Convection

1
Convection
Rate of Convective Transport S x Qu x Cr
Where S Sieving Coefficient 1 - ? Qu UF
rate Cr (Cb Cd ) / 2
S
2
Diffusion
Solute MW and Medium
3
Nearest Capillary Theory
Medium
Normal Permeability
Hyper-Permeability
Hypo-Permeability
30 40 50 60 70 80 90 100
? osm
Osmotic Force
Diffusion Distance
4
Diffusion
Effect of Capillary Location
5
MTAC

• Patient-specific parameter
• Represents maximum rate of diffusive clearance
  that can be achieved by patient

eg urea kinetics in first minute of
dialysis MTAC 30 mL/min, Cb 0.5 mM, Cd 0
mM Urea removed MTAC x (Cb - Cd) 30 x (0.5-0)
15 mmol Urea clearance (Dialysate volume x
Dialysate Urea)/Blood Urea 15 / 0.5 30
ml
6
Diffusive Mass Transport Parameters
MTAC
Kbd (ml/min)
Time (mins)