What is the Expiratory Reserve Volume (ERV)?

Expiratory Reserve Volume (ERV) refers specifically to the quantity of air that can be forcefully exhaled after the end of a normal, passive exhalation. It represents the additional volume of air that can be expelled beyond what is typically exhaled during quiet breathing, known as the tidal volume. This volume is crucial in understanding respiratory function and assessing lung health, particularly in conditions where forced expiration might be limited.

In comparison to other definitions, the amount of air remaining in the lungs after normal exhalation describes the residual volume, and the volume of air inhaled during quiet breathing is indicative of tidal volume. The air used during exercise does not uniquely define any specific volume and varies greatly based on activity levels and individual conditioning. Therefore, understanding ERV helps in assessing the efficiency of the respiratory system and can indicate underlying respiratory issues when measured alongside other lung volumes.