CAPD Varieties: Exploring Different Types of Continuous Ambulatory Peritoneal Dialysis — Cost, Top Hospitals & Success Rates | MyMedicPlus

Continuous Ambulatory Peritoneal Dialysis (CAPD) is a form of peritoneal dialysis (PD) — a renal replacement therapy for end-stage kidney disease (ESKD) that uses the peritoneum (the natural membrane lining the abdominal cavity) as a semi-permeable biological dialysis membrane. In CAPD, a sterile dialysate solution is instilled into the peritoneal cavity through a surgically placed Tenckhoff catheter, where it dwells for several hours, during which solutes (urea, creatinine, potassium, phosphate) and excess fluid diffuse across the peritoneal membrane from the peritoneal vasculature into the dialysate, driven by osmotic and concentration gradients. The spent dialysate is then drained and replaced with fresh solution. This exchange cycle is performed 3-5 times per day by the patient themselves, without machinery, allowing continuous ambulatory (mobile) dialysis.

CAPD is classified as a home dialysis modality — patients perform exchanges at home, at work, or wherever they are, having undergone training (typically 1-2 weeks) by a peritoneal dialysis nurse. Each exchange takes approximately 30-40 minutes; the catheter is otherwise capped and concealed under clothing. The continuous nature of CAPD provides a more physiological, steady-state solute clearance profile compared to the intermittent therapy of haemodialysis — analogous in some ways to residual kidney function. It is the dominant PD modality globally and is particularly valued in lower-resource settings for its independence from dialysis centres and its lower infrastructure cost.

CAPD is one of the three modalities of renal replacement therapy available to ESKD patients — alongside haemodialysis (HD) and kidney transplantation. All three modalities achieve comparable patient survival in appropriate candidates; transplantation remains the preferred long-term therapy. CAPD is an important bridge to transplantation and a definitive long-term therapy for patients who are not transplant candidates. The decision between CAPD, automated peritoneal dialysis (APD/CCPD), and haemodialysis is made collaboratively based on residual kidney function, peritoneal membrane transport characteristics (assessed by peritoneal equilibration test — PET), lifestyle factors, home environment, and patient preference.

CAPD is used for end-stage kidney disease (eGFR persistently below 10-15 ml/min/1.73m² with uraemic symptoms) requiring renal replacement therapy. The common primary causes of ESKD leading to CAPD include: diabetic nephropathy (the leading cause globally, accounting for approximately 40% of ESKD); hypertensive nephrosclerosis; glomerulonephritis (IgA nephropathy, focal segmental glomerulosclerosis); polycystic kidney disease; renovascular disease; and obstructive uropathy.

CAPD is also used in acute kidney injury (AKI) in some resource-limited settings where haemodialysis machines are unavailable, in paediatric patients (where PD has particular advantages in children with residual urine output and smaller body size), and in diabetic ESKD patients (where PD avoids the haemodynamic stress of intermittent HD and may better preserve residual renal function). Relative indications for PD over HD include: preference for home therapy and independence; haemodynamic instability making HD poorly tolerated; exhausted vascular access for HD; active cardiovascular disease making HD haemodynamic stress problematic; and geographic remoteness from dialysis centres.

CAPD is appropriate for patients with ESKD who: have sufficient dexterity and cognitive function to perform exchanges safely (or have a caregiver trained to assist); have intact peritoneal membrane without prior major abdominal surgery causing peritoneal adhesions (relative contraindication — prior surgery is assessed case by case); do not have active intra-abdominal infection, abdominal hernias (that must be repaired before commencing PD), or inflammatory bowel disease causing peritoneal compromise; are not morbidly obese (PD is technically feasible but membrane function may be compromised with very high adipose tissue mass); have a home environment suitable for maintaining sterile technique during exchanges (clean, uncluttered area).

Contraindications to PD include: extensive prior abdominal surgery with dense adhesions precluding free dialysate flow; active diverticulitis or inflammatory bowel disease with peritoneal inflammation; ileostomy or colostomy increasing infection risk; uncorrected hernias (must be repaired pre-PD); protein malnutrition (PD causes protein losses of 5-15g/day via dialysate, worsening pre-existing malnutrition); and patient/caregiver inability to perform technique safely despite training. High peritoneal transport status (assessed by PET) may make CAPD inadequate — such patients may be better served by APD (nocturnal automated PD) or haemodialysis.

Standard CAPD involves 4 daily exchanges: typically three exchanges of 2 litres during the day (with 4-6 hour dwell times) and one overnight long dwell (8-10 hour dwell) using a hypertonic glucose dialysate (1.36%, 2.27%, or 3.86% glucose) or icodextrin (a glucose polymer that maintains osmotic gradient for long dwells without glucose absorption). Each exchange is performed using sterile 'spike and drain' technique with Y-set tubing — the old dialysate is drained, the Y-set is flushed, and fresh dialysate is instilled. Rigorous hand hygiene and aseptic technique are essential to prevent peritonitis.

Automated Peritoneal Dialysis (APD or CCPD — Continuous Cycling Peritoneal Dialysis) uses a cycler machine at night to perform multiple short exchanges (1-2 litres, 60-90 minute dwell) while the patient sleeps — daytime is free of exchanges. APD is often preferred for working patients and children. Both CAPD and APD achieve similar solute clearance, with APD advantageous for high-transporter patients who equilibrate rapidly. Icodextrin dialysate for the daytime dwell in APD patients improves ultrafiltration without glucose absorption. Peritoneal equilibration test (PET) is performed at 4-8 weeks after starting PD to characterise membrane transport type and guide dialysate selection and exchange frequency.

Individualised treatment planning is essential to achieve optimal outcomes. Factors including patient age, overall health status, concurrent medications, and personal goals all influence the selection and sequencing of treatment approaches. A specialist consultation — with review of relevant investigations and prior treatment history — is the appropriate first step before any therapeutic intervention is initiated. Patients are encouraged to seek a second opinion for complex or elective procedures to ensure they understand all available options and their respective risks, benefits, and costs.

CAPD preserves residual renal function better than haemodialysis — multiple cohort studies demonstrate slower decline in residual urine output in PD patients, which is associated with improved survival, better volume control, and preserved cardiovascular function. The continuous nature of CAPD avoids the haemodynamic instability and large fluid shifts of intermittent haemodialysis, making it better tolerated by patients with cardiovascular disease or haemodynamic fragility. Patient independence and quality of life are consistently rated higher by PD patients compared to in-centre HD — freedom from 3 sessions per week at dialysis centres, maintaining work and social activities, and avoiding arteriovenous fistula needling are significant advantages.

For patients on the kidney transplant waiting list, CAPD maintains patient fitness, preserves residual function, and avoids vascular access complications that can complicate HD access management. Post-transplant outcomes are comparable between patients who dialysed on PD versus HD. In the developing world, CAPD's independence from costly infrastructure makes it the dominant modality in many national kidney disease programmes — WHO recommends PD as the first-line RRT modality in low-resource health systems.

Peritonitis — infection of the peritoneal cavity, typically through touch contamination at the catheter connection — is the most common and serious complication of peritoneal dialysis. International Society for Peritoneal Dialysis (ISPD) guidelines recommend a peritonitis rate target of no more than one episode per 18-24 patient-months. Episodes present with cloudy effluent, abdominal pain, and fever; treatment is with intraperitoneal antibiotics covering both Gram-positive (typically vancomycin or cefazolin) and Gram-negative organisms. Severe or refractory peritonitis may require PD catheter removal and temporary transfer to haemodialysis. Fungal peritonitis requires immediate catheter removal. Recurrent peritonitis can cause peritoneal membrane failure (scarring and loss of filtering function), necessitating permanent transfer to HD.

Catheter-related complications include: exit-site infection (the skin entry point of the catheter), which is managed with topical antibiotics; tunnel infection (infection tracking along the catheter tunnel under the skin), requiring catheter removal; and catheter malfunction from omentum wrapping, kinking, or fibrin plugs. Metabolic complications of PD include: hyperglycaemia from glucose absorption (particularly in diabetics using high-glucose dialysate); hypertriglyceridaemia; protein-calorie malnutrition from protein losses; and electrolyte imbalances. Peritoneal membrane failure — loss of ultrafiltration and solute clearance capacity — can occur after years of PD exposure, particularly with frequent hyperosomolar dialysate use.

Patients starting CAPD undergo Tenckhoff catheter insertion (laparoscopic or open under local or general anaesthesia) as a day or overnight procedure, then commence training at a PD nurse-led education programme (1-2 weeks). Training covers sterile exchange technique, exit-site care, troubleshooting, peritonitis recognition, and 24-hour emergency contact. Patients are assessed for dialysis adequacy (Kt/V urea target ≥1.7/week for CAPD; Kt/V ≥1.7 for APD) and ultrafiltration adequacy at 1-3 monthly intervals.

Routine monitoring includes: monthly blood tests (urea, creatinine, electrolytes, albumin, haemoglobin, parathyroid hormone); dialysate glucose and protein; blood pressure and fluid balance assessment; and renal anaemia management (erythropoiesis-stimulating agents — ESA — titrated to Hb 100-120 g/L). Quarterly clinic visits with the nephrologist, PD nurse, dietitian, and pharmacist address adequacy, complications, and transplant listing. Peritoneal equilibration testing is repeated annually or when adequacy is unexpectedly poor. Exit-site evaluation at every clinic visit identifies early infection for prompt treatment.

CAPD annual costs in the USA are approximately USD 30,000-50,000 per patient-year (dialysate, supplies, monitoring, and overhead) — approximately 20-30% less than in-centre haemodialysis (USD 50,000-90,000/year) when all costs are included. In the UK, CAPD costs the NHS approximately GBP 20,000-30,000 per year compared to GBP 35,000-50,000 for in-centre HD. Both modalities are fully NHS-covered or covered by Medicare/Medicaid in the USA.

For international patients with ESKD seeking renal replacement therapy in countries with lower healthcare costs, India is a major destination. Monthly PD supply costs at leading Indian nephrology centres (Apollo, Fortis, Manipal) are INR 25,000-40,000 (USD 300-480) per month — a fraction of Western costs. Haemodialysis in India costs approximately USD 150-300 per session (3 sessions per week). Kidney transplantation, where available and ethically sourced, costs USD 15,000-25,000 in India versus USD 100,000-300,000 in the USA. Patients considering dialysis or transplant internationally should ensure accredited nephrology expertise, sterile supply chains, and comprehensive post-procedure monitoring capabilities are in place.

Haemodialysis (HD) — performed three times weekly for 4 hours per session in a dialysis centre (or 5-6 times per week for home HD users) — achieves solute clearance through an extracorporeal circuit and synthetic dialyser membrane. HD is appropriate for patients who are not candidates for PD (peritoneal adhesions, active abdominal infection, inability to perform home therapy) and for those with high transport status inadequately managed by CAPD. Outcomes (survival, cardiovascular events, quality of life) are broadly comparable between HD and PD at a population level, though individual patient factors influence the optimal modality.

Kidney transplantation is the optimal long-term renal replacement therapy for eligible patients — providing superior survival, quality of life, and cost-effectiveness compared to lifelong dialysis. All dialysis patients below a functional age threshold (typically 70-75 years) and without significant comorbidity should be assessed for transplant eligibility. Conservative kidney management (CKM — symptom management without dialysis) is an appropriate choice for elderly patients with multiple comorbidities for whom dialysis would not extend meaningful quality life — the NICE decision support tool for CKM provides structured guidance for this conversation.