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The kidneys are two bean-shaped organs, each about the size of a fist. They are located just below the rib cage, one on each side of your spine. Healthy kidneys clean your blood by removing excess fluid (and salt) and wastes.
They also make hormones, including an active form of vitamin D, which keeps your bones strong, and erythropoietin which keeps your blood healthy. When your kidneys fail (renal failure), harmful wastes build up in your body, your blood pressure may rise, and your body may retain excess fluid, leading to ankle swelling and shortness of breath because of water in the lungs.
There are many reasons for why kidneys fail including, but not limited to:
- High blood pressure – This can constrict and narrow the blood vessels, which eventually damages and weakens them throughout the body, including in the kidneys.
- Diabetes – Over time, high blood sugar from diabetes can damage blood vessels in the kidneys as well as nephrons so they don’t work as well as they should.
- Acute Kidney Injury (AKI) – This is a sudden drop in kidney function, often as a complication of another serious illness such as heart disease or liver disease. It affects 1 in 5 people admitted to hospital as an emergency and may be more deadly than a heart attack. In the UK around 100,000 deaths each year are associated with AKI, which is equivalent to ten people every hour. Research shows that 30% of these could be prevented with the right care and treatment.
- Chronic Kidney Disease (CKD) – The kidneys lose their filtering ability, dangerous levels of wastes may accumulate, and the blood’s chemical make-up may get out of balance. Every year in the UK there are 40,000–45,000 premature deaths due to CKD and around 3.5 million people in the UK have CKD, about 1,000 of these are children. Black, Asian and minority ethnic communities are five times more likely to develop CKD than all other groups. (Source: Kidney Care UK).
When your kidneys fail, you need treatment to replace the work of your failed kidneys; this treatment can include dialysis.
What is dialysis?
Dialysis is a medical procedure to remove waste products and excess fluid from the blood when the kidneys stop working properly. It often involves diverting blood to a machine to be cleaned. Dialysis can be delivered in hospital, which requires a person to visit a kidney unit three times per week for 4-hour sessions. The alternative is to have dialysis at home, although most people tend to opt for hospital dialysis.
The first dialysis unit in the UK, which opened in 1961, was at the Royal Free Hospital. This was followed by Newcastle Hospital in 1963 and the Charing Cross Hospital in 1964. Currently, there are almost 30,000 people on dialysis in the UK.
Who needs dialysis?
Dialysis is used in two different situations. When a person experiences a sudden episode of kidney failure or kidney damage that happens within a few hours or days, this is known as acute kidney injury (AKI). In severe cases, dialysis may be needed for a short time until the kidneys get better.
The second situation when dialysis is used is in cases of kidney failure through chronic kidney disease. This is when only 10–15% of the kidney function remains. At this stage, the kidneys are no longer able to keep the person alive without some extra help as they may not be able to clean the blood properly. Waste products and fluids can build up to dangerous levels in the body. Left untreated, this can cause a number of unpleasant symptoms and can eventually be fatal. Dialysis filters out unwanted substances and fluids from the blood before this happens.
In some cases, kidney failure may be a temporary problem and dialysis is only needed to be used until the kidneys recover.
In other cases, the person with kidney failure will need a kidney transplant and dialysis may be needed until a suitable donor kidney becomes available. There will, however, be cases where a kidney transplant is not a suitable option for a person. This may be because they are not well enough to have a major operation, so they will continue with dialysis, often for the rest of their life.
What is dialysis used for?
Dialysis isn’t a cure for kidney disease or other problems affecting the kidneys; it is used when a person’s kidneys are not functioning properly and cannot prevent extra water, waste and other impurities from accumulating in the body. Dialysis can help to control blood pressure and regulate the levels of chemical elements in the blood and helps keep the body running as normally as possible. Without dialysis, salts and other waste products will accumulate in the blood, poison the body, and damage other organs.
Types of dialysis
There are two different types of dialysis: haemodialysis and peritoneal dialysis. Both methods have advantages and one type may be more appropriate for a person than the other.
In both types, the principle is the same, a cleaning fluid called dialysate is used to take the impurities, salt and water away from the blood. The impurities pass from the blood into the cleaning fluid. There has to be a barrier between the blood and the cleaning fluid for this to happen.
Haemodialysis is the most commonly used treatment and is usually undertaken in hospital, although it can be done at home if the person has the right environment to accommodate the equipment. In haemodialysis, the barrier is the filter in the dialysis machine that the blood passes through.
In peritoneal dialysis, the blood is cleaned inside the body. The barrier is the layer of cells that line the abdomen and cover the intestines – the peritoneum. This is a continuous process, repeated several times a day, and is known as continuous ambulatory peritoneal dialysis (CAPD). Alternatively, the process can be done overnight, leaving daytimes free of dialysis. This is known as automated peritoneal dialysis (APD). This type of dialysis can be done at home.
How does dialysis work?
In haemodialysis the blood is allowed to flow, a few millilitres at a time, through a special filter – that is, the “dialyser” or “artificial kidney” – which removes wastes and extra fluids. The clean blood is then returned to the body. This also helps to control blood pressure and keep the proper balance of chemicals such as acid, potassium and sodium in the body. Most patients have dialysis three times a week for 3–5 hours, often in a hospital dialysis unit.
At least eight weeks before a person starts dialysis one important step is preparing a vascular access, a site on the body from which the blood is removed and returned. A fistula is the most common type. This is done by means of a small operation in which one of the arteries in the arm is re-routed to join a vein, increasing its blood flow.
Needles are inserted into the fistula at the start of haemodialysis. Many people find this to be one of the hardest parts of haemodialysis, although most report getting used to them after a few sessions. If this is painful, an anaesthetic cream or spray can be applied to the skin.
Some people elect to have home haemodialysis, which is when the dialysis treatment takes place in the person’s own home. They can carry out the dialysis themselves or with the support of a family member or friend who has been trained to help them.
Whether dialysis takes place in a hospital dialysis unit or in the person’s own home, once a month, nurses will do blood tests, before and after haemodialysis, to see whether the treatments are removing enough wastes. The blood urea level should fall by at least two thirds after a haemodialysis session.
Peritoneal dialysis became an alternative to haemodialysis in the 1980s. Many patients prefer the independence it brings, since they don’t have to have dialysis sessions at a hospital dialysis unit; they can give themselves treatments at home, at work or even on holiday. Some people are able to sleep during the session, whilst others may find the machine a bit noisy; however, many get used to it.
In peritoneal dialysis a soft tube called a catheter is used to fill the abdomen with a cleansing liquid called a “dialysis solution”. The abdominal cavity is lined with a membrane layer called the peritoneum.
The waste products, extra fluid and salt pass through the peritoneum from the blood into the dialysis solution, attracted by its high sugar/dextrose content. They then leave the body when the dialysis solution is drained. This used solution is thrown away. The process of draining and filling is called an exchange and takes about 30–40 minutes. The period the dialysis solution is in the abdomen is called the dwell time. A typical schedule is four exchanges a day, each with a dwell time of 4–8 hours.
One form of peritoneal dialysis, continuous ambulatory peritoneal dialysis (CAPD), doesn’t require a machine and it is possible to walk around with the dialysis solution in the abdomen.
Another form of peritoneal dialysis, automated peritoneal dialysis (APD), requires a machine to fill and drain the abdomen; performing three to five exchanges during the night while the person is asleep, and the process lasting for between 8 and 10 hours.
The specialist should measure the effectiveness of the peritoneal dialysis with blood tests, including urea and creatinine, at least every three months. A drawback with peritoneal dialysis is that some patients sometimes don’t perform all of their prescribed exchanges. They either skip exchanges or sometimes skip entire treatment days when using APD. This may be fine on occasion, but it is not recommended on a regular basis.
How long can dialysis work?
Not all kidney disorders are permanent. Dialysis can temporarily serve the same function as kidneys until a person’s own kidneys repair themselves and begin to work on their own again.
A person with chronic kidney disease will go on dialysis permanently, or until a kidney transplant becomes an option. In the UK the average wait for a deceased donor kidney transplant is 2–3 years; for a living donor, it usually takes just 3–6 months to have the required tests on the recipient and donor and to arrange the transplant.
Without a transplant, some patients have lived well on dialysis for 20 or 30 years, although the average life expectancy on dialysis is 5–10 years.
Dialysis does not stop working. It may be that some patients no longer can tolerate dialysis treatments and make the decision to stop the treatment.
Effects and risks of dialysis
The most common side effect of all dialysis procedures is fatigue. Other side effects and/or risks depend upon the type of dialysis.
In haemodialysis they can include:
- Low blood pressure, or hypotension – During haemodialysis this occurs due to the temporary loss of fluids during treatment. If the blood pressure drops during treatment, the person may also notice dizziness, nausea, clammy skin and blurry vision.
- Muscle cramps – These can occur during dialysis due to a change in fluid or mineral balance. Low levels of sodium, magnesium, calcium and potassium can all play a role in muscle cramping.
- Itchy skin – This can occur between haemodialysis sessions as waste products can begin to accumulate in the blood. For some people, this can lead to itchy skin. If the itchiness is primarily in the legs, it could also be due to restless legs syndrome.
- Infection – This can be caused by the frequent insertion of needles or catheters during dialysis which can increase exposure to bacteria. If bacteria enter the bloodstream during treatment, the person may be at risk of serious infection or even sepsis. Without immediate treatment, sepsis can be fatal.
- Blood clots – Sometimes installing an access point leads to the narrowing of the blood vessels; if left untreated, this can cause swelling in the upper half of the body or even blood clots.
- Other risks and side effects of haemodialysis may include anaemia, difficulty sleeping, heart conditions, or cardiac arrest. Many of these side effects are due to the fluid and mineral imbalances that dialysis can cause.
Common peritoneal dialysis side effects are slightly different from those above and can include:
- Peritonitis – This is an infection of the peritoneum that happens if bacteria enter the peritoneum during catheter insertion or usage. The symptoms of peritonitis may include abdominal pain, tenderness, bloating, nausea and diarrhoea.
- A hernia – This happens when an organ or fatty tissue pushes through an opening in the muscle. People who receive peritoneal dialysis are at risk of developing an abdominal hernia because dialysate places extra pressure on the abdominal wall. The most common symptom is a small abdominal lump.
- High blood sugar – Dialysate used during peritoneal dialysis contains a sugar called dextrose, which is commonly used during intravenous nutrition. Sugars like dextrose raise blood sugar, which may place people with diabetes who need peritoneal dialysis at risk of hyperglycaemia.
- Weight gain – This may also occur due to the additional calories from the administration of dialysate. However, there are a variety of other factors that can also impact weight gain during dialysis, such as lack of exercise and poor nutrition.
- High potassium – This is known as hyperkalaemia and is a common side effect of kidney failure. Between dialysis sessions, potassium levels can build up due to a lack of proper filtration.
- Other side effects – For some people the stress and anxiety of constant medical procedures can lead to depression. Research has also suggested a possible link between dialysis and dementia later in life.
There are some side effects that those caring for a person on dialysis should seek immediate medical advice about should they experience them, as they may indicate either a serious infection, a blood clot, hypotension or hyperglycaemia, all of which require immediate treatment.
These symptoms include:
- Difficulty breathing.
- Confusion or trouble concentrating.
- Pain, redness, or swelling in the limbs.
- Temperature above 38°C / 101°F.
- Loss of consciousness.
Alternatives to dialysis
The most effective treatment for advanced kidney disease is a kidney transplant. It involves major surgery and the person taking medicines known as immunosuppressants for the rest of their life to stop the body from attacking the donor organ. In the UK, around 5,000 people are in need of a kidney transplant. Whilst a person waits for a kidney transplant, or should they not be suitable for a kidney transplant, the alternative treatment is dialysis.
Some people with kidney failure will decide not to have dialysis treatment. There may be many reasons for this. Some may feel that the treatment will be hard to manage and impact too much on the remainder of their life, they may feel that the journey to the hospital three times a week is too much for them or they may have other diseases such as heart or respiratory diseases which may impact on their ability to do well on dialysis.
If a person decides not to have dialysis, they will still receive support and medical treatment from the hospital team. This treatment may include conservative treatment. This is prescribing medication to preserve and maintain current kidney function and to treat the symptoms associated with kidney failure including pain management. The type of medication prescribed will depend upon such things as the person’s kidney function and medical history. Kidney Care UK have produced a leaflet that describes some of the medications that may be recommended for chronic kidney disease.
Conservative treatment is also known as palliative care, which is care that aims to increase quality of life by decreasing pain or other symptoms. Palliative care is usually not used to cure a disease, but to keep the patient comfortable and as active as possible. Palliative care can be used by people who wish to carefully manage their disease without dialysis.
Everyone has the right to decide not to start dialysis if they feel that the burdens outweigh the benefits to them. For anyone who is receiving dialysis, there may come a time when they feel that they want to stop dialysis treatment.
People who choose to stop or not to start dialysis can receive palliative care. Doctors will speak with the individual about what dialysis treatment involves and what deciding not to start dialysis would mean for them. For those deciding to stop dialysis, doctors will also discuss what this decision will mean for them.
Dialysis can be a life-saving treatment, but it can also be a life-changing experience.
Sources of advice and support for those considering dialysis or already receiving dialysis treatment include: