Anuria is a pathological condition in which the amount of urine excreted is less than 50 ml per day. It is detected in acute renal failure of various genesis, at the final stage of CRF, with severe cardiovascular and multiple organ failure, various shock conditions, renal vascular thrombosis, urolithiasis. The cause of anuria is established on the basis of anamnesis, physical examination data, hardware and laboratory techniques. Treatment includes infusion therapy, extracorporeal detoxification, medications, surgical methods.
Anuria is a severe pathological condition, requires emergency medical measures, and in the absence of correction becomes the cause of death. Depending on the etiology , the following variants of anuria are distinguished:
- Arenal. A rare form. It is observed in the absence of kidneys in newborns, after bilateral nephrectomy or removal of the only functioning kidney in people of other ages.
- Prerenal. It is caused by a violation or cessation of blood circulation in the kidneys due to a critical decrease in blood pressure or overlap of the vascular lumen.
- Renal. It occurs due to damage to the renal parenchyma in severe nephrological diseases, taking nephrogenic poisons and some other conditions.
- Postrenal. Urine is formed, but cannot enter the bladder due to blockage of the ureter by a stone, tumor or inflammatory infiltrate.
- Reflex. It is caused by a malfunction of the nervous regulation of the process of urination against the background of various adverse influences, for example, hypothermia or rough instrumental manipulations.
Сauses of anuria
Prerenal anuria is observed. The condition develops with acute right ventricular failure, usually caused by pulmonary embolism. Against the background of stagnation in the large circle of blood circulation, edema, shortness of breath, pain in the heart and right hypochondrium occur. Anuria also accompanies the final stage of chronic cardiovascular insufficiency, which has developed as a result of heart defects, arterial hypertension, emphysema, pneumosclerosis, cardiomyopathies, myocarditis and other pathologies.
Multiple organ failure is formed in patients with peritonitis, sepsis, infectious and toxic shock, severe polytrauma. It is manifested by shortness of breath, cyanosis, edema, hemodynamic disorders, liver dysfunction, abdominal pain. Psychomotor agitation is replaced by depression of consciousness, tachycardia – bradycardia. The amount of urine decreases, anuria develops with severe course in the decompensation phase.
One of the characteristic signs of any shock is a drop in blood pressure. With a decrease in systolic blood pressure to 40-50 mm and below, the blood supply to the kidneys is sharply disrupted, which entails the formation of prerenal oliguria first, and then anuria. The symptom is observed in severe course, it is detected in the following conditions:
- Septic shock. It is provoked by extensive purulent processes (abscesses, phlegmons), festering wounds and open fractures. It may occur against the background of taking immunosuppressants and prolonged stay in the intensive care unit. It is accompanied by febrile fever, convulsions, respiratory failure, enlargement of the liver and spleen.
- Cardiogenic shock. It is diagnosed with extensive heart attacks, severe myocarditis, cardiac tamponade, massive PE, poisoning with cardiotoxic poisons. Initially, cardiac pain prevails, then respiratory failure, pulmonary edema, tachycardia, severe hypotension are added. A decrease in diuresis or the absence of urine is supplemented by impaired consciousness, the development of sopor or coma.
- Traumatic shock. It is more often formed with severe injuries. It may be the result of extensive operations. At first, the victim is excited, scared, anxious, complains of pain. Then he becomes sleepy, sluggish. With further deterioration of the condition, convulsions and disturbances of consciousness are noted. Symptoms of intoxication include nausea, vomiting, darkening of urine, oliguria and anuria.
- Hypovolemic shock. It is found in external and internal traumatic and non-traumatic bleeding, extensive burns, plasma accumulation in the abdominal cavity with pancreatitis and peritonitis, fluid loss in severe intestinal infections. Tachycardia, hypotension, pallor, impaired consciousness, a decrease in the amount of urine up to anuria are observed.
- Burn shock. Anuria or pronounced oliguria is characteristic of an extremely severe shock condition that occurs with deep burns of more than 40% of the body area. They are developing already at the initial stage. Urine is black or dark brown. There are disorders of thermoregulation, confusion, nausea, repeated vomiting, intestinal paresis.
Another provoking factor of prerenal anuria is blockage of blood flow in the vessels of the kidneys. The symptom is more often observed with bilateral renal vein thrombosis, sometimes with reflex termination of the activity of the second kidney against the background of unilateral occlusion. Sharp pain in the lower back, blood in the urine, a decrease in urination up to anuria, weakness, nausea, vomiting are typical. Another possible reason for the cessation of blood circulation is the compression of blood vessels by tumors, scars and inflammatory infiltrates.
Chronic renal failure
Renal anuria is detected at the final stage of CRF. The causes of renal dysfunction are:
- chronic glomerulonephritis;
- chronic pyelonephritis;
- hereditary nephritis;
- diabetic glomerulosclerosis;
- bilateral tuberculosis of the kidneys.
Signs of the terminal stage of CRF are thirst, the smell of ammonia from the mouth, weight loss, itching, grayish-yellow skin tone, decreased muscle tone, muscle twitching. Anuria is combined with increasing anemia, hemorrhagic syndrome, ascites, pulmonary edema.
Acute renal failure
In case of hemotransfusion shock, transfused erythrocytes are destroyed, forming unbound hemoglobin, which damages the kidney tissue. There is anxiety, agitation, cyanosis, pallor or marbling of the skin with redness of the face, tachycardia, shortness of breath, lower back pain. In the future, an imaginary improvement is possible, which is replaced by swelling and jaundice of the skin. Hematuria, oliguria, or anuria indicate the development of ARF.
The syndrome of prolonged crushing is formed in victims of earthquakes, building collapses, industrial accidents. A type of pathology is the syndrome of positional compression, which occurs when sleeping in a non-physiological position after taking alcohol or drugs. After the compression is eliminated, the condition improves briefly, and then worsens again. Oliguria is observed, urine is the color of meat slops, in severe cases anuria develops. Possible endotoxic shock, multiple organ failure.
Toxic nephropathy is formed when nephrotoxic (heavy metal salts, phenol, gasoline, ethylene glycol, fungal toxins) or hemolytic (copper sulfate, acetic acid, snake venom) substances enter the body. Anuria is detected in severe pathology, may be accompanied by a uremic coma.
Blockage of the ureter
Postrenal anuria is potentiated by bilateral concretions in the ureters with UTS, less often by reflex termination of the second kidney when one ureter is blocked. Patients complain of extremely intense pain in the lumbar region, sometimes with irradiation in the groin. Patients are restless, rushing. With a bilateral lesion and the absence of timely assistance, the development of acute kidney injury is possible. In addition, the ureter can be squeezed from the outside by scars, tumors or inflammatory foci.
The occurrence of reflex anuria may be due to hypothermia. With a moderate lesion, disorders of nervous regulation are aggravated by a decrease in renal blood flow. In severe hypothermia, neurogenic and vascular disorders are supplemented by the development of acute respiratory failure. Sometimes the refractory type of anuria is caused by rough therapeutic and diagnostic manipulations in the urinary tract, for example, cystoscopy or urethral augmentation.
Determining the cause of the symptom is the responsibility of a nephrologist or urologist. Anuria accompanies severe conditions, which are often associated with complex disorders of the body’s functions and pose a danger to life, therefore, resuscitators are involved in examination and treatment. Establish the time of the appearance of the symptom, previous disorders, predisposing factors. Conduct an external inspection. The examination program includes the following procedures:
- Sonography. Ultrasound of the kidneys and ureters makes it possible to confirm changes in the renal parenchyma, to identify concretions. During the ultrasound of renal vessels, hemodynamic disorders are determined. Patients with UTS undergo ultrasound of the bladder to detect stones in the lower urinary tract.
- Radiation methods. During the review urography, X-ray positive stones are viewed. In toxic nephropathy and UTS, kidney CT is informative, allowing to visualize even minor changes in renal tissue, to clarify the location, type and size of concretions. CT phlebography is recommended, if necessary, to establish the position of the thrombus, it is prescribed with caution due to the toxicity of contrast agents.
- Heart research. Patients with cardiogenic shock, cardiovascular and multiple organ failure need electrocardiography. According to echocardiography, the pumping function of the myocardium is evaluated. During MRI of the heart, defects, coronary heart disease and other cardiac pathologies are diagnosed.
- Laboratory tests. Due to the impossibility or difficulties in obtaining urine, the leading role is played by biochemical blood parameters indicating the severity of renal dysfunction (creatinine, urea, electrolytes). In case of organ failure, an extended laboratory examination is carried out with the determination of ABB, glucose, hemoglobin, liver samples, etc.
- Other studies. The list of instrumental techniques depends on the type of pathology. In case of traumatic shock, radiography of fractures is performed, if internal bleeding is suspected, endoscopic techniques are used: laparoscopy, gastroscopy, colonoscopy. Due to the severe condition of the patient, the possibilities of examination may be limited.
Therapeutic tactics are determined by the nature of the pathology that provoked anuria:
- Organ failure. In case of heart failure, cardiac glycosides, nitrates, vasodilators, diuretics, anticoagulants, beta-blockers are used. Patients with multiple organ failure require plasma transfusions, infusion therapy, antibiotics, steroid hormones.
- Shock states. Therapeutic measures include the impact on the cause of shock and normalization of vital signs. Hemotransfusion, transfusion of colloidal and crystalloid solutions are carried out. Oxygenation is used, according to the indications, a ventilator is carried out. The effect on these factors includes analgesia of fractures, the appointment of narcotic analgesics, nitrates, cardiotonics, steroids, antiarrhythmic agents.
- Kidney failure. A special diet is needed. At certain stages, stimulation of diuresis with the help of diuretics is indicated. Extracorporeal detoxification methods are widely used: plasmapheresis, hemosorption, hemofiltration, peritoneal dialysis, periodic hemodialysis at the late stage of CRF. Similar measures are recommended for toxic nephropathy.
- Urolithiasis. If there is a tendency to self-discharge of concretions, terpenes are prescribed. To eliminate renal colic, antispasmodics, analgesics and thermal procedures are used. In most cases, conservative methods are ineffective, surgery is required.
In pathological conditions accompanied by anuria, the following interventions are performed:
- CRF: kidney transplantation.
- Urolithiasis: ureterolithoextraction, ureterolithotomy, remote and contact ureterolithotripsy.
- Cardiogenic shock: balloon angioplasty, artificial ventricle, intra-aortic balloon counterpulsation.
- Hypovolemic shock: surgical removal of the source of bleeding (vascular ligation, stitching of stomach ulcers, suturing of liver ruptures, splenectomy, etc.).
- Thrombosis of renal veins: thrombectomy, installation of a cava filter.