What is dialysis?
Dialysis is artificial blood washing that cleanses the blood of toxic substances.
Every day, the body produces many toxic metabolites that are normally excreted through the kidneys in the urine. These so-called “urinary substances” include, for example, urea, uric acid, creatinine and many more.
If the kidneys are unable to adequately excrete these substances due to acute or chronic damage (acute or chronic renal insufficiency), they accumulate in the body, which can become life-threatening within a few days.
The first human dialysis was performed in Giessen in 1924 – since then it has saved the lives of millions of people. Currently, about 70,000 people in Germany undergo dialysis on a permanent basis.
Dialysis can also be used in certain cases of poisoning to remove the poison from the body.
A basic distinction is made between three dialysis procedures:
- Hemodialysis
- Peritoneal dialysis
- Hemofiltration
The principle of all three procedures is similar: blood is continuously taken from the body and filtered through a membrane (dialyzer). In some cases, a rinsing fluid (dialysate) is used to wash out the substances in the blood. The purified blood is then returned to the body.
Further information: Peritoneal dialysis When to perform peritoneal dialysis and what to look for in the article Peritoneal dialysis.
Another procedure is hemoperfusion. It is used for blood purification in cases of poisoning. In this procedure, the blood is passed into containers with activated charcoal, which extracts the poison from the blood and binds it (adsorption).
When is dialysis performed?
Dialysis can be used acutely and only for a short time or as a long-term treatment.
Acute dialysis
Acute dialysis must be used in the following situations:
- Acute kidney failure: signs of this include rising potassium levels, signs of overhydration (hypervolemia) or signs of poisoning by urinary substances (uremia)
- Poisoning: In the case of poisoning with dialyzable substances (for example, the antidepressant lithium or methanol), dialysis can be life-saving.
- Overhydration due to heart failure (e.g. pulmonary edema)
Chronic dialysis
In cases of advanced, chronic kidney dysfunction (chronic renal failure), dialysis is used as a long-term, usually lifelong treatment (long-term dialysis). Dialysis must then be performed regularly, for example every other day.
The following symptoms, among others, may indicate a deterioration in kidney function:
- Severely elevated blood pressure
- Changes in blood pH
- glomerular filtration rate (GFR) as a measure of kidney function below 10 to 15 milliliters per minute
What do you do during dialysis?
Dialysis involves removing large amounts of blood in a short time and returning it to the body in a purified form. But the blood vessels are either poorly accessible (arteries) or have too low a pressure (veins) and are therefore not suitable for dialysis. For this reason, a special vascular access is surgically created for long-term dialysis – a so-called dialysis shunt.
Vascular access for long-term dialysis (shunt)
For long-term dialysis, a surgical connection is created between the artery and vein (AV shunt) – for example, by inserting a small plastic tube (interposition device). For dialysis, the interponate is pierced with a needle. In principle, a dialysis shunt can be inserted in many places, but the less-used forearm is preferred (for example, the left arm in right-handed people).
This vascular access is permanent and avoids repeated puncturing of the vessels with the corresponding risks such as infections or injuries.
Vascular access for acute dialysis
Blood coagulation inhibition (anticoagulation).
During dialysis, the blood comes into contact with the components of the dialysis machine. These are usually made of plastic and activate blood clotting (this is also referred to as thrombogenic material). For this reason, blood clotting (anticoagulation) must be inhibited for the duration of dialysis treatment, for example by administering heparin.
Another option is so-called regional anticoagulation: citrate is added to the dialysis machine, which binds the calcium present in the blood and necessary for the coagulation process, thus inhibiting blood coagulation in the dialysis machine. At the end of blood washing, the administration of calcium cancels out the citrate effect.
Dialysis procedure
Depending on the dialysis procedure, dialysis can be performed either on an outpatient basis in a special dialysis center or at home (home dialysis).
Dialysis in the hospital or in the doctor’s office Hemodialysis and hemofiltration are performed in the hospital. In long-term dialysis, blood washing takes place three times a week for four to five hours under supervision. A shunt is needed for this type of dialysis.
What are the risks of dialysis?
Dialysis is a standard procedure in renal replacement therapy. However, it does carry certain risks. The most common dialysis side effects include:
Drop in blood pressure
Dialysis puts a significant amount of stress on the body. A common reaction is a drop in blood pressure. Lowering the filtration rate (generally, you should dialyze no more than 600 milliliters of blood per hour) can counteract the drop in blood pressure. It also helps to lower the temperature of the blood in the dialysis machine somewhat. This tends to keep the body temperature low, which in turn stabilizes blood pressure.
Muscle cramps
Dialysis deprives the body of minerals – which promotes muscle cramps. In most cases, massage helps. In addition, the doctor can administer a low-dose, muscle-relaxing sedative (for example, diazepam).
Headaches
Headaches are also a common side effect. Remedies here are classic painkillers with active ingredients such as paracetamol.
Nausea and vomiting
Rather rare is the so-called dysequilibrium syndrome: in this case, symptoms such as headaches, impaired consciousness or epileptic seizures occur. It is assumed that dialysis removes substances from the body, which leads to a transfer of fluid from the vessels into the tissue. This causes the tissue to swell, which in extreme cases can lead to life-threatening cerebral edema.
Complications of vascular access
Various complications could occur with an AV shunt:
- Infection of the shunt
- aneurysm (widening of the wall)
- reduced blood flow to the area of the body behind the shunt
- occlusions
Dialysis – Life Expectancy
Despite medical progress, dialysis patients have a lower life expectancy than healthy people, especially if there are additional concomitant diseases such as diabetes mellitus. The cause is the underlying disease (renal insufficiency), which can be accompanied by serious secondary complications such as heart attack or stroke.
What do I have to bear in mind after dialysis?
Dialysis treatment means a considerable intervention in the patient’s usual everyday life: the intensive treatment has an impact on social and professional life. To cope and avoid additional stress, support from family, friends and colleagues is particularly important.
Nutrition during dialysis
Further information: Dialysis: Nutrition How to eat right as a dialysis patient and what you need to keep in mind can be read in the article Dialysis: Nutrition.
Vacation with dialysis
The loss of mobility and independence is one of the main limitations of dialysis. However, it is still possible to take a vacation. Today, dialysis patients can travel anywhere in Germany and to most countries in the world. Within Germany, a place for hemodialysis can be found even at short notice. For trips abroad, more time should be planned for the organization. It is advisable not to go on vacation as a new dialysis patient, because the body needs time to get used to the treatment.
Dialysis cruises are offered especially for dialysis patients: this is a normal cruise with the possibility of dialysis under medical supervision at the same time.
In general, dialysis patients should not travel to areas where hygiene conditions are poor. There is a significantly higher risk of infection here. It is also important to clarify the question of costs for dialysis abroad with the health insurance company before starting a vacation.
What support do doctors offer? Before you decide to undergo hemodialysis while on vacation abroad, you should always consult your attending physician. He or she will advise you whether the vacation region you have chosen is suitable and whether your general state of health allows you to travel. The doctor will compile all the data relevant for hemodialysis, such as dry weight, dialysis duration, laboratory values or medications in preparation for the guest dialysis.
Today, dialysis is a standard procedure that, with the right care, allows patients to live a nearly normal life.
Author & source information
This text corresponds to the specifications of the medical literature, medical guidelines and current studies and has been reviewed by medical experts.
