Lung Volumes and Capacities in Respiratory Diseases

Introduction The basic 4 volumes do not overlap each other: tidal volume, inspiratory and expiratory reserve volumes and residual volume. On the other hand, lung capacities include two or more volumes: inspiratory capacity, vital capacity, functional residual capacity and total lung capacity. Spirographic examination of lung functions is characterized by the following main changes: in the obstructive type of disease the functional residual capacity increases and the rate of expiration slows down, which shows on the value of one second forced vital capacity (FEV1) and on the flow-volume loop. In diseases of the restrictive type vital capacity is reduced.