Dialysis

Dialysis is the artificial process of getting rid of waste products and unwanted water from the blood. This process is naturally done by our kidneys. When the kidneys are damaged or have failed they cannot carry out their functions properly, therefore the need for dialysis arises. In other words, dialysis is the artificial replacement for lost kidney function (renal replacement therapy). Dialysis may be used for people who have become ill and have acute kidney failure (temporary loss of kidney function), or have chronic kidney failure with permanently lost kidney function. When we are healthy, our kidneys regulate our body levels of water and minerals, and remove waste. The kidneys also produce erythropoietin and 1,25-dihydroxycholecalciferol (calcitriol) as part of the endocrine system. Dialysis does not correct the endocrine functions of failed kidneys – it only replaces some kidney functions, such as waste removal and fluid removal. Dialysis performs the two main functions of the kidneys:

• Removing waste from the blood; and
• Balancing the body’s fluid levels.

Why is dialysis necessary? Approximately 200 liters of blood are filtered by a healthy person’s kidneys each day. We could not live if waste products were not removed from our kidneys. People whose kidneys either do not work properly or not at all experience a buildup of waste in their blood. Without dialysis the amount of waste products in the blood would increase and eventually reach levels that would cause coma and death. Dialysis helps, but is not as efficient as the kidneys Although dialysis helps patients whose kidneys have failed, it is not as efficient as a normal kidney. Consequently, patients on dialysis need to be careful about what and how much they drink and eat. They will also need medications. A significant number of patients on dialysis can work and lead normal lives. It is possible to go away on vacation as long as dialysis treatment is possible at their destination. Women on dialysis will probably not be able to get pregnant. There will be a higher level of waste products in the body compared to a woman with normal kidneys – this interferes with fertility. Women who do become pregnant while on dialysis will probably need increased dialysis during the pregnancy. If a woman has a successful kidney transplant her fertility should return to normal. Dialysis has some effect on male fertility, but much less than on female fertility.   There are two types of dialysis: Peritoneal dialysis (PD) • Peritoneal dialysis (PD) uses the natural filtering ability of the peritoneum – the internal lining of the abdomen. The membrane has tiny holes that allow waste products and fluid to filter from your blood. In other words, peritoneal dialysis uses the lining of the abdomen as a filter of waste products from the blood. • Bags of dialysis fluid (dialysate) are attached to your body with a small, soft plastic tube, called a PD catheter. • Approximately 18cm of the catheter remain outside your body allowing you to easily change your dialysate as often as your doctor prescribes. A Kidney failure patient undergoing peritoneal dialysis • A sterile (dialysate) solution rich in minerals and glucose is run through the tube into the peritoneal cavity, the abdominal body cavity around the intestine, where the peritoneal membrane acts as a semi-permeable membrane. • The abdomen is the area between the chest and hips – it contains the stomach, small intestine, large intestine, liver, gallbladder, pancreas and spleen. • During the dwell phase (the time dialysate remains in the abdomen) excess water and waste products from the blood are drawn across your peritoneal membrane into the dialysate, so that it can absorb waste products. Then it is drained out through a tube and discarded. • This exchange, or cycle, is generally repeated several times during the day – with an automated system it is often done overnight. • The process of waste removal, as in haemodialysis, is called diffusion. The removal of excess water, osmosis, is aided by another substance within the dialysis fluid, usually glucose. • The elimination of unwanted water (ultrafiltration) occurs through osmosis – as the dialysis solution has a high concentration of glucose, it results in osmotic pressure which causes the fluid to move from the blood into the dialysate. Consequently, a larger quantity of fluid is drained than introduced. • Although peritoneal dialysis is not as efficient as haemodialysis, it is carried out for longer periods. The net effect in terms of total waste product and salt and water removal is about the same as haemodialysis. • Peritoneal dialysis is done at home by the patient; by a willing and motivated patient. It gives the patient a greater amount of freedom and independence because he/she does not have to come in to the clinic at multiple times each week. It can also be done while traveling with a minimum of specialized equipment. Peritoneal dialysis is said to ‘save lives and save money’. • Before having peritoneal dialysis, the patient needs to have a small surgical procedure to insert a catheter into the abdomen. This is kept closed off, except when fluid is being introduced or taken out of the abdomen. • Your doctor will prescribe the number of exchanges to be performed each day and the amount and type of dialysate to be used. There are two principal types of peritoneal dialysis: 1. Continuous ambulatory peritoneal dialysis (CAPD) – this requires no machinery and can be done by the patient or a caregiver. The dialysate is left in the abdomen for up to eight hours. It is then replaced with a fresh solution straight away. This happens every day, about four to five times per day. 2. Continuous cyclic peritoneal dialysis (CCPD) – a machine does the dialysis fluid exchanges. It is generally done during the night while the patient sleeps. This needs to be done every night. Each session lasts from ten to twelve hours. After spending the night attached to the machine, the majority of people keep fluid inside their abdomen during the day. Some patients may require another exchange during the day. Both types of PD allow you to be relatively independent and manage your own care at home. For now, Peritoneal Dialysis is not widely available in Nigeria. Heamodialysis (HD) Haemodialysis (HD) is a machine-assisted blood filtration method which removes waste and excess fluid from your blood in a dialyser (or artificial kidney) outside your body. • HD requires a doctor to surgically create permanent access to your blood stream, via your arm or thigh, allowing blood to be diverted from your body, through the dialyser and back into your blood stream. • There are two types of permanent access – a fistula and a graft. A fistula is the surgical linking of an artery to a vein, providing access to blood vessels. A graft is a tube surgically placed under the skin linking an artery to a vein. A Kidney failure patient undergoing haemodialysis • During HD treatment two needles are inserted into the access point. Plastic tubes attached to these needles connect them to a dialyzer. The blood, about 200mL at any one time, is drawn from your body via one needle and pumped through the dialyzer. • The blood circulates outside the body of the patient – it goes through a machine that has special filters. The blood comes out of the patient through a catheter (a flexible tube) that is inserted into the vein. The filters do what the kidney’s do; they filter out the waste products from the blood. The filtered blood then returns to the patient via another catheter. The patient is, in effect, connected to a kind of artificial kidney. • An artificial membrane separates the blood from the dialysis fluid but allows waste and excess water to diffuse through from the blood. • The clean blood is then returned to your body via the second needle or tube and the needles are removed at the end of each session. Each session lasts three-to-five hours and is usually performed three times a week • During treatment, you can read, write, sleep, talk, or watch TV. • It is likely you will feel tired and weak following Haemodialysis treatment.