The kidneys filter your blood by removing waste and excess fluid from your body. This waste is sent to the bladder to be eliminated when you urinate.
Dialysis performs the function of the kidneys if they’ve failed. Dialysis is a treatment that filters and purifies the blood using a machine. This helps keep your fluids and electrolytes in balance when the kidneys can’t do their job.
A healthy person’s kidneys filter around 120 to 150 quarts of blood each day. If the kidneys are not working correctly, waste builds up in the blood. Eventually, this can lead to coma and death.
The cause might be a chronic, or long-term condition, or an acute problem, such as an injury or a short-term illness that affects the kidneys.
Dialysis prevents the waste products in the blood from reaching hazardous levels. It can also remove toxins or drugs from the blood in an emergency setting.
What does dialysis do?
When your kidneys fail, dialysis keeps your body in balance by:
- removing waste, salt and extra water to prevent them from building up in the body
- keeping a safe level of certain chemicals in your blood, such as potassium, sodium and bicarbonate
- helping to control blood pressure
Types of dialysis
There are different types of dialysis.
The three main approaches are:
- Peritoneal dialysis (PD)
- Continuous renal replacement therapies (CRRT)
The choice will depend on factors such as the patient’s situation, availability, and cost.
Hemodialysis is the most common type of dialysis. This process uses an artificial kidney (hemodialyzer) to remove waste and extra fluid from the blood. The blood is removed from the body and filtered through the artificial kidney. The filtered blood is then returned to the body with the help of a dialysis machine.
To get the blood to flow to the artificial kidney, your doctor will perform surgery to create an entrance point (vascular access) into your blood vessels. The three types of entrance points are:
- Arteriovenous (AV) fistula. This type connects an artery and a vein. It’s the preferred option.
- AV graft. This type is a looped tube.
- Vascular access catheter. This may be inserted into the large vein in your neck.
Hemodialysis treatments usually last three to five hours and are performed three times per week. However, hemodialysis treatment can also be completed in shorter, more frequent sessions.
Most hemodialysis treatments are performed at a hospital, doctor’s office, or dialysis center. The length of treatment depends on your body size, the amount of waste in your body, and the current state of your health.
Peritoneal dialysis involves surgery to implant a peritoneal dialysis (PD) catheter into your abdomen.
The catheter helps filter your blood through the peritoneum, a membrane in your abdomen. During treatment, a special fluid called dialysate flows into the peritoneum. The dialysate absorbs waste. Once the dialysate draws waste out of the bloodstream, it’s drained from your abdomen.
This process takes a few hours and needs to be repeated four to six times per day. However, the exchange of fluids can be performed while you’re sleeping or awake.
Continuous renal replacement therapy (CRRT)
This therapy is used primarily in the intensive care unit for people with acute kidney failure. It’s also known as hemofiltration. A machine passes the blood through tubing. A filter then removes waste products and water. The blood is returned to the body, along with replacement fluid. This procedure is performed 12 to 24 hours a day, generally every day.
How do I prepare for dialysis?
Before your first dialysis treatment, your doctor will surgically implant a tube or device to gain access to your bloodstream. This is typically a quick operation. You should be able to return home the same day.
It’s best to wear comfortable clothing during your dialysis treatments. Also follow your doctor’s instructions. These may include fasting for a certain amount of time before the treatment.