James C. DeHaven

The dynamics of placental oxygen transfer: I. Effects of maternal hyperoxia in pregnant ewes and fetal lambs☆

Abstract The effects of hyperoxia at one atmosphere on placental oxygen transfer in the pregnant sheep have been studied. Fetal blood pO 2 does not increase proportionately to the maternal increase, but is effectively limited below values of 60 mm. Hg. Net umbilical oxygen transfer is reversibly reduced during maternal hyperoxia. The Krogh equation is inadequate to predict or explain these findings. The need for a model of placental gas diffusion employing terms dealing with blood flow rates, hemoglobin properties, concentrations, and geometric relationships is established.

Oxyhemoglobin dissociation characteristics of human and sheep maternal and fetal blood

Abstract 1.1. Oxyhemoglobin dissociation curves were obtained from in vivo studies of maternal, fetal and neonatal sheep blood. Similar studies using slightly different techniques were performed on human maternal and fetal blood. 2.2. In the sheep, the in vivo analysis results in oxygen dissociation curves that are shifted to the left of those reported by others. The fetal curves lie to the left of maternal with the neonatal in between. In the human, the fetal curve is shifted to the right and is not significantly different from the maternal curve. 3.3. Oxyhemoglobin dissociation characteristics are probably influenced by the use of metabolic antagonists and by the passage of time required for analysis of the blood. These factors may alter the ionic distribution between plasma and erythrocytes and, hence, affect the oxygen affinity of the blood.

Chemical Equilibrium Problems with Unbounded Constraint Sets

Abstract : An investigation of the use of mathematical models to explore the chemical aspects of physiological systems; this deals with the theoretical and computational aspects of understanding the chemistry of human physiological function. The question of existence of solutions to problems having unbounded constraint sets is investigated by relating their existence (or nonexistence) to a property of a solution to an auxiliary chemical equilibrium problem with a bounded constraint set. An example system is selected consisting of gases in contact with an aqueous buffer solution at a uniform total hydrostatic pressure and temperature. The numerical problem of determining the amount of CO2 to be added to achieve a specified partial pressure of CO2 in the gas phase, and its effects on the composition of the total system, is solved by using a procedure suggested by the concept of unbounded constraint sets. Findings may apply to design of artificial life-support systems needed in extraterrestrial environments related to Air Force missions.

Analysis of Chemical Constituents of Blood by Digital Computer

The sum of medical knowledge has become so vast that the human mind can no longer comprehend the complexities of the whole body system. The physician has resorted to specialization to solve this problem; the physical scientist has resorted to mathematics and high-speed computers. Computers are particularly helpful in the handling of systems with multiple variables. Since there is no machine or system with as many variables as the human body, computers could be expected to be especially applicable to the problems of medicine. Despite the availability of computer science for the past 10 to 15 years, there has been little application of computer technology