Application of the Theory of Heat Exchangers to a Physiological Study of the Goat Placenta
The exchange characteristics of the goat placenta were compared to those of several simple models. A technique is described whereby the fetal side of the placenta of the goat near term can be perfused with blood. The ratio of fetal to maternal blood flow was controlled in the range 0.17 to 4.80. The fractions of the maternal and fetal blood flows that did not enter the area of exchange (shunts) were determined by perfusion of the uterine and umbilical circulations with Krebs solution containing dextran and saturated with carbon monoxide and were found to be 36% (SD 3.9%) and 23% (SD 2.2%), respectively. These values were compatible with the shunt values obtained by graphical extrapolation of the data obtained with nitrous oxide and acetylene during perfusion with blood. The N2O and C2H2 data showed that the goat placenta has the exchange characteristics of a countercurrent exchanger with extremely unevenly distributed uterine and umbilical flows or those of a concurrent exchanger with moderately uneven distribution of flows. The only available information in the literature on the distribution of flow in this type of placenta indicates that the distribution is moderately uneven.
- Received March 18, 1968.
- Accepted December 22, 1968.
- © 1969 American Heart Association, Inc.