CAPD (Continuous Ambulatory Peritoneal Dialysis): Procedure and Management — Cost, Top Hospitals & Success Rates | MyMedicPlus

Continuous Ambulatory Peritoneal Dialysis (CAPD) is a home-based form of renal replacement therapy (RRT) that exploits the peritoneal membrane — the highly vascularised serous lining of the abdominal cavity — as a natural semipermeable filter to remove uraemic toxins and excess fluid from the body. Unlike in-centre haemodialysis, which requires 4-hour sessions at a dialysis unit three times per week, CAPD empowers patients to maintain independence through self-administered dialysis exchanges performed in their own home throughout the day.

The physiological principle is straightforward: a sterile glucose-containing dialysate solution (2 litres) is infused via a permanent Tenckhoff catheter into the peritoneal cavity. Across the peritoneal membrane, uraemic solutes (urea, creatinine, potassium, phosphate, small and middle molecules) diffuse down concentration gradients from the peritoneal blood supply into the dialysate (diffusion); simultaneously, water is drawn across the membrane by the osmotic pressure gradient generated by the glucose concentration of the dialysate (ultrafiltration). After a dwell period (4-8 hours), the spent dialysate is drained and replaced with fresh solution (one 'exchange').

The landmark CANUSA study (peritoneal dialysis patients, Canada and USA) and the NECOSAD study (Netherlands) demonstrated equivalent patient survival between peritoneal dialysis and haemodialysis in the first 2-3 years of dialysis, with PD showing an advantage in the early period — particularly for preserving residual renal function (RRF). This residual kidney function provides additional clearance of middle molecules, volume control, and is associated with substantially lower mortality on PD than its loss. HD is associated with more rapid decline of RRF than CAPD, likely due to intradialytic hypotension and haemodynamic stress on the residual nephron mass.

Two principal modalities of PD exist: CAPD (manual, continuous ambulatory) and APD/CCPD (automated peritoneal dialysis using a cycler machine overnight). Both share the same peritoneal catheter and biological principle but differ in exchange scheduling and lifestyle implications.

CAPD/PD is a form of renal replacement therapy indicated when the kidneys can no longer maintain adequate clearance of waste products and fluid balance compatible with life. Specific indications include:

• End-stage renal disease (ESRD): eGFR <10-15 mL/min/1.73m² with uraemic symptoms (nausea, vomiting, anorexia, pericarditis, encephalopathy), refractory fluid overload, or metabolic derangements (hyperkalaemia, acidosis, hyperphosphataemia) unresponsive to conservative management. Causes include diabetic nephropathy (most common globally), hypertensive nephropathy, IgA nephropathy, focal segmental glomerulosclerosis (FSGS), autosomal dominant polycystic kidney disease (ADPKD), and systemic diseases (lupus, amyloidosis).
• Acute kidney injury (AKI) — selected cases: Peritoneal dialysis is used for AKI in settings where vascular access for HD is difficult or unavailable (paediatric patients, haemodynamically unstable patients), or in resource-limited settings. Continuous PD offers haemodynamic advantages over intermittent HD in cardiovascular instability.
• Paediatric ESRD: CAPD and APD are the preferred modalities in infants and young children where arteriovenous fistula creation is anatomically challenging and in-centre HD is logistically demanding for families.
• Haemodynamic instability: Patients with recurrent intradialytic hypotension (IDH) on HD — common in diabetics, elderly, and those with systolic LV dysfunction — often tolerate CAPD better due to its slow, continuous nature.
• Remote geographic location: Patients unable to travel to a dialysis centre three times per week due to distance, disability, or lack of transport infrastructure.
• Patient preference for home-based, self-directed therapy: CAPD is the preferred modality for working-age patients, those in employment, travellers, and carers of dependants who cannot commit to fixed dialysis centre schedules.

Candidate selection for CAPD requires a comprehensive clinical, social, and anatomical assessment:

Suitable candidates: CAPD is ideally suited for motivated patients with reasonable manual dexterity (or a trained caregiver), an intact and functional peritoneal membrane (no prior extensive abdominal surgery), a clean home environment with adequate storage space, and the cognitive capacity and willingness to comply with daily exchange protocols and aseptic technique.

Preferred patient profiles:

• Diabetic nephropathy patients — CAPD avoids intradialytic hypotension and maintains haemodynamic stability better than HD.
• Patients with poor vascular access (calcified vessels, multiple prior fistula failures).
• Young working-age patients (APD overnight allows unrestricted daytime activity).
• Patients in areas with limited HD centre access.
• Candidates awaiting renal transplantation — CAPD does not compromise transplant outcomes (ANZDATA).

Relative contraindications:

• Prior abdominal surgeries with extensive peritoneal adhesions (reduces effective peritoneal surface area; high risk of catheter dysfunction).
• Active inflammatory bowel disease or diverticulitis (peritonitis risk).
• Severe protein-energy wasting (serum albumin <25 g/L) — CAPD causes 8-12 g/day protein loss across the peritoneum, worsening nutritional status.
• Severe obesity (BMI >40) — catheter placement technically more difficult; higher hernia risk.
• Inability to perform exchanges without caregiver — acceptable if a trained, committed caregiver is available.

Catheter insertion: The Tenckhoff catheter (straight or curled tip, swan-neck configuration, double-Dacron cuff for tissue anchoring) is placed laparoscopically (preferred — lower infection and malfunction rate) or by open technique under local or general anaesthesia. The exit site is positioned laterally and inferiorly on the abdominal wall, away from skin folds and the belt line. A 2-week break-in period with low-volume exchanges (<1L) in the supine position allows healing before full-volume exchanges are commenced.

1. CAPD (Continuous Ambulatory Peritoneal Dialysis) — Manual Technique:

The standard CAPD prescription involves 4 exchanges per day of 2 litres each, with dwell times of 4-6 hours during the day and 8-10 hours overnight (long overnight dwell). The Y-set twin-bag disconnect system (flush-before-fill technique) is the universal standard of care: fresh dialysate and the empty drain bag are attached as a Y to the Tenckhoff catheter; a small amount of fresh dialysate first flushes the tubing to drain away any touch contamination, then the spent dialysate is drained fully before fresh dialysate infuses. This flush-before-fill design dramatically reduced peritonitis rates vs the older 'spike-and-connect' system (from ~1 episode/patient-year to 0.4-0.6/patient-year).

Dialysate solutions are classified by glucose concentration: 1.36% glucose (isotonic — standard for most exchanges); 2.27% glucose (mildly hypertonic — additional ultrafiltration of ~200-400 mL/exchange); 3.86% glucose (hypertonic — maximum ultrafiltration ~600-800 mL/exchange, reserved for fluid overloaded patients or high/high-average membrane transporters). Icodextrin 7.5% (glucose polymer, starch-based) generates sustained osmotic ultrafiltration via a colloid mechanism unaffected by glucose absorption — used for the long overnight dwell to avoid hyperglycaemia and improve ultrafiltration in diabetics and long-dwell patients.

2. APD / CCPD (Automated Peritoneal Dialysis / Continuous Cycling PD):

An automated cycler machine performs 3-5 exchange cycles overnight (over 8-10 hours) while the patient sleeps. The patient disconnects in the morning and is ambulatory during the day with either a 'dry day' (no dialysate) or a single daytime dwell (CCPD). APD is preferred for: working patients (no exchanges during working hours); children; and high membrane transporters who need shorter dwell times for optimal small-solute clearance. Tidal PD (incomplete drainage between cycles, leaving a residual volume) reduces drain-associated pain and maximises dwell contact time in patients with pain during drain phase.

3. Peritoneal Equilibration Test (PET) and Adequacy Monitoring:

The PET classifies membrane transport type (high, high-average, low-average, low) by measuring dialysate:plasma ratios of creatinine (D/P Cr) and glucose at 0 and 4 hours. High transporters rapidly absorb glucose (losing the osmotic gradient) and transfer small solutes quickly — suited to APD with short dwells; low transporters require long dwells and high volume for adequate clearance. PD adequacy is measured by Kt/V urea (total weekly urea clearance expressed as multiples of distribution volume): international guidelines (ISPD) recommend a minimum total Kt/V ≥ 1.7/week (combined peritoneal + residual renal contribution). Residual renal function (RRF) should be preserved by avoiding nephrotoxic drugs (NSAIDs, aminoglycosides, IV contrast without prehydration).

Peritoneal dialysis, and CAPD specifically, offers several clinically important advantages over in-centre haemodialysis:

• Home-based and independent: CAPD eliminates the need for 3× weekly, 4-hour centre visits. Patients manage dialysis at home, at work, or while travelling. This independence translates to improved quality of life (QoL) scores, better ability to maintain employment, and reduced transport burden — particularly meaningful in developing-country settings.
• Haemodynamic stability: The continuous, slow nature of peritoneal fluid removal avoids the rapid intravascular volume shifts responsible for intradialytic hypotension (IDH) in haemodialysis. IDH affects 20-30% of HD sessions and causes end-organ ischaemia (myocardial stunning, mesenteric ischaemia, cerebral hypoperfusion). CAPD is substantially better tolerated in patients with cardiac failure, low blood pressure, or severe diabetes.
• Superior preservation of residual renal function (RRF): Multiple studies (CANUSA, NECOSAD) confirm that RRF declines significantly more rapidly on HD than on PD. Preserved RRF provides: additional clearance of middle and large molecules; better fluid control; maintained production of erythropoietin (reducing EPO-stimulating agent requirements); and substantially lower mortality. Every 1 mL/min/1.73m² of residual GFR is associated with a 12% reduction in mortality on PD.
• Better middle-molecule clearance: Peritoneal clearance of middle molecules (β₂-microglobulin, MW 11.8 kDa) is superior to conventional HD (though inferior to high-flux HD and haemodiafiltration). Improved clearance of middle molecules may contribute to better long-term neurological and cardiovascular outcomes.
• Fewer dietary restrictions: Because fluid removal on CAPD is continuous (rather than concentrated into HD sessions), patients on CAPD typically have less interdialytic fluid accumulation, allowing more liberal fluid and sometimes dietary potassium intake.
• No vascular access required: CAPD avoids the need for AV fistula creation (a surgical procedure with associated morbidity) or central venous catheter (CVC), eliminating catheter-related bloodstream infection risk, and preserving peripheral veins for potential future transplant-related access.

While CAPD is generally safe and well-tolerated, it carries specific risks that must be recognised and managed:

1. Peritonitis — the most common and serious complication: Intraperitoneal infection occurring at a rate of 0.4-0.6 episodes per patient-year on modern Y-set systems. Diagnosis: cloudy effluent + abdominal pain ± fever; confirmed by PD effluent white cell count >100 cells/µL with >50% neutrophils, and culture. Common causative organisms: Coagulase-negative Staphylococcus (30-40%), S. aureus (15-20%, often catheter-related), gram-negative organisms (Pseudomonas, E. coli, Klebsiella — 20-25%), and fungi (Candida — rare but mandates catheter removal). Empiric treatment: Intraperitoneal (IP) vancomycin 15-30 mg/kg every 5-7 days (for gram-positive coverage) + IP aminoglycoside (gentamicin 0.6 mg/kg or tobramycin) once daily (gram-negative coverage); adjust on culture and sensitivity at 48 hours. Biofilm-forming organisms (Pseudomonas, Stenotrophomonas, fungi) — catheter removal mandatory; HD temporarily. Peritonitis is the leading cause of PD technique failure and PD dropout (approximately 30% of peritonitis episodes result in permanent transfer to HD).

2. Catheter complications:

• Exit-site infection: Erythema, crusting, or purulent discharge at the catheter exit site. Gram-positive organisms most common. Topical mupirocin (to exit site and nasal carriage) reduces S. aureus exit-site infections by ~80%.
• Tunnel infection: Infection tracking along the subcutaneous tunnel (ultrasound confirms peri-catheter fluid). Requires prolonged antibiotics ± catheter removal.
• Catheter malfunction: Outflow obstruction due to omentum wrapping or fibrin occlusion. Managed with intraperitoneal urokinase (fibrin) or laparoscopic omentectomy (omental trapping).

3. Ultrafiltration failure: Decline in fluid removal capacity over time (years) due to peritoneal membrane changes — high glucose exposure causes neo-angiogenesis, interstitial fibrosis, and increased peritoneal permeability. Managed by reducing glucose exposure (icodextrin, lower-glucose solutions), increasing exchange frequency, or transfer to HD.

4. Encapsulating Peritoneal Sclerosis (EPS): Rare (0.5-3% prevalence after >5 years of PD) but potentially fatal complication — progressive thickening and calcification of the peritoneal membrane forming a cocoon around the bowel, leading to intestinal obstruction. Risk increases with duration of PD. Management: early recognition (CT abdomen), cessation of PD, surgery (peritoneal decortication) at specialist centres, and tamoxifen (anti-fibrotic; limited evidence).

5. Metabolic complications: Glucose absorption from dialysate (significant — up to 100-200 g glucose/day) causing hyperglycaemia (particularly problematic in diabetics; managed with intraperitoneal insulin), weight gain, dyslipidaemia (hypertriglyceridaemia). Icodextrin minimises glucose absorption.

6. Mechanical complications: Abdominal/inguinal hernia (increased intra-abdominal pressure from dialysate volume — 10-25% of CAPD patients); pleural effusion (hydrothorax due to pleuroperitoneal communication — requires cessation of PD and thoracentesis); low back pain from dialysate weight.

Ongoing monitoring of CAPD patients is essential to ensure dialysis adequacy, prevent complications, and optimise long-term outcomes:

Clinic schedule: Monthly review during the first year, then 3-monthly once stable. Each review includes: blood pressure, fluid status (weight, oedema, blood pressure), exit-site assessment, patient technique review, and biochemical panel.

Biochemical monitoring (monthly/3-monthly):

• Haemoglobin and iron stores (ferritin, transferrin saturation) — ESA (EPO or darbepoetin alfa) dose adjustment; IV iron if ferritin <200 or TSAT <20%.
• Serum phosphate, calcium, PTH — phosphate binders (calcium carbonate, sevelamer, lanthanum), vitamin D supplementation, calcimimetics (cinacalcet) for secondary hyperparathyroidism.
• Serum albumin — nutritional marker; supplementation with dietary counselling if low; protein intake target ≥1.2 g/kg/day for PD patients.
• Lipids (dyslipidaemia common on CAPD — statins if indicated).
• Residual renal function: 24-hour urine creatinine clearance and urine volume every 3-6 months.

Dialysis adequacy (6-monthly): 24-hour peritoneal and urinary Kt/V urea; PET if inadequate clearance or clinical suspicion of membrane change. If total Kt/V <1.7/week, prescription intensification (increase exchange volume to 2.5L, add a 5th exchange, or switch to APD).

Exit-site care: Daily or twice-weekly inspection by patient/caregiver; topical mupirocin cream to exit site (mupirocin-resistant S. aureus screen periodically); gentle cleaning with antiseptic and dry dressing.

Transfer decisions: PD patients are transferred to HD when: peritoneal membrane fails (ultrafiltration failure with persistent fluid overload); recurrent or refractory peritonitis; encapsulating peritoneal sclerosis; patient preference; renal transplantation (ideal outcome — PD patients have equivalent transplant outcomes to HD patients per ANZDATA and USRDS).

Peritoneal dialysis is generally more cost-effective than in-centre haemodialysis in most healthcare systems, once training and initial setup costs are excluded. The ongoing monthly cost of consumables is the primary expense:

• Tenckhoff catheter insertion and training:
  • India: USD 300-800 (catheter + surgical procedure); training programme 5-7 days inpatient, typically subsidised by dialysis fluid suppliers
  • Thailand/Malaysia: USD 800-2,000
  • USA: USD 5,000-10,000 (surgical + hospital costs)
• Monthly CAPD consumables (dialysate bags, Y-sets, connecting equipment):
  • India: USD 250-500/month (government-subsidised in some states)
  • Thailand: USD 400-700/month
  • UAE: USD 800-1,500/month
  • USA: USD 3,000-6,000/month (dialysate + delivery service)
  • UK (NHS): fully covered; patients pay no out-of-pocket cost
• APD cycler: Device cost USD 10,000-20,000 (often provided by dialysis fluid manufacturers on a contract basis, significantly reducing upfront cost). Monthly cycler consumables add 20-30% to CAPD consumable costs.
• Icodextrin (Extraneal): Significantly more expensive than glucose-based dialysate but reduces glucose exposure and improves ultrafiltration — 1 bag/day adds approximately USD 150-400/month depending on country.
• Total monthly cost comparison: CAPD in India (USD 300-600) is substantially less expensive than in-centre HD in India (USD 400-800/month, including centre costs). In the USA, CAPD (USD 3,500-6,500/month) is 30-40% less expensive than in-centre HD (USD 5,000-9,000/month), per USRDS cost data.
• Medical tourism value: Long-term dialysis patients may relocate or travel for catheter placement and training, then continue CAPD at home with local fluid supply — a model used by expatriates and travellers.

Several alternative renal replacement therapy (RRT) options exist for patients with ESRD who are not suited to or who prefer an alternative to CAPD:

1. In-Centre Haemodialysis (HD): The most widely used RRT globally. Patients attend a dialysis centre 3 times per week for 4-hour sessions; blood is pumped through an extracorporeal circuit with an artificial kidney (dialyser). Higher efficiency for small-molecule clearance per session than CAPD. Requires permanent vascular access (AV fistula — gold standard; AV graft; or tunnelled central venous catheter). Preferred for patients who cannot perform home exchanges, who have failed PD, or who have peritoneal membrane failure. Associated with more rapid loss of RRF than PD.

2. Home Haemodialysis (HHD): Performed at the patient's home 5-6 sessions per week (short daily or long slow nocturnal) using a home HD machine. Associated with improved haemodynamic stability, blood pressure control, phosphate clearance, and patient-reported wellbeing compared to conventional 3×/week in-centre HD. Requires extensive home adaptation, plumbing modification, and intensive patient training. Equivalent home-based independence to CAPD but with superior clearance of middle molecules. Available in Australia, UK, USA, and increasingly in India.

3. Kidney Transplantation: The optimal treatment for all suitable ESRD patients, offering the best long-term survival and quality of life. Successful kidney transplant corrects all metabolic derangements of ESRD and eliminates the need for dialysis. Patients on CAPD can be listed for transplant and transplanted without PD compromising surgical outcomes or graft function. Deceased donor transplant waiting times range from months (India) to 5-10 years (USA, UK). Living donor transplant (from family or unrelated altruistic donors) can be performed electively with pre-emptive (pre-dialysis) timing.

4. Conservative (Non-Dialytic) Kidney Management (CKM): For elderly, frail patients with multiple comorbidities and poor functional status (particularly those >75 years with ESRD, coronary artery disease, cardiac failure, dementia, or malignancy), the survival advantage of dialysis over conservative management may be limited or absent (da Silva Gane et al., BMJ 2012). CKM involves active symptom management (erythropoietin for anaemia, diuretics for fluid control, phosphate binders, dietary management) and specialist palliative care input, without RRT. This is not 'giving up' — it is a valid patient-centred choice that prioritises quality of remaining life over duration.