ABSTRACTS from 16th International COnference on ... - CRRT Online

<strong>ABSTRACTS</strong> FROM 17 TH INTERNATIONAL CONFERENCE ON CRRT,
SAN DIEGO, FEB 14-17, 2012
differentiation toward a tubular epithelial
cell phenotype. The results of the present
study suggest a potential role of PFC in
the improvement of RAD therapy and in
the treatment of ischemic and sepsisassociated
AKI.
74. A Multiscale Model of Citrate
Dynamics during Citrate Regional
Anticoagulation for CRRT
Steven A Conrad
Louisiana State University Health
Sciences Center in Shreveport, LA,
Regional anticoagulation with citrate
provides effective anticoagulation during
CRRT. Metabolic alkalosis and citrate
accumulation are known but
incompletely characterized
complications. A mathematical model of
citrate and bicarbonate transport during
CRRT would permit investigation of the
interaction of factors contributing to this
problem. Multiscale models combine
mathematical modeling approaches that
are based on vastly different physical
scales. A multiscale model was
developed which incorporates a finite
element model of solute handling in
hollow fibers (microliter scale) with a
dynamic compartment model of solute
distribution in extracellular fluid (liter
scale). This model can simultaneously
simulate the transport of citrate and
bicarbonate in a hollow fiber dialyzer
during therapy as well as the
accumulation, metabolism and
elimination of citrate in body
compartments. The finite element
component is based on a partial
differential equation model previously
presented at this forum (CRRT, 22), by
extending it <strong>from</strong> single solute transport
(urea) to both citrate and bicarbonate.
The model includes both momentum
transport (blood and dialysate flows) and
mass transport (solute). The influence of
protein concentration, osmotic forces,
hematocrit and the Fåhræus-Lindqvist
effect on fluid flux have also been added
to the previous model. The dynamic
compartment model is a singlecompartment
lumped parameter mass
transport model of both citrate and
bicarbonate. Model parameters include
volume of distribution, extracorporeal
blood flow and outlet concentrations,
and reaction rate for citrate to
bicarbonate conversion. The
compartment model is linked to the
finite element model through integration
of solute flux <strong>from</strong> the hemofilter as a
compartment input, and mixed
concentration in the compartment as a
finite element input. This multiscale
approach enables the evaluation of a
number of parameters that affect citrate
handling leading to citrate accumulation
and metabolic alkalosis: mode of support
(SCUF, hemofiltration, hemodialysis,
hemodiafiltration), extracorporeal blood
flow, hemofiltration rate, dialysate flow
rate and composition (bicarbonate- vs.
saline-based), citrate infusion rate and
concentration, and citrate metabolic
elimination rate (normal vs. prolonged).
As a dynamic model, it can simulate
these parameters over time scales
ranging <strong>from</strong> minutes to days, thereby
suitable for evaluating operating
parameters during continuous therapies.
75. Pharmacokinetics of Imipenem in
Continuous Venovenous
Hemodialysis (CVVHD) are
related to severity of illness and
dialyzer type.
William H Fissell, Milen Amde, Seth R
Bauer, Charbel A Salem, Michael J
Connor
Cleveland Clinic, Emory University
Background: Sepsis is the leading cause
180