Separation Technology in Dialysis - PowerPoint PPT Presentation

1 / 32
About This Presentation
Title:

Separation Technology in Dialysis

Description:

used on critically ill patients in US. more convective clearance ... Access(AV Fistula) 3-18 months to use. Minimal infection risk. Can last a lifetime ... – PowerPoint PPT presentation

Number of Views:792
Avg rating:3.0/5.0
Slides: 33
Provided by: stephaniec
Category:

less

Transcript and Presenter's Notes

Title: Separation Technology in Dialysis


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
Clearance50 ml/min
100 ml/min 100mg/dl
100 ml/min 10 mg/dl
Clearance90 ml/min
5
Options for RRT
  • Hemodialysis
  • 3X a week for 3-4 hours
  • diffusive clearance with ultrafiltration of water
  • faster blood flow ratesless hemodynamic
    stability
  • CRRT(Hemodiafiltration)
  • a continuous process
  • used on critically ill patients in US
  • more convective clearance
  • lower blood flow rates and smaller filtergreater
    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
  • QB500 ml/min
  • QD800 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 MW60 (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 (MW1355),
    ß2 microglobulin (MW11,800), albumin (MW80,000)
  • 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
  • cant tolerate large QB or large filter
  • often cant 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
CRRT
V
Gambro Prisma
with
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 areaBSA1-2 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
Write a Comment
User Comments (0)
About PowerShow.com