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Kidney Dialysis Process

Dialysis is a form of treatment that replicates the functions of the kidneys to some extent. It involves the removal of excess water, salts, and wastes from the body, and is recommended for individuals affected by end stage kidney failure. This HealthHearty write-up describes the process of dialysis.
Madhavi Ghare
Last Updated: Jan 21, 2018
The human kidneys are paired bean-shaped organs that perform the vital function of removing wastes and excess water and minerals from the blood. The waste is then removed from the body in the form of urine. In case of kidney failure, the kidneys are unable to remove wastes from the body. When excess fluids and wastes are not removed from the body, the volume of the blood increases. As a result, blood exerts more pressure on the walls of the arteries. This results in elevated blood pressure.
Also, other problems arise when the balance of electrolytes (Sodium, Potassium, Chloride, Calcium, and Magnesium) gets disturbed. These are salts that conduct electricity. Kidneys play a vital role in maintaining a balance by filtering and removing excess sodium and potassium. These electrolytes play a vital role in heart function, muscle coordination, etc. Kidneys help process vitamin D, which in turn helps in the absorption of calcium and phosphorus in the body.
It is quite obvious that the kidneys perform a very important function in the human body, and their failure can be very disastrous for the individual. Dialysis is a treatment that is recommended for individuals diagnosed with acute kidney failure or chronic kidney disease. It is a process wherein the function of the kidneys is provided artificially. It is provided as a artificial replacement for the lost kidney function.
Principle Behind Dialysis
Dialysis works on the principle of transport of a solute across a semi-permeable membrane. This was first proposed by Thomas Graham in 1854. Thereafter, several individuals contributed to the development of the process. In 1960, Scribner and Quinton made the process available to the patients affected by kidney failure via their work on the subcutaneous arteriovenous shunt. This is a plastic tube which is connected to an artery and a vein.
Kidney dialysis works on the principle of diffusion and osmosis of solutes and fluids through a semi-permeable membrane. As per the principle of diffusion, the substances tend to move from an area of high concentration to an area of low concentration. The blood flows on one side of the semi-permeable membrane, whereas the dialysate flows on the other side. The solutes and fluid pass through the membrane. Wastes are removed in the process, and high levels of undesired minerals and chemicals within the blood are replaced by healthy levels.
Types of Dialysis
There are two types of dialysis:
In this process, the patient's blood is pumped into a machine known as the dialyzer. In the dialyzer, the blood is passed through the semi-permeable membrane. As mentioned earlier, blood flows on one side of the semi-permeable membrane, and the dialysate flows on the other. Blood and dialysate move in the opposite directions. The concentration of solutes (phosphorus and urea) are high in the blood, whereas these solutes are in low concentrations or almost absent in the dialysate. Another dialysate solution may contain higher levels of bicarbonate to facilitate the diffusion of bicarbonate in the blood, and neutralize the effect of metabolic acidosis in individuals affected by kidney failure. Thus, the dialyzer removes the wastes from the blood, which is then returned into the patient's body.
Patients have to undergo this process at least 3 times a week, and each session lasts about 3 to 5 hours. Before beginning this process, the patient has to undergo a minor surgery to install the shunt in the arm. In the surgery, one of the arteries of the patient is cut and redirected into a vein, which causes the vein to become thicker and stronger. Once the vein is ready, the process of hemodialysis can begin. A needle is then stuck into that vein to remove the blood, and another needle is stuck in the patient's body for the blood to be sent back to the body.
Peritoneal Dialysis
In this process, the dialysis takes place inside the body. The peritoneal membrane acts as the filtering device. It involves the insertion of a catheter into the peritoneal cavity. One end of the catheter that sticks out of the patient's body is connected to a bag. This bag contains a dialysis fluid. The fluid enters or leaves the peritoneal cavity through the catheter. The fluid is pumped into the peritoneal cavity. The excess fluid and wastes from the blood enter this fluid, and are then removed from the body. The dialysis fluid has to be replaced by fresh fluid. The fluid has to be exchanged four times in a day. This process is further divided into Continuous Ambulatory Peritoneal Dialysis (CAPD) and Automated peritoneal dialysis (APD). In case of the latter, the exchanges are made by a machine called a cycler. These processes can be carried out at home by the patient. However, precautions must be taken. These must be conducted regularly so as to avoid the wastes for accumulating within the patient's body.
On a concluding note, the process of kidney dialysis is not perfect, and it cannot cure or restore kidney function. It is just an imitation of the process conducted by the kidneys. Though dialysis can leave one feeling exhausted, it is certainly beneficial for those who have been diagnosed with kidney failure. It must be noted that individuals affected by kidney failure need to follow the diet recommended by their doctor. They must limit their intake of sodium and potassium. They must also pay attention to their fluid intake.
Disclaimer: The information provided in this article is solely for educating the reader. It is not intended to be a substitute for the advice of a medical expert.