Emphysema

Emphysema is classified as a subtype of chronic obstructive pulmonary disease (COPD); however, some organizations use the terms "COPD" and "emphysema" interchangeably. Emphysema consists of damage to the alveoli in the lungs that inhibits oxygen supply.1 As emphysema progresses, the alveoli transform from spherical air sacs into large irregular pockets with gaping holes in the inner walls, reducing lung surface area and oxygen supply to the blood. Elastic fibers that hold open the small airways leading to the alveoli are slowly destroyed, trapping air in the lungs.2 Emphysema is classified into one of three types: centriacinar, panacinar, or paraseptal. Centriacinar emphysema begins in the respiratory bronchioles and spreads peripherally, and panacinar emphysema destroys the alveoli uniformly, although predominately in the lower lungs. Paraseptal emphysema involves the distal airway structures, ducts, and sacs.3