Acute kidney failure

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

[1], [2], [3], [4], [5], [6]

Epidemiology

On average, in various countries per million people account for between 30 and 60 cases of acute renal failure per year. The share of nephrologic 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, lethality in the development of acute renal failure is 26 to 50%, and in the combination of acute renal failure and sepsis - up to 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 is 15%.

[7], [8], [9], [10], [11], [12], [13], [14], [15], [16],

Causes of the acute renal failure

How to develop acute renal failure is still not known, but note four main reasons for its development:

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

On a large statistical material has now been proved: the morphological basis of acute renal failure is the lesion of the tubular apparatus mainly in the form of nephrothelial necrosis with or without damage to the basal membrane; with indistinctly defined lesions of glomeruli. Some foreign authors use the Russian-language term "acute tubular necrosis" as a synonym for the term "acute renal failure". Morphological changes, as a rule, are reversible, therefore, the clinical and biochemical symptom complex is also reversible. Nevertheless, in a few cases, with severe endotoxic (less exotoxic) effects, it is possible to develop bilateral total or subtotal cortical necrosis, differing in morphological and functional irreversibility.

[17], [18], [19], [20]

Pathogenesis

For a long time, renal insufficiency was identified with uremia, however, pathological changes in the body with renal dysfunction are much more complicated, dynamic and can not be explained only by the accumulation of nitrogenous slags. Depending on the speed and severity of the decrease in glomerular filtration, acute renal failure and chronic renal failure are isolated.

[21], [22], [23], [24], [25],

Symptoms of the acute renal failure

It is necessary to carefully collect an anamnesis with the specification of information about recently transferred acute diseases, the presence of chronic diseases, medication, contact with toxic substances and clinical symptoms of intoxication.

Acute renal failure occurs with the following symptoms:  dry mouth, thirst, dyspnea (extracellular hyperhydration develops, the first sign of which is interstitial edema of the lungs), soft tissue edema in the lumbar region, edema of the lower extremities (also possible accumulation of fluid in the cavities: hydrothorax, ascites , the development of edema of the brain and convulsions is not ruled out).

[26], [27]

Forms

The following forms are distinguished: prerenal (haemodynamic), renal (parenchymal) and postrenal (obstructive) acute renal failure. The most common renal acute renal failure (up to 70% of cases). The most common cause of prerenal acute renal failure is development of hypotension against the background of problems with the cardiovascular system and dehydration of the patient's body. A critical level of blood pressure is considered to be 60 mm Hg, below it, urination stops. Renal acute renal failure develops when the kidney parenchyma is affected (according to data of different authors, up to 25% of cases), caused most often by the action of nephrotoxic substances (eg, drugs). Emergency acute renal failure is associated with impaired patency of the urinary tract.

[28], [29], [30]

Diagnostics of the acute renal failure

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

Acute renal failure has typical diagnostic criteria: a  clinical analysis of blood  may show moderate anemia and an increase in ESR. Anemia in the early days of anuria is usually of a relative nature. Due to hemodilution, does not reach a high degree and does not require correction. Changes in blood are characteristic of an exacerbation of urinary tract infection. In acute renal failure, there is a decrease in immunity, resulting in a tendency to develop infectious complications: pneumonia, suppuration of surgical wounds and skin catheter sites installed in the central veins, etc.

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

[31], [32], [33], [34], [35], [36]

Treatment of the acute renal failure

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

That is why the treatment of acute renal failure will be successful in the early diagnosis of the disease, determining its cause, as well as the timely initiation of efferent therapy.

Prevention

Acute renal failure can be prevented by adequate treatment of the underlying disease, which may lead to acute renal failure. With prerenal acute renal failure, it is necessary to strive for timely correction of hypovolemia. If possible, it is necessary to avoid nephrotoxic drugs, and when used according to the indications, it is necessary to take into account GFR.

Patients from at-risk groups should avoid a sharp drop in blood pressure and BCC, the use of radiocontrast preparations, nephrotoxic drugs, as well as drugs that actively influence the renin-aldosterone-angiotensin system and reduce renal blood flow.

Use medicines, especially antibiotics, NSAIDs, heparin sodium and saluretics, should be on strict indications, with caution. At the same time, with infections caused by nephrotropic pathogens, the appointment of antibiotics is an important component of the prevention of acute renal failure.

As cytoprotectors, which reduce the risk of acute renal failure, slow calcium channel blockers (verapamil), glycine, theophylline, antioxidants, vitamin E, etc. Are recommended. Postoperative acute renal failure is prevented with the use of mannitol and loop diuretics.

[37], [38], [39], [40], [41]