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Key points related to lung capacities and lung volumes


By Med-train

  • • Vital capacity (VC) - Maximum volume of air which can be moved in and out of the lungs. OR
  • Maximum amount of air that can be expired from lungs after a maximum inhalation.
  • VC = Tidal volume + IRV + ERV

(IRV- Inspiratory Reserve Volume, ERV - Expiratory Reserve Volume)

  • Normal vital capacity is 4200 to 4800 ml. It may vary according to the size of a person.
  • Vital capacity can be measured by PFT (Pulmonary Function Test) using a Spirometer.
  • VC is decreased in COPD, neuromuscular disease, generalized fatigue, atelectasis, obesity, sedentary life style, chronic smokers, old age, chest trauma etc.
  • Vital capacity is decreased in restrictive lung disorders and often seen decreased even in obstructive lung disorders.
  • Vital capacity can be increased with regular exercise.
  • Vital capacity is decreased in all except……..
    • Emphysema B) Athletes C) Guillain Barre syndrome D) Rib Fracture Ans: Athletes

Key: Vital capacity generally seems to be decreased in a sick person.