A dialyzer is a device that is used in hemodialysis and other treatments. Dialyzers are built into dialysis machines, which cannot function without them. Dialysis treatments may be considered, for example, as part of therapy for hyperkalemia, some poisonings, certain forms of kidney failure, or hyperhydration. An example of an underlying condition that may require renal replacement therapy is the metabolic disorder diabetes.
What is a dialyzer?
Dialyzers are built into dialysis machines that cannot function without them. (White tube on left side of image).
A dialyzer is a technical device that medicine uses as an aid. One application of the dialyzer is, for example, hemodialysis, i.e. blood purification, which may be required as part of renal replacement therapy. In some cases, physicians use dialyzer and dialysis machine as synonyms, while others use dialyzer to refer to the most important piece in the dialysis machine: It contains the semipermeable (semipermeable) membrane where the actual filtration process takes place. The dialyzer is an important component of a dialysis machine and can come in one of two variations: the capillary dialyzer and the plate dialyzer. In dialysis, thin tubes carry the patient’s blood out of the body and deliver it to the dialysis machine. There it flows through the dialyzer and is filtered at the membrane. This causes the urinary substances that would normally pass through the kidneys into the urine to leave the patient’s blood. A dialysate in liquid form absorbs the substances.
Forms, types, and species
In renal replacement therapy, medicine uses the capillary dialyzer and the plate dialyzer. The capillary dialyzer is a device in which the patient’s blood flows through capillaries, which are hollow, thin vessels. A single capillary has a diameter of almost exactly 200 µm. An alternative name for them is “hollow fiber,” which is why physicians sometimes also refer to them as hollow fiber dialyzers. Capillary dialyzers are particularly widespread. In addition, plate dialyzers exist that direct blood into wide vessels rather than many thin ones.
Structure and mode of operation
An important role in the dialyzer is played by the membrane, which is the actual filter. This dialysis membrane is semi-permeable (semipermeable), which means that it does not allow every substance to automatically pass to the other side, but filters out certain substances or does not allow them to pass through the dialysis membrane. In principle, it can also be permeable in only one direction, which also corresponds to the definition of semipermeability. Dialysis uses a membrane that filters out only the urinary substances so that the patient can receive the remaining blood components back. The most important process in the dialysis procedure takes place at the dialysis membrane. It comes close to the natural functioning of the kidney. The larger the surface area of the membrane, the more efficient and effective the filtration.
Medical and health benefits
Dialyzers can be used as part of the treatment of certain diseases. Basically, it can be stated that dialysis mimics the filtering function of the kidney. This is necessary, for example, when the kidney fails or is confronted with an extraordinary amount of pollutants that it cannot cope with. For this reason, medicine also refers to dialysis as a kidney replacement procedure. However, the kidney of the patient in question may still be (partially) functional. Whether such treatment is necessary depends on the individual conditions. In a healthy person, the kidney plays a crucial role in purifying the blood. If it is damaged, there is therefore a considerable health risk. Organ damage can be due to a wide variety of causes. An acute indication for renal replacement therapy may be acute kidney failure, for example, if severe injuries in an accident impair the usual function of the cleansing organ to such an extent that there is a risk of short- or long-term damage. Another example is diabetes mellitus. This is a metabolic disease characterized by insulin resistance or a lack of insulin production in the islet cells of the pancreas.Diabetes can be both hereditary and due to personal lifestyle factors. There is widespread consensus among physicians that a person’s diet and exercise have a significant effect on the risk of developing diabetes. These two factors can also generally influence the further course of the metabolic disorder. However, diabetes patients who suffer from kidney dysfunction as a result of their underlying disease represent just one example among many of the potential need for renal replacement therapy. Another example is patients who have intentionally or unintentionally overdosed on a drug or otherwise been exposed to toxic substances. Such acute poisoning may also be an indication for dialysis. In this case, the body would be challenged beyond measure with the amount of urinary substances that the kidney must filter out of the blood. Taking an overdose of medications, among other things, can also lead to kidney and other organ damage that may require regular dialysis treatments in the long term.
