Acute renal failure

Description:

Acute renal failure  - suddenly come, potentially reversible disturbance of homeostatic function of kidneys. Now the frequency of an acute renal failure reaches 200 on 1 million population, at the same time 50% of the diseased need a hemodialysis. Since 1990th years the steady tendency according to which the acute renal failure even more often becomes not monoorgan pathology, but a component of a syndrome of multiorgan insufficiency is traced. This tendency remains in the 21st century. Classification. The acute renal failure is subdivided on prerenalny, renal and prerenal.

Symptoms of the Acute renal failure:

The course of an acute renal failure can be divided on initial, oligoanurichesky, diuretic and a phase of an absolute recovery.

The initial phase can last from several hours to several days. During this period weight of a condition of the patient is defined by the reason for the acute renal failure which caused development of the pathological mechanism. At this particular time all earlier described pathological changes develop, and all subsequent disease is their consequence. The general clinical symptom of this phase is the circulator collapse which often happens so short that remains unnoticed.

The Oligoanurichesky phase develops in the first 3 days after an episode of blood loss or influence of the toxic agent. It is considered that the later the acute renal failure developed, the worse it the forecast. Duration of an oligoanuriya fluctuates from 5 to 10 days. If this phase proceeds more than 4 weeks, it is possible to draw a conclusion about existence of a bilateral cortical necrosis though cases of recovery of renal function after 11 months of an oliguria are known. During this period the daily urine makes no more than 500 ml. Urine of dark color, contains a large amount of protein. Osmolarity does not exceed it osmolarity of plasma, and the content of sodium is reduced to 50 mmol/l. Sharply the maintenance of an urea nitrogen and creatinine of blood serum increases. Disturbances of electrolytic balance begin to be shown: hypernatremia, hyperpotassemia, fosfatemiya. There is a metabolic acidosis.

The patient during this period notes the anorexia, nausea and vomiting which is followed by a diarrhea which is replaced by a lock after a while. Patients are sleepy, slowed down, quite often fell into a coma. The overhydratation causes lung hypostasis which is shown by an asthma, wet rattles, quite often there is Kussmaul's breath.

The hyperpotassemia causes the expressed disturbances of a cordial rhythm. Quite often against the background of uraemia there is a pericardis. Other manifestation of increase in content of urea of blood serum is the uraemic gastroenterocolitis which consequence the gastrointestinal bleedings arising at 10% of patients from an acute renal failure are.

During this period the expressed oppression of phagocytal activity therefore patients become subject to an infection is noted. There are pneumonia, parotitises, stomatitises, pancreatitis, uric ways and postoperative wounds are infected. Development of sepsis is possible.

The diuretic phase proceeds 9-11 days. Gradually the amount of the emitted urine begins to increase and after 4-5 days reaches 2-4 l per day and more. At many patients loss of a large amount of potassium with urine is noted - the hyperpotassemia is replaced by a hypopotassemia that can lead to hypotonia and, even, to paresis of skeletal muscles, disturbances of a cordial rhythm. Urine has low density, in it the content of creatinine and urea is lowered, however after 1 week of a diuretic phase at the favorable course of a disease the hyperazotemia disappears and the electrolytic balance is recovered.

In a phase of an absolute recovery there is a further recovery of function of kidneys. Duration of this period reaches 6-12 months after which function of kidneys is recovered completely.

Diagnosis. Diagnosis of an acute renal failure, as a rule, does not represent difficulties. Its main marker is continuous increase in level of nitrogenous metabolites and potassium in blood along with reduction of amount of the emitted urine. At the patient with clinical displays of an acute renal failure definition of its reason is obligatory. Carrying out the differential diagnosis of a prerenalny acute renal failure from renal is extremely important as the first form can quickly pass into the second that will aggravate the course of a disease and will worsen the forecast. First of all it is necessary to carry out differential diagnosis of a prerenal acute renal failure from other its types for what carry out ultrasonography of kidneys which allows to define or exclude the fact of bilateral obstruction of upper uric ways on existence or lack of dilatation of pyelocaliceal system.

If necessary bilateral catheterization of a renal pelvis can be executed. At free carrying out ureteric catheters to a pelvis and in the absence of release of urine on them it is possible to reject a prerenal anury with confidence. Laboratory diagnosis is constructed on measurement of volume of urine, level of creatinine, urea and electrolytes of blood serum. Sometimes for the characteristic of a renal blood-groove it is necessary to resort to a renal angiography. The biopsy of a kidney should be carried out according to strict indications: at suspicion on an acute glomerulonephritis, a canalicular necrosis or a general disease.

Reasons of the Acute renal failure:

The Prerenalny acute renal failure is caused by disturbance of a hemodynamics and reduction of total amount of the circulating blood that is followed by renal vasoconstriction and decrease in renal blood circulation. Hypoperfusion of kidneys results, blood is insufficiently purified of nitrogenous metabolites, there is an azotemia. From 40 to 60% of all cases of an acute renal failure fall to the share of a prerenalny anury. The renal acute renal failure is more often caused by ischemic and toxic defeat of a renal parenchyma, is more rare - an acute inflammation of kidneys and vascular pathology. At 75% of patients of a renal acute renal failure the disease proceeds against the background of an acute canalicular necrosis. The prerenal acute renal failure is more often than other types is followed by an anury and results from obstruction at any level of extrarenal uric ways.
The cardiogenic shock, cardiac tamponade, arrhythmia, heart failure, embolism of a pulmonary artery, i.e. state which are followed by decrease in cordial emission are the main reasons for a prerenalny acute renal failure. The expressed vazodilatation caused by acute or bakteriotoksichesky anaphylaxis can be other cause. The Prerenalny acute renal failure often is caused by reduction of volume of extracellular liquid which cause such states as burns, blood loss, dehydration, diarrhea, cirrhosis and the ascites caused by it can be.

Treatment of the Acute renal failure:

Treatment. In an initial phase of an acute renal failure treatment first of all has to be directed to elimination of the reason which caused development of the pathological mechanism. At shock which is the reason of 90% of an acute renal failure the main thing is the therapy directed to normalization of arterial pressure and completion of volume of the circulating blood. Administration of proteinaceous solutions and krupnomolekulyarny dextrans which should be entered under control of an indicator of the central venous pressure is effective not to cause an overhydratation.

At poisoning with nephrotoxic poisons removal in their way of a gastric lavage and intestines is necessary. Unithiolum is a universal antidote at poisonings with salts of heavy metals. The hemosorption undertaken even before development of an acute renal failure can be especially effective.

In case of a prerenal acute renal failure therapy has to be directed to early recovery of outflow of urine.

In an oligurichesky phase at an acute renal failure of any etiology administration of osmotic diuretics in combination with furosemide which doses can reach 200 mg is necessary. Introduction of a dopamine in "renal" doses is shown that will allow to reduce renal vasoconstriction. The volume of the entered liquid has to make up for losses it with a chair, vomiting, urine and in addition 400 ml spent at Breath, sweating. The diet of patients has to be protein-free and provide up to 2000 kcal/days. For decrease in a hyperpotassemia it is necessary to limit its receipt with food, and also to carry out surgical treatment of wounds with removal of necrotic sites, drainage of cavities. At the same time an antibioticotherapia should be carried out taking into account weight of damage of kidneys.

The indication to carrying out a hemodialysis is increase in content of potassium more than 7 mmol/l, urea to 24 mmol/l, emergence of symptoms of uraemia: nausea, vomiting, block, and also overhydratation and acidosis. Now even more often resort to early or even preventive hemodialysis that prevents development of heavy metabolic complications. This procedure is carried out every day or every other day, gradually increasing a proteinaceous quota to 40 g/days.