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, establishing and maintaining hemodialysis access is crucial for patients in the uremic phase of chronic renal insufficiency.
l What is the role of dialysis?
The two basic functions of the kidneys are: i. 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 kidneys have lost their proper function in the uremic stage of renal failure, dialysis is needed to replace the kidneys’ function; otherwise, complications such as hyperkalemia, metabolic acidosis and heart failure will occur and endanger the life.
l 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 a few hours, after which the solution is drawn out carrying metabolic wastes. Hemodialysis directs the blood flow from the body to the hemodialysis machine through a needle puncture, where it is cleaned and clean blood is returned to the body by another needle puncture.
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, and mobility is limited, the home caregiver can choose peritoneal dialysis if he is highly qualified, 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 the following: high 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 foods 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 human body rapidly 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 it difficult to puncture and not easy to use repeatedly.
When do I need an arteriovenous endovascular 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’s upper extremity is too obese and the superficial vein is too deep to be punctured, then an endovascular arteriovenous fistula procedure is recommended. 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 fistula needs to wait for the fistula to “mature”, i.e., the superficial veins connected to the arteries themselves are dilated, the vein wall is hypertrophic, before puncturing the hemodialysis, usually 4-8 weeks after surgery, otherwise the vein wall is too thin, the vein is too thin, puncture is difficult, too early 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 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 as the last access for hemodialysis patients.
How is the site chosen?
Usually patients with right handedness choose the left hand for surgery and patients with left handedness choose the right hand for surgery, but only if the vascular conditions of both upper limbs are similar, otherwise the side with better vascular conditions is chosen according to the surgeon’s judgment. The procedure should be performed on the forearm, then the upper arm, and then the lower extremity or chest wall.
What is the lifespan of hemodialysis access?
Autologous endovascular fistulas generally have a longer lifespan 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. A new artificial vessel is considered only after years of use and after it has been destroyed by numerous hemodialysis punctures. 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.
l What are the possible postoperative complications?
Common postoperative complications include infection, thrombosis, endothelial proliferation, pseudoaneurysm, distal limb ischemia, and heart failure. The complication rate is generally higher for prosthetic arteriovenous fistulas than for autologous arteriovenous fistulas.
What should I do if my arteriovenous fistula is blocked?
A blockage 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.
What should I do if I have a blocked arteriovenous fistula?
When an artificial vessel is thrombosed, the traditional method is to surgically incise the artificial vessel with a small incision, remove the thrombus from the artificial vessel with a special catheter, and surgically repair the stenosis, if any. The method of local puncture thrombolysis can also be used, 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 area, dilates the stenosis area with a balloon, and restores the access. This method is less invasive, has no surgical trauma, does not affect hemodialysis, and does not require deep vein placement.
l 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 with arteries cannot return to the heart smoothly, thus causing limb swelling, superficial varicose veins, severe skin pigmentation, and even ulcers 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 generally used, with balloon dilation of the stenotic or occluded segment followed by stent placement to restore the diameter of the ileocardial vein, which relieves symptoms while keeping the fistula open.
l 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 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 fistula, to promote the maturation of the endovascular fistula as soon as possible, some fistula-building exercises can be done, such as squeezing and squeezing rubber bands, with or without tourniquet to increase blood flow and accelerate the maturation of the newly made autologous endovascular fistula.