Hemodialysis (HD)
Via needles or a catheter and blood lines the patient’s blood is directed outside the body, through an artificial kidney – the dialyzer – and back to the patient’s circulation.
The cleaning process takes place inside the dialyzer where blood and dialysis fluid flows on opposite sides of a semi-permeable membrane. By diffusion waste products pass through the dialyzer membrane from the blood and are carried away by the dialysis fluid.
In the same manner, bicarbonate and electrolytes pass the dialysis membrane in the opposite direction, from the dialysis fluid to the blood. By means of a pressure gradient exerted by the dialysis machine, the excess fluid gained between treatments, is removed over the membrane.
The entire dialysis process is monitored and controlled by the dialysis machine. HD usually involves treatments that last 3-5 hours, three times a week and can be performed either in hospital units, in satellite units or at home. A vast majority of all dialysis patients are treated with HD.
Peritoneal dialysis (PD)
The cleansing process of the blood takes place inside the body. Sterile cleansing fluid is brought into the patient’s abdominal cavity via a permanent catheter placed in the lower abdominal tract, and the peritoneum acts as a filter.
Waste products are removed by diffusion, while excess fluid is removed by osmosis. The cleansing fluid is replaced every four hours. In the most common form of peritoneal dialysis, known as CAPD (Continuous Ambulatory Peritoneal Dialysis) the patient changes the fluid manually. The second mode of peritoneal dialysis available is APD (Automated Peritoneal Dialysis), where the cleansing fluid exchanges are managed by a machine (PD cycler) mostly performed during the night when the patient is sleeping.
OTHER WORDS
Acid-base homeostasis
The proper balance between acids and bases (pH) in the body, which is affected by kidney failure .
Anabolism
An energy requiring constructive metabolism (building up). Typically in anabolism, small molecules are assembled into larger organic molecules. Example: the growth and mineralization of bone.
APD (Automated Peritoneal Dialysis)
A treatment mode where the dialysis fluid exchanges are managed by means of a machine (see above).
Artificial kidney
Synonym for dialyzer or filter
AV-fistula
The AV-fistula is surgically created by connecting an artery to a vein. During a maturation time of 2-3 months the vein expands and becomes suitable for repeated cannulations facilitating HD.
Artificial kidney
Synonym for dialyzer.
Blood lines
System of tubes used for transportation of the patient’s blood outside the body.
CAPD (Continuous Ambulatory Peritoneal Dialysis)
A treatment mode where the patient manually exchange the dialysis fluid approximately every four hours.
Central Venous Catheter (CVC)
A flexible tube that is placed in a central vein for blood access.
CKD (Chronic Kidney Disease)
Is a progressive loss of kidney function over a period of months or years through five stages. Stage 1 CKD is mildly diminished renal function, with few overt symptoms while Stage 5 CKD is a severe illness and requires some form of renal replacement therapy.
Creatinine
A muscle metabolite (break-down product).
Creatinine clearance
The volume of blood that is totally cleared of creatinine per unit time. Deteriorating kidney function can be followed by measuring the creatinine clearance, which is declining.
Cycle
A peritoneal cycle or exchange is the infusion and drainage of a specific volume of peritoneal dialysis solution consistent with the PD prescription. The PD prescription defines the volume, dwell time and sometimes the rate of infusion and drainage. The dwell time may vary from a few minutes to several hours.
Diabetes mellitus metabolic disorder (Type I)
An inability to oxidize carbohydrates, due to disturbance of the normal insulin mechanism, producing hyperglycemia, thirst, hunger, weakness, acidosis etc
Type 2 Diabetes
A metabolic disorder characterized by hyperglycemia, insulin resistance and relative insulin deficiency that initially may be managed by physical activity and diet. Eventually medications and insulin are usually required. The almost epidemically increase of Type 2 diabetes constitutes a global dilemma.
Dialysis
A method of removing excess water and toxic substances from the blood as well as restoring acid-base balance and electrolyte levels when the kidneys are unable to do so. Dialysis is most frequently used for patients who have kidney failure, but may also be used to quickly remove drugs, poisons and excess fluid in acute situations.
Dialysis concentrate
A concentrate of salt withholding electrolytes, which after dilution with water and mixing with bicarbonate fluid (performed by the dialysis machine) becomes dialysis fluid.
Dialysis fluid
The chemical bath used in dialysis to draw toxins out of the bloodstream and supply electrolytes and other chemicals to the bloodstream.
Dialysis machine
A machine, which administers and controls the flow of blood and dialysis fluid through the artificial kidney during the treatment; the machine also prepares the dialysis fluid from water and concentrate.
Dialyzer
Often referred to as the artificial kidney; it is a special filter, which is used in HD for removing toxic substances and excess water from the blood as well as restoring acid-base balance and electrolyte levels.
Diffusion
Movement of a solute from a higher to a lower concentration area, i.e. transport driven by a concentration gradient.
Erythropoietin
A hormone produced by the kidneys that stimulates red blood cell production.
ESRD (End Stage Renal Disease)
Failed kidney function which results in a toxic and fatal condition if the patient is not treated regularly with dialysis or receives a kidney transplant.
Exchange
A peritoneal exchange or cycle is the infusion and drainage of a specific volume of peritoneal dialysis solution consistent with the PD prescription. The PD prescription defines the volume, dwell time and sometimes the rate of infusion and drainage. The dwell time may vary from a few minutes to several hours.
Extracorporeal
Situated or occurring outside (extra) the body (corporeal).
Glomerulonephritis
Inflammation of the glomeruli of the kidney (see below), which is a common cause for chronic renal failure.
Glomerular filtration rate (GFR)
The volume of fluid filtered per unit time (compare creatinine clearance)
Glomerulus
A network of capillaries that compose an important part of the functional unit of the kidney. This is where fluid and waste products are filtered from the blood, forming the primary urine.
High flux membrane
Dialysis membrane that is more permeable (open to the passage of larger solutes and higher fluid volumes) than low flux membranes.
Homeostasis
Describes a stable, balanced internal environment. The condition is made possible by dynamic adjustments and regulation mechanisms in several body systems.
Hypertension
High arterial blood pressure
Immunosuppressant
A drug that inhibits immune system activity used to prevent rejection of a transplant
Kidney
A bean-shaped organ located in the abdominal cavity, one on each side of the vertebral column. More than one liter of blood normally passes through the kidneys every minute, whereby excess fluid and a variety of water-soluble waste products are eliminated from the body. The kidney’s smallest functional unit is the nephron.
By filtration of blood in the glomeruli, primary urine is formed; downstream in the tubuli the primary urine is concentrated according to body needs. The kidney function is typically expressed as renal clearance; its normal value is around 120 ml/min. When the kidney function deteriorates in response to a disease, many body functions are affected. When the clearance drops to 10-15 ml/min, renal replacement therapy becomes necessary. (The kidney is also an important hormone-producing organ.)
Membrane
A thin skin-like layer or film.
Metabolism
Is the sum of all chemical reactions that occur in a cell. Metabolism consists of two types of processes, catabolism (breaking down) and anabolism (building up).
Osmosis
Passage of fluid through a semi-permeable membrane from an area of lesser concentration to an area of greater concentration in order to achieve equilibrium of solutes.
PD cycler
A machine managing automatically exchanges of PD fluids, usually used at nights.
Peritoneum
The membrane lining the abdominal cavity. It covers and supports most of the intra-abdominal organs and serves as a canal for their blood and lymph vessels. In PD the peritoneum is used as the dialyzer membrane.
Red blood cell (erythrocyte)
Are the most numerous type of blood cells. Contains a protein called hemoglobin (the red pigment of blood), which binds oxygen and carbon dioxide and serves as a shuttle for these gases. Since the erythrocytes have a limited lifespan continuous production is a necessity, which takes place in the bone marrow and is stimulated by the hormone erythropoietin (EPO), which is produced by the kidneys.
Renin
An enzyme secreted by the kidneys that regulates the blood pressure.
RRT (Renal Replacement Therapy)
A term used to encompass life-supporting treatments for ESRD
Semi-permeable
Describes a membrane that will allow some but not all substances to pass through it.
Solute
The substance that is dissolved in a liquid (solvent) to form a solution.
Ultrafiltration
The transfer of fluid through a membrane facilitated by a pressure gradient. In dialysis often referred to as UF, i.e. the fluid volume removed from the patient during the treatment.
Urea
One of the waste products that build up in the blood. The levels of urea in the blood can be measured to give an indication of how well, or poorly, the kidneys are working.
Uremic toxins
A variety of waste products formed during metabolism.
Vascular access
The site where blood can be safely removed from and returned to the patient’s circulation. The vascular access may be an AV fistula, a graft, or a central venous catheter.
Vitamin D
The term “Vitamin D” represents a group of closely related fats present in some foods such as fish oils. Those are transformed into Vitamin D3 in the skin through the action of UV radiation (sunlight). Vitamin D3 then undergoes further chemical changes in the liver and kidney to become “active vitamin D3”, a hormone necessary for the absorption of calcium from the intestines.
Waste products
A variety of toxins formed during metabolism