1 / 32

Separation Technology in Dialysis

Separation Technology in Dialysis. Allan P. Turner M.D. February 17,2006. Kidney Function. Kidney Function. Terms Used in Dialysis. Diffusion Convection Ultrafiltration Clearance. 100 ml/min 100mg/dl. 100 ml/min 50 mg/dl. Clearance=50 ml/min. 100 ml/min 100mg/dl. 100 ml/min

taber
Download Presentation

Separation Technology in Dialysis

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Separation Technology in Dialysis Allan P. Turner M.D. February 17,2006

  2. Kidney Function

  3. Kidney Function

  4. Terms Used in Dialysis • Diffusion • Convection • Ultrafiltration • Clearance 100 ml/min 100mg/dl 100 ml/min 50 mg/dl Clearance=50 ml/min 100 ml/min 100mg/dl 100 ml/min 10 mg/dl Clearance=90 ml/min

  5. Options for RRT • Hemodialysis • 3X a week for 3-4 hours • diffusive clearance with ultrafiltration of water • faster blood flow rates=less hemodynamic stability • CRRT(Hemodiafiltration) • a continuous process • used on critically ill patients in US • more convective clearance • lower blood flow rates and smaller filter=greater hemodynamic stability • Peritoneal Dialysis • peritoneal membrane used as semipermeable membrane • batch process

  6. Description of Hemodialysis • Primarily diffusion • Dialysate • looks like blood of healthy patient • 3X week for 3-4 hours • Blood and dialysate flows are fast • QB=500 ml/min • QD=800 ml/min

  7. Membrane(Dialyzer) • Hollow Fiber Design • Biologic vs synthetic • Reuse • Terms • Biocompatibility • High efficiency • High flux

  8. Access • Difficult • Trade Offs • rapidity of use • chance of infection • patient comfort • need for addl procedures

  9. Access(PermCath) • Use immediately • No needle sticks • High infection rate • High recirculation

  10. Access(AV Graft) • Use in 2-3 weeks • Some infection risk • 2 needle sticks • low recirculation • numerous interventions to keep open

  11. Access(AV Fistula) • 3-18 months to use • Minimal infection risk • Can last a lifetime

  12. Anticoagulation • Blood clots • Heparin • discovered in 1926 • Partial clotting • limits diffusion • reduces surface area • Access must stop bleeding • Calcium • required for clotting

  13. Dialysis Machine • Blood Circuit • anticoagulate • deliver blood to membrane • safely return blood to patient • Dialysate Circuit • deliver dialysate at proper temperature, concentration, and pH • control ultrafiltration

  14. Dialysis Machine(Blood Circuit) • Roller pump • Heparin syringe pump • 2 air traps • Air detector • Venous line clamp

  15. Dialysis Machine(Dialysate Circuit) • Warm, deaerate, mix concentrates, monitor conductivity and pH, pump • Detect blood leaks • Generate and monitor ultrafiltration

  16. Dialysis Machine

  17. Dialysis Machine

  18. Dialysate

  19. Urea Clearance • ?Urea = uremic toxin? • Diffusion • Urea: MW=60 (small) • KoA • Clearance of urea of 250ml/min • Native kidneys provide urea clearance of about 90-110ml/min

  20. Urea Clearance

  21. Clearance of Other Solutes • Urea(MW 60), creatinine(MW 113), B12 (MW=1355), ß2 microglobulin (MW=11,800), albumin (MW=80,000) • Middle molecules • Diffusion not effective

  22. Hemofiltration • Convection to clear larger molecules • Replacement fluids without removed solute • Costly

  23. Continuous Renal Replacement Therapy(CRRT) • Critically ill ICU patients • low BP • can’t tolerate large QB or large filter • often can’t be systemically anticoagulated • Continuous • low clearances but runs 24/7 • Anticoagulation • regional anticoagulation instead of systemic • Combine hemodialysis and hemofiltration • hemodiafiltration • increases clearances even of middle molecules • continuous venovenous hemodiafiltration(CVVHDF)

  24. CRRT vs Hemodialysis Dialysate 40ml/min(2500ml/hr) Replacement fluid 1000ml/hr CRRT QB 150ml/hr Dialysate + Ultrafiltration +Replacement fluid Dialysate 800ml/min(48,000ml/hr) Hemodialysis QB 500ml/hr Dialysate + Ultrafiltration

  25. CRRT Citrate Anticoagulation Tri-Sodium Citrate Blood C C From C C C C patient D Liver I A Citrate HCO3 L C Y Calcium Z C C E R Blood To C C C C C C patient

  26. Prefilter Fluid: 4L bag Dialysate : 4 L bag 0.67% Trisodium Citrate Na 140 mEq /L + Citrate 23 mM /L 3- Cl 118.5 mEq /L - Na 140 mEq /L + HCO 25 mEq /L 3 K 4.0 mEq /L + Rate: 1000-1500 mL /hr Mg 1.16 mEql /L 24 mmol /h citrate Rate: 1000-2500 mL /hr Gambro Prisma Pre-Pump Pre- Q Q Dilution Set R D 2+ PF iCa (0.25-0.5 mmol /L) 2+ Ca Gluconate 78 mEq /L (20 g/L) in NS Rate: 80 mL /hr CRRT Gambro Prisma with V Gambro Prisma with V Patient M60 AN69 Filter M60 AN69 Filter Q B iCa 2+ 1.1-1.3 100-150 mL /min mmol /L (actual Q = Q – Q ) B B, machine R Q = Q Q Q + + E R FR D

  27. CRRT

  28. Peritoneal Dialysis(PD) • Salmon dialysis • Peritoneal membrane • Capillaries • Diffusion, ultrafiltration( ie osmosis), convection, and absorption

  29. PD Membrane • Pd Membrane • surface area=BSA=1-2 m2 • heteroporus, heterogeneous semipermeable membrane with complex physiology • Blood Flow • approx. 50-100 ml/min • 3 pore model • large pores(macromolecules like proteins) • small pores(small solutes) • ultrapores(aquaporins)(water without solute)

  30. PD Ultrafiltration • Dextrose(3 concentrations) added to provide gradient for UF(osmosis) • Glucose diffuses into blood and diminishes gradient • Absorption of dialysate occurs limiting UF • Newer agents

  31. PD Clearance • High Transporters • dialyze well • ultrafilter poorly • ? Icodextran ? • best with freq. short dwells • High Avg/Low AVG transporters • Low Transporters • ultrafilter well • dialyze poorly • best with longer short dwells • Options • CAPD • CCPD

  32. Future • Which separation techniques improve mortality • Less expensive RRT as population grows • Improve patients quality of life • Biological systems

More Related