Ester P. Hill

Abstract

This model of placental CO2 and O2 exchange calculates the time course of changes in PCO2, [HCO3-], and [H+] in each of four "compartments" of placental exchange vessels: maternal erythrocytes, maternal plasma, fetal plasma and fetal erythrocytes. The changes in hemoglobin-bound CO2 (carbamate) and oxyhemoglobin contents within the erythrocytes are also calculated, permitting consideration of the Haldane and Bohr effects. Equations were written to represent one-dimensional steady state CO2 and O2 diffusion between concurrent maternal and fetal capillaries and the subsequent hydration, carbamino and oxyhemoglobin reactions. The equations were solved by computer using a 4th order Runge-Kutta numerical integration. Using experimental values for the various reaction rates, diffusing capacities, volumes and flow rates, the model predicts initial rapid CO2 transfer and hydration followed by slower chloride shift and carbamino reactions. The importance of various factors was studied by varying each independently. Carbon dioxide exchange is most sensitive to uterine and umbilical artery PCO2 values, capillary blood flow rates and hemoglobin buffering. The model predicts that the Haldane effect accounts for 46% of the CO2 exchanged and the Bohr effect accounts for 8% of the oxygen exchanged. The effects of placental tissue CO2 production and delays in the Bohr shift were also considered.

School

Graduate School

First Advisor

Ivan R. Neilsen

Second Advisor

Lawrence D. Longo

Third Advisor

Gordon G. Power

Fourth Advisor

C. Duane Zimmerman

Degree Name

Doctor of Philosophy (PhD)

Degree Level

Ph.D.

Year Degree Awarded

1971

Date (Title Page)

12-1971

Language

English

Library of Congress/MESH Subject Headings

Placenta; Oxygen; Carbon Dioxide

Type

Dissertation

Page Count

x; 117

Digital Format

PDF

Digital Publisher

Loma Linda University Libraries

Usage Rights

This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights.

Collection

Loma Linda University Electronic Theses and Dissertations

Collection Website

http://scholarsrepository.llu.edu/etd/

Repository

Loma Linda University. Del E. Webb Memorial Library. University Archives

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