Lifeline of Dialysis for Uremic Patients – Hemodialysis Access
Uremic patients need regular peritoneal dialysis or hemodialysis to remove harmful substances from their bodies and maintain the balance of their internal environment. The hemodialysis access, commonly known as fistula, is the lifeline to maintain them. If the hemodialysis access is poor or occluded, they cannot be hemodialysed or cannot reach the required dialysis volume, they face serious complications such as metabolic acidosis, hyperkalemia and cardiac failure, which eventually lead to death. Therefore the establishment and maintenance of hemodialysis access is crucial for patients in the chronic uremic phase.
With the support and cooperation of the Department of Nephrology, the Department of Vascular Surgery of Peking University Hospital has accumulated rich experience in the establishment of hemodialysis access and the management of difficult cases, and has accumulated thousands of cases, with an annual average of 400 surgeries and a success rate of over 95%. The success rate is more than 95%. We are the first in China to establish a series of treatment standards, including (1) the establishment of a system of preoperative evaluation and postoperative follow-up using ultrasound, contrast and CT, which ensures a high success rate of surgery through accurate preoperative assessment of vascular conditions. ②The selection method of hemodialysis access strictly follows international guidelines, and the improvement of surgical skills has greatly increased the proportion and success rate of autologous arteriovenous fistulas. ③The establishment of artificial vascular arteriovenous fistula and the management of complications, the number of cases is leading in China. ④The first to carry out intracavitary treatment of hemodialysis access, greatly reducing the length of hospitalization and surgical trauma for patients. ⑤The first to carry out the treatment of central venous stenosis or occlusion, with distinctive features.
So what are the frequently asked questions?
1.What is the role of dialysis?
The two basic functions of the kidneys are: First, to remove the waste produced by the body after metabolism. Second, to maintain the balance of chemicals and water in the body. When the kidney has lost its proper function in the uremic phase of renal failure, dialysis is needed to replace the function of the kidney, otherwise, complications such as hyperkalemia, metabolic acidosis and heart failure will occur and endanger the life.
2.How many methods of dialysis are there?
There are two types of dialysis, hemodialysis and peritoneal dialysis. Peritoneal dialysis involves the surgical placement of a small tube in the lower abdomen through which the dialysis solution enters the abdominal cavity and remains there for several hours, and then the dialysis solution carrying the metabolic wastes in the body is drawn out. Hemodialysis directs the blood flow from the body to the hemodialysis machine through the puncture of a needle, which cleans the machine and then returns clean blood to the body through another puncture needle.
3.Which dialysis method to choose?
The choice of dialysis method generally depends on the patient’s wishes, lifestyle, age, vascular condition and various other conditions. If the patient is not too old, has good vascular condition, stable heart function, and can go to the hospital three times a week, hemodialysis treatment is recommended. On the contrary, if the blood vessels are not good, the heart function is unstable, no abdominal surgery has been done, the mobility is limited, and the home caregiver is highly qualified, you can choose peritoneal dialysis, because peritoneal dialysis requires the caregiver to learn the disinfection of the home environment and the operation of peritoneal dialysis, etc.
4. Is there anything to note about the diet of dialysis patients?
Regardless of the type of dialysis chosen, as long as the dialysis is adequate, the diet is generally not too restrictive. A little attention should be paid to the following: high quality protein, high calcium, adequate calories, low potassium, low phosphorus, and vitamin-rich diet. If edema is present, water is subject to restriction. Daily water intake = previous day’s urine volume + 500 ml – water content of all foods and medications. The protein intake for peritoneal dialysis requires eating more.
5. Does a hemodialysis “fistula” involve putting a tube in the body?
Many patients think that a hemodialysis fistula is a tube surgically placed in the forearm for hemodialysis, but this is not the case. During hemodialysis, blood from the body quickly enters the dialyzer, is washed, and then flows back into the body, a process that is repeated several times a week. The superficial veins of the upper limbs are easy to puncture, but because the venous blood flow is too slow, the blood flow is difficult to meet the requirements of dialysis; the arteries or deep veins have high blood flow and can meet the requirements of hemodialysis, but the site is deeper, making puncture difficult and not easy to use repeatedly. Therefore, it is necessary to surgically connect the artery to the superficial veins of the upper limbs, called arteriovenous endovascular surgery or fistula. In this way, arterial blood flows in the superficial vein, and during hemodialysis, the superficial vein is directly punctured so that the blood flow meets the requirements of dialysis and can be repeatedly punctured for regular hemodialysis. This method is the most common clinical procedure, which is less invasive and usually involves a 2 to 4 cm incision at the wrist or elbow, and is only an anastomosis of the arteries and veins, without putting any tubes in the body.
When do I need an endovascular arteriovenous fistula?
When the patient does not have a suitable superficial vein for puncture, such as a thin or discontinuous vein, or arteriosclerosis or arterial stenosis, or when the patient is too obese in the upper extremity and the superficial vein is too deep to be punctured, an endovascular arteriovenous fistula is proposed. A 40-cm-long artificial vessel is buried under the skin, and the two ends are connected to the artery and vein of the patient’s own body, and during hemodialysis, the artificial vessel is punctured under the skin. Because the artificial vessel is 6mm in diameter, it can be easily punctured. The material of artificial blood vessel is polytetrafluoroethylene expanded, so there is no need to worry about rejection by the body.
7.Why is it necessary to establish hemodialysis access in advance?
Neither autologous endovenous fistula nor artificial vascular arteriovenous fistula can be used immediately, but need to wait for a certain period of time. Autologous arteriovenous fistula needs to wait for the fistula to “mature”, that is, and the arterial connection of its own superficial vein expansion, vein wall hypertrophy, in order to penetrate the hemodialysis, usually 4-8 weeks after surgery, otherwise the vein wall is too thin, the vein is too thin, difficult to puncture, too early to puncture the puncture point is not easy to retract to stop bleeding, resulting in hemorrhage or to stop bleeding pressure too tight and fistula blockage The fistula may become blocked due to hemorrhage or pressure to stop bleeding. Theoretically, there is no need to wait for the vessels to “mature” after surgery, they can be punctured immediately, but often after surgery local swelling, it is impossible to feel the artificial blood vessels, and the artificial blood vessels and surrounding tissues have not yet healed, hematoma and secondary infection can easily occur after puncture, affecting the use of endovascular fistula, therefore, generally used in January after surgery.
8.What if I need emergency hemodialysis?
A deep vein cannula can be inserted into a deep vein and can be used immediately. There are generally four areas of the body that can be cannulated, namely the bilateral neck and bilateral groin. However, because one end of the catheter is exposed on the skin surface and one end is placed directly into the circulatory system, it is easy to cause infection. Deep vein hemodialysis cannulation is mainly used as an emergency access or the last access for hemodialysis patients.
9. How is the surgical site chosen?
Usually patients who use their right hand choose to operate on their left hand, and patients who use their left hand choose to operate on their right hand, but only if the vascular conditions of both upper limbs are similar, otherwise the side with better vascular conditions is chosen according to the doctor’s judgment. The first choice is to choose an autologous arteriovenous endovascular fistula, then consider an artificial vascular arteriovenous endovascular fistula, and finally consider long-term hemodialysis intubation, and consider the forearm, then the upper arm, then the lower extremity or chest wall.
10.How long is the life span of hemodialysis access?
Generally, the life span of an autologous arteriovenous fistula is longer, with fewer complications, up to more than 10 years. The life span of an arteriovenous fistula is shorter than that of an autologous arteriovenous fistula, and there may be blood clots blocking the arteriovenous vessels. The main reason for this is that scar tissue is created at the site where the artificial vessel meets the vein, narrowing the anastomosis and causing blood clots to form when the narrowing is >50%. This can be repaired surgically and continues to be used without the need for a new artificial vessel. When the artificial blood vessel has been used for many years and has been damaged by numerous hemodialysis punctures, then a new artificial blood vessel is considered. The longest artificial vessel in our hospital has a lifespan of 10 years. Although the life span of an artificial vessel arteriovenous endovascular fistula is not long, it allows for multiple procedures and preserves the opportunity for eventual deep vein hemodialysis cannulation to extend the life span of hemodialysis and extend life as long as possible.
11.What are the possible postoperative complications?
Common postoperative complications include infection, thrombosis, endothelial proliferation, pseudoaneurysm, distal limb ischemia, and heart failure. Generally, the complication rate of artificial vascular arteriovenous endovascular fistula is higher than that of autologous arteriovenous endovascular fistula.
12.What should I do if my arteriovenous fistula is blocked?
A blockage of an arteriovenous fistula is often caused by a narrowing of the puncture site or scar tissue at the anastomosis, so the simple solution is to create a new fistula at the proximal end of the blockage, which is ready for hemodialysis as soon as the vein wall is thickened.
What should I do if I have a blocked arteriovenous fistula?
After an artificial vessel thrombosis, the traditional method can be to surgically cut the artificial vessel with a small incision, remove the thrombus inside the artificial vessel with a special catheter, and surgically repair the stenosis, if any. Since 2009, our department has been the first in China to adopt the method of local puncture thrombolysis, in which a fine needle punctures the artificial vessel fistula, removes the thrombus in the artificial vessel by injecting thrombolytic drugs, and then imaging shows the stenosis, dilates the stenosis with a balloon, and restores the access (Figure 3-5). More than thirty cases have been treated, with little trauma, no surgical trauma, no interference with hemodialysis, and no need for deep vein placement.
13.What is the swelling of the limb of the hemodialysis access?
Limb swelling is often caused by venous stenosis or occlusion in the pathway of hemodialysis back to the heart. A large amount of blood flow connected with arteries cannot return to the heart smoothly, thus causing limb swelling, superficial varicose veins, severe skin pigmentation, and even ulceration and necrosis. Patients are in great pain and in severe cases even want to amputate the affected limb to relieve the pain. At the same time, swelling and venous hypertension increase the difficulty of hemodialysis puncture, easily cause bleeding and hematoma, increase the chance of infection, and increase the chance of hemodialysis access thrombosis. The most common cause is venous stenosis due to deep venous cannulation. Generally, endoluminal treatment is used to dilate the stenosis or occluded segment with a balloon, and then a stent is placed to restore the diameter of the ileocardial vein, which relieves the symptoms and keeps the fistula unobstructed.
14. The significance of vascular ultrasonography.
Preoperative use can help to select the appropriate artery or vein, detect any stenosis or occlusion, and improve the success rate of surgery. Postoperative use can monitor the stenosis of the fistula, and if the stenosis is >50%, early intervention by balloon dilation or placement of an intravascular stent can be used to reduce the occurrence of thrombosis and improve the service life of the fistula.
15. Post-operative care of hemodialysis access
The hemodialysis access is a lifeline for patients with renal failure, and no access can be maintained for life, so proper use of the internal fistula and careful care are important to prolong its use.
Learn how to judge the patency of the endovascular fistula, i.e., pulsation, tremor or vascular murmur can be felt locally on the anastomosis and venous side, and if the tremor, pulsation and murmur disappear, contact the doctor immediately for timely treatment.
In the early postoperative period, the limb on the operated side is elevated to promote venous blood return to reduce the degree of swelling.
For autologous arteriovenous endovascular fistulas, to promote the maturation of the endovascular fistula as soon as possible, some fistula-building exercises can be done, such as squeezing and pinching rubber bands, with or without tourniquets to increase blood flow and accelerate the maturation of the newly made autologous endovascular fistula.
DO NOT.
1) Do not touch the skin of the puncture site during hemodialysis.
2) Do not wear tight clothing, shirts with small cuffs, or watches on the hand where the artificial vessel is placed.
3) Do not carry heavy objects, hang bags or use them as pillows, or measure blood pressure with the operated hand.
4) Never use an arteriovenous fistula or artificial blood vessel for intravenous injection or blood sampling.
Always.
1) Do wash your arm before hemodialysis.
2)Take your medication as ordered by your doctor and do regular exercise in general.
3) Apply gentle pressure to stop the bleeding after the puncture needle is removed. Before you leave the hemodialysis room, ask the staff to help you make sure the bleeding has stopped before you leave.
4) Rotate puncture sites and avoid repeated punctures in the same area to prolong the life of the artificial vessel.
5) Signs that you may need to see a doctor.
6) Swelling, localized skin redness or discharge, which is a sign of infection.
7) Localized pain with chills and high fever, which is also a sign of infection.
8) Diffuse bruising indicates that the hemodialysis puncture site is still bleeding under the skin.
The presence of pulsating hard nodules on the skin surface indicates repeated punctures in the same area, causing fistula damage and pseudoaneurysm.
Coldness, numbness, soreness, or weakness in the hand indicates inadequate arterial blood supply; this is uncommon, but should be seen by a physician.
Loss of fistula tremor indicates that the flow of blood has stopped and there is a possibility of obstruction.