible.

• Surgical: Appropriately selected patients benefit from lung volume reduction surgery and/or resection of giant bullae. Operative mortality is minimal. Operative morbidity is significant but most patients recover and benefit with an improved quality of life.

### Introduction

#### Pathophysiology

Emphysema is a pulmonary disease that is one of the conditions that are together characterized as chronic obstructive pulmonary disease (COPD). The other diseases that are also constituents of the diagnosis of COPD are chronic bronchitis, formally defined as the presence of a productive cough for any three months of any two consecutive years, and hyperreactive airway conditions, particularly asthma. Any of these three disease processes can exist independently, but some overlap and coexistence is common. Figure 7-1 displays and discusses the interrelationships between these subsets of COPD which typically coexist.1 “Asthma” in the figure should be understood as representing all hyperreactive airway conditions. The important understanding is that pure emphysema is uncommon.

###### Figure 7-1

Schema depicting chronic obstructive pulmonary disease (COPD). A nonproportional Venn diagram shows subsets of patients with chronic bronchitis, emphysema, and asthma in three overlapping circles. Subsets of patients lying within the rectangle have airway obstruction. Patients with asthma (subset 9) are defined as having completely reversible airway obstruction and lie entirely within the rectangle; their diagnosis is unequivocal. Patients in subsets 6 and 7 have partially reversible airway obstruction with chronic productive cough or emphysema, respectively. Patients in subset 8 have features of all three disorders. It may be difficult to ascertain whether patients in subsets 6 and 8 indeed have asthma or whether they have developed bronchial hyperreactivity as a complication of chronic bronchitis or emphysema; the history helps. Patients in subset 3 have chronic productive cough with airway obstruction but no emphysema; it is not known how large this subset is, because epidemiologic studies with the CT scan, the most sensitive in vivo imaging technique for the diagnosis or exclusion of emphysema, are not available. It is much easier to identify patients with emphysema ...

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