Faculty Bibliography

Fetal umbilical artery blood was analyzed for pH and lactate at intervals over a 3-hour period. No significant change occurred in pH over the first 30 minutes, despite a progressive rise in plasma lactate. The pH changes paralleled the lactate in an inverse relationship, but remained within the error of the method for the first hour. Lactate analysis should be considered for clinical use, for confirmation of pH observations. Also pH assays may be used in any hospital with a blood-gas capability, since a 30-minute delay within the assay does not materially alter the results. A laboratory in the delivery room area is not essential to proper use of fetal blood pH analysis

Umbilical blood was analyzed for pH, pO2, pCO2, HCO3-, base excess, and plasma lactate to evaluate possible errors of fetal scalp blood analysis. Two studies to determine the effect of delayed collection and exposure to air on fetal blood acid-base measurement analyzed anaerobically collected umbilical blood in syringe and capillary samples. In the first study, 37 samples were analyzed and then placed in small droplets on a glass slide and exposed for 30 seconds and 60 seconds respectively. These samples were then collected and reanalyzed. No significant change was noted through 1 minute of exposure in any of the acid-base parameters measured. In the second study, 34 samples were again analyzed and then exposed in droplets for a full 5 minutes. Differences in measurement of pO2, base excess, and plasma lactate remained insignifiicant even up to 5 minutes. The results of this study demonstrate that the occasional slow scalp blood collection or admixture with air do not present a significant obstacle to proper use of fetal acid-base analysis

Three hundred thirty-six consecutive cesarean deliveries performed under epidural anesthesia were reviewed. Twenty per cent of mothers suffered at least a 20% fall in blood pressure following administration of epidural anesthesia. An additional 24% required ephedrine, a vasopressor with predominantly beta activity, when other corrective measures failed. Thus, 44% of these patients suffered significant hypotension. Forty-one percent of all elective repeat cesarean sections were treated wih ephedrine because of maternal hypotension. Fifty-one patients delivered by scheduled repeat cesarean section were divided into ephedrine-treated and untreated groups. There were no differences in Apgar scores among infants of both groups. Fetal acidosis was proportional to the severity of hypotension and the ephedrine dose. The metabolic abnormalities were most pronounced when severe hypotension, requiring over 15 mg of ephedrine, was present. Following restoration of blood pressure with conventional measures and ephedrine therapy, lactic acidosis persisted until delivery, whereas PO2 and PCO2 reverted toward normal values. The hypoperfusion of the intervillous space was the most likely cause of the observed significant umbilical venous and arterial lactic acidosis. Maternal hypotension remains a significant problem complicating conduction anesthesia

One hundred forty-six patients were monitored for up to 2 hours after third-trimester amniocentesis. The patterns of uterine and fetal activity, as well as fetal heart rate, were analyzed using the criteria for nonstress and contraction stress testing. There was a clear relationship between these observations and perinatal outcome. Postamniocentesis monitoring was associated with an Apgar score of 6 or less in only 10% of cases with reactive patterns, compared with in 75% of cases with nonreactive patterns and reduced variability and in all cases with late-component deceleration. All cases of immediate fetal jeopardy were detected and there was no fetal loss. Postamniocentesis monitoring appears to offer significant prognostic information for perinatal outcome in high-risk pregnancy

Twelve patients underwent induction of labor at term, seven by prostaglandin F2 alpha (PGF) and five by oxytocin infusion. Serum samples were drawn before induction and at two hour intervals after infusion was started, throughout labor. The samples were analyzed for estriol (E3) and its principal conjugates, estriol-3-sulfate (E3-3S), estriol-16-glucosiduronate (E3-16G), estriol-3-glucosiduronate (E3-3G), and estriol-3-sulfate-16-glucosiduronate (E3-SG). No significant changes occurred before eight hours of infusion. Two pre-eclamptic patients showed a 100% increase in serum E3 while receiving PGF. The increases correlated best with rising levels of E3-SG. None of the five pre-eclamptic patients given oxytocin showed this striking changes. These observations raise the possibility that PGF may alter the metabolism of estriol in pre-eclamptic patients, during labor