Dialysis is a medical procedure that filters waste products and excess fluid from the blood when a person’s kidneys can no longer perform this function adequately. It is a life-sustaining treatment for individuals with kidney failure, maintaining the body’s internal balance and preventing the harmful buildup of substances healthy kidneys would naturally remove.
Why Dialysis is Necessary
Healthy kidneys filter waste products like urea and creatinine from the blood, maintain electrolyte balance, regulate fluid levels, and produce hormones. When kidneys fail, these waste products and excess fluid accumulate, leading to uremia. This condition can cause symptoms such as fatigue, nausea, vomiting, swelling, and shortness of breath. Untreated uremia can result in severe complications, including seizures, coma, and even death.
The primary long-term reason for dialysis is End-Stage Renal Disease (ESRD), which occurs when kidney function declines to 10-15% of normal capacity. Dialysis may also be necessary in acute situations, such as severe acute kidney injury, or in cases of certain poisonings to temporarily remove toxins or drugs from the blood.
Understanding the Dialysis Process
Dialysis works by employing the scientific principles of diffusion and ultrafiltration to remove waste and excess fluid from the blood. Diffusion involves the movement of solutes, like waste products, from an area of higher concentration (the patient’s blood) across a semipermeable membrane to an area of lower concentration (the dialysate fluid). Ultrafiltration is the process of removing excess fluid from the blood, achieved by creating a pressure difference across the membrane, which forces water and dissolved substances out of the blood.
Hemodialysis
Hemodialysis is a common method where blood is drawn from the patient and circulated through an artificial kidney machine called a dialyzer. Inside the dialyzer, blood flows on one side of a semipermeable membrane, while dialysate fluid flows in the opposite direction. This counter-current flow maximizes the concentration gradient, allowing waste products to diffuse from the blood into the dialysate, and excess fluid is removed. Patients require vascular access, typically created through minor surgery to enlarge a blood vessel in the arm, forming an arteriovenous fistula or graft, or by placing a temporary catheter. Hemodialysis sessions usually last 3 to 4 hours and are performed about three times a week, often in a clinic or hospital setting.
Peritoneal Dialysis
Peritoneal dialysis offers an alternative approach where a catheter is surgically placed into the abdomen, leading into the peritoneal cavity. This cavity, lined by the peritoneum, contains numerous tiny blood vessels that serve as a natural filter. Dialysate fluid is introduced into the peritoneal cavity through the catheter, where it dwells for several hours, absorbing waste products and excess fluid from the blood vessels in the peritoneum. After the dwell time, the used fluid, now containing wastes, is drained from the abdomen.
This process, called an “exchange,” can be done manually multiple times a day (Continuous Ambulatory Peritoneal Dialysis, or CAPD) or automatically by a machine overnight (Automated Peritoneal Dialysis, or APD). Peritoneal dialysis is often performed daily at home, offering more flexibility than in-center hemodialysis.
Living with Dialysis
Individuals on long-term dialysis must adhere to dietary and fluid restrictions to manage their condition and prevent complications. This involves limiting potassium, phosphorus, and sodium intake, and carefully monitoring fluid consumption to prevent fluid overload between sessions. Non-adherence to these restrictions can lead to increased metabolic byproducts and excess fluid, negatively impacting health outcomes.
Patients also require various medications to manage associated conditions like high blood pressure, anemia, and bone disease. The regular schedule of dialysis sessions, particularly hemodialysis, requires significant adjustments to daily life and can impact energy levels, often leading to fatigue. Adherence to treatment schedules, including attending sessions and taking medications, is important for overall well-being.
Beyond the physical aspects, living with kidney failure and undergoing dialysis can have a significant emotional and social impact. Patients may experience depression and anxiety. Strong family and social support networks can aid in coping with the demands of the disease and improving treatment adherence. Ongoing medical oversight is necessary, involving continuous monitoring by a healthcare team, regular blood tests, and follow-up appointments to adjust treatment as needed.