Introduction
Our kidneys are very important organs in our body. They are so important that God gave each one of us a spare kidney to begin life with. Majority of us have two kidneys in our body, but some of us are born only with one kidney. We only need one kidney to survive and to live a happy normal life. Each day our kidneys work continuously 24 hours to produce about 1.5 to 2.5 litres of urine (depends on how much fluid we drink per day). In so doing, our kidney functions to remove excess water from our body. The kidney also is a master chemist. It removes toxic waste products from the body and to maintain the body's delicate balance of various salt and acid such as sodium, potassium, calcium and phosphate.

There are many causes of kidney failure. However, diabetes and high blood pressure are by far the most common culprits of kidney failure in the whole world. The other less common causes include kidney stone, frequent urinary tract infection, kidney inflammation, drug such as pain killer medication and certain type of infection such as malaria.

Signs and symptoms of kidney failure vary individually. Not every patient with kidney failure has the same signs and symptoms. In the early stage of kidney failure, one may feel normal. As the disease progresses, one may feel fatigue, change in urination pattern such as frequent urination, and usually swelling of the hands and feet. At the stage of complete kidney failure (so called end-stage kidney failure), one may have nausea and vomiting, decreased appetite, lack of energy, itchy skin, decreased urine and often difficulty breathing. The only way to detect kidney failure early is to have regular medical checkup and to have urine and blood tested regularly.

Each year, approximately 2000 Malaysians suffered from end-stage kidney failure. The kidneys of end-stage kidney failure patient cannot perform the daily functions of removing toxic waste and excess water from the body. It also cannot maintain a delicate balance of salt and acid in the body. These result in accumulation of water and toxic waste, as well as salt and acid imbalance in the body. These consequences are incompatible with life. In order for the end-stage kidney failure patients to survive and have a normal life, they need to have kidney replacement therapy.

Kidney replacement therapy is needed when more than 90% of the kidney function is lost (so called end-stage kidney failure). There are three types of kidney replacement therapy, each designed to take over the partial or complete functions of the failed or nonfunctioning kidneys. The three types of therapy are Haemodialysis, Peritoneal Dialysis and Kidney Transplantation.

Haemodialysis
Dialysis is a treatment process that cleanses the blood by removing toxic waste products and excess water that accumulate in the body as a result of end-stage kidney failure. In haemodialysis (HD), this cleansing process is carried out with the help of a haemodialysis machine and a special filter called a dialyzer or an "artificial kidney" in layman term. Blood is drawn from the kidney failure patient via a specially created vein in the forearm known as arterio-venous fistula (AVF). The blood is then pumped through plastic tubing into the haemodialysis machine. There it passes through the dialyzer where the actual cleansing of the blood takes place. In the dialyzer, a membrane allows the blood to come in close contact with a cleansing solution called dialysate, which removes waste products and excess water from the blood. After cleansing, blood is then pumped through another plastic tubing and returns to the body via the same AVF in the forearm as meantioned above.

In order to have haemodialysis treatment, one must have an access from which blood can be withdrawn from the body, and after cleansing, returns to the body. This is called a "haemodialysis access" or "vascular access". There are three types of vascular accesses:

• Arterio-venous fistula (AVF) - an artery and a vein in the patient's arm are surgically connected together.
• Arterio-venous graft (AVG) - same as the AVF, but a soft artificial tube (the graft) is used to connect the artery and the vein together.
• Catheter - a soft artificial tube is inserted into a large vein in the neck.

The AVF is the preferred permanent vascular access for long term haemodialysis in adults because it is more durable and has the least amount of potential complications (such as infection and clotting). After creation, the AVF usually takes 2-4 months to mature before it can be used. It is therefore important to have the AVF created well before the end-stage kidney failure sets in. The AVG is also used as a permanent vascular access for adult patients. It is usually reserved as a last resort when all native arteries and veins are used up for the AVF. Its major disadvantages include easy clotting inside the artificial tube and infection. It usually takes 2-4 weeks after creation before it is mature enough for use.

In contrast to the AVF and AVG, the catheter is usually a vascular access for temporary use. Its use is usually limited to a period of 2 to 6 months depending of the type of catheter. The catheter is the preferred vascular access in most children since their blood vessels are so small that it is difficult to create a fistula or place a graft. Compared to the AVF and AVG, the catheter is the most prone to infection and clotting. It can be used immediately after placement. It is usually used in end-stage kidney failure patient when dialysis treatment is urgently needed for life treatening situations and there is no AVF or AVG available for use.

Haemodialysis is usually carried out in hospital or a dialysis centre that is not part of a hospital. Occasionally, it can also be done at home. Usually haemodialysis treatment is done three times per week for three to five hours each time. During haemodialysis, the patient can read, watch television or sleep. A haemodialysis trained nurse initiates the treatment session and monitors vital signs, such as blood pressure, heart rate and temperature, throughout the treatment. Patient usually is comfortable and feels no pain during the treatment. However, there are some side effects that occur occasionally during haemodialysis. These may include nausea, vomiting, dizziness, headache and leg cramping. These uncomfortable side effects usually arise when the patient's body is unable to move fluid into the blood vessels as quickly as the haemodialysis machine is removing it. Controlling the excess fluid weight gain that occurs between dialysis sessions can minimize these side effects. One way to approach this is to restrict the water and salt intake in the diet.

The other two types of therapy, Peritoneal DIalysis and Kidney Care Transplantation will be covered in the following issues of Grapevine.

Dr. William Chau. MD.
(Consultant Nephrologist)