Principles of Peritoneal Dialysis

1. Principles of Peritoneal Dialysis

2. 1 2 Bicarbonate Sodium Potassium Chloride Urea Creatinine Uric acid Diffusion • Transfer by diffusion is the passive transfer of solutes across the membrane, without the passage of solvent (water). Blood Membrane Dialysate 1 - Red blood cell 2 - Bacteria Beta 2-m (Solute PM>5000)

3. Factors effecting diffusion • Membrane • Surface area, type, thickness • Blood film thickness • Dialysate flow configuration • Concentration gradient • Size of solute • Ultrafiltration • Temperature of dialysate • Qb - Blood flow rate • Qd - Dialysate flow rate • Time

4. Factors relevant to PD • Membrane • Surface area, type, thickness • Blood film thickness • Dialysate flow configuration • Concentration gradient • Size of solute • Ultrafiltration • Temperature of dialysate • Qb - Blood flow rate • Qd - Dialysate flow rate • Time

5. Weekly plasma clearances L/week

6. Solute Clearance in PD • Factors that deliver clearance • Total volume • Volume per exchange • Number of exchanges • Dwell time • Factors driving clearance requirements • Urea generation(diet, weight, metabolic rate) • Residual renal clearance(kidney function) • U.F. rate (solution tonicity, fluid intake) • Peritoneal membrane (permeability)

7. Blood 280 - 295mOsm/L Dialysis solution 347- 486mOsm/L Water Solute Water Solute Osmosis Movement of water from an area of low solute concentration to an area of high solute concentration.

8. Ultrafiltration CAPD

9. Ultrafiltration

10. Ultrafiltration

11. Clearance – Peritoneal Equilibration Twardowski, University of Missouri

13. Process of PD • Exchange • Drain(<20 Minutes) • Fill(<10 minutes) • Dwell - (CAPD = 4 - 8 hours) - (APD = 30mins – 2 hours) • CAPD • Manual • Day Time Exchanges • Procedure Every 4-8 Hours

14. Outline benefits of PD Medical • Good BP control • Minimal cardiovascular stress • Sodium and water control • No heparin • Steady state chemistries • No vascular access • Better hematocrit • Good middle molecule • clearance Psycho-social • Self care - control • Fewer dietary restrictions • Less travel to center • Easier to vacation • Easy to learn • No need for electricity or • running water

15. Disadvantages • Medical • Risk of infection • Peritoneal access • Less “effective” therapy • Biocompatibility of solutions • Long term impact on peritoneal membrane • Protein loss • Glucose absorption • Psycho-social • Self Care - control • “Constant” treatment • Body image-catheter, girth • Family commitment • Storage requirements

16. CAPD Continuous Therapy Volume Benefits Limitations 0 24 Time • High transporters will have poor UF • 4 x per day exchange • IP pressure with large volumes • Optimum dialysis for low permeability • No night time Tx • Can perform anywhere Ambulatory Anywhere 4 - 5 Exchanges Long Dwells

17. APD Intermittent Therapy Volume Benefits Limitations 0 24 Time • Optimum dialysis for High permeability • No night time Tx • Can perform anywhere Ambulatory Anywhere 4 - 5 Exchanges Shorter Dwells Dry night • Low transporter will have poor clearance • Exchange burden • IP Pressure with large volumes