RESPIRATORY COEFFICIENT

From Big Medical Encyclopedia

RESPIRATORY COEFFICIENT (outdate a synonym: respiratory relation, respiratory coefficient) — the relation of the volume allocated from an organism (body, fabric) carbon dioxide gas (VCO 2 ) to the volume of the oxygen absorbed for the same time (VO 2 ). D.'s definition to. carry out during the studying of features gas exchange (see) and metabolism and energy (see) at animal and vegetable organisms.

D.'s definition to. is important also at a research of external respiration. Many formulas for settlement definition of structure of an alveolar air include size D. to. As between size D. to. and a certain dependence, according to D. to exists the attitude of amount of the air ventilating alveoluses towards amount of the blood proceeding through their capillaries. it is possible to judge the ventilating and perfused relations. It is established that sizes D. to. for the air exhaled from top and bottom shares of lungs significantly are various because of inequality of their ventilating and perfused relations.

D.'s comparison to. the left and right lung at a separate bronkhospirometriya helps to judge features of ventilation and exchange of gases in each of them. D.'s definition to. in different parts of expired air it is used for an in-depth study of some parties of external respiration.

At the person and animal D. to. usually fluctuates ranging from 0,7 to 1. At oxidation of carbohydrates on 1 mol of the consumed oxygen in an organism 1 mol of carbon dioxide gas since all oxygen consumed from inhaled air eventually goes only for oxidation of carbon of carbohydrates is formed, and oxidation of the hydrogen which is in composition of carbohydrates to water is provided with the oxygen concluded in a molecule of carbohydrate. Gram molecule of various gases (in this case oxygen and carbon dioxide gas) occupy equal volumes therefore at oxidation of carbohydrates D. to with an identical pressure and temperature. 1 equals. At oxidation of fats which molecule contains many hydrogen atoms and few oxygen atoms oxygen consumption is quantitatively connected also with formation of water from the hydrogen which is contained in fats. As a result volume formed in an organism (and allocated) carbon dioxide gas at dissimilation of fats is less than the volume of consumed oxygen. At oxidation of fats D. to. it is equal to 0,70 — 0,72. To oxidation of proteins, as a result to-rogo are formed, except water and carbon dioxide gas, the nitrogen-containing connections which are allocated to hl. obr. with urine, there corresponds size D. to., equal 0,80 — 0,82.

The amount of the protein which is oxidized in an organism is determined by the nitrogenous products of its disintegration removed with urine. Considering this size (in approximate calculations it can be neglected), according to D. to. define share in dissimilation of fats and carbohydrates. Amount of the energy (in kilocalories) which is released in an organism at consumption of 1 l of oxygen (a so-called caloric equivalent of oxygen), at oxidation of carbohydrates equally 5,05, fats — 4,69, proteins — 4,49.

To. naturally changes depending on the size of a caloric equivalent of oxygen (tab).

Table. Change of size of a respiratory coefficient depending on the size of a caloric equivalent of oxygen



If the diet includes carbohydrates, fats and proteins, D. to. fluctuates within 0,8 — 0,9. At preferential carbohydrate food of D. to. makes 0,9 — 1; at excess consumption of carbohydrates and their partial transition in an organism to fats (e.g., during the fattening of pigs, geese) D. to. can reach 1,2 — 1,4. It is connected with the fact that upon transition of carbohydrates rich with oxygen to oxygen-deficient fats a part of the carbon dioxide gas emitted by an organism is formed with the participation of the oxygen which is released at this process and not just absorbed in lungs from inhaled air. Similar increase in D. to., but less expressed, it is observed at the people recovering the normal weight after a partial or complete starvation. The return phenomenon — D.'s decrease to. — it is observed at starvation and at hibernation. During the muscular work of moderate power, during a so-called stable state when oxygen consumption corresponds to requirement in it of an organism, D. to. in connection with the strengthened dissimilation preferential of carbohydrates usually raises, making 0.9 — 1. However during very long work connected with reduction of reserves of carbohydrates in an organism, D. to. begins to go down that demonstrates gradually increasing use of fats.

In addition to character of the oxidized substances, a row physical exerts impact on amount of the emitted carbon dioxide gas. and the chemical factors which do not have relations to processes of oxidation. The disturbances of ventilation which are often found in clinic concern to the first (see. Breath ). So, a hyperventilation, reducing the partial pressure of carbonic acid in an alveolar air, promotes its considerable washing away from blood and increases D. to. Hypoventilation, increasing tension of carbonic acid of an alveolar air, respectively reduces D. to. Accumulation in blood of not completely oxygenated products of exchange (acetone bodies, milk to - that, etc.) changing acid-base equilibrium aside belongs to chemical factors acidosis (see) and creating conditions for replacement of carbonic acid from blood (see Acid-base equilibrium). Besides, intensive transition of fats and proteins to carbohydrates (at diabetes) or carbohydrates in fats (at obesity) also influences release of carbonic acid, and, therefore, at a size D. to.

D.'s definition to. it is carried out also at researches of gas exchange of separate bodies and fabrics. About D. to. bodies in the conditions of a complete organism it is possible to judge by the oxygen content and carbonic acids in an arterial blood and in the venous blood flowing from these bodies. To. at the same time equals to the relation of a difference between the maintenance of tension of carbon dioxide gas in a venous and arterial blood to a difference between the oxygen content in an arterial and venous blood:

The results received thus indicate some features and wider borders of fluctuations of D. to. different bodies in comparison with an organism in general (D. to. the isolated fabrics — see. biological oxidation ).

Clinical studying of a respiratory coefficient. In a wedge, practice level D. to. not always characterizes the course of oxidizing processes in an organism and character of the oxidized substances since at a research of gas exchange not oxygen consumption, but its absorption is defined. Oxygen absorption is defined by that its quantity, a cut consumption — its participation in biochemical, oxidation reactions gets from an alveolar air into blood of pulmonary capillaries, and. In usual conditions of distinction between these terms do not do since absorption and oxygen consumption are almost identical.

Discrepancy between absorption and consumption arises upon transition from breath by free air to breath by pure oxygen when in a blood plasma and in fabrics its additional quantity without equivalent increase in consumption in tissue respiration is dissolved, and also at jump of oxygen capacity of blood or change of conditions of saturation of blood by oxygen in lungs.

The technique of a research of gas exchange can significantly change ventilation as towards its increase, and decrease. Therefore size D. to., defined at short-term a wedge. experiences, it is impossible to consider reliable. The existing equipment allows to determine gas exchange only by oxygen absorption, and during the calculation standard metabolism (see) D. to. conditionally undertakes in its average size (0,82 — 0,85). Results turn out similar to those which dismiss size D. to. on release of carbon dioxide gas.

Thus, only under certain conditions, which influence can be not always considered, figure D. to. really reflects character of the substances which are exposed to oxidation. Therefore data on D. to. at various diseases are contradictory. So, at disturbances carbohydrate or a lipometabolism of D. to. from 0,5 to 1 can fluctuate; various sizes D. to. are observed at a thyrotoxicosis and pregnancy.

D.'s changes to. at heart failure, apparently, are connected with changes of ventilation.

During the definition of standard metabolism of D. to. almost in 100% of cases 0,74 — 0,9 does not go beyond. Practically it is necessary to consider that figures D. to., appearing above or below these, are result of methodical errors and do not reflect the true nature of oxidizing processes in an organism.


Bibliography Dembo A. G. Nedostatochnost of functions of external respiration, L., 1957, bibliogr.; Navratil M., Kadlec To. and Daum S. Patofiziologiya of breath, the lane from Czeches., M., 1967, bibliogr.; Syrkina P. E. Gasometry in medical practice, M., 1956, bibliogr.; Physiology of breath, under the editorship of L. L. Shik, etc., M., 1973, bibliogr.; A n t h about n at And. J. Funktionspriifung der Atmung, Lpz., 1962, Bibliogr.

L. L. Shik; A. G. Dembo (wedge, value).

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