Closing Volume to Vital Capacity Ratio
Info
Inspiratory Reserve Volume
unit Liters ml
Tidal Volume
unit Liters ml
Expiratory Reserve Volume
unit Liters ml
Closing Volume
unit Liters ml
R e s u l t s
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Vital Capacity
 
Ratio of closing volume to vital Capacity
 
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Info
Closing Volume to Vital Capacity Ratio
  • The Vital Capacity (VC) is the maximum volume of air that can be forcefully expelled from the lungs following a maximal inspiration
  • The closing capacity (CC) is the volume in the lungs at which the alveoli collapse
  • The ratio of closing volume to vital Capacity appears to correlate with cirrhotic patients with esophageal varices, early obstructive lung disease and is also altered in healthy smokers

The formulas utilized in this calculation include:

  • VC=IRV+TV+ERV
  • CV/VC (%) =100*CV/VC

Abbreviations used:

  • VC=Vital Capacity
  • IRV=Inspiratory Reserve Volume (Liters)
  • TV=Tidal Volume (Liters)
  • ERV=Expiratory Reserve Volume (Liters)
  • CV=Closing Volume (Liters)

Interpretation:

One study by Becklake MR, et al., found that a single measurement of CV/VC% was only one-third as sensitive as the mean of the following 3 measurements - (CV/VC %) (CC/TLC %) and independent tracing analysis.

Another study by Marcq M, Minette A., found individual variations in CV/VC are the highest with the "best" trace analysis to assess the diurnal variation of closing volume measurements of non-smokers and  smokers, all healthy tested with the single-breath nitrogen test.

Jorfeldt L, Wranne B., found that (CV/VC %) played a significant role in criterion of early obstructive lung disease.

S. Kitano et al., found that (CV/VC %) played a vital role in calculation for patients undergoing sclerotherapy for bleeding esophageal varices

References

Becklake MR, et al. The N2 closing volume test in population studies: sources of variation and reproducibility. Am Rev Respir Dis. 1975 Feb;111(2):141-7.

Jorfeldt L, Wranne B. Hyperinflation on hyperventilation-a simple test to detect early airway disease. Clin Physiol. 1982 Apr;2(2):97-104.

S. Kitano et al. Temporary Deterioration of Pulmonary Functions after Injection Sclerotherapy for Cirrhotic Patients with Esophageal Varices. Eur Surg Res 1988;20:298-303.

Marcq M, Minette A. Diurnal variations and reproducibility of the N2 closing volume test in healthy subjects. Bull Eur Physiopathol Respir. 1976 Nov-Dec;12(6):757-70.