Continuous Ambulatory Peritoneal Dialysis (CAPD) is a form of renal replacement therapy used to treat end-stage kidney disease. It’s a method of dialysis that involves using the peritoneum, a membrane lining the abdominal cavity, as a natural filter to remove waste products and excess fluids from the body. CAPD is one of the two main types of peritoneal dialysis, the other being Automated Peritoneal Dialysis (APD).
A soft, flexible catheter is surgically inserted into the patient’s abdominal cavity. One end of the catheter remains outside the body, while the other end is positioned within the peritoneal cavity.
Dialysis Solution (Dialysate):
A special dialysis solution (also called dialysate) is introduced into the abdominal cavity through the catheter. This solution contains electrolytes and glucose. The glucose in the solution creates an osmotic gradient, causing excess fluids and waste products in the bloodstream to move into the peritoneal cavity.
After the dialysate is introduced, it remains in the peritoneal cavity for a specific period, known as the dwell time. During this time, the peritoneal membrane acts as a filter, allowing waste products and excess fluids to pass from the bloodstream into the dialysate solution.
After the dwell time, the used dialysate (now containing waste products and excess fluids) is drained from the abdominal cavity into a sterile collection bag. This process is usually done by gravity, and the patient can perform it themselves.
Once the used dialysate is drained, a fresh batch of dialysate is introduced into the peritoneal cavity, and the process continues in cycles throughout the day.
CAPD is called “ambulatory” because it allows patients to perform their dialysis while going about their daily activities. Patients typically perform several exchanges throughout the day, with each exchange taking a few hours.
Why do we need CAPD?
Continuous Ambulatory Peritoneal Dialysis (CAPD) serves as a valuable treatment option for individuals with end-stage kidney disease (also known as stage 5 chronic kidney disease) when their kidneys have lost almost all of their ability to function. In this condition, the kidneys are unable to effectively filter waste products and excess fluids from the bloodstream, which can lead to a buildup of toxins and fluid retention in the body. CAPD addresses these issues and provides several benefits:
CAPD helps remove waste products and toxins from the bloodstream that would normally be filtered out by healthy kidneys. The dialysis solution used in CAPD contains a higher concentration of waste products than the blood, creating an osmotic gradient that allows waste to move from the blood vessels into the dialysis solution.
CAPD assists in maintaining a proper fluid balance in the body. Patients with end-stage kidney disease often struggle to remove excess fluids through urine, leading to edema (swelling) and high blood pressure. CAPD helps manage fluid levels by allowing excess fluids to be removed during the draining phase of the dialysis process.
The electrolytes that are essential for various bodily functions. It can become imbalanced in people with kidney failure. CAPD helps maintain a healthier electrolyte balance by allowing these substances to pass from the bloodstream into the dialysis solution.
Convenience and Independence:
CAPD offers greater flexibility and independence compared to other forms of dialysis, such as hemodialysis. Patients can perform exchanges at home. Our Kidney specialist allows them to continue with their daily routines. This will reduce the need to visit a dialysis center multiple times a week.
CAPD can provide a gentler form of dialysis. It occurs continuously throughout the day. This steady process can be less taxing on the body than the more intense fluctuations in the fluid and waste levels that occur during intermittent hemodialysis.
Vascular Access Preservation:
Unlike hemodialysis, which often requires an arteriovenous (AV) fistula, CAPD does not necessitate significant vascular access. The catheter used in CAPD is inserted into the abdominal cavity. It reduces the risk of complications associated with traditional vascular access methods.
Suitable for Certain Patient Populations:
CAPD may be a preferred option for individuals who have limited vascular access options, or allergies to anticoagulants used in hemodialysis.
Prof (Dr) D Mukherjee is an alumnus of the prestigious Armed Forces Medical College, Pune where he did his MBBS & MD (Medicine). Subsequently he went on to do his DM (Nephrology) from PGIMER Chandigarh, which is the foremost training institution for nephrology in India.