Lab

Functional Residual Capacity

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Functional Residual Capacity, FRC

  • See Also
  1. Pulmonary Function Test
  2. Lung Volumes
  3. Diffusing Capacity
  4. Inhalation Challenge Test
  5. Exercise Spirometry
  6. Vital Capacity
  7. Peak Expiratory Flow Rate (PEFR)
  8. Spirometry Lower Limit of Normal (PFT LLN)
  9. Obstructive Lung Disease
  10. Restrictive Lung Disease
  • Physiology
  1. Volume remaining in lungs at resting expiratory level
  2. Equivalent to alveolar volume (Va)
    1. Respiratory Bronchioles and alveolar ducts: 30-40%
    2. Alveoli: 60-70%
  3. Calculation: ERV + RV
  4. Normal adult: 1.8 to 3.4 Liters
  • Causes
  • Factors that increase FRC (Hyperinflation)
  1. Emphysema
  2. Aging
  3. Asthma
  4. Peribronchial fibrosis
  • Causes
  • Factors that decrease FRC
  1. Age
  2. Obesity
  3. Supine Posture
  4. Sedation