Lung Volumes and Capacities

Inspiratory Volumes

1. Inspiratory Reserve Volume (IRV) - Maximal inspired volume from end-tidal inspiration
2. Tidal Volume (Vt) - Volume inspired and expired with each normal breath *Minimum volume: 3 ml/kg *Normal volume: 6-7 ml/kg
3. Inspiratory Capacity (IC) - Maximal volume inspired from resting expiratory level *Calculation: IRV + Vt

Expiratory Volumes

1. Expiratory Reserve Volume (ERV) - Maximal expired volume from end-tidal inspiration *Normal: 25% of Vital Capacity
2. Residual Volume (RV) - Volume remaining in lungs after maximal expiration Normal adult: 1.0 to 2.4 Liters
3. Functional Residual Capacity (FRC) - Volume remaining in lungs at resting expiratory level

Overall Lung Volumes

1. Vital Capacity (VC) - Maximal volume expelled after maximal inspiration
2. Total Lung Capacity (TLC) - Volume in lungs at end of maximal inspiration *Calculation: VC + RV *Normal adult: 4-6 Liters