Thorkild Andersen

OBSERVATIONS ON THE PLACENTAL EXCHANGE OF THE RESPIRATORY GASES IN PREGNANT WOMEN AT CESAREAN SECTION.

T H E H I G H oxygen capacity and low degree of saturation of the blood in the umbilical vessels of man observed by Eastman1 in 1930 led to the view that the blood of the fetus is exposed to a low oxygen tension while it is taking up that gas. Anselmino and Hoffman2 first suggested that the low tension was due to the resistance offered to the diffusion of oxygen by the tissue barrier of the placenta and to its intrinsic oxygen use. The fetus, in this view, appeared to be adjusted or acclimatized to an aspect of its environment it could not control, i.e., the low oxygen tension to which its blood is exposed in the placental capillaries. According to this view any reduction in the oxygen tension in the maternal placental capillaries might be expected to reduce the rate at which oxygen reaches the fetus and so to reduce its margin of safety.

CARDIOVASCULAR EFFECTS OF RAPID INTRAVENOUS INJECTION OF SYNTHETIC OXYTOCIN DURING ELECTIVE CESAREAN SECTION.

Synthetic oxytocin injected rapidly, intravenously in 22 patients during elective cesarean section caused a decrease ill blood presslIre and an increase in heart rate. In 16 patients, heart rate, cardiac output, and stroke volume increased while mean arterial pressure and total peripheral resistance decreased. All changes were pronollllced, rapid in onset, and of short duration. No serious electrocardiographic changr;s were found. Repeat injeotion in 5 patients caused similar changes. The type of anesthesia did not appear to matter.

Movements of lactate and pyruvate in the pregnant uterus of the human

Abstract In most cases lactate was transferred from the uterus to the maternal circulation and from the fetus to the placenta, but these did not occur simultaneously at all times. There were several instances where the gradient across the placenta and across the uterus was in the opposite direction. No consistent transfer of pyruvate between either the uterus and the mother or the fetus and the placenta was found. The direct relationship of the lactate and pyruvate concentrations between the mother and fetus suggests a simple passive diffusion of these substances between the two circulations.

Observations on pentothal, nitrous oxide, and succinylcholine anesthesia at cesarean section

Abstract The present report concerns itself with observations made upon 26 pregnant women who were delivered by cesarean section. Anesthesia consisted of sodium pentothal, succinylcholine, and nitrous oxide. The observations that were made involved the collection of blood from the following vessels: a maternal artery before anesthesia, a maternal artery and uterine vein prior to opening of the uterus, umbilical vein and artery at delivery, umbilical artery shortly after birth, and umbilical artery at one hour of age. Analyses consisted of determinations of oxygen, carbon dioxide, pH, lactate, pyruvate, glucose, and pentothal. From the data we have collected in the mother and in newborn infants within the first hour of life, we are able to say that the levels of the various metabolites measured are at least as close to the accepted normal ranges as those found in women undergoing cesarean section and exposed to spinal, epidural, and cyclopropane anesthesia. With due reservations for the limitations of our own studies, we favor pentothal, nitrous oxide, and succinylcholine, for we avoid the hypotension induced by autonomic blockade, and we avoid the incidence of depression in the newborn (50 per cent) that is encountered in our unit when employing cyclopropane anesthesia.

A study of the oxygenation of the fetus and newborn and its relation to that of the mother

Abstract This report deals with oxygen concentrations in maternal (artery and uterine vein), fetal (umbilical vein and artery), and newborn (umbilical artery) blood samples. Studies were made in 63 pregnant women at term, not in labor, and delivered by cesarean section. The results indicate a wide range of variation in the various samples. Data are also included for calculation of respiratory quotient and coefficient of oxygen utilization across the intact uterus. No relationship was found between Apgar scoring and percentage oxygen saturation in fetal vessels and blood in newborn infants.

Mephentermine and ephedrine in man: A comparative study on cardiovascular effects

Mephentermine and ephedrine were given to healthy volunteers, and their cardiovascular effects were compared. In doses equally effective in raising systolic blood pressure, ephedrine caused significantly greater elevations of heart rate, stroke volume, and cardiac output than mephentermine. The calculated total peripheral resistance was significantly increased by mephentermine, and reduced or not changed by ephedrine.