Hemodialysis is a blood purification procedure for patients whose kidneys cannot cope with this function. A fistula is a natural or artificially created fistula, that is, a channel that connects any body cavities or a cavity with the external environment. An arteriovenous fistula for hemodialysis is an artificial fistula required to access the blood system. The essence of the operation is that the artery is connected directly to the vein, due to which the vessel thickens, and it becomes easier to connect it to a blood purification apparatus (“artificial kidney”).

Indications for surgery

The most common indication for hemodialysis is chronic renal failure. It is also necessary for poisoning with toxins or poisons. In a healthy person, the kidneys act as a kind of filter, control the amount of water in the body and cleanse the blood of toxins. In 5 minutes, absolutely all the blood that circulates through the vascular bed passes through the kidneys. During the day, the kidneys manage to filter more than 180 liters of blood, while toxins are excreted in the urine.

In chronic renal failure, the blood must be filtered artificially, since the patient's body cannot cope with this task. For this purpose, special devices have been developed. In chronic dialysis, that is, the patient is regularly connected to the device, it is necessary to have constant access to the vascular bed. To do this, simple operations are carried out to create a fistula, which will allow you to get the maximum amount of blood for cleaning.

Operation technique

Before surgery, the patient must undergo a complete medical examination. Doctors pay attention not only to the condition of the kidneys and urinary system, but also take blood for analysis, examine the heart and blood vessels. The fistula for hemodialysis is located on the forearm, and the operation itself takes place in several stages.

1. The procedure is performed under local anesthesia. After that, the place of operational access is disinfected.
2. Next, a skin incision is made on the forearm, the artery is exposed, ligated, and all of its lateral branches are blocked.
3. The surgeon then works with the vein at a distance of 4-5 cm from the artery. With it you need to do the same manipulations as with the artery.
4. Next, these two vessels need to be sewn together. To do this, a small longitudinal incision (2-2.5 cm) is made so that a seam can be applied to the edges of the vessels.
5. At the end of the operation, the wound is stitched in layers, covered with a bandage.

After the procedure, it will take time for the fistula to form. In the first week, the patient must be in the hospital so that doctors can constantly monitor him. The discharge usually occurs on the 7-10th day, but even after that the patient comes to the hospital for examination. Hemodialysis using a fistula can be performed no earlier than one month after surgery.

Postoperative care

A mature arteriovenous fistula looks like an abscess on the forearm. With proper handling, it can last for many years and even decades without complications. To do this, the patient needs to get used to it and follow some instructions:

• do not squeeze the hand on which the fistula is located (do not sleep on it, do not wear jewelry or clothes with tight sleeves);
• exclude physical activity (you can use your hand in everyday life, but sports will be contraindicated);
• do not measure pressure on this arm;
• listen to the noise ─ it must be constantly the same;
• if possible, do not provoke jumps in blood pressure.

You need to understand that with any pathologies you need to consult a doctor. If the nature of the blood murmur in the fistula has changed or the bleeding does not stop for a long time after dialysis, the patient should be examined. An increase in local temperature should also be a cause for concern ─ this fact indicates the presence of inflammation. This situation can occur if you do not follow hygiene, especially after dialysis.

The patient must constantly bring his hand to his ear and listen to the noise. It should be long, constant and rhythmic. This sound resembles the work of mechanisms and is formed when blood moves through the veins. Any disturbance of this sound is a reason to see a doctor. A decrease in hearing or a complete absence of sounds indicates the formation of blood clots, which must be removed surgically.

At first, many patients are afraid to touch the fistula and use their hand, but then they get used to a new way of life. It is possible and necessary to touch it ─ this is the only way to feel the movement of blood through the connected vessels and control the local temperature.

Do not be afraid that light household loads will be harmful. On the contrary, moderate movements will prevent blood stasis and keep the fistula in working order for a long time.

Advantages of arteriovenous fistula over other methods

An arteriovenous fistula is not the only way to gain access to the vascular bed for hemodialysis. Artificial fistulas, subclavian or femoral catheters are also used. There is also a method of peritoneal dialysis, which does not require access to the vessels. Sterile fluid is poured through a special catheter tube directly into the abdominal cavity, and in this case the peritoneum acts as a filter. Then the solution is drained.

However, an arteriovenous fistula is considered the best option for the patient and, if there are several options, it is chosen. There are several reasons for this:

• To create a fistula, the patient's own tissues are taken, which cannot cause rejection or allergies, unlike artificial materials.
• The fistula is located just under the skin and is easy to use to gain access to the blood.
• The risk of infection, as well as the formation of blood clots, is minimal with this method.
• The same fistula can last for many years if properly cared for.

The result of treatment depends not only on the implementation of hemodialysis, but also on the responsibility of the patient. Arteriovenous fistula is one of the most benign and affordable options for chronic renal failure. Compared to other blood purification methods and kidney transplant surgery, this procedure is the safest.

Disadvantages and possible complications

Unfortunately, this method is not suitable for all patients. If the patient has low blood pressure or anemia, a fistula may not form after the vessels are sutured. In this case, it will be impossible to access the vessel through a non-working fistula. Among the shortcomings, one can also single out the duration of the maturation of the fistula. The first hemodialysis can be performed only one month after the operation.

Complications occur in rare cases. Among them are possible:

• the formation of an aneurysm (expansion of the walls of blood vessels with the risk of their rupture);
• decrease or loss of hand sensitivity;
• insufficient supply of oxygen to the myocardium;
• compression of the carpal (carpal) nerve, due to which the hand may function worse.

Complications appear in isolated cases. It must be understood that chronic renal failure is a disease with which the patient will have to fight all his life. In this case, a person needs to get used to a new lifestyle, constant procedures, prohibitions and diet. The hemodialysis fistula allows for regular blood purification without much danger to the body.

Vascular access is the way of life for hemodialysis patients. Vascular access enables life-saving hemodialysis treatment. Hemodialysis is a treatment for kidney failure in which a machine sends the patient's blood through a filter called a dialyzer outside the body. Access is a vein operation done to remove and restore blood during hemodialysis.

Blood flows through the needles, several ounces at a time. The blood then moves through a tube that delivers it to the dialyzer. Inside the dialyzer, blood flows through fine fibers that filter out waste and excess fluid. The machine returns the blood filtered to the body through another tube. Vascular access allows a large amount of continuous blood flow during a hemodialysis procedure to filter out as much blood as possible for each procedure. About 500 ml of blood passes through the machine every minute. Vascular access should be made several weeks or months before the first hemodialysis session.

Two types of vascular access designed for long-term use include arteriovenous (AV) fistula and AV graft. The third type of vascular access is a catheter vein for short-term use.

What is an arteriovenous fistula?

An AV fistula is a connection made by a vascular surgeon from an artery to a vein. Arteries carry blood from the heart to the body, while veins carry blood from the body back to the heart. Vascular surgeons specialize in vascular surgery. The surgeon usually places an AV fistula in the arm or forearm. An AV fistula causes extra pressure and extra blood to flow into the vein so it gets bigger and stronger. Large veins provide easy and reliable access to blood vessels. Without such access, regular hemodialysis sessions will not be possible. Unregulated veins cannot withstand multiple needle insertions. The veins will be damaged like broken straw due to the strong suction force.

• provide good blood flow for dialysis
• last longer than other types of access
• less chance of infection or blood clots than other types of access

Before an AV fistula operation, the surgeon may do a blood smear test. Vascular mapping uses Doppler ultrasound to evaluate blood vessels, which surgeons can use to create AV fistulas. An ultrasound uses a device called a transducer that reflects sound waves into an organ to create an image of the organ's structure. A trained technician specifically performs procedures in a healthcare provider's office, outpatient center, or hospital. A radiologist who specializes in interpreting medical images. The patient is not anesthetized. Doppler ultrasound shows how much and how fast blood is flowing through arteries and veins so surgeons can select the best blood vessels to use.

A surgeon performs an operation on a fistula in an outpatient center or hospital. Vascular access procedures may require an overnight stay in the hospital; However, many patients go home afterwards. Medical professionals use local anesthesia to numb the area where the surgeon is creating the fistula.

AV fistulas often take 2 to 3 months to form or can be used before a patient can use them for hemodialysis. If the AV fistula fails after surgery, the surgeon must repeat the procedure.

What is an arteriovenous graft?

An AV graft is a looped plastic tube that connects arteries to veins. A vascular surgeon performs an AV transplant operation, such as fistula surgery, in an outpatient center or hospital. As with AV fistula surgery, patients may need to stay in the hospital, although many patients may return home after the procedure. The healthcare professional uses local anesthesia to numb the area where the surgeon creates the AV graft.

The patient can usually use the AV graft 2 to 3 weeks after surgery. AV grafts are more likely than AV fistulas to have problems with infection and clotting. Blood clots can block blood flow through damaged sperm. However, a good transplant can take several years.

What is a venous catheter?

A venous catheter is a tube that is inserted into a vein in the neck, chest, or leg near the groin, usually only for short-term hemodialysis. The tube is divided into two tubes from the body. The two tubes have a top designed to connect to a channel that brings blood into the dialyzer and a channel that brings blood from the dialyzer back into the body. The person must close the clamp each time the catheter is connected and removed from the tube.

If kidney disease has developed rapidly, patients may not have time to place an AV fistula or AV graft before starting hemodialysis treatment.

A nephrologist, kidney doctor, or radiologist uses medical imaging equipment to perform a venous catheter surgery in a hospital or outpatient center. The patient receives local anesthesia and sedation to remain calm and relaxed during the procedure.

Venous catheters are not ideal for long-term use. With a venous catheter, patients may experience blood clots, infections, or injury to the veins, causing narrowing of the blood vessels. However, if the patient needs to start hemodialysis directly, the venous catheter will work for several weeks or months until the surgeon can perform long-term access surgery and the AV fistula or AV graft can be used.

If fistula or graft surgery fails, the patient will need access to a long-term venous catheter. When a patient needs a venous catheter for more than 3 weeks, the surgeon will "tunnel" the catheter under the skin instead of inserting it directly into a vein. The catheter tunnel is more convenient and has fewer problems. But the tunneled catheter can also become infected.

What problems can be caused by vascular access?

All three types of vascular access (AV fistula, AV graft, and catheter vein) can cause problems that require further treatment or surgery. The most common problems include access infection and low blood flow due to access to blood clots.

Infection and poor blood flow are less common in AV fistulas, which are well formed than in AV graft and venous catheter. However, the presence of an AV fistula does not guarantee access will be problem-free.

The AV graft is more likely to experience poor blood flow, signs of clotting, or access narrowing. A damaged AV may require angioplasty, a procedure to widen a narrow area. Another option involves surgery on the AV graft to replace the narrow part.

A venous catheter most commonly causes infections and clotting problems. If this problem develops, the use of medications may help. Antibiotics are medicines that fight bacteria that can cause an infection. Blood thinners such as warfarin help prevent blood from clotting. If this treatment fails, the catheter should be replaced by a nephrologist or radiological intervention specialist.

Vascular access for hemodialysis

Conducting a blood purification session by hemodialysis requires access to the patient's circulatory system, the meaning of which is to obtain a sufficient volume of blood to pass through the dialyzer and return to the body. The more blood is purified in the dialyzer, the more effective hemodialysis is.

There are temporary and permanent vascular accesses to provide program hemodialysis. The former are used for emergency connection of the patient to the equipment in threatening conditions or the inability to use permanent access, the latter - for a long time provide purification of the blood of patients and thus the possibility of a full life.

The main temporary access is catheterization of the main veins with special one- or two-lumen catheters that provide blood sampling and its return after purification in the dialyzer. The most common method of installing catheters in the central veins according to the Seldinger method. Femoral vein catheterization is used (not allowed when planning donor kidney transplantation) and internal jugular vein. The latter technique has significant advantages, since it leads to less vascular stenosis and provides a high level of blood flow. Catheters for catheterization of the great vessels are produced industrially in the form of special sterile sets, which include the catheters themselves and additional devices: a guide wire, puncture tunnel dilators, puncture needles, a scalpel, suture material, etc., which allows manipulation to provide vascular access in the shortest possible time. The term of use of such catheters is 14-21 days.

There are also so-called permanent catheters for long-term dialysis. They are used in cases of recurrent thrombosis of arteriovenous fistulas, with low blood pressure (BP) in a patient, with a small caliber of peripheral vessels that prevent the formation of permanent accesses for hemodialysis. A distinctive feature of permanent catheters is the presence of Dacron cuffs on their surface, which are located in the subcutaneous tunnel, firmly fixing the catheter and preventing infection of its bed. Such catheters, with proper hygienic care and regular flushing of the lumen with a heparin solution, can function for several years.

Arteriovenous fistulas for programmed hemodialysis - the main type of vascular access for connecting artificial kidney devices. The principle underlying the functioning of the arteriovenous fistulas of the vessels on the extremities is to create a constant discharge of blood from the artery into the vein, which prevents thrombosis and makes it possible to receive regular and high-volume blood for purification in the “artificial kidney” apparatus. The most common are Cimino and Breshia fistulas, in which a vascular anastomosis is formed between the radial artery and the cephalic vein in the lower part of the forearm using microsurgical techniques. The wound is sutured tightly and no artificial materials are used to shed blood. Within a short time (3-4 weeks), arterialization of the head vein occurs with the expansion of its lumen, thickening of the walls. The volume of blood passing through such an anastomosis reaches 150 ml/min and more. The section of the arterialized vein is punctured with two fistula needles to obtain blood and return it after the purification process in the dialyzer. Other vascular accesses are also used using the principle of arterialization of veins of various localization. In the absence of main veins suitable for puncture on the lower or upper extremities, venous autografts are used, for example, from the great saphenous vein of the thigh, placed in the form of a loop or direct bridge between a large artery and a vein. As a vascular graft, special synthetic prostheses are also used, which can be punctured for a long time and continue with program hemodialysis. The formation of AVF by any method is carried out under sterile operating conditions using microvascular equipment (loupe or microscope, microvascular atraumatic needles and instruments). Within 3-4 weeks, arterialization of the vein occurs, which becomes suitable for multiple punctures with fistula needles. Sometimes, due to the deterioration of the patient's condition, it is necessary to start connecting the equipment at an earlier date, otherwise you may encounter an increase in the number of dangerous complications - bleeding outward and into the subcutaneous tissue, anastomosis thrombosis, etc.

In this regard, emergency hemodialysis sessions must be carried out through an external catheter in one of the main veins. At the same time, the formation of AVFs is carried out in a planned manner and the time period for their “maturation” is maintained. Only later can you switch to

using the puncture method of access to the vessels, and then remove the catheter from the vein. Table 5 shows the indications for the use of various vascular accesses for hemodialysis in different categories of patients with acute and chronic renal failure.

A translation into Russian of this remarkable work was published in March 2010 by a well-known specialist in hemodialysis, author of several books, Doctor of Medical Sciences Evgeny Stetsyuk (website "Hemodialysis for Specialists", www.hd13.ru). However, the work has not lost its relevance so far. It is written for practicing physicians, but the language will also be understandable for patients.

Fistula. Introduction

Vascular access makes chronic dialysis possible by allowing staff access to the circulation. Access can be internal (inside the body) or external (outside the body).

Vascular access should:

— make it possible to re-access the circulation.

- to ensure sufficient blood flow for effective hemodialysis.

- be made of a material that does not cause a reaction or predisposition to infection.

Three main types accesses are: fistula, prosthesis and catheter. When applying a fistula, the surgeon sews together an artery and a vein, most often in the arm. Arteries carry oxygen-rich blood from the heart and lungs to the rest of the body. These vessels chosen for the fistula are large and have good blood flow, but they lie deep under the skin and are difficult to puncture. Veins carry blood back to the heart and lungs. They are located superficially, accessible, but too thin and the blood flow through them is insufficient for dialysis.

The connection of an artery and a vein is the best solution to the situation. After 4-6 weeks, high pressure and high arterial blood flow lead to thickening of the vein wall and its dilatation (expansion). As a result, the vessel can be punctured with thick needles. The fistula is located under the skin and is created only from the tissues of the patient himself. Therefore, the fistula is less prone to infection and thrombosis, unlike other approaches. The fistula can work for years and even decades. Research has shown that the fistula is currently the best approach available. New surgical techniques for creating a fistula, puncture techniques, and vascular preservation techniques have made the fistula the preferred choice for most patients.

Steps before surgery:

– After the state of the vessels is assessed, the place for creating an access is chosen, the patient should be well informed about the upcoming operation and the rules of postoperative care for the access should be explained in detail. The patient should be aware that an arm with a functioning fistula should not be used to puncture a vein and to monitor blood pressure.

The operation is performed under local, regional or general anesthesia. The patient must be adequately hydrated, necessarily above dry weight, if hemodialysis was the day before. On this day, you can not prescribe antihypertensive drugs. It is possible to prescribe prophylactic antibiotics before surgery.

Postoperative care of fistula and prosthesis

Immediately after surgery, the area of ​​operation should be examined (initially every half an hour) for:

- excessive bleeding;

- swelling;

- warmth of the limb, to make sure that there is a satisfactory peripheral circulation;

- the presence of a trill (the sensation of a buzzing of blood as it flows through the fistula) or noise (the whistle of blood that can be heard with a stethoscope) clearly indicates the presence of blood flow through the fistula;

- to prevent thrombosis, blood pressure should be maintained at an acceptable level and dehydration should not be allowed;

— Access should be in an elevated position to avoid excess swelling and swelling.

When implanting a prosthesis, the surgeon connects the artery and vein with a segment of an artificial blood vessel. Like a fistula, the prosthesis allows you to get enough blood flow for hemodialysis. In prostheses, stenoses (narrowing of the vessel) more often occur, which lead to thrombosis (the formation of blood clots). Dentures are more likely to become infected and less durable than a fistula, averaging less than 5 years. The prosthesis is sewn only when the patient no longer has vessels for fistula.

The catheter consists of hollow plastic tubes. The catheter is located on the chest when it is inserted into the central vein, or on the thigh when the catheter is inserted into the femoral vein.

With the help of a catheter, a vascular access is created for long-term or short-term use. Deep central veins have sufficient blood flow to carry out effective hemodialysis. The material of the catheter (plastic) is foreign to the body, and the catheter is inserted by piercing the skin. This creates a place for bacteria to enter. In catheters, stenoses, blood clots and foci of infection are often formed. For these reasons, catheters are often replaced with a new catheter placed in the same or a different vessel.

Catheters are installed in the following cases:

- Impossible to install a fistula or prosthesis

- When time is needed for engraftment of the prosthesis or maturation of the fistula

- In acute renal failure, when there is hope for a speedy recovery of kidney function

- Awaiting placement of a peritoneal catheter

- Waiting for transplantation from a living donor

Despite more than 65 years of vascular access efforts, this problem is fundamental to successful hemodialysis. Approximately 25-50% of dialysis patient admissions are related to access problems. It costs over $1 billion a year according to Medicare accounts (2). Patients with poorly functioning access cannot receive adequate dialysis. Patients become uremic, look sick and tired. They cannot work, exercise or do what they love, and their quality of life is reduced. If a patient feels ill, it reflects on his family, friends and staff.

Access problems strain both staff and patients. Problems with puncture (insertion of a needle) into a vessel or prosthesis are stressful for both the staff and the patient. A failed puncture can destroy access, which is life-threatening. In this case, access is corrected or made elsewhere, if possible. Access problems cause hospitalizations, surgical interventions, morbidity, and can lead to limb loss and even death. Problems with access take a lot of time from the staff, disrupt the planned work. In addition, while the patient is in the hospital, the dialysis beds in the center remain unoccupied. All types of vascular access have their advantages and disadvantages. Researchers continue to search for optimal vascular access for dialysis patients.

The NKF (National Kidney Foundation, USA) Kidney Disease Outcomes Quality Initiative (KDOQI) and the Fistula First program continue their efforts to improve outcomes with vascular access. Evaluation and preservation of vessels to create a fistula are the main focus, and early fistula placement is encouraged if possible.

In this module, we will tell you about the fistula, prosthesis, catheters and other devices. Each section includes definitions, evaluation and monitoring of access. Consider the KDOQI recommendations, patient education and complications of different types of approaches. How you help the patient in working with access directly affects his life. Proper care of the vascular access will greatly improve the patient's quality of life and will bring true professional satisfaction to all staff.

How to make a fistula

A native arteriovenous fistula (AVF) is created surgically by stitching together an artery and a vein. This connection is called an anastomosis and a scar remains at the site of the operation. It takes 1-3 months until the AVF becomes powerful enough to puncture it with thick needles. Therefore, it is desirable to create a fistula early before the start of hemodialysis.

After the fistula is made, a powerful arterial blood flow begins through the vein, which begins to expand the fistula vein and make its wall elastic. This is the arterialization of the fistula, which we call AVF maturation. After about a week, the patient can begin exercises that help the fistula mature. This could be squeezing a rubber ball or lifting light weights.

The most common type of native AVF is an anastomosis between the radial artery and the cephalic vein. Stitching is performed on the forearm between the wrist and elbow. This is the so-called radiocephalic fistula.

Brachiocephalic fistulas are created on the shoulder by stitching a.brachialis and v.cephalica. If for some reason this pair of vessels cannot be used, you can take other vessels:

– V. basilica

— Transposition v. basilica (deep vein is moved closer to the surface of the skin to make it easier to puncture)

- Transposition of one of the brachial veins (the brachial artery is closely accompanied by two brachial veins that flow into the axillary vein)

- The perforating vein in the cubital fossa anastomoses with the brachial artery (the perforating vein connects the deep and superficial veins)

- ulnar artery

— Proximal radial artery.

Although AVF is the best vascular access, not every patient can have it. The surgeon must be sure that after the application of the AVF, the blood flow in the limb will remain sufficient. The selected vein should be healthy, straight, and thick enough to be punctured with thick needles. In addition, the vein must be long enough to allow sufficient puncture sites. After a fistula is placed, the patient's heart must be able to increase cardiac output (the amount of blood passing through the heart) by 10% or more. The new access is an additional burden on the heart, since arterial blood quickly returns through the fistula, instead of slowly passing through thin vessels and capillaries.

Exists a number of reasons why an AVF cannot be placed on a patient:

- Veins damaged due to infusion of intravenous drugs

- Previous operations on arteries and veins

- Atherosclerosis: plaque or waxy cholesterol blocks blood vessels

Poor arterial health due to peripheral vascular disease or severe advanced diabetes

- The only working artery that brings blood to the hand

- Damage to blood vessels from intravenous drug use.

Creating a fistula

Before the operation, it is necessary to draw a diagram of the vessels in order to select the best ones for the AVF. When applying AVF, these vessels are marked on the skin. A skin incision is made over the selected vessels. The vessels are then sutured together.

Exists four ways to connect arteries and veins to create an AVF . Each method has its pros and cons:

- Anastomosis side to side (side of the artery to the side of the vein). This is the very first technique that surgeons began to perform. Taco anastomosis often causes venous hypertension. Due to venous hypertension, the hand is somewhat edematous. Therefore, sometimes surgeons, when performing a side-to-side anastomosis, tie one or more vessels towards the arm.

- Side-to-end anastomosis (side of artery to end of vein) is preferred by many surgeons, despite the fact that such an operation is more difficult to perform. This method allows you to get good blood flow and the number of complications is small.

— An end-to-side anastomosis (end of an artery to the side of a vein) gives slightly less blood flow than a side-to-side anastomosis.

End-to-end anastomosis (end of artery to end of vein) results in less blood flow in the access.

After suturing the skin incision over the fistula, a trill or purr can be heard. You should be able to listen for this hissing noise over the fistula with a stethoscope throughout the fistula vein. The noise should be long and low in tone. Both the trill and the noise help make sure the fistula is working.

Advantages and disadvantages of a fistula

Advantages: AVF is the gold standard for vascular access. As a rule, the fistula lasts longer than other approaches and has fewer complications, including infection. To create an AVF, the patient's own vessels are used. If possible, a fistula should always be placed.

Flaws: The main disadvantage of the fistula is the long period of its maturation: 4-6 weeks or more. Some fistulas do not mature at all. The problem is called early or primary insufficiency.

The fistula may not mature for the following reasons:

— The anastomosis is too small and there is insufficient blood flow to the fistula.

- Between the anastomosis and the entrance to the fistula formed a stenosis.

- The lateral veins that branch from the fistula vein reduce the blood pressure in the fistula and it does not arterialize.

— The vessel chosen by the surgeon to create the fistula is too small (< 2 мм).

Preoperative marking of the vessels helps the surgeon to select the appropriate vessel to create the fistula.

Assessment of fistula maturity

A new technician is usually not trusted to puncture a new fistula. But you must be able to assess the condition of the fistula before hemodialysis. For this you need:

— Examine the fistula for signs of inflammation such as redness, discharge, or abscess formation.

- See how the area of ​​the surgical incision heals.

- Determine the presence of a trill - it should be constant like a purr or vibration, but not a strong pulsation.

- Feel the diameter of the vessel - it should become larger immediately after the operation and growth should be noticeable within 2 weeks.

- Listen to the noise - the tone should be low and the sounds should follow one after another without interruption.

- After a week, apply a tourniquet and feel the tension of the fistula vein. This shows that the vessel becomes more powerful and thicker.

Fistula First Program in the USA

Centers for Medicare and Medicaid Services (CMS) started the Fistula First (Fistula First) program in 2003. The first steps of CMS were to increase the frequency of fistula use in hemodialysis patients by up to 40% and reduce the frequency of catheter use.

Fistula Fest works with nephrologists, angiosurgeons, interventional nephrologists, nurses, emergency physicians, patients and other specialists. The participants in the program are working to change the established practice and convince everyone that fistula is an access of choice for those who can get it. Run the ESRD Network program and CMS.

The Fistula Fest program consists of 11 guidelines that dialysis centers must implement to increase the use of fistulas:

— Continuous improvement of the quality of routine examination of vascular access.

- Timely referral to a nephrologist.

- Early referral to the surgeon for the imposition of exclusively fistula and on time.

- The choice of surgeon is based on the best results, good will and the ability to provide curation of the fistula.

— Full surgical assessment of fistula placement options and fistula site selection.

- Secondary fistula in patients with a prosthesis.

— Change the catheter to an AVF where possible.

— Staff training to puncture the fistula.

— Surveillance and access content in adequate working order.

— Training of attendants and patients.

— Evaluation of work results.

Your role in the Fistula Fest program includes: staying in the dialysis room and monitoring access status, learning proper fistula puncture techniques, and ongoing training in vascular access.

If the fistula vein has not changed 2-3 weeks after the operation, this should be reported to the nephrologist and surgeon. The dialysis patient should be seen 4-6 weeks after the fistula is placed. According to expert Gerald Bethard, if there are no signs of access maturation in the second week after the operation, the fistula will not mature at all. When the vein becomes sufficiently developed, the doctor may order to start punctures. The new fistula is punctured with fine needles (17 gauge) and a low flow rate (200-250 ml/min) is established for one week. This will help to avoid cutting the fistula with a needle and infiltration of blood around the fistula when piercing the fistula through. After the first week, the size of the needle can be increased and the speed of the blood pump increased.

Starting dialysis with a fistula

To wash hands always necessary before touching the dialysis access. Clean hands and clean gloves prevent bacteria on the skin from entering the bloodstream through the needle. Gloves should be changed if you touch your face or hair, a chair or other surface with them. The Occupational Safety and Health Administration (OSHA) requires handwashing to protect both you and the patient from infection. The Centers for Disease Control and Prevention (CDC) recommends the use of gloves, an apron, eye protection, and a mask to prevent hemodialysis infections, as there is always a risk of blood splatter in hemodialysis.

Fistula examination

At each hemodialysis session, you should assess the condition of the fistula, make sure that it is not a problem and that it will work well, providing the patient with the best possible dialysis. You need to know how to look, listen and feel for access.

Inspection data:

- Signs and symptoms of infection: Redness, discharge, pus, abscess, skin blemishes, fever.

- Steal syndrome (insufficient blood flow to the arm): Pale, cyanotic nail bed or skin.

- Stenosis (narrowing): swelling of the arm, pale skin, small blue or red veins on the chest at the junction of the arm and torso.

- Areas of puncture: Scabs (crusts) from previous punctures, anastomosis, folds, spots, aneurysms (bloating of blood vessels) their width, height and appearance.

Listening data:

- Noise: The sound and height of the "whistling" noise is assessed (higher or lower frequency may indicate stenosis).

- Deep locating access: Place a stethoscope over the access and listen to the noise. Then move the stethoscope from side to side until the noise disappears. This will help you pinpoint the access position.

- Feeling:

- Skin temperature: the skin feels too hot to the touch (this could be an infection) or cold (reduced blood supply).

- Trill: should be felt and be constant, but it is not a pulsation.

— Vein diameter: Start the examination by anastomosis with thumb and forefinger on both sides of the fistula. Determine whether the diameter is the same along the entire length of the fistula? Are there any aneurysms, what is their size?

— The diameter of the fistula must exceed the gauge of the needle. How deep under the skin is the access located? This is important for determining the angle of insertion of the needle.

- Determination of the puncture site: Keep 1.5 inches from the anastomosis (1 inch = 2.6 cm). Space the needles at least 1.5 inches apart, avoiding kinks, flattening, and aneurysms. When rotating puncture sites, avoid scabs and crusts from previous punctures.

- Steal Syndrome: Pay attention to whether the patient's hand is too cold compared to the other hand. During the handshake, evaluate whether motor skills have changed.

Blood flow assessment

The next step before fistula puncture is to assess blood flow. Each fistula must have a strong blood flow from the artery to the vein. In the area of ​​the anastomosis, a distinct trill should be felt, arising from the pumping of blood by the heart through the fistula.

Check for noise with a stethoscope. The noise should be distinct, continuous, and each next sound is connected with the previous one. A change in sound to a higher or muffled one may indicate the presence of a stenosis. Teach the patient to listen to his fistula and report any changes to the nurse or nephrologist. A change in the trill or the strength of the sound may mean that the blood flow through the fistula has become worse. This may be a precursor to fistula thrombosis. Report this to the responsible nurse before puncturing the fistula.

You should be aware of the normal fistula murmurs in each patient. Tell the nurse about changes in the trill and noise in order to correct the violation of blood flow through the fistula in time.

Skin preparation

The accessing arm must be washed to prevent skin bacteria from entering the bloodstream during the puncture. Staphylococcus aureus or "staph" for short is common in dialysis patients for the following reasons:

— Patients are at high risk of infection.

Many people have diabetes.

- They often go to the hospital where infectious agents are found.

— A dialysis center is a place of residence for a large number of people.

A study by Kaplowitz et al showed that staph is very common in the nose and skin of dialysis patients. Therefore, it is very important to teach patients how to clean the access with antibacterial soap and water or apply an alcohol-containing gel before sitting in the dialysis chair. These measures significantly reduce the number of bacteria on the skin and reduce the risk of infection of the patient.

Treat the patient's skin with a solution of 70% alcohol, 10% povidone iodine, or chlorhexidine gluconate with 70% alcohol according to your rules:

- Alcohol only kills bacteria while it's wet - do a circular rub on the skin on both sides for 60 seconds.

- Povidone iodine (Betadine®) only kills bacteria when dry - wait 3-5 minutes after treatment.

- Chlorhexidine gluconate (ChloraPrep®) with 70% alcohol kills bacteria only after drying - wait 30 seconds.

- Sodium hypochlorite (ExSept® Plus) - the manufacturer recommends waiting 2 minutes before puncture.

Turnstile overlay

Always use a tourniquet when puncturing a fistula, even when the size of the vessel does not seem to warrant it. The tourniquet allows a better view of the fistula, holds the fistula in place without allowing it to roll under the skin, and gives greater confidence in the puncture. Tight skin contributes to a neat puncture. Place the tourniquet as far away from the fistula as possible (just below the armpit), this allows pressure to be distributed more evenly across the veins and reduces the risk of infiltration. Tourniquets should not cause pain, numbness of the extremity and cessation of blood flow to the fingers. Tourniquets can only be used for puncture, not during dialysis.

Needle insertion

Before inserting the needle, feel how deep the vessel lies under the skin. The injection angle is highly dependent on depth. The deeper the access, the steeper the injection of the needle so that most of it is inside the vessel. This prevents infiltration if the patient moves the limb during hemodialysis.

Your department should have a written fistula puncture training program and checklists to ensure you know all the steps involved in fistula cannulation: proper skin preparation, needle insertion, needle fixation, and ligation. First, skills are worked out on a special hand model, and only then they try to puncture the patient. To become a good specialist, significant experience is required. The first puncture in a new patient should be performed by an experienced nurse.

When puncturing a fistula, the main thing to remember is that the needle insertion technique must be very delicate. You choose the angle of entry based on the depth of the vessel, and insert the needle through the skin and tissues until you feel a decrease in resistance. Check for blood in the needle tube. Lower the entry angle down and move the needle forward. The movement should be smooth, without poking, picking and searching with a needle.

Don't twist the needle. When it is in the vessel, turn it 180 degrees. Needle rotation can:

- Stretch the hole in which the needle is located, and after heparinization, blood will leak from under the needle.

- Injure the inner surface of the vessel.

- Lead to infiltration.

After a full assessment of the situation, you have finally determined how the vessel goes and how deep it is under the skin. Decide in advance where you will puncture. Leave space for venous needle puncture in case the first attempt fails or an infiltrate forms. The venous needle is usually placed closer to the heart.

Depending on your center's policies and how easy or difficult it is to tap the fistula, you may choose to do a "wet tap" or a "dry tap". Wet puncture is performed with a syringe filled with saline. This can be useful if the puncture is difficult or if the patient is clotting very quickly. Dry puncture is performed without a syringe. Before the puncture, treat the injection sites in accordance with your rules. Note: If you are unable to successfully puncture the fistula, ask someone else to do so. Most patients can point you to the one who makes the most successful puncture.

Antegrade and retrograde direction of needles

The venous needle is always located antegrade (in the direction of blood flow). This prevents turbulence in the return of blood from the extracorporeal circuit (21,23). This is also very important because the downstream position of the needle prevents recirculation of blood, i.e. freshly purified blood is not returned back to the dialyzer.

The other needle is called "arterial" because it is located closer to the anastomosis and draws arterial blood. This needle can be placed both antegrade and retrograde with respect to the direction of blood flow (23). It does not matter at all what the rules of puncture are in your center, always the tips of the needles should be at a distance of 1-1.5 inches and at least 1.5-2 cm from the anastomosis. These rules prevent recirculation and decrease in the adequacy of dialysis.

Rope ladder technique (rotation of puncture sites)

Each time the needle pierces the vein and makes a hole in it. After the needle is removed, a blood clot forms at the puncture site, closing this hole. When the patient comes in for the next HD, you see the crust and choose another site for the puncture until the old site heals. This is the so-called rotation of the puncture sites or the rope ladder technique. We draw a rope ladder with circles. On the first day, we prick the needles into two different circles. Then on each hemodialysis you choose two new circles until you get to the end of the stairs. Then you start all over again.

Rotation of puncture sites prevents the appearance of aneurysms (areas with a weak vascular wall that bulge). It seems easier and faster to place the needles in the same places, but over time this will lead to weakness of the vascular wall. If you use the entire space of the fistula for puncture, the risk of aneurysm formation is reduced. It happens that the patient asked to puncture the aneurysm, as it is less painful for him. Explain to him that the aneurysm may burst because the skin over it is thinned. This may be accompanied by significant blood loss and will require surgical intervention to restore access.

Buttonhole Technique (permanent position)

The buttonhole technique has been used in Europe and Japan for over 25 years and has become most popular in the United States. This method was first used on a fistula that did not have enough space for puncture. Dr. Z. Twardowski, who proposed this puncture method, noticed that there are fewer infections, fewer failed punctures, hematomas, bruises and infiltrates. Both the arterial and venous needles are inserted antegrade in order to obtain good hemostasis after removal of the needles.

Before puncture, it is necessary to remove the crusts from the previous puncture. First, the crust must be moistened so that it does not crumble into small crumbs.

To remove the old crust, do the following:

Moisten a gauze pad with saline or apply an alcohol-based gel on it. Next, use sterile tweezers.

- Provide the patient with alcohol wipes and ask him to apply these wipes to the puncture sites 1 hour before arriving at the dialysis center.

After removing the crusts, treat the puncture sites according to your protocol. Once the puncture sites are ready, insert the sharp needles at the same angle into the same two holes. After 3-4 weeks, a crusted puncture tunnel is formed, similar to an earring hole. During this time, the puncture should be performed by the same person to ensure that the needles are inserted at the same angle. This person may be the patient himself. Once the scar tunnel has formed, blunt needles should be used (Fig. 8) to avoid cutting the scar tunnel. These cuts can cause blood to seep out from under the needle during dialysis.

Fixation of needles after puncture

After the introduction of the needles, they must be securely fixed. To do this, you can use the butterfly ribbon technique. Gently place a piece of tape 1 inch (2.6 cm) wide and 6 inches or more long under the needle. Then fix the tape crosswise over the needle. Next, place a 2x2 (probably inch) gauze pad over the needle and secure it with another 6-inch tape. It is your responsibility to secure the position of the needles from movement and out of access. During hemodialysis, observe the needles.

Overcoming the patient's fear of puncture

In the general population, at least 1 in 10 people have a physical fear of needles, blood, or a similar phobia. People with such phobias have an involuntary vasovagal reflex to needles, to the sight of blood, to surgery:

- The pulse speeds up and blood pressure rises.

“Then the pulse slows down, blood pressure drops, stress hormones are released, and the heart rate may change.

- The patient becomes pale, wet, nausea, dizziness and there may be loss of consciousness.

It happens that because of such fears, the patient chooses peritoneal dialysis, where needles are not used. But the day will come when it will be necessary to transfer the patient to hemodialysis. The patient should be aware of the possible rapid vasovagal reaction. Some of the things that can help in this situation are:

- Position the chair horizontally so that blood flow to the head remains and the patient does not lose consciousness.

- With the permission of the patient's physician, ask the patient to tense the muscles of the non-fistulous limb for 10-20 seconds, relax the muscles, and then tighten again until the needles are inserted. This will temporarily raise blood pressure and prevent a vasovagal response.

- Try to reduce the pain of needle insertion using the techniques described in the next section. Pain is a partial cause of the phobia.

- Teach patients how to insert their own needles. This will distract patients from pain and replace it with controlling participation.

Reduce the pain of inserting needles s

Dialysis needles are quite thick to ensure sufficient blood flow. Therefore, the insertion of needles can be painful. Our goal is to ensure that the insertion of fistula needles is as painless as possible and with minimal trauma to the fistula. The three-point method helps to reduce the pain of the puncture and ensures successful cannulation. First, apply a tourniquet to stabilize the fistula vein. To reduce movement of the vein, place the thumb and forefinger of a needleless hand on the side of the vein just above the site to be punctured. Then, with your thumb and forefinger, tighten the skin and tighten it.

The stretched skin is easier to pass with a needle and it is less painful. Pressing on the skin blocks the transmission of pain impulses to the brain for up to 20 seconds, which gives staff enough time to insert the needle.

Patients who puncture themselves report that the procedure is less painful if someone else does it. Patients who puncture themselves play a significant role in maintaining their own well-being. They also contribute to better retention of access. This is due to the fact that such patients feel access from both outside and inside. It is easier for them to avoid infiltration. There is another way to help patients with a phobia. This is a fistula puncture using the buttonhole method, which significantly reduces pain.

There are other maneuvers to reduce the feeling of pain during puncture: breathing, induced image and listening to music. Distractions can work quite effectively. Ask the staff to talk to the patient while you insert the needles. The patient may be offered the use of a local anesthetic (drugs to "freeze" the skin). You can do intradermal administration of lidocaine, ethyl chloride spray, topical creams or gels. The KDOQI (Clinical Practice Recommendations for Vascular Access) recommend that patients who are able to puncture a fistula and whose fistula is easy to puncture should be referred to self-puncture, preferably by buttonhole technique.

Lidocaine injection

Intradermal injection of lidocaine is used for local anesthesia of tissues.

First, the puncture sites are prepared. Use a separate 1 ml syringe or tuberculin syringe for each site. The injection is made immediately under the skin, but above the fistula or prosthesis. Never inject lidocaine into a fistula vein to prevent the drug from entering the circulation. After injection, lidocaine forms a swelling or blister under the skin. Since lidocaine can cause a burning sensation, it is only used in very small amounts. The drug may leak back from the injection site, or minor bleeding may occur at the injection site. Sterile gauze wipes should be used to eliminate the leakage of the drug or blood and dry the puncture site.

— Note: Since lidocaine is administered through needles, its use may not be effective in patients with needle phobia.

- Lidocaine is a vasoconstrictor (vasoconstrictor drug) and can cause a decrease in the diameter of the fistula vein and move the vessel a little deeper under the skin. This makes puncture more difficult. And those patients whose fistula is located very close under the skin feel less pain during a puncture without lidocaine. The patient can compare the sensations of inserting one needle with lidocaine and another without lidocaine. Per your dialysis center's policy, allow the patient to choose what is best for them.

Chloroethyl Spray

Chloroethyl spray can be used to numb the skin. The drug causes a sensation of cold. The spray does not freeze the tissues under the skin, so in patients with a fistula deep under the skin, the feeling of the needle passing through the tissues does not disappear and the effect of anesthesia does not occur. The chloroethyl spray is non-sterile. The puncture site is first washed by the patient, then a spray is applied, and then the staff prepares the puncture site for the introduction of needles.

Local anesthetics

Patients may use local anesthetics (gels or creams that numb the skin and tissues). These medications should be applied to the skin at home and then wrapped in a plastic bandage at least one hour before starting hemodialysis. The action of local anesthetics depends on the time of contact of the drug with the skin, but does not depend on the amount of drug used. To ensure anesthesia of 3 mm of the skin surface, apply the cream 60 minutes before hemodialysis. If deeper anesthesia is desired, such as 5 mm, ask the patient to apply the cream 120 minutes before hemodialysis (30). Local anesthetics for external use are the following drugs:

- Prescription EMLA™ cream (2.5% lidocaine/2.5% prilocaine)

- Over-the-counter Less-n-pain™(4% lidocaine)

- Over-the-counter L.M.X.®(4% lidocaine)

- Over-the-counter Topicaine® (4% or 5% lidocaine)

Upon arrival at the dialysis center, the patient removes the plastic bandage and rinses off the cream. Remind the patient to wash their hands after applying the cream and not to touch their eyes with their hands, otherwise the mucous membrane of the eye may be damaged. Like injections of lidocaine, creams can cause fistula vasoconstriction.

Fistula care after hemodialysis

After hemodialysis, remove the tapes and remove the needles according to your center's protocol. Before pressing on the puncture site, make sure that the needle is completely removed. If you press too early, the needle may cut through the access. Follow your rules for applying pressure to the puncture site. The goal is to stop bleeding but not damage the access, or stop bleeding but not cause thrombosis of the access.

Teach the patient how to hold puncture sites after hemodialysis.

Tips on how to increase the duration of the fistula

— Use the buttonhole method or rotation of puncture sites at each hemodialysis. Do not prick the fistula in the same place. This can lead to an aneurysm.

- Convince the patient not to allow the fistula to be used for intravenous injections, blood sampling, and for measuring blood pressure. The “Save the Vien” card must be carried by the patient. It should be presented to the medical staff if you need to take blood for research.

- Keep accurate records of each hemodialysis session. If you notice any problems with your fistula, tell your nurse or doctor.

Complications of a fistula

For the patient, access problems can lead to impaired access function, inadequate hemodialysis, hospitalization, and even premature death. If access is lost, a new access must be created. This means performing a surgical operation and a recovery period after the operation. The habitual life of the patient is disturbed and the quality of life is reduced. There are only about 10 places on the human body suitable for creating vascular access. With each subsequent surgical intervention, the future choice is limited. Every year, several patients die because there are no more places to create access.

Access problems affect the work of staff. The way we work has changed significantly. Treatment of accesses takes a significant part of the working time of the staff.

You need to be aware of the most common circulation access problems, how to treat them, and how to maintain access and patient quality of life. By knowing how to prevent problems with access, you help the patient keep access in good condition for longer.

Infection

Never puncture a fistula if there are signs of infection. A superficially infected fistula can cause the infection to spread into the bloodstream. This leads to sepsis, blood poisoning, and this is one of the main causes of death in hemodialysis patients. If there are signs of infection, immediately call a nurse who can call a nephrologist. The doctor will make arrangements regarding the possibility of a puncture, how to observe the fistula and prescribe antibiotics.

Complications associated with diaism.Line disconnection

Exsanguination (severe blood loss) can occur if a needle pops out, a blood line is severed, or a fistula ruptures. Do not allow the needle to exit the vessel. To do this, securely fix it with adhesive tape, as we wrote above. Attach blood lines flawlessly and set blood and venous pressure limits on the monitor so you can instantly recognize what's wrong.

An air/foam detector and blood and venous pressure monitors can help avoid blood loss if they are working properly. But sometimes the displacement of the needle during hemodialysis can cause blood loss. Moreover, the leakage of blood will be insufficient for the venous pressure to drop and the alarm to work. And you may not notice the bleeding if the patient's arm is covered with a blanket.

If blood loss comes from blood lines, apply clamps to the appropriate sites. If the needle pops out, press down on the puncture site. Significant blood loss may require oxygen and volume expanders. If necessary, take immediate action (such as calling 911) according to your own rules.

Air embolism

Air entering the patient's circulation can stop blood flow, just like a real blood clot. If a lot of air has entered the circulation, the heart begins to pump foam instead of liquid blood. The efficiency of the heart falls, sometimes to the point of stopping. Blood foam in the lungs causes respiratory distress. Blood foam in the vessels of the brain can lead to a stroke. Depending on where the air went, the clinical picture of an air embolism depends: the patient may be very excited, breathing is difficult, cyanosis, visual disturbances may occur, blood pressure may decrease, confusion, paralysis or loss of consciousness appear.

Modern dialysis machines do not allow forcibly overriding the alarm condition on the monitor (override). If your center has older machines, you should always make sure that the air/foam detector is on and working properly during the entire hemodialysis time and during blood return when turned off. If the air/foam detector has tripped, look at the venous line for air bubbles. If not, then you can enable override (overcoming the alarm). If necessary, fix all connections with a plaster, carefully tighten the Luer-Lok connections to exclude the possibility of disconnection. Clamp all injection ports to prevent micro air bubbles from entering the circulation after an IV injection or blood sampling.

The patient should be taught to watch his own blood lines to be sure that no air has entered the blood line. There should be no air in the blood line from the air/foam detector (below the vein trap) to the patient. If air enters the arterial line before the dialyzer, it is trapped in an arterial trap that is located before the dialyzer inlet. The air/foam detector should stop the blood pump if there is air in the venous trap. If you suspect that a significant amount of air has nevertheless entered the venous system, lay the patient on his left side and call a nurse. The position on the left side reduces the likelihood of air entering the brain and pulmonary artery.

Tips for preventing blood loss during hemodiasis:

— Never allow the patient to cover the needles and lines connected to them with a blanket or sheet. You should always be able to see access.

- Before starting treatment, make sure that the connections of the entire extracorporeal circuit are reliable. Fix the needles with a band-aid to prevent them from popping out.

- Blood lines must not touch the floor. They can be stepped on or pulled.

— Before starting hemodialysis, make sure that the air/foam detector, arterial and venous pressure monitors are in working order and turned on at the beginning of hemodialysis.

Infiltration/hematoma

Infiltration occurs when a needle pierces through a vein, exiting the other side of the vessel, or makes a tear that allows blood to flow into the surrounding tissues.

Infiltration is the most common complication of fistula puncture. This complication becomes less frequent as staff gain experience with access punctures.

Infiltration harms access and can lead to insufficient access. In the patient, infiltration causes pain, a burning sensation, there is a need for an additional puncture, the patient loses confidence in the staff. Blood that has entered the tissues around the vessel causes swelling, thickening and sometimes redness in this area. An infiltrate in the area of ​​the venous needle raises the venous pressure above the set limit, activates an alarm and stops the blood pump. Infiltration in the area of ​​the arterial needle, on the contrary, makes arterial pressure (meaning the pressure in front of the blood pump) even lower.

To prevent infiltrations, carefully follow your center's needle insertion technique and:

- Work calmly.

- Don't freak out.

- Develop a sense of the disappearance of resistance when the needle enters the vessel.

- Advance the needle slowly up to the hub until you feel a change in resistance and until you can see the blood pulsing in the needle tube.

- Do not twist the needles.

- After inserting the needle, flush it with saline to ensure that the needle is in the correct position (no pain, no swelling, no resistance to flushing with saline).

- Use the wet puncture technique.

The needle that made the infiltrate can be removed if heparin has not yet been injected. Ask the patient to apply pressure to the puncture site if hemodialysis ends. If the infiltration occurs after heparin was given, the nurse may tell you to leave the needle in place. Then you need to make an additional puncture outside the zone of infiltration, usually higher. If a hematoma develops, give the patient an ice pack. A soft cloth can be used as a barrier between the ice and the skin. During hemodialysis, this will help reduce swelling. The ice pack should be kept for 20 minutes, then removed for 20 minutes, then put on ice again, etc.

Lastly, fistula care time is not counted as hemodialysis time. This is a waste of time for hemodialysis. Otherwise, hemodialysis will not be adequate and the patient will not receive the prescribed dose of hemodialysis. Access care time should be added to hemodialysis time.

Bleeding during hemodialysis

Bleeding during hemodialysis can be a minor problem (bleeding of blood from under the needle) or threatening (if the needle pops out while the blood pump is running). Frequent even slight blood loss during hemodialysis contributes to the development of dialysis anemia and a decrease in the number of red blood cells.

Do not twist dialysis needles. Such actions lead to stretching of the hole made by the needle, and blood will begin to seep out from under the needle. (If leakage has begun, place a sterile drape over the puncture site.) To avoid having to twist the arterial needle, use arterial needles with "side gas" only.

Profuse bleeding means rupture of the vessel. Uncontrolled bleeding is a threatening situation. Call a nurse or doctor immediately.

recycling

Recirculation occurs when purified venous blood partially mixes with blood entering the arterial needle. This mixing means that the already purified blood goes back to the dialyzer for further purification, while the remaining blood is not sufficiently purified. Thus, recirculation makes hemodialysis less effective. Over time, poor dialysis leads to symptoms of uremia. Recirculation occurs in the following cases:

- The blood flow through the fistula is lower than in the dialyzer (< 300-500 мл/мин).

— The needles are too close together.

- Reconnection of blood lines.

— There is a stenosis of the fistula.

In severe cases of recirculation, the same blood is cleared in the dialyzer, so it becomes dark in color due to the complete loss of oxygen (black blood syndrome). More often, recirculation does not cause any rapid symptoms. The presence of recirculation should be checked if a decrease in URR or Kt/V is detected: the blood flow velocity has to be reduced due to high venous pressure or the staff suspects the presence of stenosis.

Puncture needles should be correctly positioned to prevent recirculation. This requires the following steps:

- Palpate the access to know exactly the direction of blood flow.

- Make sure the needle tips are at least 1.5 inches apart.

Late Complications. Steal Syndrome

The steal syndrome consists of several symptoms caused by hypoxia (insufficient supply of oxygen to tissues). This syndrome occurs when the circulation access draws too much blood from the arm, directing it over the access. Patients complain of pain ranging from mild to severe. In most patients, pain subsides over time, as additional vessels develop, the so-called collateral circulation. Angiosurgeons warn that diabetics and those with peripheral vascular disease should be observed very carefully. Their symptoms can be very severe and often require intervention.

To identify the symptoms of "stealing", it is necessary to examine the access and interview the patient:

- Pain in the limb with access.

- Tingling or pinching in a limb with access.

- Feeling of coldness in the accessed limb.

- Change in motor skills of the hand.

- Nail beds turn blue.

- Necrotic (dead, black) spots on the skin.

- Loss of sensitivity of the limb with access.

Tell your nurse or doctor if you suspect you have steal syndrome. You may need to call an angiosurgeon. During hemodialysis, try to keep the patient's limb warm. You can use a mitten, scarf, warm socks. Sometimes changing the position of the patient's hand can increase blood flow in the hand.

Henriksson and Bergqvist found that 5% of arteriovenous fistulas cause steal syndrome). It turned out that steal syndrome can be treated by reducing blood flow through the fistula, dilating the vessels, or ligating some of the vessels surgically.

You need to know that steal syndrome can be treated, so as soon as you notice signs of this syndrome, tell your nurse immediately. Inspection of the fistula by the surgeon should be done as early as possible.

Aneurysm

Puncture of the fistula in the same place after a while leads to the formation of an aneurysm. Template puncture leads to weakness of the muscular wall of the fistula, the formation of protrusions and an inflated appearance of the fistula. Over time, blood flow in the initially normal fistula continues to increase and the fistula vein dilates. Aneurysms often form "upstream" of the bloodstream, retrograde from venous stenosis, especially at the sites of repeated punctures. These places are easily identified at a glance. Watch for enlargement of the aneurysm and note any associated skin changes.

To prevent the formation of aneurysms, use the method of rotation of puncture sites or puncture using the buttonhole method. Do not insert needles into the aneurysm. Aneurysms significantly reduce the availability of puncture sites. If the skin shows signs of imminent tearing, such as thinning, ulceration, or bleeding, surgery is needed.

Stenosis

Stenosis is a narrowing of a blood vessel that slows down the flow of blood through the access.

There are three areas where stenosis most often occurs:

— tributary- the most common type of stenosis in the anastomosis of the artery and vein. It is often referred to as juxta-anastomotic stenosis (JAS). It is formed in the vein immediately after the anastomosis. JAS does not allow the fistula to mature because it does not let enough blood flow into the fistula. JAS occurs due to stretching, torsion, or other trauma during fistula placement. On palpation, JAS is defined as a flattening just behind the anastomosis.

— outflow- stenosis can be located anywhere along the outflowing vein. For example, in a place where a vein was punctured to the patient earlier. The vein after stenosis has a small diameter, which makes puncture difficult and increases the likelihood of infiltration.

— central vein Central venous stenosis occurs in the large veins of the arm, often in the shoulder area. If stenosis is suspected, the entire venous system from the anastomosis to the heart should be examined. This is the only way to detect central stenosis. These stenoses most often result from past central venous catheterization.

Anyone caring for a patient should be aware of the following: symptoms:

— Noise becomes higher or lower.

- The pulse is hard, sometimes resembling water hammer.

- Noise ceases to be continuous: each sound becomes, as it were, separate

- The trill is reduced.

- Problems begin with the puncture of the fistula.

- The limb becomes swollen.

- During hemodialysis, high venous pressure, which causes a decrease in blood flow.

— Recycling.

- Thrombosis of the extracorporeal circle during hemodialysis.

- Increased bleeding time after removal of needles.

- "Black Blood Syndrome"

— Decreased Kt/V and URR.

— The inability to obtain a given blood flow velocity.

Stenosis is caused by damage to the inner surface of the vessel and the formation of a scar that causes turbulence in the movement of blood. In turn, this leads either to the proliferation of muscle cells or the formation of an aneurysm. Stenoses are treatable.

To detect arterial or venous stenosis, a contrast agent is injected into the vessels. In this way, on the radiograph, it is possible to obtain a picture of the narrowing (fistulography, venography). Stenosis can also be detected using color Doppler ultrasound. Ultrasound is a non-invasive technique for studying blood vessels and blood flow. These methods allow the physician to localize the site of the stenosis.

- Some types of stenosis can be eliminated with angioplasty, which is an outpatient procedure. The doctor inserts a catheter with an inflatable balloon at the end into the vessel. Once the balloon has been advanced to the desired site, the balloon is inflated and the lumen of the vessel expands. In other cases, revision of the access and its surgical correction may be necessary.

Thrombosis

Thrombosis (formation of a thrombus or blood clot) occurs in all types of vascular access, but fistulas are 6 times less likely to thrombose than prostheses. There are many components in the blood that stop bleeding from a wound by forming a blood clot. These components are made up of proteins (plasma coagulants) and platelets (platelets) - thin blood cells that tend to clump together and seal the damaged vessel.

Platelets stick together only if they are activated by a damaged vessel wall or by turbulent blood flow within the vessel. Activated platelets and damaged tissues signal clotting proteins to form a fibrin network. Platelets and erythrocytes also enter this network. The clot becomes harder and increases in size.

A clot can start to form in any shape and any location where blood flow is low due to hypotension, dehydration, or too much pressure on the access. Under these circumstances, blood stagnates on damaged surfaces, for example, at the puncture site. If there is a stenosis in the fistula, then blood turbulence in this area may be sufficient to activate platelets and adhere to the vascular wall.

Early thrombosis is most often associated with surgical problems or vascular torsion. Thrombosis also occurs due to stenosis, reduced blood flow due to hypotension on dialysis, cardiac arrest, or vascular compression. Vascular compression can occur after surgery if blood leaks into the tissues to form a hematoma. A hematoma may form as a result of infiltration at the puncture, or if the fistula is used too early after surgery to access the circulation. Prolonged pressing of the fistula under pressure after puncture can also cause thrombosis. Do not press the puncture site for more than 20 minutes. If bleeding continues for more than 20 minutes, the nurse should check the dose of heparin administered and examine the access for possible stenosis or other problems. Late thrombosis can also occur in working fistulas. They are caused by turbulence in the area of ​​stenosis. Untreated thrombosis can destroy the fistula. According to interventional radiologist Dr. Perry Arnold, a thrombosed fistula can be salvaged up to 14 days after thrombosis.

Thrombosis most often occurs due to stenosis or low blood flow. Signs of impending thrombosis:

— Reducing the level of trills and noise.

— Poor blood flow through the access.

- Inability to get good blood flow.

- Sudden swelling of the fistulous arm in a patient with a history of stenosis and blood flow problems.

- Abnormally high venous pressure during hemodialysis.

— High degree of recycling. Always check the position of the needles (their position may cause recirculation) before calling a nephrologist.

- Increased transmembrane pressure (TMP).

Thrombosis is suspected if there is no pulse on the arm, there is no trill and noise over the outflow vein. Thrombosis of a previously functioning fistula usually follows stenosis. Early detection and correction of stenosis can help save access.

Staff should be aware of key information about signs of stenosis and thrombosis. Cases of poor access blood flow, decreased trilling and noise over the access, and swelling of the arm should be reported. If you correctly insert the needles, when you turn off, moderately press the puncture site, this will reduce the risk of thrombosis.

Monitoring of vascular access can identify patients at risk of developing thrombosis. KDOQI (Clinical Practice Guidelines for Vascular Access) recommends an access monitoring program. AVF monitoring consists of measuring static and dynamic venous pressure, measuring blood flow velocity, and duplex ultrasound. An access monitoring program helps improve access survivability by identifying problems early.

Access thrombectomy can be performed surgically, mechanically and chemically (using drugs that dissolve the clot). In more than 90% of cases, the cause of thrombosis is stenosis. Stenosis can be corrected with surgery or angioplasty after the clot has been removed.

High output heart failure

Arteriovenous fistula may be one of the causes of high output heart failure. This condition is due to the following factors:

A fistula brings more blood to the heart.

- It is harder for the heart to work, overcoming the resistance of the arteries.

- Blood pressure drops.

- Lowering blood pressure activates the renin-angiotensin system.

Patients with heart failure due to high output have a rapid pulse, as their heart must pump the additional volume of blood coming from the access (20% or more). Patients may be short of breath if the blood contains insufficient oxygen. There may be swelling in a fistulous arm or leg due to poor blood flow to the heart. Over time, if these problems are not addressed, chest pains, fluid accumulation in the lungs, heart rhythm disturbances and death begin.

High output heart failure also occurs due to anemia or due to heart disease that the patient had before the installation of circulation access. Therefore, the best way to prevent high output heart failure is to correct the anemia and create an access that does not harm the heart significantly.

If high output heart failure is present, interdialysis weight gain should be limited. This will significantly reduce the load on the heart. Longer or more frequent dialysis may help with this problem. They also prescribe medications that help the work of the heart. Ask patients to report general well-being and activity levels. Occasionally, surgery may be required to reduce access shunting. Surgeons perform either anastomosis tie or complete fistula ligation.

And also read about dialysis on our website:

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Chronic renal failure (CRF) is an inevitable outcome of a number of kidney diseases. The number of patients with chronic renal failure is constantly growing. In 2014, 2 million people in the world had the last (terminal) stage of CKD, i.e. were on hemodialysis, peritoneal dialysis or needed a donor kidney.

Over the past 20 years, the number of such patients has quadrupled. The number of patients with the initial stage of CRF exceeds the number of patients with the last stage of CRF by more than 50 times. Currently, the number of patients increases annually by 10-12%.

Adequate hemodialysis therapy requires a permanent vascular access (PSA) and regular monitoring of its condition. An ideal vascular access is recognized as one that ensures that the blood flow rate corresponds to the prescribed dose of dialysis, functions for a long time (many years) and has no complications. Currently, none of the known variants of PSD is ideal, however, the native arteriovenous fistula (AVF) satisfies the requirements to a greater extent.

Complications associated with PSD are a major cause of morbidity, hospitalization, and increased cost of treatment in patients on permanent hemodialysis (PGD). Vascular access procedures require hospitalization of 14 to 45% of hemodialysis patients, and the costs represent 10% of the budget allocated for the treatment of patients with CKD: for example, such costs in the United States are estimated at more than 1 billion dollars annually.

Improvement in the quality of PGD and an increase in patient survival lead, along with a shortage of kidney transplants, to a lengthening of the time spent by patients on PGD. As a result, the requirements for a longer functioning of vascular accesses increase. On the other hand, among patients in need of the formation of primary PDS, the proportion of elderly people suffering from diabetes mellitus and cardiovascular diseases is growing, which leads to an increase in both the intensity of vascular interventions and technical difficulties in the formation of PDS.

Although significant progress has been made in dialysis technology in recent years, certain problems associated with providing permanent vascular access remain unresolved. Numerous studies are devoted to the issues of planning, priority of the type of PDS, options for treatment tactics in the development of complications.

With regard to the period of creation of the DED, there is a single point of view. The optimal situation is recognized when it is possible to form a design estimate at least a few months before the expected start of PGD. Most authors believe that such a moment occurs when the blood plasma creatinine is 4-5 mg / dl and the glomerular filtration rate is 15-25 ml / min.

The advantages of this approach are obvious: a margin of time for the “ripening” of the AVF and healing of the postoperative wound, the achievement of adequate blood flow through the AVF, the absence of the need for temporary vascular access with its attendant complications (infection, stenosis of the main vein, arterial damage). Nevertheless, the problem remains relevant due to the fact that the proportion of patients in whom PDS is formed in advance remains insufficient and, according to various authors, ranges from 32 to 50%.

Over the four decades of its existence, hemodialysis has become a completely independent and full-fledged discipline that has contributed to the development of an entire branch of the medical industry. During this period, a lot of experience has been accumulated and analyzed in the long-term replacement of lost kidney function in hundreds of thousands of patients.

The problem of hemodialysis reached a qualitatively new level at the beginning of the 19th century, when, with the development of biochemistry, many processes became clear, which subsequently formed the basis of renal replacement therapy. The physical foundations of hemodialysis were laid in 1854 by the Scottish scientist Thomas Graham, who published his work “Osmotic Force”, in which he first described a method for manufacturing semi-permeable membranes from specially treated parchment for separating colloidal and crystalloid solutions.

The first human hemodialysis (a patient suffering from uremia) was carried out in Germany by the doctor Georg Haas in October 1924. Purified hirudin was used as an anticoagulant. In 1927, heparin was used as an anticoagulant for the first time in hemodialysis. Thus, Haas was the first to bring together all the ingredients needed for successful hemodialysis.

For the first time, the successful removal of a person from a uremic coma using hemodialysis was carried out on September 3, 1945 by the Dutch physician Willem Kolf. Thus, in practice, the clinical effectiveness of the method has been unequivocally proven. In 1946, Willem Kolff published the first guidelines for the treatment of uremia patients with hemodialysis.

The beginning of the era of chronic hemodialysis is considered to be 1960, when Belding Scribner and Wayne Quinton managed to solve the problem of long-term vascular access, which was provided by implanting two thin-walled Teflon tubes into the radial artery and saphenous vein. This technique in the vast majority of cases required ligation of vessels at the end of the procedure and led to a rapid depletion of the vascular resource.

Vessel catheterization according to the method of S. I. Seldinger, first used by S. Shaldon in 1961, was associated with a high risk of infectious, hemorrhagic and thromboembolic complications. With the improvement of the materials used and the introduction of the so-called permanent catheters, the duration of their stay in vivo has increased significantly, and recently they can be considered as a permanent vascular access.

This technique, however, has many disadvantages, and therefore it is used in somatically severe patients with an exhausted vascular resource, and also as an intermediate access during the formation of a permanent one. Priority at the puncture site today is as follows: jugular vein; femoral vein; subclavian vein.

The introduction of long-term hemodialysis into wide clinical practice began after the proposal of VN Scribner (1960) to use an external arteriovenous shunt in the forearm for repeated procedures. The proposed shunt was originally made of Teflon. Subsequent use of shunts with Dacron and Teflon cuffs made it possible to avoid the development of infections, damage to the intima and, as a result, its hyperplasia. However, the high level of complications and the limited duration of operation of such shunts (maximum 1–2 years for the arterial segment, 10–12 months for the venous segment) do not allow their use as a permanent vascular access.

A breakthrough in the field of providing permanent vascular access was achieved after the development of M. J. Brescia and J. E. Cimino in 1996, the operation to create a subcutaneous arteriovenous fistula. It was proposed to form a vascular anastomosis between a. radialis and v. cephalica in the region of the lower third of the forearm according to the "side of the vein to the side of the artery" type. Currently, the priority is the method of anastomosis on the principle of the end of the vein in the side of the artery, less often the end of the vein in the end of the artery.

In 20% of patients, at a certain stage of hemodialysis, one has to resort to the implantation of vascular prostheses as an alternative to arteriovenous fistula, since the possibilities of using one's own vessels are completely exhausted. The main indications for the use of vascular prostheses are the features of the anatomical structure of peripheral vessels (insufficient diameter, loose type of structure), their pathological changes (thrombosis, stenosis, phlebitis, aneurysm), as well as previous surgical interventions.

Numerous varieties of vascular prostheses make up three main groups: biological (autovein, allovein, alloartery, xenografts), semi-biological (prosthesis from a human umbilical cord vein), synthetic (dacron, polytetrafluoroethylene).

The high frequency of thrombosis and occlusion in the late postoperative period due to the rapidly progressive biodegradation of the venous graft, the trauma and duration of surgery prevented the widespread use of autografts.

The best results were achieved when using synthetic materials for the manufacture of vascular prostheses (dacron, lavsan, velor, mandrill, polytetrafluoroethylene, polyurethane). Clinical studies have shown the absolute advantages of synthetic vascular prostheses (SSP) made of polytetrafluoroethylene (PTFE), produced under various commercial names (Goretex, DIASTAT, Impra, Vectra, etc.).

PTFE SSP is inert, mechanically and chemically stable, resistant to biological degradation, highly thrombo-resistant, elastic, does not deform when bent, simple and easy to use. The microporous structure of PTFE allows connective tissue and blood vessels to grow inside the prosthesis, promotes the formation of neointima and connective tissue capsule, giving it the properties of a semi-biological substitute.

The initial attempts at total application of SSP showed that this method has no significant advantages over native AVF, and is significantly inferior to it in a number of indicators.

In recent years, there has been a tendency both to limit the indications for the use of SSP as a primary vascular access, and to increase the proportion of operations with the use of vascular prostheses when performing repeated accesses and reconstructive interventions.

This is due, on the one hand, to the shorter duration of the SSP functioning and the large number of necessary corrective procedures (thrombectomy and angioplasty) in the immediate and late postoperative periods compared to native AVFs. In addition, CVDs are a serious risk factor for the development of infectious complications.

On the other hand, improving the quality of hemodialysis leads to an increase in both life expectancy and the proportion of elderly patients and those with comorbidities. This requires an increase in the duration of the functioning of the DPM. In such a situation, vascular prostheses are an indispensable element when performing multiple repeated surgical interventions for the formation of new and reconstruction of existing vascular accesses.

The use of cuffed silicone intravenous catheters, which has become widespread in recent years, is justified, and in many cases the only one acceptable for chronic hemodialysis when it is impossible or inappropriate to form PDS in a certain category of patients (with an exhausted resource of native vessels, the impossibility of hemodialysis, young children, patients with diabetes, etc.).

However, only about 30% of cuffed catheters remain functional after 1 year, even with thrombectomy performed, and the incidence of infectious complications and mortality significantly exceed those with AVF formation and SSP implantation. All this does not allow us to fully attribute this type of vascular access to the category of permanent access.

Candidates for cuffed intravenous catheters should only be considered for patients who are unable to form PDM or receive replacement therapy by peritoneal dialysis.

In recent years, a fundamentally new variant of vascular access has been proposed for clinical use, combining the advantages of an intravenous catheter (sufficient blood flow in the main vein, minimal effect on cardiac output, ease of installation) and subcutaneous punctures (prevention of infectious complications) - the device "Dialock hemodialysis system" (" Biolink Corp.") and "LifeSite hemodialysis access system" ("Vasca Inc.").

The system consists of a multiple puncture port implanted subcutaneously in the subclavian region and connected to two silicone catheters placed through the jugular vein into the right atrium or superior vena cava. It is assumed that such systems should become an alternative to intravenous catheters (including cuffed ones) and provide safe temporary vascular access for the period of formation and “maturation” of a permanent one. Taking into account the small to date world experience in the application of this method, it is not possible to fully evaluate its effectiveness.

Most hemodialysis centers suggest that the strategic direction for improving the safety of the function of PSD is not the formation of a new vascular access, but the provision of the longest possible function of the existing one through the timely diagnosis of complications, percutaneous intervention and angioplasty, stenting, and surgical reconstruction.

After summarizing all available data, the vascular access working group concluded that the quality of life of hemodialysis patients and overall treatment outcomes can be markedly improved if the number of formed native AVFs increases and access dysfunction is recognized before its thrombosis develops.

To this end, considerable attention has been paid to the characteristics of the blood flow of the PSD by the methods of angiography, ultrasound, thermodilution, determination of venous resistance and recirculation. It has been proven that prospective monitoring and correction of hemodynamically significant stenosis improves the function of vascular access and reduces the number of complications, primarily thrombosis.

Despite the availability of a wide range of methods for the formation of permanent vascular access, which surgeons own, there are many unresolved problems. The main, perhaps, is stenosis and, as a result, thrombosis of the anastomosis due to the formation of neointima. Constant punctures of dialysis veins and vascular prostheses with thick needles cause protective processes of inflammation, local parietal thrombus formation. In the case of the end of the hemodialysis procedure, this process has beneficial effects, contributing to the closure of the puncture holes and preventing bleeding. In general, it leads to endothelial dysfunction and neointimal hyperplasia.

The endothelium is involved in both the initiation and completion of the inflammation process due to protein receptors (intercellular adhesion molecule-1 - ICAM-1, vascular adhesion molecule-1 - VCAM-1, endothelial leukocyte adhesion molecule-1 - ELAM-1) and cytokines secreted into the lumen of blood vessels (modified lipoproteins, inflammatory cytokines, vasoactive peptides, neuropeptides P- and E-selectins). Leukocyte adhesion molecule activators such as E-selectin, P-selectin, ICAM-1 and VCAM-1 allow leukocytes to attach to the endothelium and then move into tissues, increasing the local inflammatory response. Inflammation is one of several factors that can alter endothelial cell function and cause damage to the endothelial layer.

To date, data have been accumulated on the versatility of the influence of the endothelium on the emergence and development of various pathological conditions. This is due not only to the participation of endotheliocytes in the regulation of inflammation, but also to their direct effect on vascular tone, hemorheology and thrombus formation, protection of the integrity of the vascular wall, regulation of atherogenesis and other processes. Hemodialysis itself causes oxidative stress and the development of endothelial dysfunction (nitric oxide, endothelin 1, von Willebrand factor, etc.). Markers of endothelial dysfunction are currently well studied.

It was established that hemodialysis causes an increase in the concentration of monocytic chemoattractant protein 1, hepatocyte growth factor and pentaxin-3, a decrease in the level of asymmetric dimethylarginine and nitrate/nitrite was recorded. The serum obtained after hemodialysis stimulates the proliferation of endothelial cells. Hemodialysis-induced intravascular inflammation alters endothelial function, which can lead to the formation of neointima, obstruction of 60% of AVF and vascular prostheses within 2 years.

Endothelial cells of arteriovenous fistulas from uremia mice or hemodialysis patients are capable of expressing mesenchymal markers (FSP-1 and/or a-SMA), they are also characterized by increased expression and nuclear localization of the Notch intracellular domain. In addition, endotheliocytes derived from AVF from uremic mice showed a decrease in the level of VE-cadherin and an increase in the expression of Notch-1 and -4, Notch ligands, Notch transcription factor, RBP-JK, and target Notch genes.

Ectopic expression of Notch ligands or exposure of TGF-]31 in cultured endotheliocytes were trigger mechanisms for the expression of mesenchymal markers and caused endothelial dysfunction. Both mechanisms can be blocked by Notch inhibition or RBP-JK knockout. These results suggest that an increase in TGF-pi levels as a complication of uremia activates the Notch domain in endothelial cells, which leads to the progressive formation of neointima and obstruction of arteriovenous fistulas. Suppression of Notch activation may be a new strategy to improve AVF patency in uraemic patients.

Interesting data are presented on the content of nitric oxide in patients with chronic renal failure treated with hemodialysis. Nitric oxide levels in CKD patients on hemodialysis were markedly elevated, which is associated both with the hemodialysis procedure itself (stimulation of cytokine-induced NO synthase) and with stimulation of nitric oxide production by platelets against the background of uremia. High concentrations of nitric oxide act as cytotoxic molecules leading to dialysis complications due to nitrosative stress.

Since nitric oxide production correlates with creatinine and urea concentrations, a high level of nitric oxide may indicate insufficient blood purification. Therefore, changes in kidney function, which are reflected in fluctuations in creatinine concentration, will be accompanied by changes in the level of nitric oxide, the determination of which in peripheral blood can be useful in assessing the effectiveness of hemodialysis and used to determine the prognosis in patients with chronic renal failure. The study of the mechanisms of development of endothelial dysfunction and intimal hyperplasia can improve understanding of the processes leading to stenosis and thrombosis of permanent vascular access.

Thus, extensive knowledge has been accumulated in the field of surgical and endovascular methods for creating, correcting and maintaining the patency of a permanent vascular access in dialysis patients. Developments are underway to improve materials for the creation of vascular prostheses, the search for a new, ideal vascular access.

Currently, this is a native arteriovenous fistula. The search for medical methods for the correction and prevention of possible complications will contribute to the “life extension” of the ideal vascular access already available today.

R. E. Kalinin, I. A. Suchkov, A. S. Pshennikov, N. D. Mzhavanadze, A. A. Egorov