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Biomedical subjects

B K Young

Publications and source records attributed to B K Young.

At least 73 records · Page 4Linked to original sources
PubMed1984

Placental contribution to lactate production by the human fetoplacental unit.

Umbilical cord blood levels of lactate, base deficit, and pH were measured in 452 liveborn infants. In vigorous newborns, the mean umbilical arterial and venous concentrations of lactate were lowest with elective cesarean section, higher with cesarean section performed during labor, and highest with vaginal delivery (P less than .001). This suggests a rise in the fetal lactate level in response to labor. However, there was no concomitant increase in the mean umbilical arteriovenous lactate differences, indicating that both fetus and placenta increase their lactate production proportionately with labor. Depressed newborns had higher umbilical lactate levels than vigorous newborns irrespective of the method of delivery (P less than .001). Depressed newborns also had a higher mean umbilical arteriovenous lactate difference than vigorous newborns (P less than .001). This suggests that, under conditions that lead to neonatal depression, the fetus is the major source of the increased lactate produced, with a smaller contribution from the placenta. The fetal lactate level may be a good indicator of fetal stress in labor.

Acidosis↗
PubMed1984

Sonographic anatomy of the fetal cerebral ventricles, with reference to the early diagnosis of hydrocephaly.

Real time ultrasound was used to evaluate the anatomy of the fetal brain at different gestational ages. Anatomical correlation with the gross brain was utilized for more accurate identification of the neuroanatomical structures. The normal growth of the ventricular system was studied. Transaxial measurements of the anterior horn (AH) and maximum ventricular length (MVL) and width (MVW) were made, and enlarged as pregnancy progressed. The ratios of MVW/MVL, MVL/BPD, and MVW/BPD provide guides to the early diagnosis of hydrocephalus and intracranial abnormalities. Specific measurements of the cerebral ventricles at various gestational ages may be made accurately by utilizing the anatomical landmarks. The anterior horn and midbrain measurements are of little value in the early diagnosis of hydrocephaly. Maximum ventricular length and width are the most useful determinants of hydrocephaly, even as early as 20 weeks. A set of discordant twins in which twin B was found to be hydrocephalic by these studies in the twentieth week is presented with serial measurements for both twins. Multiple measurements of the cerebral ventricular system in utero permit early and precise diagnosis of fetal hydrocephaly.

Adult↗
PubMed1984

Human maternal-fetal lactate relationships.

This study attempts to determine the major source of lactate in the normal and in the depressed human fetus, in order to assess the applicability of fetal blood lactate measurement for the evaluation of fetal stress during labor. We obtained umbilical arterial and venous blood samples at delivery in 132 liveborn infants, together with simultaneous maternal radial arterial samples. All samples were analyzed immediately for pH, blood gases, and lactate. In vigorous newborns (1-minute Apgar score greater than or equal to 7), umbilical arterial and venous lactate levels were lowest with elective cesarean section done before the onset of labor, higher with cesarean section performed during labor, and highest at the time of vaginal delivery (p less than 0.001, Tab. I). Fetal lactate levels were also significantly higher than maternal levels in vigorous newborns (p less than 0.01), the lactate difference between umbilical artery and maternal artery being lowest with elective cesarean section, higher with cesarean section performed during labor, and highest with vaginal delivery (p less than 0.02, Tab. II). Depressed newborns (1-minute Apgar score less than 7) had higher umbilical lactates and higher fetal-maternal lactate differences than vigorous newborns (p less than 0.01, Tab. III). Our results indicate that the blood lactate levels in both mother and fetus increase with labor and reach their highest values at the time of vaginal delivery. The lactate levels are highest in the umbilical artery, lower in the umbilical vein, and lowest in the maternal artery before the onset of labor.(ABSTRACT TRUNCATED AT 250 WORDS)

Arteries↗
PubMed1983

Profile of serum estriol and its conjugates at delivery and in the immediate postpartum period in a patient with severe polycystic kidney disease: a comparison with normal pregnancy.

A patient with group C polycystic kidney disease had abnormally high concentrations of total serum estriol (E3) but low-normal urinary levels of E3 throughout the period of study (20 weeks of gestation until delivery by cesarean section at 33 weeks, 5 days). At delivery and at regular intervals until 6 hours thereafter serum specimens were analyzed for unconjugated E3 and its four major conjugates. Comparisons were made with levels in three normal volunteer subjects studied in the same way. In the 6 hours, total E3 declined 37% in the subject with polycystic kidney disease whereas in normal subjects the decline ranged from 84% to 99%. Unconjugated E3 was depleted from the serum in all subjects in about 2 hours. The major difference between the patient with polycystic kidney disease and the normal subjects was in the profile of E3 conjugates. In polycystic kidney disease, E3-3-glucosiduronate (E3-3G) and E3-3-sulfate-16-glucosiduronate (E3-SG) respectively made up 83% and 1.8% of the total serum estriol, whereas in the normal subjects the average values were 13% for E3-3G and 49% for E3-SG. There were no consistent dramatic changes in the percentage contribution of any conjugate to the total E3 level in either the patient with polycystic kidney disease or the normal subjects in the predelivery or postdelivery periods. The E3 profile in polycystic kidney disease is explainable in terms of impaired renal function coupled with normal enterohepatic metabolism of E3.

Estriol↗
PubMed1983

Effects of temperature on arterial and cutaneous pO2 in the rabbit.

Continuous transcutaneous measurement of pO2 (tcpO2) has been adapted to fetal and neonatal use, utilizing a noninvasive miniaturized modified Clark pO2 electrode attached to the skin by adhesive. The unprepared ear of the adult female Flemish Giant rabbit was used for attachment of the electrode, and blood for arterial pO2 (apO2) was taken from the auricular artery. The rabbits were gently restrained and unanesthetized. The tcpO2 and pO2 were compared at environmental temperatures of 20-23, 50, and 60 degrees C, in separate experiments. The data demonstrated that tcpO2 is not the same as pO2. It is most clearly related to local blood flow. tcpO2 only indirectly reflects apO2, when peripheral flow is comparable to central flow. Proper use of tcpO2 in the fetus and neonate requires cognizance of blood flow conditions for correct interpretation. tcpO2 is not indicative of apO2 when reduced peripheral circulation is present, in the rabbit ear.

Animals↗
PubMed1983

Pregnancy after spinal cord injury: altered maternal and fetal response to labor.

Four pregnancies in three patients with spinal cord injury are presented. The major complications encountered include anemia, pyelonephritis, decubiti, premature labor, precipitate labor, and autonomic hyperreflexia. Autonomic hyperreflexia, a severe mass autonomic reflex response to labor, is associated with tachycardia, hypertension, headache, diaphoresis, and severe anxiety. It is probably due to increased norepinephrine release, as very high urinary metanephrines were measured in the latter two cases presented. Maternal and fetal physiology in labor are altered. Despite severe maternal and fetal stress responses, no fetal depression was observed.

Adult↗
PubMed1982

Fetal lactic acidosis with epidural anesthesia.

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.

Acidosis↗
PubMed1982

Fetal blood analysis. I. Effect of delayed collection.

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.

Analysis of Variance↗
PubMed1982

Fetal blood analysis. II. Effect of delayed assay on pH and lactate.

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.

Fetal Blood↗
PubMed1982

Sinusoidal fetal heart rate pattern with vasa previa in twin pregnancy.

A case of vasa previa in twin pregnancy associated with a sinusoidal heart rate was observed. A review of the world literature revealed eight previously reported cases of vasa previa in twins. No first twin survived, and 62.5% of second twins eventually died from partial or complete exsanguination. This is the first reported case of sinusoidal fetal heart rate in association with vasa previa. Continuous fetal monitoring suggested the diagnosis of funic presentation and of fetal bleeding. A high index of suspicion, use of amnioscopy, ability to detect fetal blood in the vaginal pool, continuous fetal heart rate monitoring and ultrasonography may help in reducing the high perinatal mortality associated with vasa previa.

Adult↗
PubMed1981

Effects of prostaglandin F2 alpha or oxytocin on serum estriol and its conjugates during induced labor.

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.

Estriol↗
PubMed1981

Continuous fetal monitoring following third-trimester amniocentesis.

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.

Amniocentesis↗
PubMed1980

Intravenous dexamethasone for prevention of neonatal respiratory distress: A prospective controlled study.

A trial of intravenous dexamethasone for prevention of neonatal respiratory distress syndrome was carried out prospectively. There were 112 treated and 188 control patients, matched for gestational age, birth weight, rupture of membranes, and antepartum diagnosis. No short-term deleterious effects on mother or infant were demonstrable. There was an increased incidence of cesarean section and puerperal infection in the treated patients. This was not related to the steroid therapy. There was no increased incidence of infection in the treated neonates. At 28 to 33 weeks' gestation, the treated newborn infants had one half the perinatal mortality and one fourth the incidence of severe respiratory distress syndrome seen in the controlls. Under 28 weeks, and from 34 to 36 weeks, no difference between treated and control groups was observed. Intravenous dexamethasone is effective in reducing perinatal mortality from respiratory distress syndrome in premature infants delivered between 28 to 33 weeks' gestation.

Bacterial Infections↗