Respiratory volume is the volume of the air exchanged during inhalation and exhalation. Respiratory volume is the volume of air associated with different phases of respiratory cycle. Hence it is important indicator for the function of the respiratory system. This volume is measured with spirometer. It includes tidal volume, inspiratory reserve volume, expiratory reserve volume and residual volume.
Tidal volume (TV):- it is the volume of air that moves out of the lungs and into the lungs during normal, relaxed breathing/respiration. Its value is 0.5 lit in both adult (healthy) men and women.
Expiratory Reserve Volume (ERV) :- the maximum amount of air that can be exhaled after normal exhalation or in simple terms it is the additional air that is forcibly exhaled after exhalation of normal tidal volume. Its value in healthy adults is 1.0 litre in men and 0.7 litres in women.
Inspiratory reserve volume (IRV) :- the maximum amount of air that can be inhaled after normal inspiration or it is the additional air that is forcibly inhaled after inspiration of normal tidal volume. Its value in healthy adults is 3.3 lit in men and 1.9 lit in women.
Residual volume (RV) :- the volume of air remaining in the lungs after maximum exhalation or the volume of the air remaining in the lungs after expiratory reserve volume. Its value in healthy adults is 1.2 lit in men and 1.1 lit in women.