Understanding Chronic Kidney Failure
Definition and Stages
Chronic kidney failure, also known as chronic renal failure, refers to the gradual loss of kidney function over time. This condition is categorized into five stages, each reflecting a decline in kidney function, with the final stage termed end-stage renal disease. Patients with chronic kidney failure often require dialysis treatment to compensate for their damaged renal system.
The Role of Kidneys
The kidneys play a crucial role in the renal system by filtering waste products, excess fluids, salts, vitamins, and minerals from the bloodstream. They also regulate blood pressure through the secretion of hormones. Each kidney contains approximately one million functional units called nephrons. Blood flows into these nephrons, where it is filtered, allowing only small molecules to pass into the nephron tubule while blocking essential components from being eliminated. The nephron reabsorbs necessary substances back into the bloodstream, while waste and surplus fluids are converted into urine for excretion. Without proper kidney function, harmful substances accumulate in the blood, potentially impairing the function of other organs.
What is Dialysis?
Function of Dialysis
Dialysis is a vital treatment for patients with chronic kidney failure, as it removes waste products and excess fluids that the kidneys can no longer filter. While dialysis mimics some kidney functions, it cannot fully replicate the efficiency of healthy kidneys. It serves primarily to manage the effects of kidney damage. The process involves the movement of waste substances from the blood across a semi-permeable membrane into a dialysis fluid with a lower concentration of these substances, a mechanism known as diffusion. There are two primary types of dialysis: hemodialysis and peritoneal dialysis.
How Hemodialysis Works
Procedure Overview
Hemodialysis involves a machine that pumps a patient’s blood to and from a dialyzer, an artificial kidney that filters the blood externally to remove waste and excess fluid. Before starting hemodialysis, a minor surgical procedure is performed to establish vascular access, where two needles are inserted—one to draw blood and another to return the filtered blood.
Vascular Access Options
The preferred vascular access method is a fistula, created by surgically connecting an artery to a vein to facilitate easier needle insertion and faster blood flow. If a fistula is not feasible, a graft may be used to connect an artery and vein. As a temporary solution, a venous catheter can be inserted into a vein, commonly in the neck.
Dialysis Process
During hemodialysis, blood is drawn from the patient’s arm and pumped into the dialyzer, which contains two sections separated by a semi-permeable membrane. The dialysis solution flows in the opposite direction to the blood, aiding the removal of waste. To eliminate excess fluid, the dialyzer maintains higher pressure in the blood section, forcing fluid across the membrane into the solution. The waste-laden dialysis solution is discarded, and the filtered blood is returned to the patient’s body.
Home Hemodialysis
Home hemodialysis is an option that allows patients and a partner to undergo training for performing dialysis at home. This flexibility enhances their treatment schedule and lifestyle.
How Peritoneal Dialysis Works
Mechanism of Action
Peritoneal dialysis differs from hemodialysis as it utilizes the body’s natural peritoneal membrane as a filter instead of an external dialyzer. A catheter is surgically placed to fill the peritoneal cavity with dialysis solution, enabling waste to diffuse from the blood into the peritoneal fluid.
Catheter Insertion and Patient Autonomy
The catheter is typically inserted slightly below the umbilicus, with various exit locations possible. Once the catheter is in place, patients receive training on how to perform peritoneal dialysis at home, which offers greater autonomy compared to hemodialysis.
Automated Peritoneal Dialysis
Peritoneal dialysis can also be automated, using a machine to fill and drain the peritoneal cavity, simplifying the process for patients.
Complications Associated with Dialysis
Moderate and Severe Complications
Patients undergoing dialysis may experience moderate complications such as hypotension and muscle cramps due to the rapid removal of fluid. More severe complications can arise, including an increased production of free radicals, which may lead to oxidative stress and damage to various tissues. Additionally, there is a risk of infection at the vascular access site.
References
– Buffington, M., Sequeira, A., Sachdeva, B., & Abreo, K. (2012). Peritoneal dialysis catheter placement techniques. The Open Urology & Nephrology Journal, 5(1), 4-11.
– Dalal, R., Bruss, Z. S., & Sehdev, J. S. (2019). Physiology, renal blood flow and filtration. In StatPearls [Internet]. StatPearls Publishing.
– Ogobuiro, I., & Tuma, F. (2019). Physiology, renal. In StatPearls [Internet]. StatPearls Publishing.
– National Institute of Diabetes and Digestive and Kidney Diseases. (2018). Hemodialysis. Retrieved from https://www.niddk.nih.gov/health-information/kidney-disease/kidney-failure/hemodialysis
– Punj, S., Enaam, A., Marquez, A., Atkinson, A. J., Jr, & Batlle, D. (2020). A survey on dialysis-related muscle cramping and a hypothesis of angiotensin II on its pathophysiology. Kidney International Reports, 5(6), 924–926. https://doi.org/10.1016/j.ekir.2020.03.003
– Sachdeva, B., Zulfiqar, H., & Aeddula, N. R. (2019). Peritoneal dialysis. Retrieved from https://www.ncbi.nlm.nih.gov/books/NBK532979/
– Vadakedath, S., & Kandi, V. (2017). Dialysis: A review of the mechanisms underlying complications in the management of chronic renal failure. Cureus, 9(8), e1603. https://doi.org/10.7759/cureus.1603