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B A Yoder

Publications and source records attributed to B A Yoder.

At least 19 recordsLinked to original sources
PubMed2001

Single versus repeated-course antenatal corticosteroids: outcomes in singleton and multiple-gestation pregnancies.

The objectives of this study are to compare the neonatal risks and benefits of antenatal single-course versus repeated-course corticosteroids in singleton and multiple-gestation pregnancies. A comprehensive analysis was performed of the inpatient records of all neonates admitted to our center from 1 January 1994 through 31 May 1999. The primary outcome measure was survival without chronic lung disease (CLD). Secondary outcome measures included birth weight; head circumference; interval weight ratios; respiratory disease severity; intraventricular hemorrhage rate and severity; severe retinopathy of prematurity; early infection; and hospital days. All singletons 27-32 completed weeks' gestation, and multiples 26-32 weeks' gestation, whose mothers had received betamethasone before delivery, were included. One hundred and fifteen singleton and 53 multiple-gestation infants (total 168) were stratified by multiplicity, gestational-age (< or =29 or > or =30 weeks), and number of steroid courses. Repeated courses of antenatal betamethasone were not associated with greater survival without CLD, in either singleton- or multiple-gestation infants. In singletons there was no difference in any outcome measure between groups. In multiples, the only difference was greater postnatal weight gain in the lower gestation group. Mean birth head circumference was smaller in repetitively-treated singletons < or =29 weeks. There are no clinically significant neonatal benefits of repeated-course antenatal steroids in singletons > or =27 weeks estimated gestational age (EGA) or multiple-gestation infants > or =26 weeks EGA. Prospective randomized trials of single-course versus repetitive antenatal corticosteroid therapy are warranted.

Adult↗
PubMed2001

Deficiencies in lung surfactant proteins A and D are associated with lung infection in very premature neonatal baboons.

Surfactant proteins A (SP-A) and D (SP-D) are important in the innate host defense against pathogenic microorganisms. A deficit in these proteins in premature infants, either because of immaturity or as a consequence of superimposed chronic lung disease (CLD), could increase their susceptibility to infection. The study reported here examined infection in CLD in the premature newborn baboon, and correlated it with the amounts of SP-A and SP-D in lung tissue and lavage fluid. Two groups of baboons were delivered prematurely, at 125 d gestational age (g.a.), and differed principally in whether they developed naturally acquired pulmonary infections and sepsis. Group I animals were ventilated with clinically appropriate oxygen for 6 d and 14 d without clinical incident. Group II animals were ventilated for 5 to 71 d, but differed from those in Group I in that most developed pulmonary infection and/or sepsis. In Group I animals, tissue pools of both SP-A and SP-D were equal to or exceeded those in adults, and lavage pools of SP-A increased progressively with the time of ventilation to about 35% of adult levels after 14 d. In contrast, most Group II animals had concentrations of lavage SP-A that were less than 20% of that in adult animals. A low concentration of lavage SP-A correlated with the release of interleukin-8, and with a high "infection index" based on histopathology, microbiologic cultures, and clinical indications of sepsis. Our data suggest that the amounts of SP-A and SP-D in lavage fluid are indicators of the risk of infection in the evolution of neonatal CLD. Deficits in the amount of lavage SP-A, even after 60 d of ventilation, may have inhibited the resolution of infection and thereby contributed to the developing injury among our Group II animals.

Animals↗
PubMed2000

High-frequency oscillatory ventilation: effects on lung function, mechanics, and airway cytokines in the immature baboon model for neonatal chronic lung disease.

Acute lung injury models demonstrate that high-frequency oscillatory ventilation (HFOV) improves lung function, mechanics, and histopathology with reduced inflammatory mediators. Neither human HFOV trials nor premature animal studies have adequately evaluated these factors during prolonged HFOV. The objective of this study was to compare the effect of prolonged HFOV with low tidal volume (VT) positive pressure ventilation (LV-PPV) in an immature baboon model for neonatal chronic lung disease (CLD). After administration of prenatal steroids, 18 baboons were delivered by cesarean section at 125 d (term = 185 d), treated with exogenous surfactant, then randomized to either HFOV or LV-PPV by 5 min age. Animals were maintained on oxygen on an "as needed" basis and on nutritional support for 1 to 2 mo. Serial pulmonary function testing (PFT) was performed. Tracheal aspirates were analyzed for interleukin-6 (IL-6), IL-8, tumor necrosis factor-alpha (TNF-alpha), IL-1beta, and IL-10. Lungs were inflation fixed for morphometric analyses. From 12 h through 10 d age, HFOV animals had consistently lower fraction of inspired oxygen (FI(O(2))) and higher a/ A ratio. Pulmonary mechanics were significantly improved in HFOV animals at nearly every time point analyzed from 12 h to 28 d. There were no consistent differences in tracheal IL-6, TNF-alpha, IL-1beta, or IL-10 after 24 h age. Higher tracheal IL-8 values and macrophage/monocyte numbers were found in LV-PPV animals after 1 wk and 3 to 4 wk ventilation. Both groups exhibited pulmonary pathologic lesions found in extremely immature humans, including alveolar hypoplasia, variable saccular wall fibrosis, and minimal airway disease. HFOV animals had significantly better lung inflation patterns by panel of standards analysis. Early, prolonged HFOV significantly improved early lung function with sustained improvement in pulmonary mechanics out to 28 d. Immature baboons managed with HFOV had less pulmonary inflammation in the hyaline membrane disease (HMD) recovery phase. Though enhanced alveolization was not observed, HFOV for 1 to 2 mo resulted in consistently more uniform lung inflation than LV-PPV.

Animals↗
PubMed1999

Early prediction of neonatal chronic lung disease: a comparison of three scoring methods.

A variety of postnatal therapies have been and will be evaluated for prevention or treatment of neonatal chronic lung disease (CLD). A simple method for early selection of the highest risk infants would optimize intervention trials. Our study compared a clinical scoring system for predicting neonatal CLD (defined at 36 weeks postconceptional age) with previous regression models developed by Sinkin et al. (Sinkin model) [Pediatrics 1990;86:728-736] and Ryan et al. (Ryan model) [Eur J Pediatr 1996;668-671] in two distinct populations. A respiratory failure score (RFS) was prospectively developed for infants at <32 weeks of gestation admitted to the Wilford Hall Medical Center from January 1990-December 1992. Logistic regression modeling identified three independent predictors of CLD: gestation, birth weight, and RFS. Applying a modified RFS score (to include gestation and birth weight), the RFS, Sinkin, and Ryan models were compared among high-risk infants admitted to Wilford Hall from January 1993-December 1995, and to Crawford Long Hospital (Atlanta, GA) from January 1993-December 1994. Predictive values, sensitivity, specificity, and receiver operating characteristic (ROC) curves were determined for the primary outcome variable: CLD at 36 weeks of corrected gestation. Of 248 infants at <32 weeks admitted to Wilford Hall, 220 survived >7 days. Thirty of 31 (97%) infants diagnosed with CLD were <29 weeks or < or =1,000 g at birth. Despite important demographic and treatment differences between the study populations, similar ROC curves were found for each scoring method when individually evaluated among the three study groups. The RFS method at 72 h demonstrated the greatest area under the ROC curve for prediction of neonatal CLD in the groups as a whole. Application of the RFS method for early prediction of neonatal CLD at age 72 h should improve patient selection for early prevention trials.

Chronic Disease↗
PubMed1999

Neonatal chronic lung disease in extremely immature baboons.

A borderline viability model of bronchopulmonary dysplasia (BPD)/chronic lung disease of infancy (CLD) with pathophysiologic parameters consistent with those in extremely immature humans with BPD/CLD is described. After prenatal steroid treatment of pregnant dams, 12 premature baboons were delivered by cesarean-section at 125 d (term gestation, 185 d), treated with exogenous surfactant, and maintained on appropriate oxygen and positive pressure ventilation for at least 1 to 2 mo. In spite of appropriate oxygenation (median FI(O(2)) at 28 d = 0.32; range, 0.21 to 0.50) and ventilatory strategies to prevent volutrauma, the baboons exhibited pulmonary pathologic lesions known to occur in extremely immature humans of less than 1,000 g: alveolar hypoplasia, variable saccular wall fibrosis, and minimal, if any, airway disease. The CLD baboon lungs showed significantly decreased alveolization and internal surface area measurements when compared with term and term + 2-mo air-breathing controls. A decrease in capillary vasculature was evident by PECAM staining, accompanied by dysmorphic changes. Significant elevations of TNF-alpha, IL-6, IL-8 levels, but not of IL-1beta and IL-10, in tracheal aspirate fluids were present at various times during the period of ventilatory support, supporting a role for mediator-induced autoinflammation. IL-8 levels were elevated in necropsy lavages of animals with significant lung infection. This model demonstrates that impaired alveolization and capillary development occur in immature lungs, even in the absence of marked hyperoxia and high ventilation settings.

Animals↗
PubMed1999

Improved outcome of extremely premature infants in the 1990s.

OBJECTIVE: To study the impact of new treatment modalities on premature infants, we compared the effects of surfactant and antenatal steroid use on outcome in two military medical centers. STUDY DESIGN: We performed a retrospective chart review of 234 infants delivered at 22 to 26 weeks estimated gestational age (EGA) at our institutions between 1986 and 1996. The patients were divided into two groups: the presurfactant group included deliveries from 1986 to 1989; and deliveries from 1990 to 1996 were in the surfactant group. RESULTS: At 23 weeks EGA or less, there was only one survivor. At 24 weeks EGA, survival was improved in the surfactant group (46% vs. 5%; p < 0.005). Survival rates at 25 and 26 weeks EGA did not differ significantly. Combined survival at 24 to 26 weeks in the surfactant group exposed to antenatal steroids was 75% versus 44% in the presurfactant group (p = 0.02) Among survivors, the incidence of grade 3 or higher intraventricular hemorrhage was less in the surfactant group (18% vs. 42%; p = 0.038). CONCLUSIONS: Use of surfactant and antenatal steroids are associated with improved survival and decreased incidence of severe intraventricular hemorrhage among the most premature infants delivered in our institutions.

Anti-Inflammatory Agents↗
PubMed1998

Bombesin-like peptide mediates lung injury in a baboon model of bronchopulmonary dysplasia.

The etiology of bronchopulmonary dysplasia (BPD), a chronic lung disease of infants surviving respiratory distress syndrome, remains fundamentally enigmatic. BPD is decreasing in severity but continues to be a major problem in pediatric medicine, being especially prevalent among very premature infants. Increased numbers of pulmonary neuroendocrine cells containing bombesin-like peptide (BLP) have been reported to occur in human infants with BPD. We tested the hypothesis that BLP mediates BPD using the hyperoxic baboon model. Urine BLP levels increased soon after birth only in 100% O2-treated 140-d animals which developed BPD, correlating closely with severity of subsequent chronic lung disease. Similar elevations in urine BLP were observed in the 125-d baboon "interrupted gestation" model of BPD. Postnatal administration of anti-BLP antibody attenuated clinical and pathological evidence of chronic lung disease in the hyperoxic baboon model. Urine BLP could be a biological predictor of infants at risk for BPD, and blocking BLP postnatally could be useful for BPD prevention.

Animals↗
PubMed1998

Early high dose antioxidant vitamins do not prevent bronchopulmonary dysplasia in premature baboons exposed to prolonged hyperoxia: a pilot study.

The antioxidant vitamins ascorbic acid (AA) and alpha-tocopherol (alpha-TP) effectively inhibit oxygen free radical-induced lipid peroxidation. Using a premature baboon model of hyperoxia-induced bronchopulmonary dysplasia (BPD), we measured concentrations of AA, alpha-TP, and conjugated dienes (CD, marker of lipid peroxidation) in four animals (hyperoxic antioxidant group) receiving high dose antioxidant vitamin supplementation (AA, 100 mg x kg x(-1) x d(-1); alpha-TP; 20 mg x kg x(-1) x d(-1)) and one animal receiving standard dose antioxidant vitamin supplementation (AA, 10 mg x kg x(-1) x d(-1); alpha-TP, 1 mg x kg x(-1) x d(-1)). Respiratory and histopathologic data were compared with data from 10 historical animals exposed to hyperoxia (hyperoxic control group) and 11 historical animals treated as required with oxygen (normoxic control group) who had received standard dose antioxidant vitamin supplementation. Compared with standard dose antioxidant vitamin supplementation, high dose antioxidant vitamin supplementation effectively raised AA concentrations in plasma (37 +/- 22 micromol/L and 395 +/- 216 micromol/L, respectively) and tracheal aspirates (62 +/- 35 micromol/L and 286 +/- 205 micromol/L, respectively), and alpha-TP concentrations in plasma (10.1 +/- 2.5 micromol/L and 24.6 +/- 17.5 micromol/L, respectively). However, there was no apparent effect on tracheal aspirate CD concentrations (482 +/- 333 micromol/L and 1050 +/- 1111 micromol/L, respectively), and respiratory parameters in the hyperoxic antioxidant group were comparable to those of the hyperoxic control group but significantly worse than in the normoxic control group. Finally, no protective effect of high dose antioxidant vitamin supplementation was noted at the histopathologic level.

Animals↗
PubMed1997

Oxytocin labor stimulation of twin gestations: effective and efficient.

OBJECTIVE: To test the hypothesis that oxytocin labor stimulation of twin gestations is similar to that of singletons regarding dosage, time, complications, and ability to achieve vaginal delivery. METHODS: This retrospective investigation included 124 gravidas receiving oxytocin for augmentation or induction of labor. Sixty-two women with twin gestations were matched by parity, cervical dilation at initiation of oxytocin, gestational age, oxytocin dosage regimen, and indications for oxytocin to controls with singleton pregnancies. Outcome variables included maximum dosage of oxytocin, incidence of hyperstimulation and fetal heart rate (FHR) abnormalities, time from oxytocin to delivery, cesarean deliveries, and maternal and neonatal outcomes. Statistical analysis was done using McNemar test, paired t test, and Wilcoxon signed-rank test for paired samples. RESULTS: Women with twin pregnancies and those with singletons responded similarly regarding maximum oxytocin dosage (21 +/- 1.5 and 18 +/- 2.4 mU/minute, respectively, P = .1), time from oxytocin to delivery (7.0 +/- 0.8 and 6.7 +/- 0.6 hours, respectively, P = .88), and successful vaginal delivery (90% and 90%, respectively). Oxytocin stimulation of twins resulted in fewer interruptions of the infusion for FHR abnormalities (5% compared with 26%, odds ratio [OR] 0.27, 95% confidence interval [CI] 0.16, 0.47) and hyperstimulation (6% compared with 18%, OR 0.19, 95% CI 0.36, 0.99). CONCLUSION: Twin gestation has no adverse impact on the effectiveness or efficiency of oxytocin labor stimulation. Twin pregnancy seems to be associated with fewer side effects.

Adult↗
PubMed1997

Neonatal outcomes of teenage pregnancy in a military population.

OBJECTIVE: To compare the use of prenatal care, incidence of pregnancy complications, and neonatal outcomes among adolescent mothers with those among older mothers in a military population with equal access to a tertiary care center. METHODS: We reviewed the neonatal data base of a military tertiary care center for the period 1990-1996. All singleton births at least 20 weeks' estimated gestational age (EGA) or with birth weight at least 500 g were included. Maternal transfers were excluded. Mothers were divided into five age groups, with the ranges 13-17, 18-19, 20-24, 25-29, and 30 or more years. Prenatal care was assessed by the Kessner index. Data were analyzed by chi 2 test, t test, Mann-Whitney U test, and logistic regression techniques. RESULTS: Included in the study were 10,168 infants (344 aged 13-17, 893 aged 18-19, 3244 aged 20-24, 3095 aged 25-29, and 2592 aged 30 or more years). There was a greater percentage of Hispanic mothers among adolescents aged 13-17 years (48.3%); this percentage decreased as maternal age increased (32.7% to 14.6%). The percentage of white mothers was greatest for mothers over 30 years old (72.1%), and this percentage decreased as maternal age decreased (70.3% to 35.8%). The percentage of black mothers remained relatively constant in all age groups (12.2-16.0%). There were significant differences in sponsor's rank distribution among groups; mothers 25-29 years old and over 30 years old had higher-paying ranks whereas both teenage groups were of predominantly lower-paying ranks. Gestational age at the first prenatal visit and overall use of prenatal care were significantly improved as maternal age increased for each successive age group. Older mothers had significantly higher rates for diabetes and abnormal fetal sonograms than younger mothers; younger mothers had increased rates for sexually transmitted disease, fetal growth restriction, and tobacco use. Multivariate analysis demonstrated that fetal complications, adequate prenatal care, black maternal race, and lower rank were significant independent risk factors for high-risk outcomes. Young maternal age was not an independent risk factor for prematurity or low birth weight. CONCLUSION: Although adolescent mothers (13-17 years old) used prenatal care less than older mothers, there were no differences in the incidence of prematurity, low birth weight (LBW), or neonatal survival among this group of women cared for in a military tertiary health care setting. In this health care setting, risk for premature birth and LBW are related to complications of pregnancy, maternal race, and lower-paying rank.

Adolescent↗
PubMed1997

Effect of excessive GnRH-binding substance on circulating maternal hCG in human pregnancy.

Gonadotropin-releasing hormone (GnRH) can stimulate the release of placental human chorionic gonadotropin (hCG). Thus, at the onset of these studies it was the objective to define the relationship of hCG to GnRH in the maternal circulation throughout pregnancy, focusing on early pregnancy. Blood samples were collected at 8, 10, 12, 14, 16, 28 and 36 weeks of gestation during labor and the GnRH and hCG levels were determined by radioimmunoassay. Of 39 pregnancies, a GnRH-binding substance was found in the maternal circulation of three. This GnRH-binding substance resulted in erroneous GnRH levels, due to the very high non-specific binding. In the pregnant women without this GnRH-binding substance, GnRH attained highest concentrations at 12-14 weeks. The typical peak of hCG at 8-10 weeks of gestation was observed in this group, while the group of patients having the GnRH-binding substance had significantly lower hCG levels. Each of the patients with circulating GnRH-binding substance had prior pregnancy(s) and two of the three had a prior pregnancy loss. The nature of this GnRH-binding substance was investigated using gel chromatography. After incubation of [125I]GnRH with patient plasma for 3 days this substance was shown to be of high molecular weight which was ethanol precipitable. This binding substance may therefore be an antibody, since it appears to be a high molecular weight protein requiring a number of days to bind the [125I] GnRH. This GnRH-binding substance may be of physiological importance, since the circulating hCG level was significantly less in the group of patients with this substance than in those without.

Adolescent↗
PubMed1996

Circulating maternal corticotropin-releasing hormone and gonadotropin-releasing hormone in normal and abnormal pregnancies.

OBJECTIVE: Corticotropin-releasing hormone and gonadotropin-releasing hormone are produced by the human placenta and have been measured in the maternal circulation during pregnancy. Our objective was to determine concentrations of these substances in maternal plasma throughout normal pregnancies and in early pregnancy loss. STUDY DESIGN: Fifty-one pregnant women were followed up prospectively and plasma samples were drawn at 8, 10, 12, 14, 16, 28, and 36 weeks' gestation and during labor. Specific and sensitive radioimmunoassays were used to determine corticotropin-releasing hormone and gonadotropin-releasing hormone concentrations in these samples. RESULTS: Blood samples were drawn at all time points and outcome data were available from 33 women who completed their pregnancies at term without complications. In this normal group circulating corticotropin-releasing hormone concentrations increased from low or undetectable concentrations at 8 weeks (< or = 23.2 +/- 1.3 pg/ml, mean +/- SEM) to measurable values at 16 weeks (34.3 +/- 2.2 pg/ml). Thereafter there was a significant increase to 1294 +/- 113 pg/ml in labor. Gonadotropin-releasing hormone demonstrated a trimodal distribution, increasing significantly from 8 to 14 weeks, decreasing at 16 weeks, and increasing again by term. The ratio of corticotropin-releasing hormone to gonadotropin-releasing hormone in the normal group demonstrated a 30-fold increase from 8 weeks to term. In eight cases of early pregnancy loss corticotropin-releasing hormone and gonadotropin-releasing hormone concentrations were not significantly different from those of the normal group in early pregnancy. In two cases of premature delivery gonadotropin-releasing hormone concentrations and ratios were within the normal range; corticotropin-releasing hormone levels were normal in both cases of premature delivery. CONCLUSION: In this study we determined maternal concentrations of corticotropin-releasing hormone and gonadotropin-releasing hormone in normal pregnancies and in labor at term. Neither maternal concentrations of corticotropin-releasing hormone nor gonadotropin-releasing hormone were useful in identifying pregnant women at risk for early pregnancy loss.

Abortion, Spontaneous↗
PubMed1996

Volume of blood required to detect common neonatal pathogens.

OBJECTIVE: To determine the minimum volume of blood and the absolute number of organisms required for detection of bacteremia and fungemia by an automated colorimetric blood culture system (BacT/Alert, Organon Teknika). DESIGN: Common neonatal pathogens, Escherichia coli, Streptococcus agalactiae (group B streptococcus (GBS): one American Type Culture Collection (ATCC) strain and one clinical isolate), Staphylococcus epidermidis, and Candida albicans, were seeded into blood to produce bacteremia or fungemia with low colony counts (1 to 3 colony-forming units (CFU) per milliliter) and ultra-low colony counts (<1 CFU/ml). For each organism, 96 culture bottles were inoculated with either 0.25, 0.5, 1.0, or 4.0 ml of the two seeded blood concentrations. Blood culture bottles were incubated in the BacT/Alert device for 5 days, and time to positivity was noted when applicable. All bottles were subcultured on plated media. DATA ANALYSIS: The Poisson statistic was used to calculate the probability of finding at least one viable CFU per inoculated culture bottle. The fraction of culture bottles with positive findings per group was divided by the probability of one or more organisms present to give the positivity index. RESULTS: Plated subculture identified no growth of organisms not detected by the colorimetric detection system. The false-positive rate for the automated device was less than 1%. The positivity index for the GBS clinical isolate was 1.13, for the GBS ATCC isolate 0.96, for S. epidermidis 0.94, for C. albicans 0.97, and for E. coli 0.95. There was a statistically significant difference with time to positivity and inocula volume (p <0.01), but the difference was not clinically important. CONCLUSIONS: If one or two viable colony-forming units are in the blood inoculated into culture media, the BacT/Alert system will detect growth rapidly. Because there appears to be a sizable subset of neonates who are at risk of sepsis with a colony count less than 4 CFU/ml, then a 0.5 ml inoculum of blood into the culture media is inadequate for sensitive and timely detection of bacteremia. One to two milliliters of blood should increase microorganism recovery in the face of low-colony-count sepsis.

Bacteremia↗
PubMed1995

Differentiation of segmented and band neutrophils during the early newborn period.

This prospective study evaluated the degree of inter-reader variability in the identification of segmented and band neutrophils from blood smears of full-term, healthy neonates. Wide inter-reader differences of band neutrophil identification and the immature to total neutrophil ratio were observed. Because of poor correlation between evaluators of the same blood smear, the clinical utility of the manual differential leukocyte count in the evaluation of neonates is limited.

Blood Specimen Collection↗
PubMed1995

Sensitivity and specificity of rapid diagnostic tests for detection of group B streptococcal antigen in bacteremic neonates.

Latex particle agglutination (LPA) testing for antigen to group B streptococcus (GBS) has been useful in the diagnosis of GBS sepsis in newborns. However, recent reports have demonstrated that the sensitivity of LPA assays may be as low as 27 to 54%. The purposes of the present study were to directly compare the abilities of four urine antigen assays to detect GBS antigen with clinical urine samples from neonates with GBS bacteremia and to evaluate the effect of the urine concentration on the sensitivities and specificities of these assays. Urine samples were collected serially from neonates with blood cultures positive for GBS or on admission from healthy full-term infants. One milliliter of urine was removed, and the remainder was concentrated to a volume of 1 ml. Unconcentrated samples were serially diluted with normal saline and were assayed to determine the highest dilution which would produce a positive test result. The Wellcogen, Bactigen, and Directigen LPA tests and ICON immunoassay were directly compared by using concentrated and unconcentrated urine specimens and urine specimens with known titers. A total of 94 urine specimens, including 61 concentrated and 75 unconcentrated specimens, from bacteremic infants were available for sensitivity testing, and 220 urine specimens from uninfected infants were available for specificity testing. There were significant differences in sensitivity among the four assays when they were performed on concentrated urine specimens, as follows: Directigen, 98%; Bactigen, 92%; ICON, 89%; Wellcogen, 68%. When the assays were performed on unconcentrated urine specimens, the Directigen (84%) and Bactigen (76%) assays were each significantly more sensitive than the ICON (59%) or Wellcogen (43%) assay. All four assays were significantly more sensitive in detecting GBS antigen in concentrated than in unconcentrated urine. The Directigen assay detected antigen in higher dilutions (geometric mean titer, 1:5) than the ICON (1:3), Bactigen (1.2), or Wellcogen (1:1) assay. The specificity was 99.5% for all four assays when concentrated urine was used and for the Bactigen, Directigen, and ICON assays when unconcentrated urine was used; the Wellcogen assay was 100% specific when unconcentrated urine was used. We conclude that there are significant differences in sensitivity but not specificity among the commercially available assays for the detection of GBS antigenuria when concentrated and unconcentrated urine specimens are tested. These differences in sensitivity may affect the abilities of clinicians to accurately diagnose GBS sepsis before culture results are available.

Antigens, Bacterial↗
PubMed1995

Predictors of failure of high-frequency oscillatory ventilation in term infants with severe respiratory failure.

OBJECTIVE: To identify clinical factors in term neonates with severe respiratory failure that predict which neonates are unlikely to respond to high-frequency oscillatory ventilation (HFOV). DESIGN: This was a retrospective review of patient charts and medical records. PATIENTS: We studied 190 newborns treated with HFOV between July 1985 and December 1992. All patients were at least 35 weeks' estimated gestational age and had severe respiratory failure, defined as arterial to alveolar oxygen ratio (a/A ratio) of less than 0.2 or the need for peak inspiratory pressure greater than 35 cm H2O on conventional ventilation. RESULTS: Of the 190 patients, 111 (58%) responded to HFOV (HFOV responders), and 79 (42%) were placed on extracorporeal membrane oxygenation (ECMO) after HFOV failed to improve gas exchange (nonresponders). The two groups were similar in gender and birth weight. Factors associated with failure of HFOV to produce a sustained improvement in gas exchange were a diagnosis of congenital diaphragmatic hernia and more severe respiratory compromise as assessed by admission blood gas. Stepwise logistic regression analysis showed that a diagnosis of congenital diaphragmatic hernia/lung hypoplasia (CDH/LH) and the a/A ratio at initiation of and after 6 hours of HFOV were the only significant independent predictors of the need for ECMO. Among all the patients, the presence of CDH/LH or an initial a/A ratio of 0.05 or lower yielded a sensitivity of 74% and specificity of 77% in correctly identifying neonates in whom HFOV failed to produce a sustained improvement in oxygenation. When neonates with CDH/LH were excluded from analysis, the most significant predictor of failure of HFOV was the a/A ratio after 6 hours of HFOV. In neonates without CHD/LH, a 6-hour a/A ratio of 0.08 or lower discriminated responders from nonresponders (ie, treatment with ECMO) with a sensitivity of 77% and specificity of 92%. CONCLUSIONS: In our patients, the presence of CDH/LH, severe respiratory failure (a/A ratio 0.05 or lower) at initiation of HFOV, and lack of improvement in oxygenation (a/A ratio 0.08 or lower after 6 hours of HFOV) were associated with failure of HFOV and treatment with ECMO. This information should help other centers to identify neonates who are at the greatest risk for requiring ECMO support and thus allow prompt transfer to an ECMO center.

Acute Disease↗