Biomedical Engineering Reference
In-Depth Information
healthy - experiments
healthy - simulations
parasitemia 5%
parasitemia 25%
parasitemia 50%
parasitemia 100%
schizont, parasitemia 25%
2.8
3
Suarez, Kaul, et al., PNAS, 1985 1
Numerical Simulation
Ht = 0.45
2.6
2.4
X
2.5
2.2
2
2
1.8
X
1.6
1.5
1.4
1.2
1
1
0
20
40
60
80
100
0
5
10
15
20
25
30
% parasitemia
(a)
μ
(b)
Tube diameter ( m)
Fig. 10.25. Flow resistance in malaria: (a) Healthy (red) and Pf-RBCs (blue) in Poiseuille flow in
a tube of diameter D
45, parasitemia level 25 %. Plotted is the relative apparent
viscosity of blood in malaria for various parasitemia levels and tube diameters. Symbol “x” corre-
sponds to the schizont stage with a near-spherical shape. Experimental data from the empirical fit
by Pries et al. [72]. (From [51]). (b) Bulk viscosity versus parasitemia level for 30 % hematocrit
using a Couette device setup at shear rate 230 s 1 . The square symbols are measurements from
[85] and the triangles are simulations of Huan Lei (Brown University)
=
20
μ
m. H t
=
0
.
contributions from the interaction of Pf-RBCs with the glycocalyx [69, 86]; such im-
portant interactions are complex as they may include cytoadhesion. In Fig. 10.25(b)
we also present the bulk viscosity of infected blood (schizont stage) simulated in a
Couette type device at shear rate
230 s 1 . The DPD simulations compare favor-
ably with the experimental data obtained with a corresponding rheometer in [85].
These validated predictions were obtained without an explicit adhesion model be-
tween Pf-RBCs. It seems that such cell-cell interactions are not important at this high
shear rate value.
γ =
10.6 Summary
In this chapter we have presented a comprehensive simulation methodology based
on dissipative particle dynamics (DPD), which is effective in predicting the blood
flow behaviour (mechanics, dynamics and rheology) in health and disease. We em-
phasized, in particular, how single-RBC experiments - using optical tweezers and
novel microfluidic devices - can provide data from which we can extract the macro-
scopic parameters of the model, which can then be related to the microscopic param-
eters required by the two RBC models we presented. In addition, these single-RBC
data can serve as a validation test bed over a wide range of operating conditions.
The success of the DPD models is then to predict whole blood behaviour in health or
disease without any further “tuning” of the models' parameters. We demonstrated
that this is indeed the case for healthy and malaria-infected whole blood in two dif-
ferent set ups, i.e., blood flow in a tube as well as in Couette flow. In particular, we
Search WWH ::




Custom Search