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Influence of AAB disorders upon functions of the organism

A. Influence of respiratory alkalosis

— on hemodynamics — dilates vessels, decreases a vascular tone,
diminishes VCB because of deposition of a portion of blood in dilated vessels,
lowers AP, MVC that leads to a decrease of tissue blood flow as a result of
which a tissue metabolic acidosis develops (as a defence reaction), an oxygen
supply to the brain reduces.

B. Influence of respiratory acidosis

— on patency of bronchial tree — a partial bronchospasm leading to a sharp
increase of bronchial resistance, increase of bronchial mucus production that
causes a greater narrowing of bronchi and a sharp drop of alveolar ventilation.
As a result: insufficient removal of C0₂ from blood, oxygen deprivation of tissues,
increased consumption of oxygen by respiratory musculature, a decrease of
tissues blood supply. A combined respiratory and metabolic acidosis, dyspnea

(because of acidosis in respiratory muscles) and development of carbon dioxide narcosis (coma);

— on blood pressure in a. pulmonalis that sharply increases because of narrowing of pulmonary vessels on the background of intensification of tone of the sympathoadrenal system that leads to the increase of vascular resistance to the blood flow and a rise of load on the right heart;

— on intracranial pressure: a dilation of cerebral vessels leads to a hyperproduction of liquor and elevation of intracranial pressure. This kind of elevated ICP is not lowered under the effect of osmodiuretics, but it is normalized upon Tris-buffer administration;

— osmotic pressure of plasma is elevated at the expense of increase of H⁺ and HC0₃" concentration in blood;

— Hb0₂ decreases at the expense of pH lowering and Hb affinity to oxygen. At the initial phase AP, SV, MVC grow up, then when a metabolic acidosis is added, a myocardial function is depressed and indices of hemodynamics drop;

— uropoiesis decreases at the expense of spasm of renal arteries, K⁺ excretion with urine reduces.

B. Influence of metabolic alkalosis

It is quite often encountered in clinic. This form of AAB disorders is the most dangerous for the organism, since the organism, least of all, has at his disposal mechanisms of compensation of metabolic acidosis. Its influence upon the organism is expressed as follows:

— a change of Hb0₂ dissociation in acidosis: a pH drop leads to a decrease of Hb affinity to 0₂, as a result a release of oxygen from Hb0₂ in tissues and formation of Hb0₂ in alveoli are impeded. All this leads to hypoxemia and oxygen deprivation. An oxygen inhalation does not eliminate a hypoxia, but when pH is elevated with bicarbonates, a saturation of blood with oxygen is sharply increased;

— a myocardial function is depressed. Adrenalin, if pH is low, may cause dangerous disorders of myocardial function;

— on the ECG: changes of excitation (arrhythmias), disturbances of conduction (blocks), ST is under the isoline;

— tone of arteries: a narrowing of vessels and a decrease of blood flow in them at pH < 7.2 and > 7.4;

— cerebral blood circulation: a narrowing of cerebral vessels and a depression of the myocardium lead to a decrease of cerebral blood supply;

— decrease of diuresis at the expense of inhibition of renal blood flow;

— retention of water in the extracellular fluid, increase of Na⁺, K⁺, CI' concentration; decrease of lactic acid and HC0₃" contents;

— reflex intensification of adrenals function, CoA content is elevated in blood at the expense of decrease of mechanisms of adrenalin degradation in acidosis, and adrenalin, per se, intensifies acidosis. A circus viciosus is formed:

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