Introduction
Dialysis is a treatment prescribed to patients suffering from kidney failure. Due to kidney failure, the kidney cannot filter blood at full capacity. As a consequence, toxins and waste build up in the bloodstream. In such a situation, dialysis does the work of the kidney by removing excess fluid and waste products from the blood.
The dialysis process balances the body through the following three functions:
- Removing excess salt, water and waste from the bloodstream and preventing its buildup
- Maintaining a safe level of a required chemical such as potassium, bicarbonate and sodium in the bloodstream
- Helping in controlling blood pressure
The dialysis process works on the principle of osmosis. In osmosis, a fluid containing higher water concentration moves to an area containing lower water concentration through a semipermeable membrane until equilibrium is reached. Similarly, in the dialysis process, excess fluid from the blood moves to the dialysate fluid through a semipermeable membrane until the blood and dialysate are at the same level.
Who needs dialysis?
Individuals who have kidney failure may need dialysis. Kidney failure, also called end-stage renal disease (ESRD), can be caused by injuries and conditions, including high blood pressure, diabetes, and lupus. These conditions can cause damage to the kidney resulting in kidney disease.
Types of Dialysis
There are two types of dialysis:
- Hemodialysis
- Peritoneal dialysis
Haemodialysis Process
The haemodialysis process removes the blood outside the body through a machine and pumps it into a dialyser. This dialyser is like an artificial kidney. It filters out metabolic waste products from the pumped out blood and pumps purified blood into the person. The total amount of fluid pumped back in can be adjusted. It helps remove the excess fluid that can build up due to kidney failure.
The haemodialysis process requires continuous and repeated access to the bloodstream. It is done by artificially connecting an artery and vein through surgery for long-term access. During the haemodialysis process, Heparin, which is a drug that prevents clotting, is given. This is done to prevent clotting in the dialyser.
Dialysis is done in the dialyser through a porous artificial membrane. The small pores of the membrane can separate fluid, waste products, and electrolytes from the blood. They can’t separate blood cells and large proteins from the bloodstream, so these substances continue remaining in the blood when the blood returns to the body.
A haemodialysis treatment can take up to 3 to 5 hours for one cycle. Most people with chronic kidney failure require haemodialysis three times a week. Some of the common complications of haemodialysis include low blood pressure after the dialysis process.
Peritoneal Dialysis Process
The stomach and intestines are abdominal organs that exist inside a large, hollow space known as the abdominal cavity. This abdominal cavity has a membrane called the peritoneum that lines it. In the peritoneal dialysis process, this membrane performs the function of a filter. The membrane has a large surface area and a rich network of blood vessels. Therefore, substances from the bloodstream can easily pass through the peritoneal membrane into the abdominal cavity.
In the peritoneal dialysis process, a fluid known as dialysate is infused into the space within the abdominal cavity through a catheter. The dialysate is then left in the abdomen for a sufficient time. During this time, the waste products in the bloodstream pass through the fluid slowly. Once this is done, the dialysate is drained out, discarded, and then replaced with fresh dialysate.
Peritoneal dialysis is done manually or through a machine. Manual peritoneal dialysis has two types:
- Manual Intermittent Dialysis
In this type, dialysate contained in bags is warmed up to room temperature and then infused into the peritoneal cavity. The dialysate is allowed to stay in the cavity for 60 to 90 minutes and then drained out. This process is repeated continuously, and the treatment can take up to 12 to 24 hours.
- Continuous Ambulatory Dialysis
In this type, the dialysate is taken out and replenished 4 to 5 times a day. The continuous ambulatory dialysis process differs from the intermittent manual process in a continuous ambulatory one. The dialysate always remains in the peritoneal cavity.
Automated peritoneal dialysis is the most commonly used form of peritoneal dialysis. This is because the automated device minimises the number of exchanges of fluid. This process is usually undertaken at home and can eliminate the need to go to the hospital for hemodialysis.
Conclusion
The dialysis process is an essential substitute in case of kidney failure. This process works on the principle of osmosis. There are two types of dialysis – hemodialysis dialysis and peritoneal dialysis – as discussed above. The primary difference between these processes is that in hemodialysis, blood is pumped out; in peritoneal dialysis, a dialysate fluid is infused inside the abdominal cavity to conduct dialysis. Dialysis is a temporary solution in situations where the kidney is not functioning properly, and it can be continued until the kidney function returns to normal.