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Vital capacity (VC) is the maximum amount of air a person can expel from the lungs after a maximum inhalation. It is equal to the sum of inspiratory reserve volume, tidal volume, and expiratory reserve volume. It is approximately equal to Forced Vital Capacity (FVC).

A person's vital capacity can be measured by a wet or regular spirometer. In combination with other physiological measurements, the vital capacity can help make a diagnosis of underlying lung disease. Furthermore, the vital capacity is used to determine the severity of respiratory muscle involvement in neuromuscular disease, and can guide treatment decisions in Guillain–Barré syndrome and myasthenic crisis.

A normal adult has a vital capacity between 3 and 5 litres. A human's vital capacity depends on age, sex, height, mass, and possibly ethnicity. However, the dependence on ethnicity is poorly understood or defined, as it was first established by studying black slaves in the 19th century and may be the result of conflation with environmental factors.

Lung volumes and lung capacities refer to the volume of air associated with different phases of the respiratory cycle. Lung volumes are directly measured, whereas lung capacities are inferred from volumes.

Role in diagnosis

The vital capacity can be used to help differentiate causes of lung disease. In restrictive lung disease the vital capacity is decreased. In obstructive lung disease it is usually normal or only slightly decreased.

Estimated vital capacities

Formulas

Vital capacity increases with height and decreases with age. Formulas to estimate vital capacity are:

$${\displaystyle {\begin{aligned}vc_{female}=(21.78-0.101a)\cdot h\\vc_{male}=(27.63-0.112a)\cdot h\\\end{aligned}}}$$ where ${\displaystyle vc}$ is approximate vital capacity in cm, ${\displaystyle a}$ is age in years, and ${\displaystyle h}$ is height in cm.

References

1. Chhabra, S. K. (January 1998). "Forced Vital Capacity, Slow Vital Capacity, or Inspiratory Vital Capacity: Which Is the Best Measure of Vital Capacity?". Journal of Asthma. 35 (4): 361–365. doi:10.3109/02770909809075669. PMID 9669830.
2. "Forced Expiratory Volume and Forced Vital Capacity". Michigan Medicine.
3. ^ "Vital Capacity". Family Practice Notebook. Retrieved 19 February 2015.
4. Hutchinson, John (January 1846). "On the Capacity of the Lungs, and on the Respiratory Functions, with a View of Establishing a Precise and Easy Method of Detecting Disease by the Spirometer". Journal of the Royal Society of Medicine. MCT-29 (1): 137–252. doi:10.1177/095952874602900113. PMC 2116876. PMID 20895846.
5. Villarosa, Linda (14 August 2019). "How False Beliefs in Physical Racial Difference Still Live in Medicine Today". The New York Times.
6. Braun, Lundy (2015). "Race, ethnicity and lung function: A brief history". Canadian Journal of Respiratory Therapy. 51 (4): 99–101. PMC 4631137. PMID 26566381.
7. "Pulmonary Function Tests". UCSD. Retrieved 19 February 2015.
8. ^ Pratt, Joseph H. (December 1922). "Long-Continued Observations on the Vital Capacity in Health and Heart Disease". The American Journal of the Medical Sciences. 164 (6): 819–831. doi:10.1097/00000441-192212000-00003. S2CID 71818743. ProQuest 125233939.

Further reading

Several studies have been made to measure and predict vital capacity:

• Berglund, E.; Birath, G.; Bjure, J.; Grimby, G.; Kjellmer, I.; Sandqvist, L.; Söderholm, B. (1963). "Spirometric Studies in Normal Subjects I: Forced Expirograms in Subjects Between 7 and 70 Years of Age". Acta Medica Scandinavica. 173 (2): 185–192. doi:10.1111/j.0954-6820.1963.tb16520.x. PMID 13970718.
• Birath, G.; Kjellmer, I.; Sandqvist, L. (1963). "Spirometric Studies in Normal Subjects: II. Ventilatory Capacity Tests in Adults". Acta Medica Scandinavica. 173 (2): 193–198. doi:10.1111/j.0954-6820.1963.tb16521.x. PMID 13968399.
• Grimby, G.; Sóderholm, B. (1963). "Spirometric Studies in Normal Subjects: III. Static Lung Volumes and Maximum Voluntary Ventilation in Adults with a Note on Physical Fitness". Acta Medica Scandinavica. 173 (2): 199–206. doi:10.1111/j.0954-6820.1963.tb16523.x.
• Forche, Günther; Stadlober, Ernst; Harnoncourt, Karl (1988). "Neue spirometrische Bezugswerte für Kinder, Jugendliche und Erwachsene" [New spirometric reference values for children, adolescents and adults]. Österreichische Ärztezeitung (in German). 43 (15, 16): 40–42.
• Gulsvik, A.; Tosteson, T.; Bakke, P.; Humerfelt, S.; Weiss, S. T.; Speizer, F. E. (30 November 2001). "Expiratory and inspiratory forced vital capacity and one-second forced volume in asymptomatic never-smokers in Norway: Spirometric standards in Norway". Clinical Physiology. 21 (6): 648–660. doi:10.1046/j.1365-2281.2001.00377.x. PMID 11722472.
• Hedenström, H; Malmberg, P; Agarwal, K (November 1985). "Reference values for lung function tests in females. Regression equations with smoking variables". Bulletin Européen de Physiopathologie Respiratoire. 21 (6): 551–557. OCLC 114155676. PMID 4074961. INIST 8470928.
• Langhammer, A.; Johnsen, R.; Gulsvik, A.; Holmen, T.L.; Bjermer, L. (1 November 2001). "Forced spirometry reference values for Norwegian adults: the Bronchial Obstruction in Nord-Trøndelag study". European Respiratory Journal. 18 (5): 770–779. doi:10.1183/09031936.01.00255301. PMID 11757626.

• Respiratory physiology