Lab

Lung Volume

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Lung Volume, Inspiratory Reserve Volume, Tidal Volume, Inspiratory Capacity, Expiratory Reserve Volume, Residual Volume, Total Lung Capacity

  • Interpretation
  • Inspiratory Volumes
  1. Inspiratory Reserve Volume (IRV)
    1. Maximal inspired volume from end-tidal inspiration
  2. Tidal Volume (Vt)
    1. Volume inspired and expired with each normal breath
    2. Minimum volume: 3 ml/kg
    3. Typical ventilator Tidal Volume settings: 6-8 ml/kg
    4. Normal volume: 6-7 ml/kg
  3. Inspiratory Capacity (IC)
    1. Maximal volume inspired from resting expiratory level
    2. Calculation: IRV + Vt
  • Interpretation
  • Expiratory Volumes
  1. Expiratory Reserve Volume (ERV)
    1. Maximal expired volume from end-tidal inspiration
    2. Normal: 25% of Vital Capacity
  2. Residual Volume (RV)
    1. Volume remaining in lungs after maximal expiration
    2. Normal adult: 1.0 to 2.4 Liters
  3. Functional Residual Capacity (FRC)
    1. Volume remaining in lungs at resting expiratory level
  • Interpretation
  • Overall Lung Volumes
  1. Vital Capacity (VC)
    1. Maximal volume expelled after maximal inspiration
  2. Total Lung Capacity (TLC)
    1. Volume in lungs at end of maximal inspiration
    2. Calculation: VC + RV
    3. Normal adult: 4-6 Liters
  • References
  1. Rollings (1984) Facts and Formulas, McNaughton & Gunn
  2. Marini (1987) Respiratory Medicine, Williams & Wilkins