The contrast-induced nephropathy
The contrast-induced nephropathy — sharp renal dysfunction which arises within 1-3 days after introduction of X-ray contrast agent leads to increase in level of serumal creatinine at least on 26,5 µmol/l (25%) and more in comparison with initial level. Usually proceeds asymptomatically. In hard cases it is shown by an oliguriya, renal hypostases, weakness, drowsiness, appetite loss, nausea. It is diagnosed on the basis of data on dynamics of concentration of creatinine and potassium in serum of blood, results of the general analysis of urine, biochemistry of blood, kidney tests. For treatment inject infusional alkalizing drugs, carry out pochechnozameshchayushchy therapy.
The contrast-induced nephropathy
The contrast-induced nephropathy option at patients with normal function of kidneys meets no more than in 0,5-5% of cases of carrying out researches application of iodinated X-ray contrast means. The probability of development of frustration significantly increases with risk factors. So, by results of clinical observations in the field of urology, after carrying out KT of various bodies, a peripheral and kardialny angiography renal dysfunction of this or that degree was shown at 50-90% of patients with diabetic defeat of a kidney parenchyma. Taking into account growth of popularity of a computer tomography and other modern methods of x-ray researches relevance of timely detection of risk factors and prevention of sharp renal dysfunction which is possible when using contrast means on the basis of iodine increases.
The reasons contrast - the induced nephropathy
Sharp yatrogenny damage of kidneys is connected with introduction of iodinated X-ray contrast substance. The greatest nefrotoksichnost is shown by vysokoosmolyarny medicines with a high density and concentration of iodine. Experts in the sphere of nephrology allocate five key factors causing toxic damage of various elements of renal fabric at contrast introduction:
- Increase in osmolarity in kidney tubules. Iodinated contrast connections it is well filtered by nefrona and is not exposed to a reabsorption because of what urine becomes more concentrated. Increase in viscosity makes the direct damaging impact on epiteliotsita of tubules.
- Violation of kidney haemo dynamics. The contrast-induced expansion and the subsequent spazmirovaniye of renalny arteries influences intensity of a blood-groove in the microvascular course. After temporary rush of blood intensity of renalny blood supply sharply falls, in fabrics there is ischemia.
- Release of active forms of oxygen. After restoration of an adequate blood-groove in ischemic fabrics the reperfusion "oxygen paradox" develops. Because of sharp activation of perekisny oxidation of lipids free radicals of oxygen which toxic influence cellular membranes are formed.
- Inflammatory reaction. In response to introduction of iodinated medicine in various bodies, including kidneys, there is a contrast - the mediated activation of a complement and emission of tsitokin. As a result toxic damages of a parenchyma can be aggravated with action of mediators of an inflammation.
- Tubulyarny obstruction. Pretsipitation of vnutrikanaltsevy proteins induced by X-ray contrast substance breaks an intra kidney passage of urine. Owing to obstruction of tubules the urine reabsorption is broken, and the mediated influence on nefrona worsens processes of a filtration.
The probability of emergence contrast - the induced nephropathy increases at patients, is long also other chronic diseases of the kidneys, HPN which transferred transplantation of a kidney having pyelonephritis, glomerulonefrity, amiloidozy, a gouty nephropathy, polikistozy. Patients with the heavy accompanying pathology — arterial hypertension, diabetes of the 2nd type, cirrhosis, cardiological diseases with stagnant heart failure, decrease in fraction of emission of the left ventricle to 35% and less, a multiple myeloma enter into risk group.
Age more than 75 years are also considered as the contributing factors, the proteinuria, the content of serumal creatinine is higher than 1,5 mg/dl, reception of diuretics, APF inhibitors, nefrotoksichny medicines (NPVS, aminoglycosides, sulfanylamides, immunosupressor, salts of lithium, antineoplastic medicines). Frustration develops in the presence of the pathological states aggravating a fabric hypoxia more often — persistent hypotension, anemia, blood loss, dehydration, a sharp myocardial infarction, cardiogenic shock. Direct dependence between probability of emergence of the induced nephropathy and volume of the entered contrast is established.
The mechanism contrast - the induced renalny dysfunction is based on the combined manifestation of ischemic and toxic effects. Local violation of haemo dynamics becomes the starting moment in development of pathological process. Under the influence of X-ray contrast connections angiotensin II, antidiuretic hormone, dopamine 1, adenosine, , causing a renalny vazokonstriktion are activated. At the same time activity of prostaglandins and an oxide of nitrogen having vazodilatiruyushchy effect decreases. As a result of a long spasm of arteries and in a brain layer, the most susceptible to action of a hypoxia, there is ischemia.
High viscosity of x-ray contrast exponentiates aggregation of erythrocytes and delay of the kidney blood-groove aggravating ischemia and reducing the speed of a glomerular filtration. Increase of a medullary hypoxia is also promoted by compensatory shunting of blood in a cortical layer. Owing to direct toxic effect of contrast substance on kidney epiteliotsita there is a vakuolization of cages, cellular membranes are damaged, there is mitochondrial dysfunction that finally leads to an interstitsialny inflammation, a necrosis of fabrics, apoptosis with violation of kidney functions.
Symptoms contrast - the induced nephropathy
Pathology develops within the first days after intra vascular introduction of X-ray contrast substances. At most of patients the nephropathy proceeds without clinical manifestations, with change of laboratory indicators of biochemical blood tests and urine. The heavy option of a course of frustration is shown by the symptoms characteristic of the sharp renal failure (SRF): reduction of daily amount of urine up to complete cessation of its allocation, hypostases on a face. At contrast - the induced damage of kidneys there can also be violations of the general state — drowsiness, weakness, nausea, appetite loss.
When progressing a state the tubulyarny necrosis which leads to reduction of filtrational ability of body is observed. Owing to functional insolvency of kidneys the patients suffering contrast - the induced nephropathy option, can have clinical signs of violations of water and electrolytic composition of blood. Most often the giperkaliyemiya which is shown by muscular weakness, bradycardia, in adverse cases — hypostasis of lungs, violation of a warm rhythm up to cardiac arrest develops. Against the background of disorder of urination and long increase in volume of the circulating blood arterial hypertension and stagnant heart failure can develop.
About probable contrast - the induced origin of a nephropathy testifies temporary connection of renal pathology with carrying out a contrast radiological research. Diagnostic search is directed to identification of characteristic markers of frustration and assessment of a functional solvency of kidneys. The most informative methods of diagnostics are:
- Determination of content of serumal creatinine. At contrast - the induced renal dysfunction its concentration in comparison with basic data within 24-48 hours after the procedure increases for 25% or 26,5 µmol/l and more. The creatinine level peak in serum is reached for 2-5 days then within 7-10 days the indicator gradually decreases. At some patients of SK remains raised for 3 weeks.
- The analysis of concentration of potassium in blood. A characteristic laboratory symptom contrast - the induced nephropathy — a giperkaliyemiya. Increase in an indicator more than 5,1 mmol/l serves as a marker of toxic damage of tubules. Often the giperkaliyemiya is combined with decrease in pH of blood less than 7,2 (at a research of the acid and main state), signs of a gemoliz, fall of the contents of platelets, increase in concentration of bilirubin.
In the general analysis of urine at contrast - the induced renalny dysfunctions the proteinuria, a tsilindruriya, an eritrotsituriya, a leykotsituriya often come to light. At a heavy current of a nephropathy laboratory symptoms of uraemia are noted. Disorder of filtrational function of balls is demonstrated by increase in levels of nitrogen of urea, uric acid, change of serumal concentration of calcium, sodium, inorganic phosphorus in biochemical blood test with violation of the corresponding indicators in a nephrological complex. Reduction of speed of a glomerular filtration of creatinine in Reberg's test is defined. The tool methods of inspection assuming introduction of x-ray contrast are forbidden. Results of ultrasonography of kidneys are often not specific. Changes on the ECGs confirming violation of conductivity owing to a giperkaliyemiya are characteristic.
The contrast-induced form of a nephropathy is differentiated with a kidney ateroemboliya, fast-progressing glomerulonefrity, chronic pyelonephritis, gouty interstitsialny nephrite, OPN of a prerenalny, renalny, postrenalny origin, nephrological pathology at system diseases of connecting fabric, an amiloidoza, a berillioza, a sarkoidoza. According to indications except the urologist or the nephrologist of the patient the therapist, the cardiologist, the pulmonologist, the rheumatologist, the intensivist, the toxicologist, the oncologist, advises.
Treatment contrast - the induced nephropathy
Tactics of maintaining patients with damage of a kidney parenchyma by X-ray contrast substances is similar to the therapeutic scheme at OPN. Patients about contrast - the induced form of a nephropathy are hospitalized in an urological hospital or chamber of intensive therapy of reanimatologichesky office. The first days the bed rest with the subsequent transfer to the general ward is shown. In a diet at the sufficient caloric content of food limit reception of table salt and liquid taking into account diuresis volume. At emergence and increase of renal hypostases reduce quantity of proteinaceous products. A main objective of treatment is correction of metabolic violations. Taking into account given about the filtering function of nefron can be recommended:
- Infusional alkalizing therapy. For correction of fabric and system effects of metabolic acidosis, a giperkaliyemiya intravenously inject calcium drugs, glucose with insulin, sodium bicarbonate. Infusional therapy is supplemented with oral administration or rectal introduction of helatny forms of calcium under control of level of potassium every 2-4 hour.
- Replacement kidney therapy. At considerable decrease in a diuresis, increase of laboratory and clinical symptoms of a renal failure transfer of the patient to ZPT is considered. Taking into account a condition of the patient and technical capabilities of medical institution appoint a hemodialysis, a haemo filtration, hemodiafiltration, peritonealny dialysis.
Forecast and prevention
At patients who have no diseases of kidneys in the anamnesis, normalization of work of body within several days without any treatment is usually noted. In other cases the forecast also usually favorable. For prevention contrast - the induced nephropathy needs to limit carrying out researches with introduction of x-ray contrast if for diagnostics it is possible to use other methods. At assessment of probability of renalny dysfunction use the verified scales and stratification tables. Introduction of izoosmolyarny not ionic contrast substances in the minimum doses is recommended to patients from risk group. For the purpose of improvement of elimination of medicines preliminary hydration therapy with injection of physiological solution before and after the procedure is carried out. For the prevention of development of a nephropathy a day before the research it can be appointed in addition .