Harry S. McGaughey

The effects of magnesium therapy on the duration of labor.

Abstract Magnesium is an accepted drug in the management of toxemia of pregnancy, and is employed by many physicians as the anticonvulsant agent of choice in the therapy of this commonly encountered gestational disease. Many modes of administration and variable dosage schedules have been evolved over the past half century, ranging from small quantities given orally to relatively large amounts introduced by the parenteral route. In a recent study conducted at the University of Virginia Hospital, 5 it was suggested that prompt, rapidly attained, and effective magnesium blood levels (7 to 8 mEq. per liter) could best be effected by introducing this agent intravenously. Therefore, during the last 30 months, pre-eclamptic and eclamptic patients admitted to the Obstetric and Gynecologic Service of the University Hospital have received magnesium intravenously in high dosages. Clinical observations carried out in our labor and delivery suites have, however, given the impression that the intravenous administration of magnesium sulfate, in sufficient concentration, results in a prolongation of labor. Inasmuch as the commonly utilized sedative drugs morphine, meperidine, and phenobarbital used in the therapy of toxemia have been seemingly exonerated of a direct uterine depressant activity, 14 and since the only departure from the customary therapeutic regimen during the past 30 months from that employed previously was the elevation of the serum magnesium level, it appeared probable that, if labor were in truth prolonged in these patients, the magnesium ion was depressant to the human myometrium during labor. It was in an attempt to clarify this point that the present study was undertaken.

INTERMITTENT FUNCTIONING OF THE UTEROPLACENTAL ARTERIES.

Abstract Repeated radioarteriographic placentograms carried out during uterine relaxation demonstrated alterations in the pattern of arterial entries visualized. Spurts appeared, or disappeared, independent of recorded myometrial activity or significant change in maternal blood pressure. The pattern of the variations was such that vasomotion of the arteries supplying the intervillous space seemed to be the most probable explanation for intermittent functional patency of the entries.

Congenital anomalies of the uterus associated with pregnancy: An analysis of one hundred eighteen cases from the literature with a report of nine additional cases

( !oMMANDER WILLIAM S. BAIiER, .JR., &~EDIcAL COW’S, ~NITEI) STATW YAvY, LIEUTENANT ROBERT 1,. ROY, B~EDICAL CORPS, ~JNITED STATES NAVAL RESERVE:. LIEUTENANT C. E. BANCROFT, MEDICAL CORPS, UNITED STATES NAVY, LIEUTENAKT HARRY MCGAUGHEY, MEDICaL CORPS, UNITED STATES NAVY, LIEUTENANT (JO) F. NORTON DICKMAN, MEDICAL CORPS, UNITED STATES NAVAL RESERVE, AND LIEUTENANT (JG) GEORGE W. TUCKER, MEDICAL CORPS, TJNITED STATES NAVAL RESERVE

Venous drainage of the placenta in rhesus monkeys: Radiographic studies

Abstract 1. 1. Drainage from the intervillous space of the placenta has been studied in 41 rhesus monkeys by serial and cineradioangiography following introduction of contrast medium into the maternal arterial bloodstream and directly into the intervillous space. 2. 2. When dye is injected into the intervillous space during uterine relaxation, it drains promptly through venous orifices into the uterine mural veins and thence to the pelvic veins (primarily the ovarian veins). 3. 3. During uterine contraction, there is partial or complete disappearance of dye from drainage channels, but the size and configuration of the placental blood pool is maintained. 4. 4. Inflow through arterial channels is halted during contractions, and any dye spurts which may have begun to form are arrested until the contraction peak has passed. 5. 5. The study indicates the controlling role played by arterial inflow in the maintenance of placental circulation. Continuing inflow provides the impetus whereby blood is eventually pushed toward orifices of exit and drained into uterine and pelvic veins. When intrauterine pressure is raised by myometrial contractions, both inflow and outflow are reduced or even halted though the volume of blood in the intervillous space appears to be maintained, thus providing for continued (though reduced) maternal-fetal exchange.

Placental transfer in normal and toxic gestation

Abstract 1.1. Transabdominal aspiration of blood from the intervillous space at varying intervals after the intravenous injection of antipyrine shown that the concentration of antipyrine in intervillous blood has a mean value of 98 per cent of that in peripheral venous blood with a standard deviation of 8 per cent. This circumstance is analyzed in terms of the anatomy and physiology of the circulations to the placenta. 2.2. A method is presented for the calculation of the instantaneous intervillous concentration of antipyrine from the peripheral venous concentration. 3.3. Comparison of the concentrations of antipyrine in the umbilical vein with the calculated simultaneous intervillous concentration indicates that, in the time maternal and fetal blood are exposed at the placental barrier, equilibration of antipyrine is complete. 4.4. Similar studies employing sodium 24 indicate that the diffusion of charged particles is impeded. 5.5. In similar studies on patients with toxemias of pregnancy, no constant relationship is found between intervillous and peripheral venous concentration of either antipyrine or sodium. 6.6. The data from toxemic patients are analyzed in terms of possible anatomic and vascular changes that may occur in toxemia.

Effects of anesthetic and sedative agents commonly employed in obstetric practice on isolated human uterine muscle

Abstract 1. 1. An attempt to assay the effects of commonly employed anesthetic and sedative agents on human uterine muscle tissues is described. 2. 2. All of the inhalation anesthetics tested were found to be markedly depressant to gravid and nongravid uterine muscle activity in vitro, with the single exception of trichloroethylene. 3. 3. Morphine, scopolamine, Demerol, atropine, and phenobarbital produced no significant effect on the activity and tonus of uterine muscle samples obtained from both nongravid and gravid uteri. 4. 4. Nembutal was found to be without marked effect on tissues from nongravid uteri, but to possess a depressant action on samples from the gravid uterus when in sufficiently high concentration. 5. 5. Magnesium sulfate depressed contractility and lowered tonus in muscle strips from both nongravid and gravid uteri.

An evaluation of the action of relaxin on isolated human uterine muscle and cervical tissues in vitro

Abstract 1. 1. Relaxin had no demonstrable effect on the spontaneous contractility of isolated human uterine muscle, or on the tension of cervical tissues in vitro. 2. 2. This was true for tissue samples taken from both nongravid and gravid uteri. 3. 3. It appears that the evaluation of relaxin as an adjunct to the armamentarium of the obstetrician and gynecologist must await the result of extensive clinical experience and trial.

Electromyography of the human uterus

Abstract 1. A simple, nontraumatic method for recording bioelectric potentials emanating from the human uterus in situ is described. 2. Potential shifts as recorded from the nongravid organ were predominantly monophasic, the frequency varying with the ovarian cycle. This frequency of potential change was highest just prior to and immediately following menstruation and lowest at a time approximating ovulation. 3. Potential shifts during pregnancy were characteristically and predominantly biphasic. The frequency of such potential changes remained relatively constant throughout gestation, approximating that seen during the ovulatory phase of the menstrual cycle. 4. Records from isolated uterine muscle strips were of such a character as to be interpreted as evidence that tracings secured from the uterus in situ represented true uterine electropotential changes. These records gave indication of the equipotentiality of various portions of the uterus as regards bioelectric activity. 5. Bioelectric activity is present in the human uterus until at least the age of 82 years.

Definition of the stimulatory response of isolated human uterine tissues ☆: The effect of posterior pituitary extract, vasopressin, and oxytocin on pregnant and nonpregnant human myometrial samplings in vitro

effects of test stimuli upon isolated human myometrial samplings is dependent upon the ability of this study method to appraise correctly the direct, local response of uterine tissues to the stimulus applied. It has been shown that adequate oxygenation of the muscle strip, control of temperature, pH, ionic composition, and osmolality of the solution in which the tissue is suspended, and a knowledge of the preponderant hormonal stimulus to which the intact uterus was exposed prior to sampling are essential for a correct evaluation of the experimental data obtained.le6 In addition, since the patterns of spontaneous activity displayed by isolated strips of human uterine smooth muscle frequently are not quantitatively

Effect of certain smooth muscle depressants on isolated human myometrial tissues

PRE MAT u RI T Y is a leading cause of perinatal mortality. In many instances the exact mechanism for the premature expulsion of the products of conception is not known. However, enhanced uterine activity prior to full fetal development is an obvious suspect. It is now generally accepted that myometrial activity can be suppressed temporarily by a variety of agents including ether, nitrous oxide, magnesium, etc.1-4 Search for a myometrial depressant capable of being administered to the parturient over an extended period of time without appreciable disturbance to the total physiology of mother and fetus continues. The present study was initiated in an endeavor to assess the direct? local effect of certain smooth muscle depressants on the contractility of human myometrial tissues.