AJP - Regulatory, Integrative and Comparative Physiology, Vol 249, Issue 2 192-R202, Copyright © 1985 by American Physiological Society
Mathematical model of fetal circulation and oxygen delivery
F. J. Huikeshoven, I. D. Hope, G. G. Power, R. D. Gilbert and L. D. Longo
To better understand the fetal circulation and its regulation we
constructed a dynamic model of fetal circulation as a transport system. The
fetal vascular system is divided into 16 compartments which incorporate the
peculiarities of the fetal circulation that produce a difference in oxygen
concentration in blood supplying the upper and lower body. Recently
published data is used to provide a firm experimental base for the model.
The model is used to examine how the results on parts of the fetal
cardiovascular system and fetal oxygen consumption are compatible and form
a coherent description. We also studied the effects of disturbances from
the normal steady state produced by changes in patterns of and resistances
to blood flow. A maternal placental blood flow of less than 200 ml X min-1
X kg fetal wt-1 produces a steady-state value of oxygen tension in the
fetal ascending aorta of less than 17 mmHg, which is incompatible with
normal oxygen delivery. A minimal value of umbilical flow providing an
adequate oxygen supply to the fetal body is 87 ml X min-1 X kg fetal wt-1.
Due to the geometry of the fetal circulation, the highest normal oxygen
tension in the fetal ascending aorta is approximately 25 mmHg, only 8 mmHg
above the lowest normal tension of 17 mmHg. Dynamic studies using the model
demonstrate differences in response of fetal arterial oxygen tension to
temporal cord occlusion and temporal decrease in maternal placental flow.
