Haemodialysis uses a filter, called a dialyzer, which is connected to a machine. A special solution, dialysate and your blood are perfused on opposite sides of a semi-permeable membrane. Your blood travels to the filter through tubes. Water and solute move from your blood across the membrane to the dialysate. Fluid and waste products are filtered out in this process and the cleaned blood is returned to your body via a different set of tubes.
Access to your bloodstream is needed, and for long-term haemodialysis a fistula is created. This is a small procedure, usually done on the arm, by connecting an artery to a nearby vein. It takes 4 to 8 weeks for the fistula to thicken and the lumen to enlarge, a process called maturation. During that time, temporary access is achieved through an indwelling catheter placed in a vein near the neck. If for any reason the fistula fails, a graft can be used to create access to your blood. However, the fistula is superior to the graft.
Caring for your fistula
If the fistula is looked after it can remain functional for a long time. Infection must be avoided and any small abrasion or wound treated. Keep the hand on the fistula’s side warm at all times – wear a glove during cold winter days. Don’t wear tight clothes, wristbands, watches or anything that places pressure on the fistula-arm. The opposite arm must be used for blood pressure measurement. The fistula-arm must not be used to take blood samples or for injections.
Haemodialysis is usually done at the renal unit of a hospital, three times a week. Each treatment takes about 3 to 4 hours. During treatment the patient can do paperwork, read, sleep, talk or watch television.
Possible side effects
It usually takes a few months to adjust to haemodialysis. Most side effects are caused by rapid changes to your fluid and chemical balance during the procedure. Always report any side effects to the medical staff. They are well trained and will explain what to expect during and after dialysis.
Side effects or complications during haemodialysis:
- Hypotension – when fluid is removed rapidly your blood pressure may fall suddenly. You may feel weak, dizzy and nauseous.
- Muscle cramps – occurs commonly during rapid high-volume filtration. This can partially be prevented by limiting intake of water between treatments and checking your weight. Aim to gain no more than 1,5 to 2 kilograms. Stretching exercises may be helpful.
- Disequilibrium syndrome – when urea is removed from the blood too quickly, a net movement of fluid to the brain seems to occur. This is rare and causes headache, nausea and vomiting and a feeling of lethargy.
- Disturbances of heart rhythm – rapid changes in the levels of electrolytes, especially potassium contribute to abnormal heart rhythm. High-risk patients may require ECG monitoring.
- Bleeding – high levels of urea affect the blood’s ability to clot. Heparin, a blood-thinning substance is also used to prevent clotting during the procedure, and the dosage may need to be adjusted. Heparin may increase menstrual bleeding in female patients.
Other side effects or complications in patients receiving haemodialysis:
- High blood pressure – usually due to insufficient removal of salt and fluid. Excess fluid can be removed by ultra-filtration, when only water is removed.
- Hypotension – occurs due to excessive removal of fluid and can be corrected by giving you an intravenous saline solution.
- Anaemia – a common finding in chronic renal failure, is due to decreased red blood cell production as well as loss of blood cells during dialysis. Erythropoietin therapy and iron is given to correct anemia.
- Cardiac problems – angina can occur and is worsened by anemia. Fluid overload could lead to heart failure or an enlarged heart. High levels of urea or insufficient dialysis can cause inflammation of the outer layer of the heart, the pericardium, over a period of time. Intensive or even daily dialysis may be necessary.
- Potassium imbalance – high blood levels of potassium can be deadly. Patients have to follow a diet low in potassium and never skip a dialysis session. Certain drugs may aggravate the problem.
- Bone disease – High blood levels of phosphate increase the demand for calcium. This leads to bone loss. Patients must take phosphate-binding medications with every meal. Various other factors also contribute to bone disease in these patients. Calcium deposits can cause painful joints.
- Restless legs – the cause is not always clear but may be due to insufficient dialysis. Diabetic patients are more prone to experience this condition.
- Sexual dysfunction – impotence and low sperm counts may occur. Medication and other factors can also play a role. Discuss this problem with your doctor. Fertility is reduced in female patients.
- Depression – having end-stage renal disease and requiring dialysis have a major impact on your life and it may sometimes feel overwhelming. It is important to discuss your feelings with the doctor or psychologist.
- Constipation – the medication given to bind phosphates in your blood can cause constipation. The traditional use of dried fruit, like prunes, to aid bowel movement must be avoided because of the high potassium content.
- Transfusion-related diseases - fewer blood transfusions are required with the introduction of erythropoietin therapy for anemia. Although screening is done, patient receiving blood transfusions may be at risk of blood-borne diseases like Hepatitis B and HIV infection. Special precautions are necessary in Hepatitis B positive patients that add to the workload and it also puts the medical staff at risk.
A dietician can help you plan your meals according to the doctor’s orders. The correct diet is crucial to limit the build-up of wastes in your blood. Intake of fluids, salt, potassium and protein must be controlled.
- Control of fluid and salt intake – the kidneys cannot handle excess fluid and intake will be limited and adapted by your doctor according to your excretion of urine. Fluid can build up quickly if your kidneys are not working and cause high blood pressure, swelling or heart problems. Salt must be avoided as it causes thirst and water retention.
- Weight control – you should not gain more than 1,5 to 2 kilograms between dialysis sessions. Weigh yourself at home and try to control your fluid intake.
- Limit intake of potassium – high levels of potassium can be life threatening. Fruits, including dried fruit, and fruit juice contains high amounts of this mineral and should be avoided. Salt substitutes, nuts, chocolate and milk also contains potassium.
- Limit foods high in phosphates – including red meat, milk, cheese, nuts, dried beans and soft drinks. Too much of this mineral causes calcium to be taken from your bones. Take the medication prescribed with your meals to bind phosphates.
Written by Dr K. Coetzee, reviewed by Dr R. Moosa, head of the Renal Unit, Tygerberg Academic Hospital.