Maintaining the lifeline of hemodialysis patients – hemodialysis access
Patients with renal failure need regular peritoneal dialysis or hemodialysis to remove harmful substances from the body and maintain the balance of the body’s 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 uremic phase of chronic renal insufficiency.
We have taken the lead in establishing a series of treatment standards in China, including: ① Establishment of preoperative assessment and postoperative follow-up system using ultrasound, contrast and CT, which ensures an extremely high success rate of surgery through accurate preoperative assessment of vascular conditions. ②The way of selecting 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 common problems?
What is the role of dialysis?
The two basic functions of the kidneys are: First, to remove the waste products 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 stage of kidney failure, it needs to be replaced by dialysis, otherwise there will be complications such as hyperkalemia, metabolic acidosis, heart failure and other life-threatening conditions.
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 dialysis solution enters the abdominal cavity and remains there for several hours, after which the solution is drawn out carrying metabolic waste. Hemodialysis is performed through a needle puncture that directs blood flow from the body to a hemodialysis machine, where it is cleaned and clean blood is returned to the body by another puncture needle.
What type of dialysis is chosen?
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, 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.
Is there anything I should know 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: good quality protein, high calcium, adequate calories, low potassium, low phosphorus, and a 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 food and medications. For peritoneal dialysis, a higher protein intake is required.
Does a hemodialysis “fistula” involve putting a tube in the body?
Many patients think that a hemodialysis fistula is created by surgically placing a tube 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, a surgical method is needed to connect the artery to the superficial veins of the upper extremity, called arteriovenous endovascular surgery or fistula (Figure 1). 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 artery and vein, without putting any tube 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 performed. 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 (Figure 2), and during hemodialysis, the artificial vessel is punctured under the skin. Because the artificial vessel has a diameter of 6 mm, it is easy to puncture. The material of the artificial blood vessel is polytetrafluoroethylene expanded, so there is no need to worry about rejection by the body.
Why is it necessary to establish hemodialysis access in advance?
Neither autologous endovenous fistula nor artificial vascular arteriovenous fistula can be used immediately, but it is necessary to wait for a certain period of time. Autologous arteriovenous fistulas need to wait until the fistula is “mature”, that is, the superficial veins connected to the arteries themselves are dilated, the vein wall is hypertrophic, before puncturing hemodialysis, usually 4-8 weeks after surgery, otherwise the vein wall is too thin, the vein is too thin, puncture is difficult, too early to puncture the puncture point is not easy to retract to stop bleeding, resulting in hemorrhage or to stop bleeding pressure is too tight and the fistula is blocked. The fistula may become blocked due to hemorrhage or pressure to stop bleeding. Theoretically, there is no need to wait for the blood vessels to “mature” after surgery, and they can be punctured immediately. However, the local swelling after surgery often makes it impossible to feel the artificial blood vessels, and the artificial blood vessels have not yet healed with the surrounding tissues, so hematoma and secondary infection can easily occur after puncture, which affects the use of the fistula, so it is usually used in January after surgery.
What if I need emergency hemodialysis?
A deep vein cannula can be inserted into a deep vein for immediate use. 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 as a last resort for hemodialysis patients.
How is the site chosen?
Usually patients with right handedness choose to operate on the left hand and patients with left handedness choose to operate on the 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 procedure is performed on the forearm, then on the upper arm, and then on the lower extremity or chest wall.
What is the lifespan of hemodialysis access?
Generally, the life expectancy of an autologous endovascular fistula is longer, with fewer complications, up to 10 years or more. 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 vessel. 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 9 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.
What are the possible post-operative complications?
Common postoperative complications include infection, thrombosis, endothelial proliferation, pseudoaneurysm, distal limb ischemia, and heart failure. Complication rates are generally higher for prosthetic arteriovenous fistulas than for autologous arteriovenous fistulas.
What should I do if my arteriovenous fistula is blocked?
The simple solution is to create a new fistula at the proximal end of the blockage, since the vein wall is already thickened, the new fistula can be hemodialyzed immediately after creation.
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 minimal trauma, no surgical trauma, no interference with hemodialysis, and no need for deep vein placement.
What is the swelling of the limb of the hemodialysis access?
Limb swelling is often caused by venous stenosis or occlusion in the hemodialysis pathway back to the heart. A large amount of blood flow connected to the 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. Endoluminal treatment is usually used, with balloon dilation of the stenotic or occluded segment followed by placement of a stent to restore the diameter of the ileocardial vein, which relieves symptoms while keeping the fistula open.
Significance of vascular ultrasonography.
Preoperative use can help select the appropriate artery or vein, detect any stenosis or occlusion, and improve the success rate of the procedure. Postoperative use can monitor the stenosis of the fistula, and if the stenosis is >50%, early intervention by balloon dilation or placement of an endovascular stent can be used to reduce the occurrence of thrombosis and improve the service life of the fistula.
Post-operative care of hemodialysis access
Hemodialysis access is a lifeline for patients with renal failure, and no access can be maintained for life, so proper use and careful care of the internal fistula is 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.
Do not touch the skin at the puncture site during hemodialysis.
Do not wear tight clothing, shirts with small cuffs, or watches on the hand where the artificial vessel is placed.
Do not carry heavy objects, hang bags or use them as pillows, or measure blood pressure in the operated hand.
Do not use an arteriovenous fistula or artificial blood vessel for intravenous injections or blood draws.
Always.
Do wash your arm before hemodialysis.
Take your medications as ordered by your doctor and do regular exercise during the day.
Apply gentle pressure to stop the bleeding after the puncture needle is removed and ask the staff to help make sure the bleeding has stopped before you leave the hemodialysis unit.
Rotate puncture sites and avoid repeated punctures in the same area to prolong the life of the artificial vessel.
Signs that you may need to see a doctor.
Swelling, localized redness of the skin or discharge, which is a sign of infection.
Localized pain with chills and high fever, which is also a sign of infection.
Diffuse bruising indicates that the hemodialysis puncture site is still bleeding under the skin.
Pulsating hard nodules on the skin surface indicate repeated punctures in the same area, resulting in 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.