Respiratory Volumes and Capacities: TV, IRV, ERV, RV, IC, EC, FRC and Total Lung Capacity

Tidal Volume (TV)

Volume of air inspired or expired during a normal respiration. It is approx. 500 mL., i.e., a healthy man can inspire or expire approximately 6000 to 8000 mL of air per minute.

Inspiratory Reserve Volume (IRV)

Additional volume of air, a person can inspireby a forcible inspiration. This averages 2500mL to 3000 mL.

Expiratory Reserve Volume (ERV)

Additional volume of air, a person can expireby a forcible expiration. This averages 1000mL to 1100 mL.

Residual Volume (RV)

Volume of air remaining in the lungs even after aforcible expiration. This averages 1100 mL to 1200 mL.By adding up a few respiratory volumes described above, one canderive various pulmonary capacities, which can be used in clinicaldiagnosis.

Inspiratory Capacity (IC)

Total volume of air a person can inspire aftera normal expiration. This includes tidal volume and inspiratory reserve volume (TV+IRV).

Expiratory Capacity (EC)

Total volume of air a person can expire aftera normal inspiration. This includes tidal volume and expiratory reservevolume (TV+ERV).

Functional Residual Capacity (FRC)

Volume of air that will remain inthe lungs after a normal expiration. This includes ERV+RV.

Vital Capacity (VC)

The maximum volume of air a person can breathe inafter a forced expiration. This includes ERV, TV and IRV or the maximumvolume of air a person can breathe out after a forced inspiration.

Total Lung Capacity

Total volume of air accommodated in the lungs atthe end of a forced inspiration. This includes RV, ERV, TV and IRV orvital capacity + residual volume.