How to define and quantify

Haemodiafiltration

James Tattersall

Leeds, UK

jamestattersall@nhs.net

What uraemic toxins?

RR (%, mean ± SD, n = 14) of the water-soluble compo unds (A: urea, B: uric acid), protein-bound solutes (C: hippuric acid, D: indole acetic a cid, E: indoxylsulphate, F: p-

cresylsulphate) and LMWPs (G: b2-microglobulin, H: cystatin C, I: myoglobin, J: retinol-binding protein) in HD, pre-HDF and post-HDF.

Meert N et al. Nephrol. Dial. Transplant. 2011;26:2 624-2630

Box-plot representation of reduction percentages in kappa (KL) and lambda (LL) FLC after correction for fluid removal, for HD and HDF treatm ent groups.

Granger Vallée A et al. Nephrol. Dial. Transplant. 2011;26:3627-3633

© The Author 2011. Published by Oxford University Press on behalf of ERA-EDTA. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com

Serum FLC reduction percentage corrected for fluid removal (a) and clearance (b) as a function of substitution volume in post-dilution HD F. Corrected reduction percentages show

a linear correlation, both for κ (r = 0.61; P = 0.04) and λ (r = 0.58; P < 0.05) FLC, while clearances show a trend in the same direction witho ut reaching statistical significance ( κ, r =

0.55; P = 0.07 and λ, r = 0.53; P = 0.07).

Granger Vallée A et al. Nephrol. Dial. Transplant. 2011;26:3627-3633

© The Author 2011. Published by Oxford University Press on behalf of ERA-EDTA. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com

Serum phosphate in hemodialysis and hemodiafiltrati on cohorts.

Davenport A et al. Nephrol. Dial. Transplant. 2010; 25:897-901

© The Author 2009. Published by Oxford University Press on behalf of ERA-EDTA. All rights reserved. For Permissions, please e-mail: journals.permissions@oxfordjournals.org

Cheung et al. J Am Soc Nephrol 17: 546–555, 2006.

HEMO study

http://www.ncbi.nlm.nih.gov/corecgi/tileshop

/tileshop.fcgi?p=PMC3&id=626080&s=14&r=3

&c=1

HEMO study, infections mortality

Cheung Clin J Am Soc Nephrol. 2008 January; 3(1): 69–77

Senji Okuno Nephrol Dial Transplant (2009) 24: 571–577

HDF and survival

Vilar E Clin J Am Soc Nephrol. 2009 Dec;4(12):1944-53

Contrast study

April 2012

Diffusion

Convection / filtration

Temperature, velocity and energy

E = Average energy

T = Absolute temperature

m= mass

V = average velocity

K = Boltzmann’s constant

Einstein’s theory of diffusion

Albert Einstein considered diffusion to be a consequence of Brownian

motion of solute molecules. The process could be predicted

mathematically from temperature, radius of the molecule and the

viscosity of the solute.

tr

TKDtx b

ηπ322 ==

Where x is the average distance travelled by a molecule in time t, D is the

diffusivity. Kb is Boltzmann’s constant linking temperature to kinetic energy,

T is the absolute temperature, r is the effective radius of the molecule and ȃ

is the viscosity of the solution.

Brownian motion

Average absolute distance moved is proportional to

the square toot of time and diffusion coefficient

Urea and B-2-Microglobulin

B-2-M

M.Wt = 12800

Urea

M.Wt = 60Diffusion 15 x

Diffusion 1 x

Diffusion

M.Wt

Sieving

SC=1

SC=0

Sieving

SC=0.5

Convection / filtration

Pure convection

Convection + diffusion

Convection + diffusion

Jaffrin 1995

20 0083.043.0 QfQfKKt ++=

Waniewski 1979

QfQb

KSKKt

−+= 00 1

Waniewski 2003

Diffusion and convection

Ficheux. KI 2000 57

Ficheux. KI 2000 57

Ficheux. KI 2000 57

High-flux backfiltration

Super-flux

Recommendation

Definitions

• HDF requires effective ultrafiltration at least

20% of blood flow rate.

• Effective ultrafiltration takes account of pre-

dilution.

– In pre-dilution HDF, UF rate needs to be 2-3 times

greater compared to post-dilution.

• The HDF component is quantified as the total

effective volume ultrafiltered.

Effective ultrafiltration

Qpw = Qb x (1-Hct) x (1-Pct)

DF = Qpw / (Qpw + Qinf)

Effective UF= actual UF x DF

Out of scope

• Mid-dilution

• Internal filtration

For these modes, manufacturers should indicate effective ultrafiltration rates for range of likely flow conditions.

• How to normalize (surface area, urea distribution volume)

• “Adequate dose”.