Dialysis refers to an artificial means of removal of the waste substances from the body using a specialised membrane.
There are two forms namely Haemodialysis (HD) or blood dialysis, and Peritoneal Dialysis (PD).
In Haemodialysis (HD), a mechanised blood pump is needed to draw blood from the patient. The blood is circulated into the machine and passes along a specialised membrane (a dialyser) which in essence functions as an artificial kidney. Waste substances from the blood move across the membrane into the solution called a dialysate by a physical process called diffusion. The cleaned blood exits the dialyser and is returned back to the patient.
In Haemodialysis (HD), the patient needs to have a surgically created vein that is large enough and with a high enough blood flow to allow efficient and adequate dialysis. The surgeon will create this specialised vein called an arterio-venous fistula (aka vascular access) by connecting 2 blood vessels together. Usually the operation is done at the wrist initially but other sites along the arm can also be chosen. Sometimes patients' veins are too small for such surgery. Under these circumstances, the surgeon may create the vascular access by placing a graft that essentially functions as an artificial blood vessel connecting two adjacent vessels. This artificial graft is left permanently under the skin of the patient and is repeatedly needled for dialysis.
In Peritoneal Dialysis (PD), a permanent tube (called a tenchkoff catheter) is placed under sterile conditions into the abdominal cavity. Using this tube, specialised fluid called dialysate is filled into the abdomen. The lining of the abdomen has a membrane called peritoneal membrane that can function like a dialyser membrane. Waste substances present in the blood flowing through the blood vessels of the abdomen itself move across the peritoneal membrane into the dialysate. The used dialysate with waste products is then drained out of the abdomen via the tenchkoff catheter, discarded, and a fresh bag of dialysate is filled back into the abdomen to continue dialysis.
Both Haemodialysis (HD) and Peritoneal Dialysis (PD) can effectively remove waste products from patients. Both however cannot entirely replace the kidney function. Apart from removal of waste products, the normal kidneys also produce substances called hormones, of which the two major ones are erythropoietin and vitamin D. Erythropoetin is essential in maintaining appropriate levels of blood counts, hemoglobin, in the body. In renal disease, the amount of erythropoetin progressively lessens, and the patient develops the problem of anaemia, which essentially is a problem of low hemoglobin. The kidney also produces vitamin D. Vitamin D is a hormone that works on the bone and intestine to maintain an appropriate level of calcium for the body. Calcium is essential in maintaining the health of bones and teeth. As with erythropoetin, vitamin D likewise becomes progressively reduced in quantity as the kidneys fail. The bones become brittle and prone to injury. The artificial kidneys used in both Haemodialysis (HD) and Peritoneal Dialysis (PD) are unable to produce the hormones like the normal kidney. Because of this, these hormones need to given in the forms of injections or oral medication to patients with renal disease.
Every patient who has kidney failure and facing the prospect of dialysis will usually ask the following questions. "Which is the best form of dialysis?" and "Which one is the most suitable for me?" The answer is not simple. One form of dialysis is not necessarily superior to another. As each patient is different, the type of treatment that they choose must eventually be acceptable to themselves, their families and caregivers. Thus either treatment may be best form of treatment for an individual patient. Sometimes treatments are chosen because of varying lifestyles, ease of access to a dialysis centre, family support, and often because of medical issues.
Peritoneal Dialysis (PD) nevertheless may have certain advantages over Haemodialysis (HD) in certain groups of patients.
Dialysis patients need to be careful about their choice of foods. Dialysis cannot replace the kidney function totally, and because of this, patients will need to continue to be wary about what they eat.The type of diets permissible differs between haemodialysis and peritoneal dialysis patients. Individual preferences also vary a great deal. It is important that patients see a dietician to discuss a meal plan that is varied and palatable enough for them to eat well and adequately.
Dialysis cannot correct all the abnormalities that occur with renal failure. Most patients will require several medications to treat the kidney failure. These medications will be in addition to the other medication that they need to take for other non-kidney related disease. Some of the common medications that dialysis patients need to be on are listed below.
All medical treatment potentially have side effects or complications. Dialysis likewise, whether peritoneal or haemodialysis, similarly have potential problems.The problems in dialysis include: