Hemodialysis Why do arteriovenous fistula?

Hemodialysis refers to the use of blood purification device (namely artificial kidney), remove a variety of toxins and excess water in the blood of uremia patients, and at the same time add a variety of beneficial substances, to achieve the purpose of blood purification. Hemodialysis is one of the common means to treat uremia, which can effectively maintain the life of uremia patients. Uremia patients must establish a vascular access before receiving hemodialysis treatment. Vascular access refers to the way blood is drawn from the body, into the extracorporeal circulation device and back into the body. It's a lifeline for those who rely on hemodialysis to survive. Establishing and maintaining a reliable vascular access is a prerequisite for hemodialysis therapy. Vascular access is generally divided into temporary vascular access and permanent vascular access two kinds. During dialysis, the blood flow in the extracorporeal circulation reaches 250 ml per minute, while the blood flow in the arm vein is usually only tens of ml, which is far from meeting the needs of dialysis. Moreover, the venous wall is thin and cannot tolerate the repeated puncture of dialysis needles. Therefore, temporary vascular access requires percutaneous puncture of special dialysis catheter into large veins or arteries of the body to achieve sufficient blood flow to meet the needs of hemodialysis. The right internal jugular vein, femoral vein and subclavian vein are generally selected for deep vein puncture, and the right internal jugular vein is the most commonly used one. It is characterized by simple operation and can be used after puncture, but the maintenance time of the catheter is short, usually only a few weeks, which cannot meet the needs of patients with long-term maintenance hemodialysis. For permanent vascular access, the radial artery and cephalic vein of the forearm and wrist are often used for autologous arteriovenous anastomosis (i.e., fistula). The radial artery and the cephalic vein of the patient's side wrist are connected, so that the long-term direct impact of arterial blood into the venous wall, resulting in increased local venous blood pressure, venous wall thickening and expansion, after a few months can not only make the cephalic vein obtain sufficient blood flow, but also can be repeated puncture on the venous wall, to meet the needs of long-term hemodialysis. Arteriovenous fistula solves the vascular access problem of uremia patients undergoing long-term dialysis, and is the safest, most economical and longest maintained vascular access at present. However, for some patients, such as the elderly, diabetes mellitus, hypertension, coronary heart disease or arteriosclerosis, especially those with thin vessels, venous embolism and vascular stenosis caused by repeated puncture, arteriovenous fistula surgery is more difficult and the surgical effect is poor. As a vascular access vein, should be mature in structure and function before use. The maturity time of the internal fistula is only human. Autologous arteriovenous fistula is not considered mature until its inner diameter is large enough to ensure successful puncture and provide sufficient blood flow. This process needs at least one month, so it is best to use it 3-4 months after internal fistula plasty. For patients with poor vascular conditions, the maturity of internal fistula even takes up to half a year. Therefore, for patients who choose hemodialysis treatment in the future, autologous arteriovenous fistula should be performed in advance. For patients who may require internal fistula surgery, care should be taken to protect their limb veins. If surgery is performed one year earlier than the expected start time of dialysis, sufficient time can be given for the fistula to mature. In addition, if surgery fails, there is time for additional vascular access to avoid the need for a Central Line.