Biomedical subjects
Publications and source records attributed to T J Benedetti.
Two cases of amniotic fluid embolus resulted in patient survival. Both were manifested by fetal bradycardia, respiratory distress and disseminated intravascular coagulopathy. Rapid diagnosis and treatment and anticipation of subsequent events, especially coagulopathy, appear to offer the best chance of a successful outcome.
A new oral sustained release formulation of ritodrine was tested for patient tolerance in this open study. The doses tested were 120 mg/day, 240 mg/day, and 360 mg/day. No objective toxicity was seen at any level. Doses of 120 mg/day and 240 mg/day were well-tolerated. Of the subjects who received the 360 mg/day dose, most tolerated it well.
The outcomes of 77 fetal intraperitoneal transfusions in 35 pregnancies managed with direct ultrasound guidance and intensive perinatal management were reviewed. Patients were monitored with amniocentesis, and standard indications were used for timing of transfusions. The mean gestational age at first transfusion was 27.3 weeks (range 22-33). The overall mortality rate was 14% (five of 35). No immediate transfusion-related deaths occurred; all fetuses who were not hydropic at first transfusion survived (26 of 26). The mean gestational age at delivery was 33.6 weeks (range 25-36). One infant developed respiratory distress syndrome (RDS). Transfusion-related complications occurred in five cases (fetal colon infusions in two, fetal retroperitoneal infusion in two, and fetal abdominal wall hematoma in one). None of these infants required urgent delivery or suffered long-term sequelae. In nonhydropic fetuses, intraperitoneal transfusions under direct ultrasound guidance had a low incidence of morbidity and no mortality. These results should provide baseline data against which to compare new techniques, such as direct cord transfusion. With neonatal mortality rates of 10% and significant morbidity rates of 10-20% in infants delivered at 32 weeks who develop RDS, intraperitoneal transfusion should be considered in the 32- to 33-week fetus with marked pulmonary immaturity.
Antepartum testing in postdate pregnancy was reviewed. No method of testing has been uniformly found to prevent all antepartum deaths in pregnancies with confirmed dates greater than 42 weeks. Perinatal mortality varies according to both the test and the institution. When comparing results according to the method of testing, perinatal mortality appears to be lowest (1.8/1,000) with the use of a 3-cm vertical pocket on ultrasound. Nearly as good is the use of a contraction stress test (2.5/1,000) on a weekly basis. Ultrasound using a 1-cm pocket and a biweekly non-stress test (NST) resulted in slightly worse perinatal mortality (5/1,000 and 6/1,000, respectively). If variable decelerations during the NST are not interpreted as abnormal, the perinatal mortality using a biweekly NST is 15/1,000. Induction of labor at 41-42 weeks with a favorable Bishop score will obviate the need for antepartum testing in some patients.
Aortic stenosis is uncommon during pregnancy. Five cases are described in which clinical management was facilitated by the use of Doppler echocardiography to assess the severity of disease and pulmonary artery catheterization to manage maternal hemodynamics. Regional anesthesia was used without complication. In patients with severe stenosis, significant morbidity and mortality were experienced when aortic valve replacement was delayed beyond the postpartum period.
The effects of orthostatic stress on cardiac output and systemic vascular resistance have not been previously studied in pregnancy. A Doppler technique of measuring cardiac output was used to study 15 nonpregnant women, 14 pregnant women in the first trimester, and 16 pregnant women in the third trimester. Subjects were studied in recumbent, sitting, and standing positions. In each group, the change from recumbent to standing positions resulted in a fall in cardiac output of 1.7-1.8 L/minute (P = .001). Systemic vascular resistance rose in each group (P = .001). The magnitude of the rise was greatest in nonpregnant women and smallest in the third trimester (P = .005). The observed fall in cardiac output and rise in systemic vascular resistance may be clinically significant in pregnancies complicated by uteroplacental insufficiency.
We evaluated the relationship of infant status at birth to neonatal morbidity and long-term development in 246 low birth weight infants (600 to 1750 gm). Nineteen percent of infants had 1-minute Apgar scores of less than or equal to 3, and 8% had an umbilical artery pH of less than or equal to 7.2. Acidosis was associated with an increased risk of grade 3 to 4 intracranial hemorrhage (odds ratio = 3.3). Low 1-minute Apgar score was associated with an increased risk of death (odds ratio = 4.8). Grade 3 to 4 intracranial hemorrhage was a strong risk factor for cerebral palsy among survivors (odds ratio = 16.1), as was low 1-minute Apgar score (odds ratio = 2.9). Only 15% of cases of cerebral palsy in this study were associated with acidosis at birth.
Maternal counting of fetal movement (FM) to assess fetal well-being was studied in 394 pregnancies followed by family physicians. Counting was well accepted, with 85% of women finding it reassuring and 91% wanting to include it in subsequent pregnancies. Eighty-eight percent of women reported counting five or more days per week. Thirteen women reported decreased activity a total of 20 times. A nonstress test (NST) was performed 20 times and an oxytocin challenge test (OCT) was performed four times as a result of these reports. One of the 20 reports of decreased activity was followed by a nonreactive NST and suspicious OCT, and led to the induction of a viable 38-week fetus. There were no stillbirths in the group and only one neonatal death of an anencephalic infant.
All cases (884) of placental abruption reported on Washington State birth or fetal death certificates in 1980 and 1981 were compared with 789 randomly selected births from the same time period. The incidence of reported cases of placental abruption was 6.5 per 1000 total births. The combined stillbirth and first month death rate of all abruption cases was 21%. Increased risks of placental abruption were associated with pre-eclampsia, diabetes, and unmarried status. Neither parity nor maternal age was associated with an increased risk. Infants born after abruption were significantly smaller-for-gestation than control infants, more likely to be male, and had malformations more frequently than control infants. Apgar scores of liveborn abruption infants were significantly lower than those of controls after adjustment for infant weight, gestational age, and sex.
Sixty-nine cases of placental abruption and placental hemorrhage detected with ultrasonography (US) were reviewed retrospectively to determine whether US findings correlate with fetal outcome. Four patients were lost to follow-up, and in the remaining 65 patients fetal outcome included demise in 12 cases (18%), termination of pregnancy in six (9%), premature delivery of a living infant in 15 (23%), term delivery of an infant who was small for gestational age in four (6%), and normal term delivery in 28 (43%). Fetal mortality correlated best with the estimated percentage of placental detachment, but was also significantly (P less than .01) associated with the location (retroplacental) and size (greater than 60 ml) of hemorrhage. Premature labor was associated (P less than .001) only with gestational age at the time of clinical presentation. No sonographic finding was identified as a risk factor for small-for-gestational-age infants. Sonographic findings of placental abruption correlate with fetal outcome, and this information may be useful for guiding obstetric management.
Forty-nine cases of meningomyelocele diagnosed in utero and another 10 cases delivered by prelabor cesarean section (N = 59) are compared to all other cases of meningomyelocele (N = 98) born following labor and seen during the same period. Prenatal diagnosis was established for 19 cases before and 30 cases after 24 weeks gestational age. Ten cases were delivered by prelabor cesarean section for maternal indications. Eight of 12 cases diagnosed before 24 weeks and given a guarded prognosis and one given a poor prognosis, elected cesarean section. One of the 8 was stillborn. Four of the 12 given a guarded prognosis and 6 an extremely poor prognoses elected termination of the pregnancy. Nineteen of the 30 cases diagnosed after 24 weeks were delivered by prelabor cesarean section and two by cesarean section after inadvertent labor. Of the 35 cases born by prelabor cesarean section, 48% have sacral levels or no loss of motor function compared to 14% of the 98 born after labor (P = 0.0001). We recommend prelabor cesarean section before onset of labor to preserve neural function of a baby with meningomyelocele and leg movement in utero when parents refuse termination or have a diagnosis made after 24 weeks gestational age.
Intrapartum electronic fetal heart rate (FHR) monitoring and fetal blood gas sampling were compared with periodic auscultation of FHR in a multicentered randomized trial of preterm singleton pregnancies with fetal weights of 700-1750 g. Two hundred forty-six pregnancies were studied (electronic FHR monitoring N = 122, auscultation N = 124). Perinatal or infant death was associated with 14% of pregnancies with electronic FHR monitoring and 15% with auscultation. No significant differences were noted in the prevalence of low five-minute Apgar scores, intrapartum acidosis, intracranial hemorrhage, or frequency of cesarean section (P greater than .10). Compared with electronic FHR monitoring, intrapartum auscultation as done in this study is unlikely to be associated with detectable differences in perinatal outcomes within the high-risk setting of preterm labor.
In 12 patients requiring pulmonary artery catheterization, cardiac output was measured using Doppler and thermodilution techniques. The Doppler technique accurately predicted measurements made by thermodilution (r = 0.91; P less than .001). Eighteen normal patients in the third trimester and 36 preeclamptics who had not been treated with medications other than magnesium sulfate were evaluated with Doppler alone. Of note was the heterogeneity among preeclamptics. Although their mean systemic vascular resistance was elevated, it ranged from 2256-648 dyne X sec X cm-5. Cardiac output ranged from 13.2-3.9 L/minute.
We performed a prospective clinical evaluation of our newly developed fluorescence polarization procedure to predict fetal lung maturity (Clin Chem 1986;32:248-54). Net fluorescence polarization was measured at 34 degrees C after a 6.5-min incubation of amniotic fluid with fluorophore. For the 26 cases of neonatal respiratory distress syndrome encountered in 196 deliveries, the net polarization exceeded 0.287 for 22 (85%) of these, and exceeded 0.260 for all 26. The specificity of the polarization assay equaled or exceeded the specificity of the lecithin/sphingomyelin ratio for all sensitivities greater than 70%. Neither assay was a good predictor of the clinical severity of respiratory distress. For a separate group of 21 amniotic fluid specimens clinically contaminated with blood or meconium, the discriminatory power of the polarization assay was decreased, but six of seven respiratory-distress cases still had polarization values greater than 0.260. We conclude that this fluorescence polarization assay is a better overall predictor of fetal lung maturity than is the lecithin/sphingomyelin ratio, and that polarization values less than 0.260 are associated with little risk of respiratory distress.
Betamimetic administration for inhibition of preterm labor can result in a number of severe complications for the mother. An understanding of clinical situations that increase the risk of complications and suggested treatment of adverse effects are discussed in this review.
One hundred three fetal heart rate (FHR) tracings in term fetuses with simultaneous fetal blood pH sampling were reviewed. In 71 fetuses accelerations were present in direct response to blood sampling or within 30 minutes of the sampling procedure, and in 70 of these the pH was above 7.20. Of 32 fetuses without FHR acceleration during fetal blood sampling, seven had pH values below 7.20, and in five of these the values were confirmed by cord pH measurement.
Methods of delivery, maternal and neonatal characteristics were examined to determine their role in the occurrence of Erb/Duchenne's palsy. Data from 210,947 Washington state birth certificates from 1980 through 1982 were examined. The incidence was 50.2 cases of Erb's palsy per 100,000 live births. A case control study design was used to analyze 106 cases and 386 controls by both univariable and multivariable analysis. Birth weight was shown to be a significant risk factor regardless of which method of delivery was used. A high birth weight infant (4001-4500 g) had 2.5 times the risk of incurring an upper brachial plexus injury compared with normal size infants (2501-4000 g). The risk for infants greater than 4500 g increased another tenfold (OR = 21.0). When birth weight was controlled for in the analysis, midforceps (OR = 18.3), vacuum extraction (OR = 17.2), and low forceps (OR = 3.7) remained significantly associated with the Erb's palsy. Delivery by cesarean section was associated with a significant protective effect (OR = 0.5) compared with instrumental vaginal delivery. These data demonstrate a high risk for serious birth injury associated with instrumental midpelvic delivery.
The relationship between five conditions of chronic fetal stress and the incidence of infant respiratory distress syndrome (RDS) was investigated among 614 premature (less than or equal to 36 weeks) infants delivered at the University of Washington Hospital from 1977 to 1980. The strongest association found was a protective effect of abnormal antepartum testing (nonreactive nonstress test, positive contraction stress test, or low or falling maternal urinary estriols). Among the 45 infants with abnormal antepartum testing, the probability of RDS was 15.0 versus 33.8% for the infants without the complication (odds ratio = 0.35, P less than or equal to .01, adjusted for gestational age and mode of delivery). Rupture of the membranes for greater than 24 hours (N = 151), amnionitis (N = 63), and vaginal bleeding beginning more than 24 hours before delivery (N = 108) were each associated with a reduced risk of RDS (adjusted odds ratios = 0.63, 0.51, and 0.58, respectively, P less than or equal to .05). Hypertensive disease of pregnancy was not associated with a decreased risk of RDS; in fact, the opposite trend occurred (N = 96, odds ratio = 1.67, P = .07). The associations with RDS were not explained by differences between births with and without each complication in terms of gestational age, mode of delivery, absence of labor, administration of antenatal steroids, and other complications of pregnancy. This study adds support to the hypothesis that certain conditions associated with chronic fetal stress lead to an acceleration in pulmonary maturity.