Also Known as “Lung Capacities”

Definition: The Volume of Air Moved the Lungs Through Different Phases of the Respiratory Cycle

Base Volumes

• Tidal Volume (TV): Normal Breath
• Inspiratory Residual Volume (IRV): Maximum Extra Inhaled Beyond a Normal Breath
• Expiratory Reserve Volume (ERV): Maximum Extra Exhaled Beyond a Normal Breath
• Residual Volume (RV): Volume Unable to Exhale Out of the Lung

Summative Volumes

• Inspiratory Capacity (IC): The Maximum Volume Able to Be Inhaled (Including TV and IRV)
  • IC = TV + IRV
• Functional Residual Capacity (FRC): The Volume Functionally Not Exhaled During a Breath Without Forced Expiration
  • FRC = ERV + RV
  • Causes of Increased FRC: PEEP
  • Causes of Decreased FRC: Surgery, ARDS, Trauma
• Vital Capacity (VC): The Maximum Volume Able to Be Functionally Moved in and Out of the Lungs During a Breath
  • VC = TV + IRV + ERV = TLC – RV
  • Also Known as “Functional Vital Capacity (FVC)”
• Total Lung Capacity (TLC): The Total Possible Capacity of the Lungs During a Maximal Inhalation
  • TLC = VC + RV