A Dialysis Access is the means by which an external system to cleanse the blood gets access to the blood. Since the native kidneys are not functioning, we need to rely on an external mechanism to perform the primary function of the kidney - purification of the blood to remove the excess solutes and water. The other functions of the kidney like regulating the production of Red Blood Corpuscles and regulating absorption of Calcium from the gut are not replaced by dialysis.
For Peritoneal Dialysis (PD), the access is the Catheter that goes into the abdomen into the peritoneal cavity. One end of the catheter is in the cavity while the other end is outside. This enables the PD fluid to be infused into the Peritoneal Cavity. Here, through the peritoneum (which is a semi-permeable membrane), the solutes and excess water diffuse into the PD fluid. After a few hours, the saturated fluid is drained through the same catheter.
It is obviously very important that those on PD take utmost care of the PD catheter. Daily Exit Site dressing is mandatory. Watch for signs of infection on the exit site (the point where the catheter comes out of the abdomen) which could include redness, itching, tenderness, presence of puss etc. A fever could also be a symptom of an infection. Immediately alert your doctor if you suspect an infection. Early intervention can save your catheter.
For Hemodialysis (HD), the access could be a temporary access like a jugular or femoral catheter or a more permanent access like an Arteriovenous Fistula (AVF), an Arteriovenous Graft (AVG) or a Permanent Catheter (Perm Cath). All these types of accesses perform the same function - provide access to a vein to draw the blood and return it after purification in the artificial kidney (the dialyser).
In a temporary access, a double-lumen catheter is inserted into a vein in the body allowing the blood to be drawn through one lumen and returned through the other lumen. In an AVF, a surgery is performed to join an artery and a vein. This causes blood to flow at a higher pressure through the vein and allow better cleaning during dialysis. In an AVG, the vein and artery are joined by an artificial tube.
Temporary accesses are used when dialysis needs to be done immediately. AVFs and AVGs need a few weeks for them to become suitable to use for dialysis.
AVFs are the gold standard for accesses in HD followed by AVGs followed by Perm Caths.
For temporary or permanent catheters, it is important to not allow the site of insertion of the catheter to get wet. Proper dressing after cleaning the site during dialysis is important. Again, watch for the signs of infection mentioned earlier for a PD catheter.
For accesses like an AVF or an AVG, it is important to exercise the arm in which the surgery was done until it matures. Typically a squeeze ball is given and this exercise must be done several times a day to encourage the veins to become big enough for effective dialysis.
Once it is formed, care must be taken to keep the access healthy and efficient. The area must be cleaned thoroughly before cannulation. Care must be take to avoid cross-punctures during cannulation. This is done by levelling off (going in horizontally rather than at an angle) once the needle enters the vein. Cannulation of both needles should ideally be done such that the needle is in the direction of blood flow (away from the hand). This reduces the chance of aneurysms. Avoid carrying heavy objects with the access hand. Try not to hang purses or bags on the access sites.
Remember, there are limitations of the number of sites you can get an access. So, to be assured of a long, trouble-free life with your access, take every precaution possible to keep it healthy and efficient.
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