Dialysis: Process, Types, & Risk Factors

Dialysis is a medical procedure carried out to remove extra fluids and impurities from the blood. These impurities are sent to the bladder and are excreted out through urine.

• Kidneys help in the removal of waste and other toxic substances present in our bodies and also help in purifying blood. 
• This treatment is performed when your kidneys fail to perform the above functions due to kidney failure.
• In kidney failure, only 10-15% of the kidneys are functional this may happen due to any injury or disease.

In this article, we will read what is dialysis, the principle of dialysis, the types of dialysis, the success rate, and the risks associated with dialysis.

Figure: Dialysis Diagram

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What is Dialysis?

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A kidney filters about 189 liters of liquids every day. It removes excess fluids through urine. Dialysis is generally performed on those patients whose kidneys fail to filter the blood.

• Poor functioning of the kidneys results in the accumulation of toxic substances in the blood, hence kidney dialysis is necessary in such cases.
• It helps to maintain the mineral balance in the blood and helps regulate blood pressure.
• Dialysis treatment is performed on people suffering from end-stage renal disease and other problems like hypertension and diabetes.
• This treatment was first used in the 1940s and by 1970, it was introduced as a standard treatment method.

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Principle of Dialysis

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Dialysis works on the principle of ultrafiltration. It is a process that occurs when the fluids pass through a semipermeable membrane via pressure.

• Ultrafiltration is the principal step for removing elements like uric acid, creatine, and urea through a semipermeable membrane.
• In dialysis, the blood is made to pass from one side of the membrane, and the dialysis fluid flows on the opposite side.
• The semipermeable membrane is a layer that consists of pores that allow the movement of only certain molecules.
• Molecules that are small in size tend to pass through the membrane easily while the movement of larger molecules is hindered.
• This process of filtration is similar to the function of kidneys.

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Types of Dialysis

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There are two types of dialysis methods performed: hemodialysis and peritoneal dialysis. In this section, we will discuss both the kinds of dialysis in detail.

Hemodialysis

In hemodialysis, the blood is purified using a dialysis machine and a purifier called a dialyzer.

• To perform hemodialysis, the doctor performs a minor surgery on the arm by making an entry into the blood vessels also called the vascular access site.
• This site is important for easy access to blood from the body of the patient.
• It takes 3 to 4 hours to perform this treatment. One is required to take dialysis sessions three times a week.
• Some people suffer from extreme nausea and fatigue after hemodialysis treatment. 

Peritoneal Dialysis

In peritoneal dialysis or abdominal dialysis, the blood is purified by a cleaning liquid that flows through a tube into the abdomen.

• The inner portion of the abdomen called peritoneum behaves like a filter and removes all the impurities from the blood.
• After some time, the cleaning liquid with the filtered impurities is thrown out of the abdomen. This process takes 4 to 6 hours to complete. 
• Continuous Ambulatory Peritoneal dialysis (CAPD) and Automated Peritoneal Dialysis (APD) are the two types of abdominal dialysis.
• Patients might feel a bloated stomach leaving them uncomfortable.

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Risks Associated with Dialysis

Although hemodialysis and peritoneal dialysis help in performing kidney functions, there are also some complications or risks associated with dialysis. Such risks are not faced by every individual but a few of them might suffer from the following risks:

• Muscle Pain: Due to the excess removal of fluids, the patient might experience pain in the muscles. Loss of sodium salts is also one of the reasons for muscle pain.
• Low Blood Pressure: A person undergoing dialysis may experience a drop in blood pressure as their body does not respond properly to the loss of fluids during dialysis.
• High Blood Pressure: During hemodialysis, the levels of sodium is increased which is the major cause of high blood pressure. It can also lead to stiffness of arteries.
• Skin Problems: The patient might experience itching of skin, dryness, and skin discoloration after dialysis. 
• Peritonitis: In peritoneal dialysis, the patient suffers from peritonitis which is the inflammation of the peritoneum, a thin layer covering the wall of the abdomen and other organs.
• Improper sleep cycle: Due to restlessness, cramps, and difficulty in breathing caused by dialysis, a person is likely to experience discomfort and difficulty in sleeping.

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Success Rate of Dialysis

A large number of studies have been conducted to determine the success rate of dialysis. According to a study conducted in India, it was found that 7 out of 10 patients tend to survive more than 6 months.

• In this study, around 6,600 patients (28%) who had undergone hemodialysis died within 10 months. 
• According to the Dialysis Outcomes and Practice Patterns study, the death rate in India is twice the global rate.
• Another foundation reported that patients who have undergone dialysis have survived for 5 to 10 years. 
• Due to an increased number of patients receiving this treatment, there are only limited clinical findings on the survival rates. 

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Things to Remember

• Renal dialysis is the removal of waste and toxic products from the body.
• This procedure is also called continuous renal replacement therapy or CRRT.
• A heparin pump is used in this renal treatment to avoid clotting of blood. 
• The cleaning liquid used in peritoneal dialysis is called dialysate. 
• Dialysate is prepared by mixing water with equal amounts of electrolytes.
• Bleeding and seizures are the complications of hemodialysis.