What is Peritoneal Dialysis?

Peritoneal dialysis is a dialysis method that uses the patient's own peritoneum as a natural filtration membrane. Its core principle is:

· Intra-abdominal catheter access: A soft silicone tube is pre-implanted into the abdominal cavity to serve as the channel for dialysate inflow and outflow.

· Dialysate infusion and exchange: Sterile dialysate (containing electrolytes and glucose) is infused into the peritoneal cavity via the catheter and retained for several hours. During this time, metabolic waste (e.g., urea, creatinine) and excess water in the blood continuously diffuse into the dialysate through the peritoneal capillaries due to the concentration and osmotic pressure gradients.

· Waste fluid drainage: After the dwell period, the waste-filled effluent is drained from the body and replaced with fresh dialysate. This process (dialysate exchange) must be repeated 3–5 times daily. Its primary feature is the gentle, continuous treatment, simulating part of the natural kidney function.

Key advantages include suitability for home use, flexible scheduling, and reduced cardiovascular burden. Limitations include strict sterile technique requirements to prevent peritonitis and potential long-term loss of intraperitoneal proteins and glucose fluctuations.

Indicated for patients with residual renal function (>5%), those wishing to maintain work/study flexibility, and those without significant abdominal surgical history or severe pulmonary disease.

Advantages of Peritoneal Dialysis

Flexible and Independent Lifestyle

Home-based treatment: Eliminates the need for frequent trips to dialysis centers, allowing patients to manage treatment time and location independently.

Continuous dialysis: Multiple daily exchanges (or nighttime automated dialysis) offer smoother toxin clearance, closer to natural kidney function.

Work/education compatible: Patients can maintain regular work and study schedules with minimal disruption.

Preservation of Residual Kidney Function

More stable hemodynamics: Gradual fluid and toxin removal prevents blood pressure fluctuations and lessens cardiac strain.

Research shows peritoneal dialysis maintains residual kidney function longer than hemodialysis.

Non-invasive Procedure (No Puncture Pain)

Only requires fluid exchange via a catheter, avoiding repeated vascular punctures (as in AV fistulas for hemodialysis), resulting in less discomfort.

Relatively Lenient Dietary Restrictions

Due to continuous clearance, fluctuations in blood potassium and phosphorus are milder, allowing more dietary flexibility compared to hemodialysis.

Low Technical Barrier

Simplified steps are easy to learn. Most patients can perform home exchanges independently after training.

Nighttime automated dialysis is supported, enabling treatment during sleep and complete freedom during the day.

Common Peritoneal Dialysis Supplies

Dialysate Bags

Single-use sterile soft bags used to hold dialysate. Made of multi-layer co-extruded film to ensure sterility and partial transparency for observation. The "twin bag" system includes a solution bag and a drainage bag, connected via a pre-installed Y-line and spike to the external short tubing for dialysate infusion, dwell, and drainage, significantly reducing contamination risk during connection.

Peritoneal Dialysis Solution

A sterile, pyrogen-free, allergen-free solution housed in dialysate bags, serving as the core medium for substance exchange. Main components include osmotic agents and electrolytes.

Classified by Osmotic agent:

· Glucose-based dialysate: Most common. Uses varying glucose concentrations to create osmotic gradients for ultrafiltration. Higher concentrations yield stronger ultrafiltration.

· Icodextrin-based dialysate: Contains glucose polymers that extend dwell time (e.g., CAPD long dwell or APD daytime long dwell), enabling more sustained isotonic or near-isotonic ultrafiltration. Less glucose absorption; suitable for patients with ultrafiltration failure or poor glucose control.

· Amino acid-based dialysate: Replaces glucose with amino acids as the osmotic agent, providing nutritional support and reducing glucose absorption. Less commonly used.

Classified by Buffer type:

· Lactate-buffered solution: Most common; metabolized in the body to bicarbonate.

· Bicarbonate-buffered solution/dual-chamber design: Two compartments kept separate pre-use, then mixed to achieve final bicarbonate concentration.

· Bicarbonate/lactate mix buffer: Combines features of both types.

Peritoneal Dialysis Catheter

A permanent access device placed in the abdominal cavity. Surgically implanted and fixed to the abdominal wall. Made of biocompatible silicone or polyurethane.

Three main segments:

· Intra-abdominal segment: Positioned at the lowest part of the peritoneal cavity (rectovesical or rectouterine pouch) with multiple side holes for fluid exchange.

· Subcutaneous tunnel segment: Passes through the abdominal muscles and subcutaneous tissue to create an infection barrier.

· External segment: Ends with a titanium connector to link with external short tubing.

Types (by tip and tunnel shape):

· Straight catheter (Tenckhoff): Most common.

· Coiled catheter: Helical tip reduces discomfort, poor drainage, or omental wrapping caused by tip pressure.

· Swan-neck catheter: Permanently curved to reduce kinking, migration, and leakage.

· Balloon/sieve-type (Missouri): Surface covered with tiny sieve pores instead of side holes, increasing fluid contact area and reducing adhesion or omental wrapping, improving drainage.

Extended PD Transfer set

A directly operated component connected to the titanium connector.

· Material: Usually plastic with a silicone sheath for better handling, containing a spiral valve for open/close control.

· Features: Short length for convenient daily operation and tubing connection/disconnection.

· Replaceable part: Not for permanent use. Typically replaced upon malfunction or periodically (e.g., every 1–2 years) to reduce infection risk.

· A sterile cap should always cover the open end before each exchange.

Locking Titanium Adapter

Essential permanent connector between the abdominal catheter and the external short tubing. Single-use permanent part (replaced only with catheter replacement).

· Material: Medical-grade titanium alloy, selected for its excellent biocompatibility, corrosion resistance, structural strength, and lightweight nature.

· Function: Ensures a firm, sterile, leak-proof connection. Its high reliability and inertness reduce connector-related complications.

Povidone-Iodine Protective Cap

A small disposable sealed cap. The core contains an antimicrobial sponge or material soaked in povidone-iodine.

· Function: During non-use intervals between dialysate connections, the cap tightly covers the external tubing port or titanium connector, providing continuous physical and chemical disinfection, significantly reducing peritonitis risk.

· Features: Easy to apply/remove. Short effective lifespan, requires frequent replacement (typically weekly or per product instructions) to maintain disinfection efficacy. Always replaced with a new cap before each connection.

Conclusion

Peritoneal dialysis consumables are the physical foundation and technical support for safe and effective treatment. Through precision design and sterile assurance, they enable the feasibility of home dialysis, empowering patients to maintain quality of life with flexible management. Future advancements must further improve biocompatibility and automation, reducing infection risks while enhancing long-term treatment tolerance—an effort that speaks not only to medical efficiency but to the profound protection of dignity in patients living with kidney disease.