is a rapidly developing disease that leads to damage to the renal parenchyma of different pathogenesis with disturbances in the excretory function and without them. In fact, the term OPP replaced the term acute renal failure.
Acute damage to the kidney
Acute organ damage is rapid, but has nonspecific symptoms. The disease is often diagnosed too late, and mistakes occur when the diagnosis is made. All this leads to an increase in mortality.
The need to replace the concept of acute renal failure was due to several factors. First, it is the need for precise definition and unification of diagnostic criteria. In the English literature, for example, there are 30 definitions of arrester.
Secondly, the accumulated data allow us to conclude that even a relatively small temporary increase in creatinine in the blood plasma leads to an increase in mortality, both in the early and in the distant period. And the cause of death is not always a failure of the kidneys. This means that in a number of cases complex pathogenetic connections are formed that lead to damage not only to the kidney tissue, but also to other organs.
As a result, for the time being, OPP is defined as a syndrome of a sharp decrease in renal function associated with the risk of early or long-term mortality. Often it leads to the formation of chronic kidney failure. The working group of AKIN experts, charged with developing the problem, suggested that the level of severity of the disease should be classified according to the concentration of creatinine in blood plasma and by volume of urine. The clearance of creatinine from among the determining factors was excluded. Thus, the diagnosis of the disease has been reduced to two simple methods that can be performed in any hospital.
The conceptual model of OPP includes 5 stages. The norm is not included in the scale.
- Risk - is characterized by an increase in the concentration of creatinine in 1.5-2 p.compared with baseline or more than 0.3 mg / dl. Diuresis - volume of urine, less than 0,5 ml / kg / for 6 hours. Functional markers are absent, but it is possible to identify lesions during examinations.
- Damage - the creatine concentration increases 2-3 times, diuresis - less than 0.5 ml / kg / for 12 hours. There are weak functional markers and markers of damage.
- Insufficiency - concentration increases by 3 times or more than 4 mg / dl. With an acute increase, it increases by more than 0.5 mg / dL.Less than 0.5 ml / kg of urine per day or anuria is observed within 12 hours. Biomarkers indicate tissue damage. Changes at the listed stages are potentially reversible.
- Loss - renal failure is observed for 4 weeks unchanged.
- The terminal stage is fixed if renal failure lasts more than 3 months unchanged.
Acute damage to the kidney is also common in children. The situation in this area is even worse, since there is no sufficiently reliable diagnostic test to determine the violation. To date, this definition of the concentration of lipocalin in the blood, serum cystatin C, NGAL is a protein that normally filters in the glomeruli and is completely absorbed in the tubules. Also, interleukin-18 in urine and KIM-1, a molecule of kidney damage, can serve as a marker.
The degree of severity of the disease in children is classified according to the glomerular filtration rate - creatine clearance, and by volume of excreted urine:
- Risk - reduced filtering by 25%.Diuresis is less than 0.5 ml / kg / for 8 hours.
- Damage - a reduction in GFR by 50%, within 16 hours, less than 0.5 ml / kg of urine will be released.
- Insufficiency - GFR falls by 75% - less than 35 ml / min
1.73 square meters.m, diuresis - less than 0.3 ml / kg per day or anuria for 12 hours.
- Loss of function occurs with an unchanged kidney condition for more than 4 weeks.
- Terminal stage - the invariance of dysfunction for 3 months.
OPP is a very serious complication. According to statistics, the mortality rate among children who have an OPP revealed is 12 times higher. Statistics relative to adult patients is incomplete and distorted due to ambiguous treatment of the disease. In general, the mortality of adult patients with OPP is higher by 25% than in patients without OPP.
There are 3 forms of acute kidney damage: prerenal - the incidence rate of 50-60%, renal - 35-40% and postrenal - less than 5%.Separation makes sense, because each category has its own pathophysiological mechanism, and, hence, the peculiarities of treatment.
Children have a slightly different picture. Prerenal OPP is observed in 85% of cases, renal is 12%, postrenal OPP is fixed in 3%.
This form of OPP is the most common and, in fact, is the functional response of the body to insufficient blood supply to the kidney. As a rule, a structural disorder of the renal tissue is not accompanied by an ailment. Accordingly, with the restoration of normal blood supply, the kidney function is also quickly restored.
OPP can be triggered by any disease that causes a deficiency in blood supply to the kidney.
This is most often due to a decrease in the volume of arterial blood. The lack of it activates the work of the renin-angiotensin-aldosterone system. An increase in the concentration of angiotensin II ultimately leads to a narrowing of the vessels, as a result of which the glomerular filtration rate does not decrease. However, in the patient with OPP, this mechanism is no longer able to compensate for the lack of blood, and GFR begins to decrease.
The reason for the decrease in arterial blood volume may be myocardial infarction, pericardium, valves, pulmonary hypertension, systemic vasodilation, hypercalcemia and other diseases. To provoke violations in the work of the kidney can and medications.
In children, the main cause of the disease is hypoxia, hypothermia, congenital heart and vascular malformations.
The cause of the formation of renal OPP is damage to the renal parenchyma, that is, the anil- ogy was preceded by some kidney damage. Accordingly, the elimination of existing factors - insufficiency of blood supply, does not always lead to recovery.
The following diseases are the causes of the renal acute injury:
- Acute tubular necrosis is most often caused by an ischemic and nephrotic process caused by hypotension, sepsis, and the like. This is the most frequent cause of OPP and with the most unfavorable prognosis, as it is accompanied by severe concomitant diseases. OTN doctors are considered as an additional risk factor, as necrosis leads to the death of the patient in 50-70%.On recovery, the renal function is restored, although not completely, as some of the nephrons died during the illness.
- Ischemic acute tubular necrosis - has ischemic origin, that is, also due to insufficient blood supply. In the first stage, tubular cells are damaged, which is associated with narrowing of blood vessels and a lack of blood. On the second unfolding inflammatory process, already independent of the actions of the ischemic factor. The restoration of functions is possible in 3 stages.
Ischemic heart failure is most often due to heart failure. Significantly increase the risk of diabetes mellitus, chronic kidney failure, as well as cardiac surgery.
The cause of the disease of children is most often associated with congenital malformations - polycystic kidney, hypoplasia, as well as with inflammatory and vascular anomalies. A very dangerous feature of the course of the disease in children is the transition of the pre-renal form to the renal: if within a week the factor acting on the kidneys could not be eliminated, then it is already an organic lesion of the kidney.
This form is provoked by obstruction of the urinary system, that is, difficulty in removing urine at the level of the urethra, bladder, kidneys, ureters. With unilateral obstruction especially at the level of the kidneys, OPP, as a rule, does not develop.
In bilateral OPP can be observed with partial or complete obstruction. In the first case, fix nocturia, frequent urination, false desires, in the second - anuria.
The causes of development of the postrenal form are thrombi, concrements in the bladder, papillary necrosis, nephrolithiasis and so on.
The cause of the disease in children is also bilateral obstruction of the urinary tract. At an early age, the postrenal form is 1%.
On the video about the causes and symptoms of acute kidney damage:
Diuresis - the volume of urine output per day, hour, minute, is an extremely indicative sign of renal diseases. In a healthy person, a normal volume of urine is a volume equal to 75% of the fluid used. Deviation in one direction or another indicates dysfunction of the kidneys or urinary tract.
Renal OPP in the initial stages often maintain a normal diuresis, which is what makes such an important study of urine and blood.
In acute lesions, 3 phases of diuresis are considered:
- Prodromal is the period between the incubation period and the actual disease. Most often there is a normal diuresis. The duration of the prodromal period depends on the cause of the ailment, the toxicity of the toxin and so on.
- Oligouric phase - on average, lasts 10-14 days, but can last up to 8 weeks. Diuresis - 50-400 ml / day. Oligouric phase may not occur: in this case, mortality is much lower and the recovery forecast is much more favorable.
- Postoliguric restoration of normal diuresis. In this case, the concentration of creatinine in the plasma and the level of urea can remain elevated for some time. There may be abnormalities in renal tubule function, polyuria, hypercholesteremic acidosis.
Symptoms and signs
OPP is not so much an independent disease as a stage of it or a secondary acting factor that increases the risk of death. The clinical picture of the disease is not specific and coincides with the symptoms of the underlying disease or poisoning. If the cause of OPP is sepsis, then his symptoms are observed in the patient. If the cause is poisoning, the symptoms will be characteristic of poisoning by a certain substance.
Detection of OPP, especially at an early stage, is possible only if the level of creatinine and urea in the blood is continuously monitored:
- Specific signs are observed in a stage classified as insufficiency. These symptoms are common with azotemia: nausea, vomiting, swelling of subcutaneous fat. Perhaps the development of hypervolemia - an increase in the volume of blood, accompanied by the phenomena of heart failure. In severe cases, pulmonary edema develops.
- Hyperkalemia - a frequent complication of OPP, proceeds without external signs. Its influence is often found already at the stage of tachycardia or heart failure.
- Hyponatremia is expressed more clearly: the CNS is affected, cramps and muscle tremors appear, and gastrointestinal disturbances appear.
The presence of the disease is accurately established only by diagnostic methods. And because of the coincidence of many signs with the symptoms of chronic renal failure diagnosis is always difficult.
The OPP is diagnosed if at least one of the following three factors is observed:
- increase in the level of creatinine in the blood by more than 26 μmol / l for 48 hours;
- increase in creatinine concentration in the blood 1.5 times from the baseline, which was observed or presumably was a week ago;
- urine output no more than 0.5 ml / kg / hour for 6 hours.
When diagnosing children, the level of creatinine in the blood, diuresis for 8 or 12 hours and the glomerular filtration rate is reduced by 25%.
Depending on the concentration of creatinine and the amount of diuresis, the degree of severity is refined. However, both observation and further treatment should be carried out against a background of constant monitoring of the level of creatinine, potassium, sodium and so on.
The first analyzes that are performed during the examination are blood tests:
- biochemical blood test - determined by the level of creatinine, urea, potassium, sodium, protein fractions, total and direct bilirubin and so on;
- acid-base blood state;
- arterial blood gasometry;
- general urine analysis - urine density, proteinuria, pathological components are determined: granular cylinders, erythrocyte cylinders, erythrocytes;
- additional studies if a diagnosis is required.
Urine and blood sampling for tests should be performed prior to the introduction of diuretics and fluid, otherwise the analysis data will be distorted.
Patients with diagnosed OPP or those at risk - after cardiac surgery, for example, should be under constant supervision.
- diuresis control, hourly preferred daily;
- volume of consumed and injected liquid - the first preventive measure is the restoration of the normal water balance, therefore the volume of injected and withdrawn liquid must be strictly taken into account;
- body weight - measured on an empty stomach twice a day;
- stool observation;
- pulse oximetry;
Of the instrumental methods, ultrasound is prescribed in the OPP usually increased, as well as chest radiography in order to detect stagnation, blood flow and others.
It is important to determine exactly which category the disease belongs to, since in the case of prerenal OPP the renal function will recover as soon as the normal blood supply is restored. For this, differential diagnostics is used.
For prerenal OPP are characteristic:
- diuresis - less than 400 ml per day;
- urinary osmolality - more than 500 mOsm / kg;
- density - more than 1,023 g / ml;
- urea ratio in plasma to creatinine in plasma - more than 20;
- the ratio of creatinine in urine to creatinine in the blood - more than 40;
- the ratio of urea in urine to urea in plasma is more than 20;
- concentration of sodium in urine - less than 20 mmol / l;
- urine sediment - pathologies are not observed.
For renal OPP are characterized by:
- diuresis - can be different, no exact signs;
- urine osmolality - less than 400 mOsm / kg;
- density is less than 1,012 g / ml;
- the plasma urea ratio in plasma to creatinine in plasma is less than 20;
- the ratio of creatinine in urine to creatinine in the blood is less than 40;
- the ratio of urea in urine to urea in plasma is less than 20;
- concentration of sodium in urine - more than 40 mmol / l;
- urine sediment - observed epithelial, hyaline cells, epithelial cylinders.
If the patient has had kidney disease, especially chronic renal failure, all of the above criteria will not be characteristic.
The diagnosis of postrenal OPP is somewhat simpler. The diagnosis is confirmed by stagnant phenomena in the kidneys, bladder, ureters, which is accurately determined by ultrasound.
Purpose of treatment of patients with OPP multitasking:
- elimination of metabolic and volume disorders;
- preservation or restoration of renal function;
- prevention of chronic renal failure.
Therapeutic tactics are determined by the form of the ailment, but in any case imply the complete abolition of any nephrotoxic drugs: potassium-sparing diuretics, nephrotoxic antibiotics, non-steroidal analgesics and others.
The cause of the disease is a violation in the blood supply, so the main goal of therapy here is the restoration of normal blood supply to the body. To do this, the body must enter a sufficient amount of fluid to make up for the lost volume of blood. Several methods of substitution therapy are used for this.
Liquid is injected through a dropper. Its composition is determined by the composition of the withdrawn liquid. So, with hypervolemia against a background of unstable hemodynamics, a solution with erythrocyte mass is injected. If the hemodynamics is stable, then a normal physiological solution is sufficient. The level of creatinine and urea in the blood and urine in a patient is controlled at least 1 p per knock. On the basis of these data, the composition of the solutions varies.
Hemodialysis - appointed 1 r per day or 2 days in the absence of effect or in case of emergency. . Hemofiltration and hemodiafiltration is performed. The latter are used less often, since they take from 12 to 36 hours.
The basis of treatment is conservative therapy. But in acute cases, appoint emergency hemodialysis. Indications for the procedure are as follows:
- laboratory confirmation of kidney dysfunction - glomerular filtration rate below 20-25 ml / min;
- violation of the concentration of sodium in the blood - either less than 115, or more than 165 mmol / l;
- the urea content in the blood is more than 25-36 mmol / l;
- pericarditis - tamponade or a high risk of bleeding;
- hyperkalemia with ineffective drugs;
- metabolic acidosis in the background of oliguria;
- is a progressing fluid overload.
The main component of the treatment of prerenal OPP is the treatment of the underlying disease. Actually this is for children and adults. Drugs are prescribed taking into account this ailment, therefore, there are no general recommendations on this matter. Preparations are introduced taking into account the parameters of potassium, calcium, sodium, phosphate and so on in order to restore and maintain the electrolytic balance.
Thus, with hyperkalemia, glucose and insulin are administered in the required ratio, calcium chloride intravenously, sodium hydrogen carbonate in decompensated acidosis and so on. With a sharp drop in the potassium level - less than 7 mmol / l, inject furosemide, if there is no hypovolemia or renal obstruction. Pi hyperhydration and pulmonary edema also introduce furosemide.
To date, there is no effective therapy for renal OPP.General recommendations are similar to the methods used in the treatment of prerenal form - support of electrolyte balance, replenishment of fluid volume, if hypovolemia is observed, and the elimination of nephrotoxic drugs.
Several drugs are used to restore renal function.
However, the effect is not as significant as expected, especially with acute tubular necrosis of ischemic or nephrotic origin:
- The main task of most methods is to transfer the patient from the oliguria stage to neoligouric, as this reduces mortality. To do this, appoint furosemide - a loop diuretic in doses not more than 600 mg / day. At the same time, low doses are ineffective. As a rule, furosemide is administered intravenously, very slowly. As modern studies show, the diuretic does not have a therapeutic effect, but only restores diuresis.
- Dopamine - used quite actively, but for severe patients it is potentially toxic, causes tachycardia, myocardial ischemia.
- Atrial natriuretic peptide - increases the glomerular filtration rate, slows the reabsorption of sodium. However, its synthetic analogue does not exert such influence.
- Dialysis therapy does not affect the duration of the disease and the rate of recovery. Today dialysis is a means of supporting and restoring the electrolytic balance.
- In the treatment, supportive therapy is of great importance, that is, dietary restrictions that prevent the ingestion of certain substances and the introduction of the missing substances by artificial means.
No one of the modern approaches provides a stable favorable influence.
The aim of treatment in this case is to eliminate as quickly as possible the violations in the outflow of urine in order to minimize damage to the kidney.
Methods depend on the level of obstruction:
- If the outflow is disturbed at the level of the neck of the bladder or urethra, then a transurethral catheter is sufficient.
- If the level of disturbances is higher, then nephrostomy is required - the introduction into the kidney of an artificial drainage system.
As a rule, these measures will help to prevent violations in the kidney and lead to a complete restoration of its function.
children Significantly, treatment of OPP in young children does not differ from the therapeutic methods applied to adults.
In the first place is support and replenishment of intravascular volume. Infusion program is the safest, trouble-free reception and in many cases allows to precede the transition of prerenal OPP to tubular necrosis.
For patients with acute decrease in blood volume this may not be enough:
- The use of diuretics for treatment for today is not considered an effective technique. However, the drugs are used, are appointed, if necessary, to maintain or restore diuresis.
- In case of oligo / anuric insufficiency or OTN, it is not recommended to prescribe potassium or sodium preparations if the patients have not had hypokalemia or hypophosphatemia. With polyuria, the replenishment of substances is necessary.
- Hyperkalemia requires urgent therapy - the administration of calcium gluconate, sodium hydrogen carbonate, the use of sorbents and so on.
- If the medication methods are not valid, hemodialysis and peritoneal dialysis are included in the course.
Consequences and predictions of
OPP is considered as a factor increasing lethality with all other conditions being equal. A relatively favorable prognosis is prerenal and postrenal, since in these cases, damage to the kidney tissue can be prevented. In the case of renal OPP, mortality is 50-70%.In elderly patients, with cardiac or respiratory failure, lethality reaches 80%.
Surviving patients need long-term follow-up and recovery. More than 50% develop chronic renal failure. About 5% of patients need constant dialysis. Statistics of this kind are incomplete and distorted by improper diagnosis and lack of modern equipment.
Children have better statistics. The average survival rate is 79.9%, of which a full recovery can be achieved in 58%.39% of patients develop chronic renal failure.
The prognosis of the disease in newborns is unfavorable. Without dialysis, mortality in this group is 80%.
Acute kidney damage is a serious, but potentially reversible, disease. As a rule, the ailment accompanies the underlying illness and greatly complicates the treatment.
Video lecture on acute renal damage: