PubMed Health⌕ Search

Biomedical subjects

L I Mann

Publications and source records attributed to L I Mann.

At least 19 recordsLinked to original sources
PubMed1992

Response of fetal heart rate to scalp stimulation related to fetal acid-base status.

The correlation of the response of the fetal heart rate (FHR) to scalp stimulation and the acid-base status of the fetal scalp blood (FSB pH) was studied in 104 term fetuses during labor. The mean FHR was determined for the 5-minute period before the preparation for fetal scalp blood pH determination and 1 minute following FSB pH. The analysis was performed for three pH groups: (a) Normal (pH more than 7.25, = 73); (2) preacidotic (pH 7.20 to 7.25, = 16); and (3) acidotic (pH less than 7.20, = 15). The pH was confirmed at delivery by determination of umbilical cord blood acid-base status. Regression analysis of the number of fetuses responding by changing their heart rate against time was significant only for the nonacidotic fetuses. There was no significant difference in the number of subjects whose mean FHR increased, decreased, or remained unchanged between the three pH groups. Furthermore, there was no difference between the three pH groups in the number of fetuses who demonstrated significant mean heart rate changes (p less than 0.05) following the stimulation compared to those who did not. Further analysis between fetuses in the three pH groups who increased FHR 15 beats/min or more following stimulation did not discriminate between groups. We conclude that scalp stimulation results in a FHR response in all three pH categories. However, the net change in the mean heart rate following the stimulation may be negative or positive. The magnitude and the direction of this change in FHR is not significantly related to FSB pH.(ABSTRACT TRUNCATED AT 250 WORDS)

Acid-Base Equilibrium↗
PubMed1991

Effect of ranitidine on bupivacaine disposition.

This study was undertaken to determine the effect, if any, of ranitidine on bupivacaine disposition in 28 women undergoing cesarean section. Before epidural anesthesia, ranitidine (50 mg IM) or sodium citrate (30 mL orally) was administered to groups of 14 parturients each. Ranitidine was administered 2 h before epidural anesthesia and sodium citrate was administered 10 min before the epidural. Maternal plasma samples were collected after epidural anesthesia with bupivacaine. A total of 15 maternal plasma samples were taken from the time of administration of epidural anesthesia up to 180 min. Postpartum plasma and urine samples were also collected from both mothers and neonates. Plasma samples were collected up to 48 h postpartum at intervals of 12, 24, and 48 h. Urine samples were collected at six 6-h intervals up to 36 h postpartum. A two-way analysis of variance with repeated measures demonstrated that there was no significant difference in bupivacaine levels between the maternal plasma curves of the ranitidine and the control groups. At the time of delivery, plasma levels of bupivacaine and its N-dealkylated metabolite PPX (2,6-pipecolylxylidine) were no different in the mothers or neonates of either group. There was no significant difference in plasma protein binding of bupivacaine in the presence of ranitidine. The excretion rates of bupivacaine and PPX were not measurably influenced by ranitidine. The amount of bupivacaine excreted, the amount of metabolite excreted, and the percentage of drug excreted as metabolite in maternal urine were not significantly different. These data indicate that there is no measurable effect of ranitidine on the disposition of bupivacaine in parturients.

Adult↗
PubMed1990

Detection of fetal blood contamination by amniotic fluid obtained during cordocentesis.

When a fetal blood sample is obtained by cordocentesis it is important to know whether the sample is diluted with amniotic fluid. This study was designed to assess whether contaminated fetal blood samples could be discriminated from noncontaminated ones by the ferning test, and if so what is the minimum dilution ratio of amniotic fluid/fetal blood that is detectable. Fetal blood samples were diluted with amniotic fluid and were tested for ferning under the microscope after the plasma was separated from the cells. At a dilution ratio of 0.2 ml of amniotic fluid to 1 ml of fetal blood, 30% of the samples tested positive for ferning. A rate of 100% detection of ferning was achieved at a dilution ratio of 0.6:1. In conclusion, screening fetal blood samples for ferning can detect amniotic fluid contamination. The sensitivity of the test for ferning depends on the dilution ratio. The test cannot assess how much amniotic fluid was added to the blood sample.

Amniotic Fluid↗
PubMed1989

Intravenous, deltoid, or gluteus administration of meperidine during labor?

It has been suggested, but not well verified, that drug absorption from traditional intramuscular injection sites is altered during labor. This study tested the hypothesis that absorption of meperidine from the gluteus muscle would be impeded when compared with deltoid or intravenous administration. Five patients in labor were given 50 mg intravenously, 10 were given 50 mg in the gluteus muscle, and five were given 50 mg in the deltoid muscle. Five nonpregnant subjects served as their own controls for all three routes of administration. Blood samples were obtained at intervals after injection, meperidine was determined by gas chromatography/mass spectrometry, and mean plasma levels of meperidine versus time after administration were plotted. Repeated measures analysis of variance was used to determine whether the curves were significantly different from 30 to 150 minutes. Maternal plasma levels after gluteus injection were significantly lower than those after intravenous injection (F[1,8] = 10.53; p less than 0.01). In nonpregnant subjects, drug levels were not significantly different from 30 to 150 minutes after either gluteus or intravenous injection. Plasma levels after deltoid injection were always higher than those after gluteus injection in both pregnant and nonpregnant subjects (F[1,8] = 9.7; p less than 0.02; F[1,8] = 14.5; p less than 0.004). These findings support impaired absorption of drugs from the gluteus muscle and suggest the deltoid muscle as the favored intramuscular site during labor.

Absorption↗
PubMed1989

Cervical change and uterine activity as predictors of preterm delivery.

Premature uterine activity and early cervical change have both been shown to be useful in predicting preterm delivery. Prospective studies evaluating weekly uterine activity and cervical change were performed in 20 women, 17 of whom were at risk for preterm delivery, starting at 20 to 25 weeks' gestation. Patients were followed weekly until either 36 weeks' gestation or until the onset of premature labor or delivery. Seven women delivered before 37 weeks' gestation (preterm group). Thirteen women did not require tocolysis and delivered after 37 weeks' gestation (term group). A Bishop score was assessed weekly and the score added to the prior values in order to obtain a cumulative cervical score. A similar process was used to assess uterine activity. The cumulative values of Bishop score and uterine activity were plotted against gestational age in both groups. There was no observed increase in cumulative uterine activity in the preterm group before delivery. However, there was a progressive increase in cumulative cervical change weeks before delivery in the preterm group (p less than 0.05). Despite the small sample size, we conclude that progressive cervical change precedes the onset of labor and may be a better predictor of preterm delivery than is weekly monitoring of uterine activity.

Cervix Uteri↗
PubMed1989

Clinical associations of variable decelerations during reactive nonstress tests.

Six hundred ninety-three patients at or beyond 30 weeks' gestation with reactive nonstress tests (NSTs) were divided into groups based on the occurrence of variable decelerations of 15 seconds or more in duration and of 20 or more beats per minute in severity. Ultrasound examination within a month of testing showed no increases in nuchal cord localization or decreased amniotic fluid volumes in a subgroup of 181 patients. Fetuses with antepartum variable decelerations were more likely to demonstrate similar decelerations in labor (P less than .001), to undergo operative delivery for a diagnosis of "distress" (P less than .05), to require intensive care nursery admission (P less than .01), and to be small for gestational age (P less than .01). No significant differences were noted in frequency of nuchal or other cord entanglements, overall cesarean section rate, or low pH or Apgar score values. We conclude that variable decelerations in the absence of other alarming NST findings may aid in identifying patients at risk for adverse perinatal occurrences, although factors other than nuchal cord placement or oligohydramnios may be responsible.

Amniotic Fluid↗
PubMed1988

Brain damage after intermittent partial cord occlusion in the chronically instrumented fetal lamb.

The relationship between intermittent partial occlusion of the umbilical circulation and fetal acid base status, brain function, and neuropathologic outcome was assessed in nine control and nine experimental singleton fetal lambs to determine if transient episodes of partial cord occlusion play a role in antenatal brain damage in this species. Intermittent partial occlusion of the umbilical circulation for 1 minute of every 3 minutes for 2 hours was associated with a 89% incidence of histologically confirmed damage confined to the cerebral white matter. This occurred without systemic evidence of progressive acidosis, but both fetal heart rate patterns and electrocortical activity were altered. We conclude that in the late gestation fetal lamb, umbilical cord compromise plays a causal role in a specific type of antenatal central nervous system injury.

Acid-Base Equilibrium↗
PubMed1986

Pregnancy events and brain damage.

A national standard of perinatal care has been established for the early detection and appropriate management of the fetus-neonate who is at risk for distress, brain damage, or death. While perinatal and infant mortality has significantly decreased during the past 10 years, a similar reduction in conditions of severe handicap has not been observed. Undetected antenatal umbilical cord compression is suggested as a possible cause of unexplained brain damage. Basic animal experimentation and clinical experience is reviewed to support the hypothesis.

Animals↗
PubMed1985

Vaginal delivery after cesarean section: a five-year study.

All pregnancies that were complicated by a previous cesarean section were reviewed for a five-year period from 1978 to 1982. Of 799 such pregnancies, 216 underwent a trial of labor, and 66% experienced successful vaginal delivery. When the primary cesarean section was for cephalopelvic disproportion, 54% delivered vaginally, 75% breech, and 70% for fetal distress or other nonrepeating indications. There was no evidence of uterine scar disruption in the vaginally delivered group. Vaginal delivery after previous cesarean section can be a safe alternative for carefully selected patients cared for in the proper environment.

Breech Presentation↗
PubMed1985

A vaginal delivery protocol for the term breech infant utilizing ball pelvimetry.

Ball pelvimetry has been utilized at the Medical Center Hospital of Vermont to evaluate infants with breech presentation for vaginal delivery. That technique provided measurements of both the fetal head volume and maternal pelvic capacity so that relative fetomaternal relationships could be established. Between January 1979 and December 1981, 107 patients in spontaneous labor with term pregnancy were evaluated with the protocol. Inadequate pelvimetry and hyperextension of the fetal head occurred in 21 patients (20%). Of the 86 patients who were allowed to labor, 51 (59%) had a vaginal delivery. The total cesarean section rate was 52%. Vaginal delivery in our highly selected patient population did not increase neonatal morbidity. There were no neonatal deaths.

Adolescent↗
PubMed1984

Glycohemoglobin determinations in pregnant diabetic patients.

Glycohemoglobins (GH), minor variants of hemoglobin A, are elevated in patients with diabetes mellitus. We examined the clinical usefulness of GH levels in human pregnancy. There was no correlation between GH levels and gestational age or neonatal birth weight. Insulin-dependent diabetics had higher GH levels than did normal controls (greater than or equal to 33 weeks' gestation). There was a significant correlation between fasting plasma glucose concentration and GH levels in insulin-dependent diabetics, especially when the former was determined six to 12 weeks before GH determination. Because of the wide scatter of data and the a posteriori relationship, however, we were unable to use this information at the clinical level.

Birth Weight↗
PubMed1984

Use of breast stimulation for antepartum stress testing.

Bilateral breast stimulation was used to evoke a spontaneous contraction stress test. The success rate and incidence of abnormal uterine activity using the stimulus was compared with patients tested by the authors' standard oxytocin stress test protocol. Bilateral breast stimulation was initially used for 346 tests between 32 and 43 weeks of gestational age. A satisfactory test, or three contractions within ten minutes, was obtained in 239 (69%) patients. The testing time was reduced with successful breast stimulation. The incidence of abnormal uterine activity after breast stimulation was not statistically different from that observed with oxytocin administration alone. However, when oxytocin was administered after breast stimulation, there was a significant increase in the incidence of prolonged contractions.

Adult↗
PubMed1982

The uterine hemodynamic response to repetitive unilateral vascular embolization in the pregnant ewe.

The longitudinal hemodynamic response of the uterine circulation to pregnancy and to repetitive embolic insult was assessed in 23 singleton ewe pregnancies by means of electromagnetic flow transducers and radionuclide-labeled microspheres. The data indicate that the longitudinal hemodynamic changes observed in the uterine circulation were directly related to the growth rate of the tissue which it supplied. The hemodynamic impact of embolization appears to be secondary to its impact on tissue growth. Embolization simply blunts the normal incremental increases in uterine perfusion and the cross-sectional area of the uterine vascular bed. It alters actual tissue perfusion only within a portion of the cotyledonary circulation. Finally, the data support the presence of functional arterial anastomoses between the two sides of the uterine circulation in this species.

Animals↗
PubMed1982

The ovine fetoplacental endocrine response to placental damage.

In the chronic pregnant ewe preparation, daily blood samples, for the determination of plasma cortisol and progesterone levels by specific radioimmunoassay, were obtained from the fetal distal aorta, uterine vein, and uterine artery prior to, during, and after repetitive embolization of the uterine circulation with 15 mu microspheres. A significant increase in fetal cortisol was observed in all animals during the first 3 days of embolization. In those which subsequently entered premature labor, this increase was progressive and was associated with a fall in the uterine venous progesterone level but was unrelated to changes in either the maternal cortisol level or fetal physiologic parameters. In animals which did not enter premature labor, progesterone levels in the uterine vein and estimated progesterone release rates were elevated with an accentuated peak-trough pattern during the postembolization period. In these animals fetal cortisol returned to control levels. The data suggest that cortisol and progesterone biosynthesis within the fetoplacental unit is altered by microembolic placental damage.

Animals↗