Respiratory Volumes

Inspiratory Capacity(IC)

Sum of the tidal volume plus the inspiratory reserve volume(TV+IRV)

Residual Volume(RV)

The residual volume is the volume of air in the lungs at the end of maximal expiration (the volume of air which you cannot voluntarily exhale from your lungs) Residual air cannot be exhaled. Volume can be estimated through gas dilution techniques and the use of helium in inspired air.

Total Lung Capacity(TLC)

The residual volume(air you cannot expire)+vital capacity(total volume available for use)=TLC. TLC is the total volume of the lungs

Vital Capacity(VC)

The total usable volume of the lungs which is under voluntary control. Does not include the entire lung volume as it is not possible to breath all the air out of lungs

Forced Expiratory Volume 1(FEV1)

The volume of air that can be expired during the first second of expiration in a vital capacity determination...80% of VC

Expiratory Reserve Volume(ERV)

This is the difference between the volume of air left in the lung at the conclusion of normal expiration vs. at the conclusion of maximal expiration

Resting Tidal Volume(Vt)

This is the volume of air taken into the lungs when you inhale. It increases with exercise or activity

Inspiratory Reserve Volume(IRV)

Total lung capacity minus the volume of air in the lung at the end of a normal respiration.

Functional Residual Capacity

Total volume of air left in the lungs at the conclusion of normal resting expiration. Includes the expiratory reserve volume plus the residual volume(ERV+RV)

Minimal Volume(MV)

should the volume of the lungs fall below this value, the lungs will collapse

Minute Respiratory Volume(MRV)

the volume of air exchanged in 1 min(respiratory frequency is approx. 12-15 breaths/min X tidal volume =12 to 15 X 500 mL=6000 to 7500 mL/min. Average is closer to 6 L/min)