Medical Health Encyclopedia

Dialysis

Permanent access is created by surgically joining an artery to a vein. This allows the vein to receive blood at high pressure, leading to thickening of the vein's wall. Now this "arterialized vein" can sustain repeated puncture and also provides excellent blood flow rates. The connection between an artery and a vein can be made using blood vessels (an arteriovenous fistula, or AVF) or a synthetic bridge (arteriovenous graft, or AVG).

The AVF is more desirable, because rates of infection are very low and it is quite durable. It may take many months for the AVF to mature, so careful planning is required.

The AVG can be accessed a few weeks after creation. It provides good flows but has a high complication rate. It should be attempted only if the AVF is not feasible.

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Blood is diverted from the access point in the patient's body to a dialysis machine. Here, the blood flows counter-current to a special solution called the dialysate. The chemical imbalances and impurities of the blood are corrected and the blood is then returned to the body. Typically, most patients undergo hemodialysis for three sessions every week. Each session lasts 3-4 hours.

How to prepare for the test:

It is important to adhere to the diet and medicines prescribed by the dialysis staff and your nephrologist.

Just before your health care provider begins the hemodialysis procedure, the following assessments will be made:

• Blood pressure
• Temperature
• Heart rate
• Breathing rate
• Weight
• Chest assessment
• Examination of venous access

How the test will feel:

Since dialysis takes several hours, it may become tedious. With children, it is especially important to have games, something to read, or other distractions.

Why the test is performed:

This procedure removes contaminants from the blood that could, and eventually would, result in death if the kidney is not functioning.