Kidney dialysis is a life-saving medical treatment for individuals whose kidneys are no longer able to function properly. The kidneys are essential organs that filter waste, toxins, and excess fluids from the blood, maintaining a delicate balance of electrolytes and fluids in the body. When the kidneys fail due to chronic kidney disease (CKD), injury, or other medical conditions, dialysis is used to perform the essential functions that the kidneys can no longer handle. It serves as an artificial replacement for the natural filtration process of healthy kidneys.
This comprehensive guide will explain the different types of dialysis, how they work, and what to expect from the dialysis process. We’ll also explore when dialysis becomes necessary, the benefits and limitations of this treatment, and lifestyle tips for individuals undergoing dialysis.
What is Kidney Dialysis?
In its simplest terms, kidney dialysis is a medical procedure designed to remove waste products and excess fluids from the blood when the kidneys can no longer perform these tasks. Dialysis helps to:
- Maintain electrolyte balance (such as sodium, potassium, and calcium) in the body
- Control blood pressure
- Remove urea, creatinine, and other toxins from the bloodstream
- Prevent fluid buildup in the body
Dialysis is not a cure for kidney disease, but it serves as a life-sustaining treatment that mimics some of the kidneys’ critical functions. It is generally recommended when a patient has lost around 85% to 90% of their kidney function or when their glomerular filtration rate (GFR) drops below a critical threshold. Patients with end-stage renal disease (ESRD), the final stage of chronic kidney disease, often require dialysis or a kidney transplant to survive.
There are two primary types of dialysis:
- Hemodialysis
- Peritoneal Dialysis
Let’s explore each of these in detail to understand how they work and how they differ.
Hemodialysis: The Most Common Form of Dialysis
Hemodialysis is the most commonly used method of dialysis, particularly for patients with chronic kidney failure. In hemodialysis, a machine is used to filter waste, toxins, and excess fluid from the patient’s blood outside the body. The filtered blood is then returned to the patient’s body. Hemodialysis typically requires patients to visit a dialysis center, hospital, or clinic, although home hemodialysis is also possible with the right equipment and training.
How Hemodialysis Works
Hemodialysis involves creating access to the patient’s blood vessels, either through a fistula, graft, or catheter. Blood is drawn from the patient and passed through a special filter called a dialyzer, often referred to as an artificial kidney. The process involves the following steps:
- Access to the bloodstream: A vascular access point is required for the dialysis machine to draw blood from the patient. The three types of vascular access are:
- Arteriovenous (AV) fistula: A surgically created connection between an artery and a vein in the arm, allowing easy access to the bloodstream. This is considered the best option because it is durable and long-lasting.
- Arteriovenous (AV) graft: A synthetic tube is implanted under the skin to connect an artery to a vein. This is used when a fistula is not an option.
- Central venous catheter (CVC): A flexible tube is placed in a large vein in the neck, chest, or groin. This is typically used for short-term or emergency access.
- Blood is pumped into the dialyzer: Once access is established, blood is drawn from the patient and pumped into the dialyzer, which contains two chambers separated by a thin membrane. The patient’s blood flows on one side of the membrane, while a special dialysis fluid called dialysate flows on the other side.
- Filtration process: The membrane in the dialyzer is semipermeable, meaning it allows small molecules like urea, creatinine, and excess electrolytes to pass through while keeping larger molecules like proteins and blood cells in the bloodstream. Waste products and excess fluid from the blood diffuse across the membrane into the dialysate, effectively cleansing the blood.
- Clean blood returns to the body: After filtration, the clean, filtered blood is returned to the patient’s body through the vascular access point. The process continues for several hours until a sufficient amount of blood has been filtered.
- Removal of excess fluid: During dialysis, excess fluid that has built up in the body is also removed. This helps prevent fluid overload, which can lead to high blood pressure, swelling, and heart failure.
How Long Does Hemodialysis Take?
A typical hemodialysis session lasts around 3 to 5 hours and is usually performed three times per week. The duration and frequency of treatments depend on the patient’s individual needs, including how much kidney function they still have, how much waste and fluid need to be removed, and their overall health.
While hemodialysis is often performed at a dialysis center, home hemodialysis is becoming increasingly popular. Patients who undergo home dialysis are trained to use the dialysis machine and monitor their own treatments, offering them greater flexibility and control over their schedule.
Benefits of Hemodialysis
- Efficient waste removal: Hemodialysis effectively removes waste and excess fluid from the body, helping to control symptoms of kidney failure.
- Professionally supervised: When performed at a dialysis center, hemodialysis is supervised by healthcare professionals who can monitor the treatment and adjust it as needed.
- Established treatment: Hemodialysis has been widely used for decades and is a proven, life-saving treatment for patients with kidney failure.
Limitations of Hemodialysis
- Time-consuming: Hemodialysis requires frequent trips to the dialysis center and long treatment sessions, which can be disruptive to a patient’s daily life.
- Side effects: Some patients experience low blood pressure, cramping, or fatigue during or after treatment due to rapid changes in fluid and electrolyte levels.
- Dietary restrictions: Patients on hemodialysis must often follow a strict diet to avoid high levels of potassium, phosphorus, and sodium, which can build up between dialysis sessions.
Peritoneal Dialysis: A Home-Based Option
Peritoneal dialysis (PD) is another type of dialysis that allows the patient to filter their blood at home using the natural lining of the abdomen (the peritoneum) as the filter. Unlike hemodialysis, which uses a machine to filter blood, peritoneal dialysis uses the body’s own peritoneal membrane to perform the filtration process.
How Peritoneal Dialysis Works
In peritoneal dialysis, a sterile dialysis fluid called dialysate is introduced into the patient’s abdominal cavity through a catheter that has been surgically placed in the abdomen. The dialysate absorbs waste products and excess fluids from the blood vessels in the peritoneum, and the waste-filled fluid is later drained from the abdomen. This process is repeated multiple times a day.
The steps involved in peritoneal dialysis include:
- Catheter insertion: A permanent catheter is surgically placed in the patient’s abdomen, usually near the navel. This catheter allows dialysate to enter and exit the abdominal cavity.
- Filling the abdomen with dialysate: Dialysate is a special solution that contains water, glucose, and other electrolytes. The solution is inserted into the abdominal cavity through the catheter. The glucose in the dialysate helps draw waste products and excess fluid from the blood vessels into the abdominal cavity.
- Dwell time: The dialysate remains in the abdomen for a set period, called the dwell time, which typically lasts between 4 and 6 hours. During this time, waste products and excess fluids are drawn from the blood into the dialysate through the peritoneal membrane.
- Draining the fluid: After the dwell time, the waste-filled dialysate is drained from the abdomen through the catheter and discarded. The process is then repeated with fresh dialysate.
There are two main types of peritoneal dialysis:
- Continuous Ambulatory Peritoneal Dialysis (CAPD): This method is performed manually by the patient throughout the day. The patient fills their abdomen with dialysate, allows it to dwell, and then drains it several times per day. Each cycle takes about 30 minutes, and the patient can go about their daily activities during the dwell time.
- Automated Peritoneal Dialysis (APD): APD uses a machine called a cycler to perform the dialysis process automatically, typically while the patient sleeps at night. The cycler fills the abdomen with dialysate, allows it to dwell, and drains it several times throughout the night.
Benefits of Peritoneal Dialysis
- Home-based treatment: Peritoneal dialysis allows patients to perform dialysis at home, offering greater flexibility and independence. Patients can manage their treatment schedule and do not need to visit a dialysis center as frequently.
- Continuous process: Peritoneal dialysis is a gentler, continuous process that may better mimic the natural function of the kidneys. It removes waste and fluid more gradually, which may lead to fewer side effects like cramping or low blood pressure.
- Diet flexibility: Patients on peritoneal dialysis may have fewer dietary restrictions compared to those on hemodialysis since the filtration process is more continuous.
Limitations of Peritoneal Dialysis
- Risk of infection: Since peritoneal dialysis involves the use of a permanent catheter, there is a risk of infection at the catheter site or inside the abdominal cavity (called peritonitis). Patients must follow strict hygiene protocols to prevent infections.
- Daily commitment: Peritoneal dialysis requires daily attention, and patients must perform the treatment multiple times per day or use a cycler overnight.
- Not suitable for everyone: Some patients, especially those with abdominal scarring or certain medical conditions, may not be good candidates for peritoneal dialysis.
When is Dialysis Necessary?
Dialysis becomes necessary when a person’s kidneys are no longer able to filter waste, regulate electrolytes, or maintain fluid balance on their own. The need for dialysis is often determined by the patient’s glomerular filtration rate (GFR), which measures how well the kidneys are filtering blood. Dialysis is typically recommended when the GFR falls below 15 mL/min or when a patient develops severe symptoms of kidney failure, such as:
- Fluid overload (causing swelling in the legs, ankles, and lungs)
- High potassium levels (which can cause dangerous heart rhythms)
- Severe acidosis (buildup of acid in the body)
- Uremia (buildup of waste products in the blood leading to nausea, vomiting, or confusion)
Dialysis is used as either a temporary measure (in cases of acute kidney injury) or as a long-term treatment for patients with chronic kidney disease or end-stage renal disease.
What to Expect During Dialysis
For patients undergoing dialysis, the experience can vary depending on whether they are receiving hemodialysis or peritoneal dialysis. Here’s what patients can generally expect:
Hemodialysis
- In-center hemodialysis: Patients will typically visit a dialysis center three times a week for sessions lasting between 3 and 5 hours. During the treatment, patients sit in a comfortable chair while their blood is filtered through the dialysis machine. A nurse or technician monitors the patient’s blood pressure and fluid levels throughout the session.
- Home hemodialysis: For those who choose home dialysis, patients or their caregivers are trained to use the dialysis machine. The process is similar to in-center hemodialysis but is performed at home with greater flexibility in scheduling.
Peritoneal Dialysis
- CAPD: Patients perform manual exchanges of dialysate several times throughout the day. Each exchange takes about 30 minutes, and the patient can go about their normal activities during the dwell time.
- APD: Patients connect to a dialysis machine (cycler) at night, which automatically fills and drains the abdomen while they sleep. This allows for uninterrupted dialysis while the patient is resting.
Benefits of Dialysis
Dialysis offers several life-saving benefits for individuals with kidney failure:
- Removes toxins and waste: Dialysis filters the blood, removing harmful waste products that the kidneys can no longer filter on their own.
- Controls fluid balance: Dialysis helps regulate fluid levels in the body, preventing dangerous fluid buildup in tissues and organs.
- Improves quality of life: By managing the symptoms of kidney failure, dialysis can improve a patient’s quality of life, allowing them to maintain an active lifestyle.
Limitations of Dialysis
While dialysis is an essential treatment for kidney failure, it does have some limitations:
- Not a cure: Dialysis does not cure kidney disease; it only manages the symptoms. Patients will need dialysis for the rest of their lives unless they receive a kidney transplant.
- Time-consuming: Hemodialysis, in particular, requires frequent and lengthy treatment sessions, which can be disruptive to daily life.
- Side effects: Some patients experience fatigue, cramping, or low blood pressure during or after dialysis sessions.
Conclusion
Kidney dialysis is a vital treatment for individuals with kidney failure, providing a way to remove waste, toxins, and excess fluids from the body when the kidneys can no longer perform these functions. Whether through hemodialysis or peritoneal dialysis, this treatment helps patients manage the symptoms of kidney disease, improve their quality of life, and maintain overall health. While dialysis is not a cure for kidney disease, it serves as an essential life-sustaining therapy for millions of people worldwide.
