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Biomedical subjects

W E Roberts

Publications and source records attributed to W E Roberts.

At least 73 records · Page 4Linked to original sources
PubMed1994

Plasma exchange for preeclampsia: III. Immediate peripartal utilization for selected patients with HELLP syndrome.

OBJECTIVE: To explore the potential efficacy of plasma exchange as an ancillary interventive therapeutic tool immediately before or after delivery in the patient with severe preeclampsia/eclampsia and hemolysis, elevated liver enzymes, and low platelet count (HELLP) syndrome. STUDY DESIGN: Two gravidas with complicated severe preeclampsia/eclampsia/HELLP syndrome were treated emergently in the immediate peripartal period with single-volume plasma exchange and fresh frozen plasma fluid replacement using the IBM 2997 Cell Separator. RESULTS: Despite multiple platelet unit infusions, one primigravida in active labor at 5 cm cervical dilation and 39 weeks' gestation remained at a platelet count of 14,000/microL and began to ooze from her guns. A second primigravida remained obtunded, oliguric, and thrombocytopenic with epistaxis and hematuria following cesarean delivery and platelet transfusions. A single expedited 3-liter plasma exchange procedure reversed the rapidly deteriorating clinical situation for each patient and accelerated recovery from HELLP syndrome. Both patients and progeny suffered no permanent sequelae. CONCLUSION: Based on our experience, we believe that the therapeutic modality of plasma exchange with fresh frozen plasma can be employed effectively for the pregnant patient with severe atypical HELLP syndrome that progressively worsens during labor or the early puerperium despite the use of conventional transfusion therapy.

Adolescent↗
PubMed1994

The intrapartum platelet count in patients with HELLP (hemolysis, elevated liver enzymes, and low platelets) syndrome: is it predictive of later hemorrhagic complications?

OBJECTIVE: We wished to determine in patients with HELLP syndrome (hemolysis, elevated liver enzymes, and low platelets) whether (1) there is an intrapartum threshold platelet count that is predictive of immediate or delayed hemorrhagic complications and (2) whether prophylactic platelet transfusion at delivery prevents these outcomes. STUDY DESIGN: In this retrospective, descriptive study, the peripartal courses of 132 patients with class 1 (< or = 50,000/microliters platelet nadir) and 160 patients with class 2 (> 50,000 but < or = 100,000/microliters platelet nadir) HELLP syndrome were reviewed with special attention to laboratory data, evidence of hemorrhage, and details of platelet transfusion therapy. RESULTS: A higher incidence of postpartum hemorrhagic complications (p < 0.001) occurred in class 1 versus class 2 HELLP pregnancies. The tendency to have postpartum incisional bleeding after abdominal or vaginal delivery was related to the degree of thrombocytopenia (p = 0.006). The antepartum threshold platelet count most predictive of subsequent postpartum hemorrhagic complications was < or = 40,000/microliters. The prophylactic administration of platelets does not appear to have either significantly decreased the incidence of postpartum hemorrhagic complications or significantly hastened normalization of the postpartum platelet count. CONCLUSIONS: Although bleeding in the gravid patient is related to more factors than platelet count alone, patients with HELLP syndrome in whom an intrapartum platelet count above 40,000/microliters maintained are unlikely to have clinically significant postpartum bleeding. Patients with intrapartum platelet counts < or = 40,000/microliters, however, are at significant risk for postpartum bleeding, but prophylactic platelet transfusion at delivery does not ensure a significantly lower incidence of postpartum hemorrhagic complications.

Adolescent↗
PubMed1994

Mechanical simulation of the human mandible with and without an endosseous implant.

Clinical research has demonstrated that a high remodelling rate for cortical bone exists around a rigid endosseous implant. This phenomenon may be regulated by change in the mechanical environment. 3D finite element models of the human mandible with and without an endosseous implant have been created to investigate the mechanical environment adjacent to the left retromolar area where the ipsilateral implant was located. A bite force of 100 N was applied in the left premolar region. The mechanical environment before and after implantation were computed. The environment was characterized by the following parameters: the principal stresses, dilatational stress, and von Mises stress. The changes in these parameters due to the implantation were calculated. The results showed that the mechanical environment adjacent to the implant changed drastically due to the implant. The major changes in the mechanical parameters occurred adjacent to the bone-implant interface at the bony surface. The changes of the distribution of the mechanical parameters due to implantation were different. Implantation effects were local, and did not alter the overall mechanical environment.

Bite Force↗
PubMed1994

The recurrence risk of the syndrome of hemolysis, elevated liver enzymes, and low platelets (HELLP) in subsequent gestations.

OBJECTIVE: Although it is an important clinical issue, accurate prediction of recurrence risk for the syndrome of hemolysis, elevated liver enzymes, and low platelets (HELLP) has been problematic because of limited patient experience. This study was undertaken to determine the likelihood that this form of severe preeclampsia-eclampsia or any other hypertensive disorder would occur in a subsequent pregnancy. STUDY DESIGN: An extensive retrospective analysis of medical records and patient follow-up regarding subsequent pregnancy outcome were undertaken for the 481 patients with HELLP syndrome managed at this tertiary medical center between Jan. 1, 1980, and Oct. 30, 1991. The Mississippi three-class system was used to define severity of disease on the basis of the lowest observed perinatal platelet count (class 1 < or = 50,000/microliters, class 2 > 50,000/microliters to < or = 100,000/microliters, and class 3 > 100,000/microliters to < or = 150,000/microliters). RESULTS: Subsequent gestations (n = 195) occurred in 122 of 481 patients. Evaluable data were available for analysis in 161 of 195 possible pregnancies. Seventy-eight (48%) pregnancies were complicated by some type of hypertensive disorder, 44 (27%) of which had class 1, 2, or 3 HELLP syndrome. Non-HELLP preeclampsia-eclampsia was detected in 25 subsequent gestations (15%). Thus the total frequency of preeclampsia was 69 in 161 (43%). If the data for class 3 HELLP are completely excluded from the analysis, 81 subsequent evaluable and viable gestations were identified, 19 pregnancies with preeclampsia-eclampsia (23%) and 15 patients with HELLP syndrome (19%), for a total recurrence rate of 42%. Subsequent HELLP gestations were frequently delivered abdominally (64%) on average 2 weeks later than the index pregnancy (32.6 +/- 5.0 weeks versus 34.7 +/- 5.3 weeks). Delivery at < 32 weeks conferred a high risk (61%) for a similar preterm delivery in a subsequent gestation. CONCLUSION: The risk of recurrence of the HELLP syndrome in our population is 19% to 27%. When data from all pregnancies with all forms of preeclampsia are considered, the risk of recurrence for any type of preeclampsia-eclampsia is 42% to 43%. A previous preterm delivery is a very high risk factor for recurrence of prematurity with preeclampsia-eclampsia.

Adolescent↗
PubMed1994

Prediction of hemorrhage at cesarean delivery.

OBJECTIVE: To identify and quantitate the risk factors that might be predictive of hemorrhage during abdominal delivery. METHODS: Over a 2-year period, 1610 women underwent cesarean delivery and 127 (7.9%) had hemorrhage, defined as a decrease in hematocrit of 10% or greater, estimated blood loss greater than 1500 mL, or packed red blood cell administration. These women were compared through a case-control study design with the next abdominal birth without hemorrhage that could be matched for age, parity, indication for cesarean delivery, type of anesthesia, type of skin incision, and antepartum hematocrit. RESULTS: Preeclampsia (odds ratio 3.6, 95% confidence interval [CI] 1.8-7.4), disorders of active labor (odds ratio 4.4, 95% CI 1.4-13.7), Native American ethnicity (odds ratio 6.4, 95% CI 1.8-22.4), previous postpartum hemorrhage (odds ratio 8.4, 95% CI 1.9-37.4), and obesity of greater than 250 lb (odds ratio 13.1, 95% CI 1.7-102.7) were all statistically associated with significant bleeding during abdominal delivery. Combinations of two or more of these factors were associated with a markedly increased risk for hemorrhage, with odds ratios of 18.4 or greater. CONCLUSIONS: Patients undergoing cesarean delivery who have factors exposing them to increased risk of hemorrhage can be identified prospectively. These women will benefit greatly from extended preoperative counseling when possible, effective utilization of blood bank technology through type and cross-match requests, and preventive measures during abdominal delivery to minimize blood loss.

Blood Loss, Surgical↗
PubMed1994

Tocolysis for recurrent preterm labor using a continuous subcutaneous infusion pump.

This study attempted to determine the best method of treatment for patients with recurrent preterm labor: administration of terbutaline via an automated, programmable, subcutaneous infusion pump or oral terbutaline. In this retrospective, controlled study, 32 patients diagnosed with recurrent preterm labor, as determined by persistent uterine contractions with cervical change, were treated with a programmable infusion pump adjusted to control uterine contraction frequency to < or = 4 contractions per hour. Patients in this group were matched for age, race, parity, gestational age and cervical dilation at diagnosis of recurrent preterm labor in subjects taking oral terbutaline. The patients receiving oral terbutaline were given an average of 6.5 mg every four to six hours to maintain uterine quiescence, while those in the pump group were given basal rates of terbutaline and in addition received four to six boluses per day (< 3 mg/d total dose) to achieve this outcome. Patients using the pump were more likely to reach term and less likely to fail tocolytic therapy than were those taking oral terbutaline. The terbutaline pump appeared to be more successful in prolonging pregnancies to term after the diagnosis of recurrent preterm labor than did oral terbutaline.

Administration, Oral↗
PubMed1994

Assessment of fetal well-being using the nonstress test in the home setting.

OBJECTIVE: To determine the feasibility of performing nonstress tests (NSTs) in the home setting instead of the health clinic environment. METHODS: In this prospective study, ten women were tested using a Sonicaid TEAM portable monitor and a Hewlett-Packard device in the health clinic. The women were then instructed on use of the Sonicaid device and were tested once a week in the home as well as in the high-risk clinic. All tests were reviewed independently by two of the authors to assess agreement in interpreting the NST. In the health clinic setting, a nonreactive NST was followed by a nipple stimulation contraction stress test (CST); in the home, a nonreactive NST was followed by maternal voice acoustic stimulation. RESULTS: There was 100% correlation during the concurrent study. Two blinded authors agreed on all tests. During the second phase, eight of the ten subjects had NSTs that were consistently reactive in both the home and office settings. In one woman, a nonreactive NST in the clinic was followed by a negative CST. In the remaining patient, a reactive NST in the health clinic was followed 3 days later by a nonreactive NST in the home, which persisted in the provider's office. CONCLUSION: Nonstress testing in the home appears to be an accurate method of antenatal fetal health assessment that adds convenience and potential cost savings.

Feasibility Studies↗
PubMed1994

Factors relevant to mode of preterm delivery with syndrome of HELLP (hemolysis, elevated liver enzymes, and low platelets).

OBJECTIVE: Our purpose was to investigate factors relevant to mode of delivery for patients with preterm (< 34 weeks) gestation complicated by the syndrome of hemolysis, elevated liver enzymes, and low platelets (HELLP). STUDY DESIGN: The pregnancies of 189 patients with HELLP syndrome and delivery < 34 weeks' gestation between January 1980 and October 1991 were studied retrospectively. Only patients with class 1 (platelet nadir < or = 50,000 per microliter, n = 83) and class 2 (platelet nadir > 50,000 to < or = 100,000 per microliter, n = 106) HELLP syndrome were included. Maternal and perinatal factors relevant to type of delivery were reviewed. RESULTS: The incidence of cesarean delivery for all patients was 76.2% (primary rate 72.4%). Abdominal delivery occurred equally between class 1 (78.3%) and class 2 (74.5%) patients. Cesarean section was the mode of delivery for 87% of pregnancies at < 30 weeks' gestation in contrast to 68% of pregnancies at > or = 30 weeks but < 34 weeks' gestation (odds ratio 3.2, 95% confidence interval 1.4 to 7.5, p < 0.005). Indications for cesarean section included deteriorating maternal condition alone (50%), deteriorating maternal and fetal condition (27%), nonvertex fetal presentation (11.5%), and failure to progress (11%). Induction of labor was significantly more successful during the > or = 30 but < 34 weeks' pregnancy interval (47.5%) than in pregnancies at < 30 weeks (15.2%) (odds ratio 0.2, 95% confidence interval 0.1 to 0.55, p < 0.001). A trial of labor was successful in 22% of patients with an initial modified Bishop score < or = 2 versus 45% with an initial Bishop > 2 (odds ratio 0.5, 95% confidence interval 0.2 to 1.3, p = 0.16). CONCLUSION: Parturients with class 1 and 2 HELLP syndrome at < 34 weeks' gestation are at high risk for cesarean delivery. At a gestational age < 30 weeks, the likelihood of successful labor induction with vaginal delivery is remote, especially in association with an unfavorable cervix or the absence of labor.

Adult↗
PubMed1993

Poikilocytic hereditary elliptocytosis associated with spectrin Alexandria: an alpha I/50b Kd variant that is caused by a single amino acid deletion.

Hereditary elliptocytosis (HE) is a heterogeneous disorder of red blood cells frequently associated with abnormal limited tryptic digestion of the alpha I domain of spectrin and impaired spectrin dimer self-association. We studied two related individuals with poikilocytic hereditary elliptocytosis (HE) of different severity. Limited tryptic digestion of spectrin from these individuals showed the presence of a variant alpha I/50b Kd peptide at the expense of the normal alpha I/80 Kd peptide. Amino acid sequence analysis of the abnormal peptide showed that the proteolytic cleavage occurred after the arginine at position 470 of the alpha spectrin chain. Spectrin from these patients had an impaired ability to undergo self-association, as evidenced by increased amounts of spectrin dimers in 4 degrees C extracts of erythrocyte membrane from affected individuals. The polymerase chain reaction was used to study the DNA sequence of the alpha spectrin gene encoding the region of the alpha spectrin chain surrounding the abnormal proteolytic cleavage site. We detected the in-frame deletion of the trinucleotide CAT, encoding histidine 469, two amino acid residues to the N-terminal side of the abnormal proteolytic cleavage site between residues 470 and 471. Similar to many other defects of spectrin associated with HE, this deletion occurs in helix three of repeat 5 of the proposed triple helical model of spectrin repeats.

Alleles↗
PubMed1993

Oncofetal fibronectin in patients with false labor as a predictor of preterm delivery.

OBJECTIVE: Our objective was to determine whether fetal fibronectin is a discriminator for preterm labor and early delivery in women who have intact membranes and uterine activity. STUDY DESIGN: In our prospective study 28 women between 24 and 34 weeks' gestation with regular, persistent uterine contractions (> 10/hr) and intact membranes were assessed for presence of fetal fibronectin. A Dacron swab was applied to the external os for 10 seconds. The cervix was < or = 1 cm, and all patients were diagnosed as having false labor. The assay was performed by using monoclonal antibody FDC-6 to bind fetal fibronectin. RESULTS: Of the 28 patients with false labor, 14 had a positive fetal fibronectin, and all had preterm labor (specificity and positive predictive value 100%). Of these, nine delivered preterm, yielding a specificity and positive predictive value of 72% and 64%, respectively. Among the 14 women with a negative fetal fibronectin, only four developed preterm labor (sensitivity 78%, negative predictive value 71%). One patient delivered preterm at 34 weeks (sensitivity 90% and negative predictive value 93%). CONCLUSIONS: A positive fetal fibronectin in women who have false labor indicates a significant risk for preterm labor and early delivery. A negative fetal fibronectin is a reassuring sign.

Adult↗
PubMed1993

Intrapartum fetal heart rate assessment: monitoring by auscultation or electronic means.

OBJECTIVE: Our purpose was to assess the frequency with which auscultation could be used as the primary mode of fetal assessment during labor in a busy labor and delivery suite by means of published criteria. STUDY DESIGN: During a 3-month period, 862 patients in labor with live fetuses between 24 and 43 weeks of gestation were available for auscultation in the prospective study. Auscultation was initiated during a contraction and extended for 30 seconds after uterine activity ceased. It was repeated every 15 minutes in the first stage and every 5 minutes in the second stage of labor. RESULTS: In 420 patients this modality was not begun because of inability of the nurses to meet 1:1 staffing requirements. In 19 patients auscultation was not performed because of obesity (12) or patient refusal (7). Of the 423 assessed by auscultation 392 were unable to complete monitoring caused by the frequency requirement (n = 212) or the recording criteria (n = 163). Of the 31 patients where auscultation was successfully completed, there was a 1:1 nurse ratio during the entire labor. CONCLUSIONS: Auscultation with stringent evaluation and recording frequency is not feasible under normal labor and delivery room conditions unless 1:1 nursing care is always available.

Adult↗
PubMed1993

The interrelationship of eclampsia, HELLP syndrome, and prematurity: cofactors for significant maternal and perinatal risk.

OBJECTIVE: To determine if there are differences between mothers and fetuses in eclamptic pregnancies with or without concurrent HELLP syndrome. DESIGN: Retrospective review. SETTING: A single tertiary perinatal centre, the University of Mississippi Medical Center. SUBJECTS: All eclamptic pregnancies treated during a 141 month period from 1980 until the end of 1991. METHODS: Pregnancies were grouped according to the presence or absence of HELLP syndrome subclassified as class 1 = platelet nadir < or = 50,000/microliters, class 2 = platelet nadir > 50,000 to < or = 100,000/microliters, and class 3 = platelet nadir > 100,000 to < or = 150,000/microliters. RESULTS: Among 49,782 live births, there were 117 women with eclampsia prior to delivery (incidence 1:425), 62 of which had HELLP syndrome. The group with HELLP syndrome were delivered significantly earlier (32.1 vs 36.4 weeks), and had lower birthweights (1821 vs 2550 grams) and higher perinatal mortality (113 vs 18:100). They were also transfused more frequently (65% vs 35%), and suffered greater overall serious maternal morbidity and mortality. CONCLUSION: Eclampsia is more likely to be associated with the HELLP syndrome at early gestations. Although eclamptic patients are already at risk, the presence of HELLP syndrome accentuates the risk for adverse maternal-perinatal outcome.

Adolescent↗
PubMed1993

Placenta praevia: does uterine activity cause bleeding?

Twenty-two women > 24 weeks' gestation with a central placenta praevia were monitored to determine if an increase in uterine activity precedes bleeding in patients with central praevias. Monitoring of all subjects began at 26.3 +/- 4.4 weeks and continued until 37 weeks (or delivery if preterm). All subjects had at least one haemorrhage, 7 women had 2, and 4 subjects had 3 episodes of bleeding. Only 3 patients delivered at term while the remainder (86%) delivered preterm. The gestational age at first episode of bleeding was 29.1 +/- 3.6 weeks and at delivery was 34.3 +/- 3.3 weeks. Nine women (41%) had an increase in uterine activity above baseline the day or the day preceding the first haemorrhage. The increase in uterine activity was not statistically significant when compared to the 6 days prior to bleeding when all 22 patients were considered.

Adult↗
PubMed1993

Corticosteroids for enhanced fetal lung maturation in patients with HELLP syndrome: impact on neonates.

This study was undertaken to determine retrospectively, in women with the HELLP syndrome, the perinatal effects of corticosteroid administration for promotion of fetal lung maturity. Twenty-seven of 427 women with the HELLP syndrome treated between 1980 and 1991 received a full course of steroids prior to preterm delivery. They were compared to 27 control patients with the HELLP syndrome matched for maternal age, severity of disease, gestational age, race, and sex of the fetus. Respiratory distress requiring mechanical ventilation occurred in 13 of 27 neonates who received steroid administration and in 23 of 27 who did not receive steroids (p < 0.001). The average stay in the neonatal intensive care unit was 29.8 +/- 50.6 days for the steroid-treated group and 45.2 +/- 35.3 days for the group without steroid use (p = NS). The incidence of neonatal deaths, intraventricular haemorrhage type III and IV, necrotizing enterocolitis, and retrolental fibroplasia was greater in the control group but the difference was not statistically significant.

Dexamethasone↗
PubMed1993

Force-moment systems on single maxillary anterior implants: effects of incisal guidance, fixture orientation, and loss of bone support.

An engineering model of maxillary single anterior implants was developed to calculate the force-moment systems resulting from occlusal contacts. Analysis of a clinical example showed that flattening the incisal guidance and/or placing the implant in a more upright position reduced the moment and the labial component of the force but increased the intrusive component. The calculations are applicable to the design of implants and may help in the long-term evaluation of clinical success.

Algorithms↗
PubMed1993

The University of Mississippi Medical Center's Antenatal Diagnostic Unit: on the cutting edge of tomorrow.

Prenatal diagnosis is a rapidly expanding field in the specialty of obstetrics. Modern providers of perinatal care must understand the fundamentals of inherited disease and keep abreast of advances in antenatal diagnosis. Pivotal in providing appropriate evaluation in this area is a referral center that is capable of affording the necessary evaluation, documentation and consultation. Although pregnancy termination is an option for some couples, many will use the information provided to prepare emotionally and financially for the birth of a child with special problems and needs. Some diagnoses will change obstetric management during the remainder of pregnancy or will lead to a recommendation for delivery at a tertiary medical facility. Other women with medical conditions warrant preconception counseling regarding pregnancy management and likelihood of a successful outcome. Patients with genetic disorders within their families may desire carrier detection through DNA analysis. Finally, women on medications at or near the time of conception frequently have concerns regarding potential teratogenesis. The ADU represents a commitment by both the Department of Obstetrics and Gynecology and the University of Mississippi Medical Center to furnish these services to providers and patients of the State of Mississippi.

Academic Medical Centers↗
PubMed1993

Intrapartum assessment by house staff of birth weight among twins.

OBJECTIVE: To determine among twins in labor: 1) the relative accuracy of an intrapartum sonographic estimate of the birth weight for both fetuses using biparietal diameter and abdominal circumference, 2) the accuracy of detecting discordant growth (difference in actual birth weights greater than or equal to 15%), and 3) the estimate of fetal weight for nonvertex twin B that would reliably avoid breech extraction of infants less than 1500 g. METHODS: Retrospectively, we identified and analyzed parturients with twins who had an intrapartum sonogram performed by a house officer assigned to the labor and delivery suite. RESULTS: The mean birth weight (+/- standard deviation) for the twin A group was 1910 +/- 628 g and for twin B was 1869 +/- 668 g. The mean standardized absolute errors for the twin A group (121 +/- 118 g/kg) and the twin B group (92 +/- 67 g/kg) were not significantly different (P = .06). Analysis of variance revealed that regardless of the presentation of the fetuses, the mean standardized absolute error was not significantly different (P = .10). Using a difference in the estimates of birth weight of 15% or greater, the positive and negative predictive values of detecting discordant growth within a twin pair were 53 and 83%, respectively. Among 30 vertex-nonvertex twin pairs, 12 of the second fetuses had actual birth weights of 1500 g or less, and all were estimated to weigh less than 1700 g. CONCLUSIONS: The intrapartum sonographic estimate of fetal weight in twin pregnancy by house staff appears reliable, and the accuracy of prediction is similar regardless of presentation, discordance, or actual birth weight greater or less than 1500 g. To avoid vaginal delivery of a persistent nonvertex twin B with a birth weight of 1500 g or less, a sonographic estimate of 1700 g for the second fetus may be adequate.

Adult↗