Acute renal failure

Acute renal failure is a syndrome caused by sudden (within hours or days) potentially reversible impairment of renal function or kidney function, which develops on the basis of damage to the tubular apparatus (tubular necrosis) due to the influence of exogenous or endogenous factors.

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Epidemiology

On average, in different countries there are 30 to 60 cases of acute renal failure per 1 million population per year. The share of nephrological patients with acute renal failure in intensive care units is 10-15%. Despite the constant improvement of hemodialysis technology and the creation of new dialysis-filtration technologies, the mortality rate in the development of acute renal failure is from 26 to 50%, and with a combination of acute renal failure and sepsis - reaches 74%. Acute renal failure in pediatric practice occurs with a frequency of 0.5-1.6%, and in newborns it reaches 8-24%. While the share of renal and postrenal acute renal failure accounts for 15%.

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Causes acute renal failure

How acute renal failure develops is still unknown, but four main reasons for its development are noted:

• tubular obstruction;
• interstitial edema and passive reverse flow of glomerular filtrate at the level of the tubules;
• renal hemodynamic disorder;
• disseminated intravascular coagulation.

Based on a large amount of statistical material, it has now been proven that the morphological basis of acute renal failure is damage to the predominantly tubular apparatus in the form of nephrothelial necrosis with or without damage to the basement membrane; with poorly defined damage to the glomeruli. Some foreign authors use the Russian term "acute tubular necrosis" as a synonym for the term "acute renal failure". Morphological changes are usually reversible, therefore, the clinical and biochemical symptom complex is also reversible. However, in a few cases, with severe endotoxic (less often exotoxic) effects, the development of bilateral total or subtotal cortical necrosis is possible, characterized by morphological and functional irreversibility.

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Pathogenesis

For a long time, renal failure was identified with uremia, but pathological changes in the body with impaired renal function are much more complex, dynamic and cannot be explained only by the accumulation of nitrogenous waste. Depending on the speed and severity of the decrease in glomerular filtration, acute renal failure and chronic renal failure are distinguished.

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Symptoms acute renal failure

A thorough anamnesis is required, specifying information about recent acute illnesses, the presence of chronic illnesses, medication intake, contact with toxic substances and clinical symptoms of intoxication.

Acute renal failure occurs with the following symptoms: dry mouth, thirst, shortness of breath (extracellular hyperhydration develops, the first sign of which is interstitial pulmonary edema), swelling of soft tissues in the lumbar region, swelling of the lower extremities (fluid accumulation in cavities is also possible: hydrothorax, ascites, the development of cerebral edema and seizures is possible).

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Forms

The following forms are distinguished: prerenal (hemodynamic), renal (parenchymatous) and postrenal (obstructive) acute renal failure. Renal acute renal failure is the most common (up to 70% of cases). The most common cause of prerenal acute renal failure is the development of hypotension against the background of problems with the cardiovascular system and dehydration of the patient's body. The critical level of blood pressure is considered to be 60 mm Hg, below which urination stops. Renal acute renal failure develops with damage to the renal parenchyma (according to various authors, up to 25% of cases), most often caused by the action of nephrotoxic substances (for example, drugs). Postrenal acute renal failure is associated with obstruction of the urinary tract.

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Diagnostics acute renal failure

Currently, there are no specific tests that allow the diagnosis of acute renal failure to be made at the earliest stage. The most reliable and simple marker of acute renal failure is a continuous increase in creatinine levels. Patients in severe condition require daily monitoring of diuresis and electrolyte composition of the blood.

Acute renal failure has typical diagnostic criteria: moderate anemia and increased ESR may be observed in clinical blood analysis. Anemia in the first days of anuria is usually relative, caused by hemodilution, does not reach a high degree and does not require correction. Blood changes are typical during exacerbation of urinary tract infection. In acute renal failure, there is a decrease in immunity, as a result of which there is a tendency to develop infectious complications: pneumonia, suppuration of surgical wounds and sites of exit to the skin of catheters installed in central veins, etc.

At the beginning of the oliguria period, the urine is dark, contains a lot of protein and cylinders, its relative density is reduced. During the period of diuresis recovery, the low relative density of urine, proteinuria, almost constant leukocyturia as a result of the release of dead tubular cells and the resorption of interstitial infiltrates, cylindruria, erythrocyturia are preserved.

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Treatment acute renal failure

Acute renal failure is treated depending on the etiology, form and stage of this disease. As is known, both prerenal and postrenal forms are necessarily transformed into the renal form during development.

This is why treatment of acute renal failure will be successful with early diagnosis of the disease, determination of its cause, and timely initiation of efferent therapy.

Prevention

Acute renal failure can be prevented by adequate treatment of the underlying disease that may cause acute renal failure. In prerenal acute renal failure, it is necessary to strive for timely correction of hypovolemia. Nephrotoxic drugs should be avoided if possible, and when they are used according to indications, the SCF should be taken into account.

In patients from risk groups, it is necessary to avoid a sharp decrease in blood pressure and BCC, the use of radiocontrast agents, nephrotoxic drugs, as well as drugs that actively affect the renin-aldosterone-angiotensin system and reduce renal blood flow.

Medicines, especially antibiotics, NSAIDs, sodium heparin and saluretics, should be used strictly according to indications and with caution. At the same time, in infections caused by nephrotropic pathogens, antibiotics are an important component of acute renal failure prevention.

Slow calcium channel blockers (verapamil), glycine, theophylline, antioxidants, vitamin E, etc. are recommended as cytoprotectors that reduce the risk of developing acute renal failure. Postoperative acute renal failure is prevented by using mannitol and loop diuretics.

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