Emphysema: Introduction

Emphysema is a lung condition whereby the respiratory unit of the lung, called the acinus, is destroyed. It is a permanent abnormal enlargement of air spaces (the areas of the pulmonary acini – the respiratory units of the lungs) distal to the terminal bronchiole (the smallest air tube without a respiratory component) accompanied by destruction of their walls (the respiratory unit’s walls). Emphysema can have various presentations and be of various types, the four main types being centrilobular, paraseptal, panlobular and paracicatricial.