Tw. Secomb et al., Theoretical simulation of oxygen transport to brain by networks of microvessels: Effects of oxygen supply and demand on tissue hypoxia, MICROCIRCUL, 7(4), 2000, pp. 237-247
Objective: Simulations of oxygen delivery by a three-dimensional network of
microvessels in rat cerebral cortex were used to examine how the distribut
ion of partial pressure of oxygen (Po-2) in tissue depends on blood flow an
d oxygen consumption rates.
Methods: Network geometry was deduced from previously published scanning el
ectron micrographs of corrosion casts. A nonlinear least-squares method, us
ing images obtained at three different angles, was used to estimate vessel
locations. The network consisted of 50 segments in a region 140 mu m x 150
mu m x 160 mu m. A Green's function method was used to predict the Po-2 dis
tribution. Effects of varying perfusion and consumption were examined, rela
tive to a control state with consumption 10 cm(3)O(2)/100 g per min and per
fusion 160 cm(3)/100 g per min.
Results: In the control state, minimum tissue Po-2 was 7 mm Hg. A Krogh-typ
e model with the same density of vessels, but with uniform spacing, predict
ed a minimum tissue Po-2 of 23 mm Hg. For perfusion below 60% of control, t
issue hypoxia (Po-2 <1 mm Hg) was predicted. When perfusion was reduced by
75%, the resulting hypoxia could be eliminated by a 31% reduction in oxygen
consumption rate.
Conclusions: The simulations suggest that tissue hypoxia resulting from a s
evere decrease in brain perfusion, as can occur in stroke, may be avoided b
y a moderate decrease in oxygen consumption rate.