Glossary — the words of dialysis, explained simply

A surgical or medical entry route that connects the bloodstream to the dialysis machine. In haemodialysis, the two main forms are the arteriovenous fistula (a long-lasting solution) and the catheter (used in emergencies or while awaiting a fistula). The quality of vascular access directly determines the effectiveness of sessions and the patient's long-term safety.

Short for "erythropoiesis-stimulating agent". These are injectable medicines that mimic the action of erythropoietin, the hormone normally produced by the kidneys. They are prescribed to patients with kidney failure whose kidneys no longer make enough of this hormone, in order to correct renal anaemia and reduce the tiredness caused by a lack of red blood cells.

A soft, thin plastic tube inserted into a blood vessel (often in the neck or groin) to gain access to the circulation. In haemodialysis it serves as temporary vascular access, particularly in emergencies or while a fistula is maturing. It can also be placed in the abdomen for peritoneal dialysis. Handling it requires strict hygiene.

A care facility dedicated to patients with severe kidney failure who require comprehensive management. A nephrologist is present at all times during sessions, supported by a nursing team. This setting suits patients whose medical condition calls for close monitoring, as opposed to self-care dialysis or home dialysis.

A waste product continuously produced by the normal functioning of the muscles, from creatine. It is eliminated by the kidneys in the urine. Measuring it in the blood and calculating its clearance make it possible to assess kidney function: the more creatinine builds up in the blood, the less effectively the kidneys are filtering. It is one of the reference markers in nephrology follow-up.

A chronic disease marked by an excessively high level of glucose (sugar) in the blood, linked to a defect in the production or action of insulin. Poorly controlled over the long term, it damages the small blood vessels, particularly those of the kidneys. About one in five diabetic patients develops kidney failure; it is one of the leading causes of dialysis worldwide.

A treatment that partially replaces the work of failing kidneys by clearing the blood of its waste products and excess water. Two techniques exist: haemodialysis, which filters the blood through an artificial kidney, and peritoneal dialysis, which uses the natural membrane of the abdomen. The choice depends on the patient's medical condition, lifestyle and preferences.

A treatment option in which the patient carries out their own dialysis at home, after supervised training. It offers great independence, better respect for personal routines, and regular but less frequent medical follow-up. It mainly concerns peritoneal dialysis, and more rarely home haemodialysis. It requires a suitable environment and a relative available to provide support.

A technique that uses the peritoneum, the thin membrane lining the abdominal cavity, as a natural filter. A dialysis solution is introduced into the abdomen through a catheter, left in place for a few hours, then drained and replaced. The treatment works continuously, 24 hours a day, more closely imitating the natural kidney. It is performed almost exclusively at home, after the patient has been trained.

The central filter of the haemodialysis machine, sometimes called an "artificial kidney". It is made up of thousands of semi-permeable hollow fibres through which the blood flows. Waste products and excess water pass from the blood into the dialysis solution, while the blood cells and proteins remain in the circulation. It is the dialyser that actually carries out the purification.

Short for "automated peritoneal dialysis". The patient connects to a small device, the cycler, which automatically carries out the exchanges of dialysis solution in the abdomen during the night, over roughly 8 to 10 hours. The daytime is thus free of handling. This technique suits people who are active or find the manual exchanges of CAPD inconvenient.

Short for "continuous ambulatory peritoneal dialysis". The patient carries out four to five exchanges of dialysis solution in the abdomen by hand during the day, at regular intervals. Each exchange lasts about 30 minutes. Between two exchanges, they can lead a normal life. This method requires no electrical device and can be carried out anywhere, provided hygiene is respected.

A common abbreviation for "erythropoietin", a hormone produced by healthy kidneys that stimulates the bone marrow to make red blood cells. In patients with kidney failure, EPO production falls, which causes anaemia. Synthetic forms are then prescribed by injection to restore a satisfactory haemoglobin level and reduce tiredness.

A hormone naturally produced by healthy kidneys. It acts on the bone marrow, stimulating it to produce red blood cells, which carry oxygen. When the kidneys are diseased, this production decreases and renal anaemia sets in, causing tiredness and breathlessness. Synthetic versions (EPO, ESA) help to make up for this deficiency.

The reference vascular access for haemodialysis, created surgically, most often in the forearm. The surgeon connects an artery to a nearby vein: the vein gradually thickens under the arterial pressure and becomes easy to needle. It provides the high blood flow required for sessions. Its maturation takes several weeks before the first use.

A surgical procedure that replaces the function of diseased kidneys with a healthy kidney from a donor. The donor may be living, often a compatible relative, or deceased. When it is possible, a transplant offers a quality of life close to normal and frees the patient from dialysis sessions. It requires lifelong immunosuppressive treatment.

A dialysis technique in which the patient's blood circulates outside the body through an artificial kidney, the dialyser. Waste products and excess water pass into the dialysis solution through a semi-permeable membrane, then the cleansed blood returns to the patient. Sessions usually take place three times a week and last four to six hours.

A protein contained in the red blood cells, responsible for carrying oxygen from the lungs to the tissues. It owes its red colour to the iron it contains. When it falls below a certain threshold, this is called anaemia, which shows up as tiredness, breathlessness and pallor. Anaemia is common in dialysis patients and is corrected with treatment.

A sudden loss, within a few hours or days, of the kidneys' ability to filter the blood. It is often temporary and reversible if managed quickly. Common causes are a drop in blood supply to the kidneys, an obstruction of the urinary tract, or damage following an operation, an accident or a serious infection. Treatment is often given in intensive care.

The most advanced stage of chronic kidney disease, where kidney function is below roughly 10% of normal (assessed by the GFR, or glomerular filtration rate). At this stage, the kidneys can no longer cleanse the blood on their own. Replacement therapy then becomes necessary: dialysis or a kidney transplant.

A slow and progressive decline in kidney function, developing over several years. It is often silent at first and discovered through blood or urine tests. Without management, it can progress to end-stage kidney failure, then requiring dialysis or a transplant. Its main causes are diabetes, high blood pressure and certain inherited diseases.

Medicines that dampen the activity of the immune system. They are prescribed for life after a kidney transplant to prevent the body from recognising the graft as foreign and rejecting it. Their balance is delicate: too little and rejection threatens, too much and the patient becomes vulnerable to infections. They require close and regular medical follow-up.

The pressure exerted by the blood on the walls of the arteries with each heartbeat. When it remains too high over time, this is called hypertension, which strains the heart, the blood vessels and the kidneys. It increases the risk of heart attack and stroke, and is among the main causes of chronic kidney disease. It is treated through lifestyle measures and medication.

A sterile fluid made up of ultra-purified water, glucose and electrolytes (sodium, potassium, calcium, magnesium, chlorides). In the dialyser it flows on the opposite side of the membrane from the blood: waste products and excess water cross over through the difference in concentration, while the useful elements are preserved. Its composition is adjusted to each patient.

In peritoneal dialysis, the period during which the fresh dialysis solution remains in the abdomen to carry out the purification. Its length varies according to the technique, from a few hours during the day to a full night. At the end of this time, the dialysate laden with waste is drained and replaced with fresh solution, either by hand by the patient or automatically by a cycler.

The mechanism by which the excess water built up in the blood is removed during dialysis. The amount to be removed is calculated before each session from the patient's weight and their target "dry weight". Well-judged ultrafiltration relieves breathlessness and oedema; if too fast, it can lead to cramps or a drop in blood pressure. The team adjusts the settings accordingly.

A facility where patients, trained and fully or partly independent, carry out their own haemodialysis session under the light supervision of a nurse. Sessions take place in small groups, often around five patients to one carer, in a friendly setting. This arrangement suits medically stable people who wish to retain their independence and social life.

A facility intermediate between the full haemodialysis centre and self-care dialysis. It takes in patients whose sessions usually run without incident, but who cannot manage their own care. A nursing team is present at all times, and a nephrologist attends on occasion, without continuous medical supervision during the session itself.

A waste product arising from the normal breakdown of proteins by the liver, carried by the blood and eliminated by the kidneys in the urine. In patients with kidney failure, it builds up in the blood and its level serves as an indicator of the remaining kidney function. Too high a level can cause tiredness, loss of appetite and nausea; one aim of dialysis is to bring it back down.