Artificial kidney

The artificial kidney apparatus for removal from the patient's blood toxic products of metabolism, which accumulate in severe renal disease (acute and chronic renal failure). In the basis of the device is the principle of dialysis - removal of low molecular weight substances of colloidal solutions due to the diffusion, and the difference in osmotic pressure from both sides of the semi-permeable plastic membrane. Ions of potassium, sodium, calcium, chlorine, molecules of urea, creatinine, ammonia, etc. freely penetrate through the pores of cellophane. At the same time, larger protein molecules, formed blood elements and bacteria cannot overcome a plastic barrier. There are two main types of artificial kidney: devices with a plastic tube diameter of 25-35 mm and apparatus plate with a plastic membrane. Domestic artificial kidney refers to the dialyzers plate with a plastic membrane. The scheme presented in Fig. The blood of the patient flows through the catheter using a pump in the dialysator, which is mounted on the tank, which seats 110 l dialysis solution. Passing between plastic plates dialysator, the person's blood stream through a plastic membrane contact with flowing towards the dialysis solution. After dialysator blood gets in measuring performance and forth through the filter and trap before the catheter is returned in the venous system of the patient. Flowing dialysis fluid standard and contains all the main ions in the blood (·, Na·, and others), glucose concentration, the concentration thereof in the blood of a healthy person. The solution automatically heated to a temperature of 38 degrees and saturated with Carbogen to a pH of 7.4. Clearance (coefficient of purification) of the device on the urea 140 ml/min
On metal basis of dialysator horizontal put the plate is made of organic glass. On it stack two plastic sheet that the top cover of the next plate. Thus stack 12 plates, which are fastened to the metal bolts. Through the holes plastic membrane any punching, resulting megalomania space are connected. Manometer check the tightness of the Assembly of the unit. Next is going pump dialysator that you connect the catheter enter the blood, and on the other side of the handset connected to the inlet of the dialysator. Connect the outlet of dialysator gauge performance, to the upper end of which is attached hose return of blood to the patient. After that the device is sterilized with diazepam, washed with sterile physiological solution and fill with blood or polyglucinum. Connection of the device with the patient is either arterio-venous or veno-venous way. In the first case after the exposure of the radial artery blood samples of the machine produces vascular catheter inserted into her crotch. The backward flow of blood from the device goes through the catheter inserted in superficial vein of the forearm. In the second method, the exposure of a large vein in the thigh is achieved sensing of the inferior Vena cava, from an opening which make the blood sample. Back blood in the cubital vein. For fast connection of the device and for multiple dializu impose a shunt (a prosthesis vessel) between catheterized radial artery and located near Vienna. After connecting the device in the blood flow is administered heparin to reduce blood clotting and prevention tromboobrazovania. Hemodialysis is carried out within 4-12 hours depending on the disease and the patient.
The artificial kidney cannot completely replace kidney function, especially for a long time. However many months it is possible to maintain a sufficient level of vitality. Artificial kidney in some cases is a preliminary stage of the operation to transplant kidneys.the device artificial kidney

Scheme of the Russian model of artificial kidney": 1 - catheter; 2 - pump blood; 3 - dialysator; 4 - meter performance; 5 - filter; 6 - vozdukhoplavatel; 7 - catheter return of blood to the patient; 8 - heater; 9 - the pump on cialisinuaeto fluid; 10 - tank for dialysis solution; 11 - rotameter oxygen; 12 - flowmeter for carbon dioxide; 13 - Gidroprivod perfusion pump.


The artificial kidney. In the basis of the device of artificial kidney is the principle of dialysis due to the diffusion, and the difference in osmotic pressure from both sides in a plastic plate with the properties of a semi-permeable membrane. Small molecules, ions Mg··, K·, Na·, Da·, Cl·HCO3 and simple organic compounds, as urea, creatinine, phenol and derivatives, freely penetrate through the pores of cellophane. At the same time, the protein molecules, formed blood elements on the one hand and possible bacteria on the other can not overcome a plastic barrier.
Among the many models of artificial kidney is possible to distinguish two main types: devices with a plastic membrane-shaped pipes with a diameter of 25-35 mm, and devices plate with a plastic membrane. The most widely abroad apply dvukhtochechnoi artificial kidney Kaffa-Wochinger (Fig. 1). An important advantage of this model of artificial kidney is that coils wound around plastic hoses come from the factory in sterile condition and, if necessary, can be used immediately. Easy installation and handling, significant dialysis surface (19 000 CM1) created the popularity of this model. The drawbacks of the device - large capacity by blood and significant resistance to blood flow due to the tight winding two dialysis hoses.
Therefore, at the entrance to the dialysator the pump is installed.
The Soviet model of artificial kidney designed at the Scientific research Institute of surgical instruments and tools (NIHAI), refers to the type of dialyzers with plate with a plastic membrane.
A large clinical experience of the Soviet and foreign clinicians shows high efficiency of dialysis in the treatment of patients with renal insufficiency.
However, the artificial kidney does not replace other therapeutic measures. It is one of the most important links of complex therapy. Artificial kidney cannot completely replace versatile function sick kidneys, moreover for a long time.
In the USSR artificial kidney began to apply since 1958 in the urological clinic of the 2nd MMI on the basis of the 1st City hospital. Currently, the artificial kidney is equipped with more than 50 branches clinical hospitals.
Connection of the device with patients usually carried out by two methods: arterial-venous or veno-venous. In the first case after the exposure of the arteries (usually beam) blood sampling in the device produces vascular catheter inserted into her crotch. The backward flow of blood from the unit to the patient occurs through the probe entered in any superficial vein (usually the elbow). When veno-venous method of the connection puncture or the exposure of a large vein in the thigh is achieved sensing and the blood from the inferior Vena cava. The backward flow of blood going through any vein of the forearm.
Currently spread puncture method catheterization vessels. Produce puncture femur artery and veins under papatowai ligament and the conductor is injected into the blood vessels relevant catheters that are using commuting routes connecting with the device. If in the course of treatment the patient assumes multiple use of hemodialysis, set on the forearm continuous arteriovenous shunt on Scribner (C. N. Scribner). The essence of the method is sounding on the forearm radial artery and the nearby Vienna. These probes are connected by special devices, and the blood comes from the arteries directly into a vein. To conduct dialysis change connector allows a few minutes to connect the bloodstream of a patient with artificial kidney. After dialysis shunt newly restored with the help of the semi-circular connector.
Artificial hemophilia carry out periodic introduction of heparin (2 mg/kg). After haemodialysis the effect of heparin in the patient's blood neutralize the introduction of the solution of proteins.what. All parts of the apparatus in contact with patient's blood should be siliconiran and sterilized.
The scheme of the Soviet model of artificial kidney presented in Fig. 2. The blood of the patient flows through the catheter (1) by means of a pump (2) in the dialysator (3). Passing between plastic plates the last (for each of its 11 sections), the person's blood stream through a plastic plate in contact with flowing towards the dialysis solution. Its composition is usually standard and contains all the main ions in the blood (·, Na·, CA··, Mg·, Cl·HCO3) and glucose concentrations required for correction of electrolyte composition of the blood of the patient. After dialysator supply blood to the measuring performance (4)where the trapped blood clots and air. Then the blood in the catheter is returned in the venous system of the patient. Dialysis solution with an automatic heater (8) brought to a temperature of 38 degrees and saturate the Carbogen so that his pH was 7.4. Using the pump (9) dialysis solution is served in the dialysator. The speed of blood flow in the dialysator usually equal to 250-300 ml/min ground Clearance of the device is the urea 140 ml/min
Currently constructed a new model of artificial kidney (Fig. 3). The main principle of its work is the same. The device has two independent sections with an area of dialysis surface 8000 cm2 each, with two separate pumps; it is equipped with a special device for regional heparinisation and more convenient for the treatment of patients with chronic renal insufficiency due to the possibility of reducing the area dialysis surface.
The most effective and convenient for clinical use are those models of artificial kidneys, which satisfy the following basic requirements: high intensity dialysis blood, simple and safe handling unit and a small amount of blood. This apparatus NIIHAU (USSR), Kaffa - Wochinger (USA) and Galotti (Italy). They are especially good in the treatment of patients with acute renal failure. In chronic renal failure the most convenient devices believe upgraded model Kaffa and double-vane artificial kidney system of Kiel. The Cadena (W. Kaden, GDR) proposed an original model of artificial kidney treatment for chronic renal failure. An important advantage is portability and low cost.
Application chronic hemodialysis in modern conditions is an important task. According to the III International Congress of nephrologists, in some countries (the USA), 100 million people annually require chronic hemodialysis up to 50 thousand patients with chronic renal insufficiency of various etiology. By applying artificial kidney patient with chronic renal failure twice a week, you can save on subnormal numbers level azotemii, the normal vodno-elektrolitnogo balance and satisfactory General condition of the patient. Thus, the life of patients in the terminal stage of chronic renal failure may be renewed for many months and even years. Artificial kidney begin to apply at home, but only in rare cases. Multiple re-hemodialysis patients with chronic renal insufficiency is associated with a number of significant challenges and complications. To them in the first place is the thrombosis of arteriovenous shunts. Application teflonovou-selectimage material allowed to prolong the life of the shunt to 6-9 months. Some patients suffer often hard place peripheral nephropathy. Disturbed metabolism of calcium, which is manifested metastatic calcification and osteoporosis. Anemia requires constant blood transfusions. Frequent complications, intermittently, infection and hypertension. Testicular atrophy (men) and amenorrhea (women) are quite ordinary phenomena. Finally, in the course of repeated hemodialysis can develop hypercalcemia, severe anaemia, septicaemia, pyrogenic reactions.
A more appropriate to apply chronic hemodialysis patients true in the terminal stage of chronic renal insufficiency, given the possible during treatment Homo - and watertransportation kidneys.
In patients with acute renal failure, hemodialysis allows for several hours to achieve significant clinical effect due to release the body of nitrogen products, the normalization vodno-elektrolitnogo balance, the elimination of acidosis. This can sometimes be a temporary effect allows the body to enhance regenerative processes in the kidneys and liver, contributing to the restoration of their functions. Therefore, when most of the causative form of acute renal failure shows the use of the artificial kidney. They include such a condition in which the kidney is often deeply disturbed: the collapse of peripheral circulation due to heavy operations, injuries, bleeding postabortne infection, incompatible blood poisoning nephrotoxic poisons, acute americas.com glomerulonephritis, occlusion of the urinary tract. In chronic kidney disease in the acute stage repeatedly applied hemodialysis can significantly improve kidney function.
Important in the determination of indications for dialysis takes into account the condition of nervous system, respiratory organs, cardiovascular system and functional status of the liver.
The use of artificial kidney patients in a state of uremic coma should be seen as a later event, and, of course, the success of treatment is not always positive.
Among biochemical disorders leading indication for hemodialysis is
hyperazotemia when the residual nitrogen in the blood serum is 150-200 mg% (the urea 350-400 mg%), the content of creatinine 12-15 mg%. The increase in potassium in the blood serum of up to 7 mEq/l and above, the reduction of alkaline reserve up to 10 mEq/l in combination with other water-electrolyte disorders are the indications for urgent hemodialysis.
Among patients with acute renal failure in a 35-45% of the disease is not too hard. Despite anuria, azotemii and other disorders, treatment of these patients can be performed without the use of hemodialysis.
Among contraindications consider the decompensation of the cardiovascular system, liver failure, active septic process in the body in the phase intermittently bakterioliticescoe shock. Fresh focus bleeding is not considered an absolute contraindication to the Hepatology. The application with the help of special equipment regional (artificial kidney) heparinisation allows to avoid the intensification of bleeding.
The use of artificial kidney on the strict condition with all due precautions and with careful monitoring of patients during dialysis and after it is almost safe and will not face any difficulties.

Fig.1. Diagram of kidney Kaffa-Wochinger connected with patients: 1 - filter by blood; 2 - pump blood; 3 - dialysator; 4 - dialysis solution; and - artery, v - Vienna.
Fig. 2. The scheme of the Soviet model of the apparatus "artificial kidney": 1 - catheter; 2 - pump blood; 3 - dialysator; 4 - meter performance; 5 - vozdukhoplavatel; 6 - filter; 7 - catheter return of blood to the patient; 8 - heater; 9 - the pump on dialysis fluid; 10 - tank for dialysis solution; 11 - rotameter oxygen; 12 - flowmeter for carbon dioxide; 13 - hydraulic drive perfusion pump.
Fig. 3. General view of the new model of the Soviet apparatus "artificial kidney" design NIIHAU.