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In Hemodialysis blood is removed via needle from the body in to the dialyser and purified in that. Purified blood is returned to the body through other needle in the body. For hemodialysis you need access into the vascular system of the body so that you can remove blood from the body in to the machine.
Preparation of Patient for Hemodialysis When a patient has moderately severe renal failure (i.e. when kidney is 80% damaged) plan should be made to do A. V. fistula for vascular access. So that you can remove impure blood from the body into the machine & put back the pure blood from the machine to the body. VASCULAR ACCESS refer to blood vessels. This means that to receive hemodialysis treatment there must be a way of to entering the blood vessels easily two or three times a week. Following are the Vascular Access:
Last three procedures are done when urgent dialysis is needed. First procedure is ideal for long term dialysis.
1) Arterio Venus Fistula (A.V.Fistula) A fistula is made from sewing two blood vessels together. Two of blood vessels, an artery and a vein, are connected underneath the skin (refer figure (A). It is generally done under local anaesthesia. It takes about two to three weeks for A.V. fistula to mature before it can be used. This new connection will build a vein with large flow of blood. This new path for blood is called a fistula. The fistula is placed between the wrist and the elbow of the arm which you do not use for writing. The force of the blood flow in the artery has pressure with it (your Blood Pressure). Normally the flow of blood in veins has almost no pressure, but when this new connection is made between the artery and vein this fistula has a flow of blood with pressure. The fistula is used for hemodialysis by placing two needles (of size 16 GA) in different places into the fistula. The needles have special tubing attached {refer fig. (E)}. Blood flows through on needle and tubing (out of the body) to the artificial kidney and back into the body through the other needle and tubing. 1 cup to 1 and half cup of blood is out of the body at any time. Patients should follow four following things to take care of fistula:
2) Shunt This type of Vascular Access is done routinely for urgent dialysis. In this silastic tube is inserted in to the artery and vein and both tubes are secured in place by sutures. When not in use, both tubes are connected with each other so that blood flows continuously through the tubes and prevents from clotting. Shunt can be used immediately for dialysis. Only problem with this is frequent clotting and infections life of shunt in majority of patients (refer fig. (B). 3) Subclavian or femoral vein cannulation This is a simple procedure and done when patient needs urgent dialysis and A-V fistula is not done or not matured. Now a days double lumen catheters are available so that we can do dialysis without any problem. Part of the tube lies in vein and part is outside the skin as shown in accompanying diagram fig.No. (C). 4) Femoral Catheter A femoral catheter is placed into the blood vessels in the groin refer fig.7 (d). It is used only when there is no other means of vascular access available. It is usually done for one or two dialysis. For Hemodialysis following things are required;
 
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