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TREATMENT OF ACUTE RENAL FAILURE

In ARF the patients die, mainly, not from azotemia, but from disorders of water-electrolyte and acid-alkaline balance.

If tubulonecrosis predominates among morphologic changes in ARF, 7-18 days are necessary for a primary repair of the epithelium of convoluted tubules. The task is to preserve patient's life at this period. At the initial stage, conservative treatment is directed to elimination or weakening of the causes produced ARF, i.e. in the beginning it bears etiopathogenetic character: fight with shock, hemolysis, exo- and endogenic intoxication, hypovolemia, infection, etc. The shorter is the period of renal ischemia, the lesser is the degree of arising changes in tubular epithelium. Therefore, one should proceed to the initial therapy as soon as possible, particularly in poisonings, in hemolysis of erythrocytes, in crush syndrome. It needs to:

1) prevent decompensation of blood circulation;

2) prevent erythrocytes' aggregation and stasis;

3) prevent disorders of microcirculation in renal vessels and in other organs;

4) normalize AAB;

5) remove a poison, as well as the products of tissue destruction from the organism.

Elimination of hypovolemia and circulatory decompensation are carried out by replenishment of VCB (crystalloids, dextrans, albumin, plasma). These preparations are Theologically active: decrease a blood viscosity, diminish anaphylactoid vascular reaction, decrease erythrocytes' aggregation and thereby maintain a microcirculation and prevent a prolonged ischemia in the kidneys. Dextrans with molecular weight 55000 exert the best effect.

Application of dextrans with low molecular weight may lead to an osmotic nephrosis of renal tubules and intensify ARF. This occurs because a high osmolarity of dextrans causes a flow of fluid from the extracellular space into the cells of tubules that swell and close a tubular lumen.

A good effect may be expected from application of hydroxyethyl-starches (refortan, stabizol — by 500-1000 ml). To diminish the antigen-antibody reaction in transfusion of the blood of different group — glucocorticoids (hydrocortisone by 500mg i/v, then every 6 hours by 100 mg) are used. They

normalize a vascular tone, improve microcirculation, diminish TPVR, stabilize cells membranes and decrease erythrocytes' aggregation. After hydrocortisone prednisolone is added (180-250 mg/day).

In the first 2 hours after hemolysis gaptoglobin is administered i/v that leads to a decrease of severe changes in the parenchymatous organs. In so doing, an injurious effect of myoglobin is maintained. A forced diuresis with alkalinization of plasma is able to remove from blood, in case of hemolysis, through the kidneys so significant portion of free hemoglobin that completely replaced earlier recommended exchange transfusion.

In acute poisonings a therapy is carried out directed to a removal of poison from the organism, as soon as possible: gastric lavage, forced diuresis in case of poisons excreted by the kidneys, hemodialysis, and in poisons of protein genesis that are not excreted by the kidneys — hemosorption.

To remove histamine influence on the vascular wall antihistaminic agents are introduced in maximally high dosages (suprastin, dimedrol, pipolph3n, diprazinum).

AAB correction is made by administration of 5% sodium bicarbonate or trisamine under control of blood and urine analyses. So achieved buffering of the inner medium improves microcirculation in the kidneys, and urne alkalinization prevents precipitation of acidic hematin in hemotransfusion conflict, DIC and intoxications with hemolytic poisons.

At first, alkalizing solutions are administered rapidly up to appearance of alkaline reaction of urine, then AAB is maintained by a drop-by-drop infusion guided by blood laboratory findings.

Trisamine is more preferable than soda since it is, at the same time, an osmotic diuretic and contributes to a removal of hemoglobin derivatives and fragments of stroma.

In order to stimulate osmotic diuresis mannitol is introduced i/v in the form of 15-20% solutions taking into account 1-1.5 g/kg body mass at the rate of 100 drops per min.

An essential condition of mannitol effect is a preliminary restoration of he extracellular space volume at the expense of crystalloids up to 1 1 (Ringer lactate, physiologic solution), a preliminary alkalinization and improvement of renal blood flow due to administration of euphillin and gangliolytics (pentamin, benzohexonium).

A contraindication for osmodiuretics use is accompanying cardiac insufficiency on the background of normovolemia and pulmonary edema. When mannitol is ineffective its repeated administration is not usually carried out. On the background of already developed ARF mannitol is ineffective and even dangerous. In this case saluretics are prescribed — lasix by 200-400 mg repeatedly up to 2000 mg for the first 24 hours, and if they are of no effect, their further administration is cancelled.

In the early period of ARF, prior to development of hypocoagulation phase, a use of heparin 10-20 thnd units i/v is justified with subsequent change over to maintenance doses in order to preserve clotting time according to Li-White to 20-25 per min. In the phase of increased coagulation a use of heparin (clexane and other LMH) is possible in combination with inhibitors of fibrinolysis (trasylol, contrycal, ACA) and to replenish a fibrinogen deficit — a transfusion of fresh frozen plasma.

In pronounced hypotension vasoactive agents are prescribed: dopamin, 200 mg of dofamin i/v drop by drop in 5% glucose 400 ml, that in small doses (to 2 mg/kg/min) decreases peripheral resistance and dilates renal vessels, increases a renal blood flow.

In the initial period a nonspecific symptomatic therapy is also carried out: oxygen therapy, broncholytics and prescription of antiserotonins. In development of acute respiratory failure and presence of indications such patients are transferred to APV.

At the stage of oliguria and anuria treatment must be directed to a maintenance of VCB and prevention of cardiovascular insufficiency, correction of water-electrolyte exchange and AAB, decrease of protein catabolism, maintenance of energy balance, fight against anemia, infection and extrarenal removal of toxic products from the organism.

The intensity of carried out therapy is defined in this period by the expression of pathologic shifts in the internal medium and the rate of their growth, duration of oliguria and rapidity of restoration of renal function.

In maintaining water-electrolyte exchange on the background of oliguria, a strict registration of liquid supplied to the patient's organism and its losses is necessary. A water balance must be equal to zero taking into account endogenic water. This section of therapy is complicated by a need to maintain an energy balance. Therefore, all infused liquids must be high-caloric, for this 20-30% glucose with insulin is used, but without potassium, lipid emulsions and vitamins. In the process one should take in consideration that 1 g glucose, as a result of its metabolism, gives 0.5 ml of endogenic water.

A diet must be high caloric consisting of easily assimilable carbohydrates and fats with restriction of animal proteins up to 35-50 g/day.

A dose of sodium must be strictly rated and potassium salts are to be excluded because of hyperkalemia that often demands urgent measures directed to a transfer of K⁺ from the extracellular space into the cells: 5% soda — 150— 200 ml, insulin with glucose, ion-exchange resins per os and as antagonistic antidote of potassium — 10% calcium chloride — 40-100 ml/day.

In order to inhibit catabolism of proteins and to prevent hyperphosphatemia novolupol (6 g aluminium hydroxide + 2.5 g Mg hydroxide + 10 g glycerol + 10 g sorbitol + 100 ml syrup) by 1 tablespoon 3-4 times per day, anabolic hormones (retabolil by 1.0 daily, nerabol, testosterone propionate) and adequate nutrition.

Suppression of infection with antibiotics of broad spectrum (cephalosporins: cefotaxime has the least toxicity, a low toxicity in cefoperazone and ceftriaxone, the greatest — in cefaloridine, cefaclor and cefalotin when they are applied in large doses, the rest cephalosporins have a moderate toxicity) and fluoroquinolones (tavanik) is acrried out. Nephrotoxic preparations (tetracyc­lines, aminoglycosides and sulfanilamides) are excluded. Dosage of antibiotics must be 3-5 times lower than usual because of their cumulation on the background of renal function disorders.

There is always a threat of anemia development in ARF, in particular because of hemopoiesis depression, therefore, there are direct indications for hemo­transfusions in anemia.

Too strict regimen in such patients is unfavorable since it increases a danger of pulmonary atelectasis and development of bronchopneumonia.

Simultaneously with conservative therapy the extrarenal methods of detoxication are carried on:

— daily gastric lavages and siphon enemas with 2% soda solution;

— salt laxatives or food sorbitol in irregular stool (40-50 g sorbitol per 100 ml of warm water through a tube) contribute to a removal from the organi sm not only toxic products, but significant amounts of liquid by virtue of osmotic activity of sorbitol.

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