Marlene R. Sachtleben

Placental oxygen consumption in vitro. I. Baseline studies.

Abstract Barcroft-Warburg respirometric observations of fresh in vitro placental tissue have been reported as part of a correlative study of the effects of various clinical features upon placental metabolism and their relationship to fetal development and survival. Data are presented to illustrate the rates of decay of placental activity under various conditions of storage, indicating the urgent need to study the material in the freshest possible state. Similarly, degradation occurs so rapidly during manometric studies that consecutive observations for the purpose of determining the effects of adding substrates are interdicted. The reduction of the oxygen concentration of the gas phase produces a corresponding, although nonlinear, reduction in oxygen uptake. Normal term placentas consume 2.02 ± 0.03 μl of oxygen per milligram of dry weight per hour. A linear decline is seen from early pregnancy to term. Numerous clinical factors are correlated with placental oxygen consumption, but, except in rare instances, the data are not sufficiently numerous to allow for statistical verification of observed trends.

Placental oxygen consumption in vitro. II. Total uptake as an index of placental function.

Abstract The average total oxygen consumption of a series of placentas has been determined to be 86,800 ± 2,500 μl per hour. It appears to be unrelated to changing gestational age and to placental or fetal weight after the twenty-eighth week of gestation, and remains essentially a constant during the third trimester. Corresponding clinical material has been studied and the total placental oxygen requirement has been found to be diminished in association with pre-eclampsia, fetal distress, depressed infants, and in infarcted placentas; and to be elevated after prolonged general inhalation anesthesia. The potential significance of these findings is discussed.

Station of the fetal presenting part: III. Interrelationship with cervical dilatation

Abstract The correlation between cervical dilatation and station, as these factors affect labor, has been studied. A partial dependency was demonstrated between cervical dilatation and station. Tendencies were shown to exist for lower presenting stations in association with larger cervical dilatation at both the onset of labor and the onset of the active phase. These latter relationships were clear-cut in multiparas and only suggestive in nulliparas. Despite this, the course of labor was affected in rather well-defined directions by either factor acting in an apparently independent manner with reference to the other. In point of fact, dilatation and station appeared to be mutually compensatory (when one was salutory and the other unfavorable) or ougmentative (both choice or both disadvantageous) with regard to their influence on progression in labor.

Placental oxygen consumption in vitro

Placental oxygen consumption was studied by Warburg respirometric techniques in 617 placentas obtained at delivery. Correlations between Apgar score, gestational age, and infant weight were analyzed. Elevated oxygen consumption was encountered among placentas from infants with low Apgar scores, short gestational age, and low birth weight when these factors were examined separately. When corrections were applied for fetal size, the correlation between placental oxygen consumption and Apgar score disappeared.

Placental oxygen consumption in vitro: V. Hypertensive disorders

Abstract Respirometric examination of placentas obtained from 71 patients with documented toxemia of pregnancy, hypertensive cardiovascular disease, and renal disorders is presented. Pre-eclampsia was found associated with progressively diminishing placental oxygen consumption with increasing severity of clinical syndrome. Placentas from patients with hypertensive cardiovascular disease, on the other hand, utilized somewhat more oxygen than expected. Pre-eclampsia superimposed on hypertensive disease resulted in normal levels of placental metabolic activity. Patients with documented renal disease, and to a lesser extent those with albuminuria, had only moderate elevations of oxygen consumption. The potential significance of these findings is discussed in light of recent studies suggesting that renin production secondary to placental ischemia may be etiologic in toxemia.

Dysfunctional labor. IX. Delivery outcome.

Abstract A series of 1,194 patients were studied in labor by means of clinical observations and separately by cervical dilatation time and descent time function curves. Clinical diagnostic criteria of abnormalities were found to be discrepant from the more objective graphic criteria. Delivery outcome was determined on the basis of clinical and graphic diagnoses of abnormality, respectively. From the prognostic point of view, the diagnosis arrived at by cervimetric means was shown to be more likely to be correct, and therefore more useful, than the diagnosis made clinically.

OBSTETRICSPlacental oxygen consumption in vitro: IV. Variations with Apgar score

Placental oxygen consumption was studied by Warburg respirometric techniques in 617 placentas obtained at delivery. Correlations between Apgar score, gestational age, and infant weight were analyzed. Elevated oxygen consumption was encountered among placentas from infants with low Apgar scores, short gestational age, and low birth weight when these factors were examined separately. When corrections were applied for fetal size, the correlation between placental oxygen consumption and Apgar score disappeared.