VITAL CAPACITY OF LUNGS (ZHEL) — the maximum quantity of air exhaled after the maximum deep breath. ZhEL is one of indicators external breath (see) also represents set of three pulmonary volumes (fig.) — respiratory volume (the volume of the inhaled or expired air at each respiratory cycle), the reserve volume of a breath (the volume of gas which can be inhaled after a quiet breath) and the reserve volume of an exhalation (volume of gas which can be exhaled after a quiet exhalation). After the maximum exhalation in lungs there is a certain amount of air — the so-called residual volume (OO). ZhEL and OO totally make the total capacity of lungs (TCL). Air volume, being in lungs after a quiet exhalation (the sum of reserve and residual volumes), is called the functional residual capacity (FRC).
The first research ZhEL at the person is conducted by Getchinson (J. Hutchinson, 1846) who established dependence of ZhEL on a floor, growth, weight and age and constancy of size for each person. Dependence of ZhEL on growth, weight, gender and age is expressed in so-called due ZhEL [A. J. Anthony, 1937].
It can be determined by due standard metabolism approximately (see. Standard metabolism ). Also empirical formulas of calculation of due ZhEL (DZhEL) are applied; for men — on a formula: 0,052 • growth — 0,029 • age — 3,20 and for women: 0,049 • growth — 0,019 age — 3,76, where growth — in cm, age — advanced in years, DZhEL — in l.
For children aged from 4 up to 17 years due sizes of vital capacity of lungs calculate on a formula (I. S. Shiryaeva, B. A. Markov, 1973): boys of DZhEL (l) = 4,53 • growth — 3,9, with a height from 1,00 to 1,64 m; DZhEL (l) = 10,00 • growth — 12,85, with a growth from 1,65 m; girls of DZhEL (l) = 3,75 • growth — 3,15, with a height from 1,00 to 1,75 m.
Definition of ZhEL is widely applied in a wedge, and sports medicine. This indicator is most available to measurement and objectively characterizes functions of external respiration. ZhEL depends on biomechanical characteristics of lungs and a thorax, and also allows to judge the sizes of an alveolar surface of lungs indirectly. Forster (R. E. Forster) et al.
(1957), A. By A. Markosyan (1974), etc. it is established that the more ZhEL, the more diffusion capacity of lungs. Size ZhEL depends on position of a body (in a standing position it more, than in a sitting position or lying).
Increase in ZhEL is observed in the course of physical. trainings. Reduction of ZhEL happens at many diseases which are followed by weakening of respiratory muscles, reduction of distensibility of lungs and a thorax, venous stagnation in a small circle of blood circulation.
At disturbance of bronchial passability and decrease in distensibility of easy ZhEL decreases at the expense of a delay of air in lungs and increases in residual volume.
Measurement of ZhEL is taken by means of spirometry, spirographies (see), volyumometriya and other methods. However more informatively measurement of ZhEL along with measurement of other pulmonary volumes. For this purpose apply the general pletizmografiya (see), an azotografiya, a dilution method of helium in the closed system, a tracer technique, etc. The measured size ZhEL and the parts making it needs to be given to conditions of the BTPS system (i.e. temperature 37 °, to the barometric pressure and saturation of the atmosphere water vapors at the time of measurement).
Bibliography: Votchal B. E. and Magazanik N. A. Vital capacity of lungs and bronchial passability, Klin, medical, t. 47, No. 5, page 21, 1969; To about m r about D. G., etc. Easy, Clinical and functional trials, the lane with English, M., 1961; Organizational and methodical issues of clinical physiology of breath, under the editorship of A. D. Smirnov, L., 1973; Rosenblat W. W., Mezenina L. B. and Shmelkova T.M.O due sizes for assessment of vital capacity of lungs, Klin, medical, t. 45, No. 12, page 95, 1967; Physiology of breath, under the editorship of L. JI. Chic, etc., page 4, L., 1973; Functional researches of breath in pulmonary practice, under the editorship of H. N. Kanayeva, L., 1976; Hasis G. L. Indicators of external respiration of the healthy person, p.1 — 2, Kemerovo, 1975; Cotes J. E, Lung function, Oxford — Edinburgh, 1968; Handbook of physiology, ed. by W. O. Fenn a. H. Rahn, sect. 3 — Respiration, v. 1 — 2, Washington, 1964 — 1965.
I. S. Shiryaeva.