Adjusting for bias in C-reactive protein levels when using a vitros slide method in infants.

OBJECTIVE: Low total serum protein levels may cause a positive bias on C-reactive protein (CRP) detected by the Vitros 250 Chemistry System (Ortho-Clinical Diagnostics, Inc., Johnson & Johnson Co., Raritan, NJ). Low total serum protein levels are observed in some infants. Our objective was to define a cutoff value for normal levels of CRP measured on the Vitros System that is comparable to the cutoff value of 1.0 mg/dL measured by rate nephelometry on a Beckman Array System (Beckman Instruments Inc., Fullerton, CA). STUDY DESIGN: CRP was prospectively measured on the same serum sample on Vitros and Beckman systems. Using a result of ≥1.0 as the "gold standard" definition of an abnormal CRP, measures of association were calculated. RESULTS: CRP was measured in 981 blood samples that were collected from 361 infants. A cutoff CRP level using the Vitros system at 1.5 mg/dL had the highest sensitivity and negative predictive value comparable to 1.0 mg/dL measured by nephelometry. By regression analysis, each increase by 1 mg/dL by nephelometry caused an increase by 1.5 mg/dL on the Vitros system (R(2) = 0.94; p < 0.001; slope = 0.66; 95% confidence intervals, 0.65, 0.67). CONCLUSION: In infants, when measuring CRP levels by Vitros CRP slide system, a normal reference level of 1.5 mg/dL instead of 1 mg/dL should be used.

Death or neurodevelopmental impairment at 18 to 22 months corrected age in a randomized trial of early dexamethasone to prevent death or chronic lung disease in extremely low birth weight infants.

OBJECTIVE: To evaluate the incidence of death or neurodevelopmental impairment (NDI) at 18-22 months corrected age in subjects enrolled in a trial of early dexamethasone treatment to prevent death or chronic lung disease in extremely low birth weight infants. STUDY DESIGN: Evaluation of infants at 18-22 months corrected age included anthropomorphic measurements, a standard neurological examination, and the Bayley Scales of Infant Development-II, including the Mental Developmental Index and the Psychomotor Developmental Index. NDI was defined as moderate or severe cerebral palsy, Mental Developmental Index or Psychomotor Developmental Index <70, blindness, or hearing impairment. RESULTS: Death or NDI at 18-22 months corrected age was similar in the dexamethasone and placebo groups (65% vs 66%, P = .99 among those with known outcome). The proportion of survivors with NDI was also similar, as were mean values for weight, length, and head circumference and the proportion of infants with poor growth (50% vs 41%, P = .42 for weight less than 10th percentile); 49% of infants in the placebo group received treatment with corticosteroid compared with 32% in the dexamethasone group (P = .02). CONCLUSION: The risk of death or NDI and rate of poor growth were high but similar in the dexamethasone and placebo groups. The lack of a discernible effect of early dexamethasone on neurodevelopmental outcome may be due to frequent clinical corticosteroid use in the placebo group.

Cytokines and neurodevelopmental outcomes in extremely low birth weight infants.

OBJECTIVE: To determine if selected pro-inflammatory and anti-inflammatory cytokines and/or mediators of inflammation reported to be related to the development of cerebral palsy (CP) predict neurodevelopmental outcome in extremely low birth weight infants. STUDY DESIGN: Infants with birth weights ≤1000 g (n = 1067) had blood samples collected at birth and on days 3 ± 1, 7 ± 1, 14 ± 3, and 21 ± 3 to examine the association between cytokines and neurodevelopmental outcomes. The analyses were focused on 5 cytokines (interleukin [IL] 1ß; IL-8; tumor necrosis factor-α; regulated upon activation, normal T-cell expressed, and secreted (RANTES); and IL-2) reported to be most predictive of CP in term and late preterm infants. RESULTS: IL-8 was higher on days 0-4 and subsequently in infants who developed CP compared with infants who did not develop CP in both unadjusted and adjusted analyses. Other cytokines (IL-12, IL-17, tumor necrosis factor-ß, soluble IL rα, macrophage inflammatory protein 1ß) were found to be altered on days 0-4 in infants who developed CP. CONCLUSIONS: CP in former preterm infants may, in part, have a late perinatal and/or early neonatal inflammatory origin.

Primary immunization of premature infants with gestational age <35 weeks: cardiorespiratory complications and C-reactive protein responses associated with administration of single and multiple separate vaccines simultaneously.

OBJECTIVE: To determine the incidence of cardiorespiratory events and abnormal C-reactive protein (CRP) level associated with administration of a single vaccine or multiple separate vaccines simultaneously. STUDY DESIGN: Prospective observational study on 239 preterm infants at > or =2 months of age in the neonatal intensive care unit (NICU). Each infant received either a single vaccine or multiple vaccines on one day. CRP levels and cardiorespiratory manifestations were monitored for 3 days following immunization. RESULTS: Abnormal elevation of CRP level occurred in 85% of infants administered multiple vaccines and up to 70% of those given a single vaccine. Overall, 16% of infants had vaccine-associated cardiorespiratory events within 48 hours postimmunization. In logistic regression analysis, abnormal CRP values were associated with multiple vaccines (OR, 15.77; 95% CI 5.10-48.77) and severe intraventricular hemorrhage (IVH) (OR, 2.28; 95% CI 1.02-5.13). Cardiorespiratory events were associated marginally with receipt of multiple injections (OR, 3.62; 95% CI 0.99-13.25) and significantly with gastroesophageal reflux (GER) (OR, 4.76; 95% CI 1.22-18.52). CONCLUSION: CRP level is expected to be elevated in the 48 hours following immunization. In a minority of infants immunized, cardiorespiratory events were associated with presumed need for intervention. Underlying medical conditions and possibly multiple injections are associated with cardiorespiratory events. Precautionary monitoring following immunizations is warranted.

Trends in neonatal morbidity and mortality for very low birthweight infants.

OBJECTIVE: To document the mortality and morbidity of infants weighing 501-1500 g at birth according to gestational age, birthweight, and sex. STUDY DESIGN: Prospective collection of perinatal events and neonatal course to 120 days of life, discharge, or death from January 1990 through December 2002 for infants born at 16 participating centers of the National Institute of Child Health & Human Development Neonatal Research Network. RESULTS: Compared with 1995-1996, for 1997-2002 the survival of infants with birthweight of 501-1500 g increased by 1 percentage point (from 84% to 85%). Survival without major neonatal morbidity remained static, at 70%; this includes bronchopulmonary dysplasia (BPD), intraventricular hemorrhage (IVH), and necrotizing enterocolitis (NEC). Survival increased for multiple births (26%, up from 22%), antenatal corticosteroid use (79%, up from 71%), and maternal antibiotics (70%, up from 62%) (P < .05). From 1997 to 2002, birthweight-specific survival was 55% for infants weighing 501-750 g, 88% for 751-1000 g, 94% for 1001-1250 g, and 96% for 1251-1500 g. More females survived. The incidence of NEC (7%), severe IVH (12%), and late-onset septicemia (22%) remained essentially unchanged, but BPD decreased slightly, from 23% to 22%. The use of postnatal corticosteroids declined from 20% in 1997-2000 to 12% in 2001-2002. Growth failure (weight <10th percentile) at 36 weeks' postmenstrual age decreased from 97% in 1995-1996 to 91% in 1997-2002. CONCLUSION: There have been no significant increases in survival without neonatal and long-term morbidity among VLBW infants between 1997 and 2002. We speculate that to improve survival without morbidity requires determining, disseminating, and applying best practices using therapies currently available, and also identifying new strategies and interventions.

C-reactive protein in the diagnosis, management, and prognosis of neonatal necrotizing enterocolitis.

OBJECTIVE: In this prospective, observational study, we determined whether serum C-reactive protein (CRP) correlated with necrotizing enterocolitis (NEC) stages II and III. We hypothesized that serial CRP measurement if used as an adjunct to abdominal radiographs would improve the identification of infants with NEC. METHODS: Serum CRP level was measured every 12 hours for 3 measurements and, when abnormal, once daily. When clinical signs persisted and the initial abdominal radiographs were abnormal, follow-up radiographs were obtained. RESULTS: Of 241 infants who were evaluated for gastrointestinal signs, 11 had ileus or benign pneumatosis intestinalis with persistently normal CRP; gastrointestinal manifestations resolved within 48 hours, antibiotics were discontinued in <48 hours, and feedings were restarted early without complications. Fifty-five infants had NEC stages II and III; all had abnormal CRP regardless of their blood culture results. In infants with stage II NEC, CRP returned to normal at a mean of 9 days except in those who developed complications such as stricture or abscess formation. CONCLUSIONS: In infants with suspected NEC, normal serial CRP values would favor aborted antibiotic therapy and early resumption of feedings. CRP becomes abnormal in both stage II and stage III NEC. In infants with NEC, persistently elevated CRP after initiation of appropriate medical management suggests associated complications, which may require surgical intervention.

Combination of early perinatal factors to identify near-term and term neonates for neuroprotection.

OBJECTIVE: To determine early predictors of abnormal outcome at > or =24 months' age in neonates at risk for hypoxic-ischemic brain injury. STUDY DESIGN: A prospective cohort study with developmental follow-up of > or =24 months. Infants were selected based on risk factors, and neurologic outcome was determined. Variables affecting the outcome were evaluated with univariate and multivariate methods, and a scoring system was devised to predict adverse outcome. RESULTS: A total of 41 infants born > or =35 weeks' gestational age with possibility of hypoxic-ischemic insult were enrolled. In all, 39 (95%) had known outcomes, of whom 17 (48%) had an abnormal neurologic outcome, including five deaths. The variables within the first hour of life correlating with the adverse outcome were 1- and 5-minute Apgar scores, intubation in the delivery room and cord/initial base-deficit > or =20 mmol/l. A scoring system was derived based on significant variables, and a score > or =5 had a 90% positive predictive value for abnormal outcome. Seizures, multiorgan failure and abnormal imaging studies were also significantly associated with abnormal outcome. CONCLUSIONS: The proposed scoring system, being highly predictive of outcome at 24 months' age, may be potentially useful in selecting subjects for preventive or therapeutic interventions to prevent or minimize neurologic morbidity due to hypoxic brain injury.

Chronic prenatal exposure to cocaine alters cerebrovascular responses in newborn pigs.

Maternal cocaine abuse may increase the incidence of perinatal asphyxia. In nonexposed asphyxiated neonates, decreased cerebrospinal fluid (CSF) cAMP concentrations are associated with poor neurological outcome. On the other hand, cocaine increases central nervous system (CNS) cAMP. Therefore, we hypothesized that in utero cocaine exposure may increase brain cAMP and thereby preserve cerebrovascular responses to cAMP-dependent stimuli following asphyxia. Pregnant pigs received either cocaine (1 mg/kg, i.v.) twice weekly during the last trimester or normal saline vehicle (sham-control) and were allowed to deliver vaginally at term. Cranial windows were implanted in the newborn pigs within the first week of life and used to collect CSF for cAMP determinations and to assess changes in pial arteriolar diameters (PAD). In the first part of the study, pial arteriolar responses to different vasodilator and vasoconstrictor stimuli were evaluated in piglets prior to asphyxia (n = 20). In newborn pigs exposed to cocaine, cerebrovascular responses to hypercapnia and norepinephrine were significantly exaggerated compared to controls. Then, piglets were randomly selected for the second part of the study that involved prolonged asphyxia (n = 12). In cocaine-exposed but not sham-control piglets, CSF cAMP increased markedly during asphyxia. In the sham piglets, but not the cocaine-exposed piglets, CSF cAMP fell progressively below the baseline during recovery. Cerebrovascular reactivity to cAMP-dependent stimuli (hypercapnia and isoproterenol) was preserved during recovery from asphyxia in the cocaine-exposed piglets but significantly attenuated in the sham controls. We conclude that piglets with chronic prenatal exposure to cocaine show exaggerated cerebrovascular responses to vasogenic stimuli and preserved cAMP-dependent cerebral vasoreactivity following asphyxia.

To tap or not to tap: high likelihood of meningitis without sepsis among very low birth weight infants.

CONTEXT: Neonatal meningitis is associated with significant morbidity and mortality. We speculated that meningitis may be underdiagnosed among very low birth weight (VLBW) infants because of the failure to perform lumbar punctures (LPs) in infants with suspected sepsis. OBJECTIVE: This study was undertaken to review the epidemiology of late-onset meningitis in VLBW (401-1500 g) infants and to evaluate the concordance of cerebrospinal fluid (CSF) and blood culture (BC) results. METHODS: VLBW infants (excluding those with intraventricular shunts) born at centers of the National Institute of Child Health and Human Development Neonatal Research Network from September 1, 1998, through December 31, 2001, were studied. Late-onset meningitis was defined by culture-based criteria and classified as meningitis with or without associated sepsis. Unadjusted comparisons were made using chi2 tests and adjusted comparisons using regression models. RESULTS: Of 9641 VLBW infants who survived >3 days, 2877 (30%) had > or = 1 LPs, and 6056 (63%) had > or = 1 BC performed after day 3. One hundred thirty-four infants had late-onset meningitis (1.4% of all patients; 5% of those with an LP). Pathogens associated with meningitis were similar to those associated with sepsis. One third (45 of 134) of the infants with meningitis had negative BCs. Lower gestational age and prior sepsis increased risk for meningitis. Compared with uninfected infants, those with meningitis had a longer time on mechanical ventilation (28 vs 18 days), had longer hospitalizations (91 vs 79 days), were more likely to have seizures (25% vs 2%), and were more likely to die (23% vs 2%). CONCLUSIONS: Meningitis is a serious complication among VLBW infants, associated with increased severity of illness and risk of death. Of note, one third of the infants with meningitis had meningitis in the absence of sepsis. Because CSF cultures were performed only half as often as BCs, this discordance in blood and CSF culture results suggests that meningitis may be underdiagnosed among VLBW infants.

Parenteral glutamine supplementation does not reduce the risk of mortality or late-onset sepsis in extremely low birth weight infants.

BACKGROUND: Glutamine is one of the most abundant amino acids in both plasma and human milk, yet it is not included in standard intravenous amino acid solutions. Previous studies have suggested that parenteral nutrition (PN) supplemented with glutamine may reduce sepsis and mortality in critically ill adults. Whether glutamine supplementation would provide a similar benefit to extremely low birth weight (ELBW) infants is not known. METHODS: We performed a multicenter, randomized, double-masked, clinical trial to assess the safety and efficacy of early PN supplemented with glutamine in decreasing the risk of death or late-onset sepsis in ELBW infants. Infants 401 to 1000 g were randomized within 72 hours of birth to receive either TrophAmine (control) or an isonitrogenous study amino acid solution with 20% glutamine whenever they received PN up to 120 days of age, death, or discharge from the hospital. The primary outcome was death or late-onset sepsis. RESULTS: Of the 721 infants who were assigned to glutamine supplementation, 370 (51%) died or developed late-onset sepsis, as compared with 343 of the 712 infants (48%) assigned to control (relative risk: 1.07; 95% confidence interval: 0.97-1.17). Glutamine had no effect on tolerance of enteral feeds, necrotizing enterocolitis, or growth. No significant adverse events were observed with glutamine supplementation. CONCLUSIONS: Parenteral glutamine supplementation as studied did not decrease mortality or the incidence of late-onset sepsis in ELBW infants. Consequently, although no harm was demonstrated, routine use of parenteral glutamine supplementation cannot be recommended in this population.

Effect of parenteral glutamine supplementation on plasma amino acid concentrations in extremely low-birth-weight infants.

BACKGROUND: Glutamine is one of the most abundant amino acids in both plasma and human milk and may be conditionally essential in premature infants. However, glutamine is not provided by standard intravenous amino acid solutions. OBJECTIVE: We assessed the effect of parenteral glutamine supplementation on plasma amino acid concentrations in extremely low-birth-weight infants receiving parenteral nutrition (PN). DESIGN: A total of 141 infants with birth weights of 401-1000 g were randomly assigned to receive a standard intravenous amino acid solution that did not contain glutamine or an isonitrogenous amino acid solution with 20% of the total amino acids as glutamine. Blood samples were obtained just before initiation of study PN and again after the infants had received study PN (mean intake: 2.3 +/- 1.0 g amino acids x kg(-1) x d(-1)) for approximately 10 d. RESULTS: Infants randomly assigned to receive glutamine had mean plasma glutamine concentrations that increased significantly and were approximately 30% higher than those in the control group in response to PN (425 +/- 182 and 332 +/- 148 micromol/L for the glutamine and control groups, respectively). There was no significant difference between the 2 groups in the relative change in plasma glutamate concentration between the baseline and PN samples. In both groups, there were significant decreases in plasma phenylalanine and tyrosine between the baseline and PN samples; the decrease in tyrosine was greater in the group that received glutamine. CONCLUSIONS: In extremely low-birth-weight infants, parenteral glutamine supplementation can increase plasma glutamine concentrations without apparent biochemical risk. Currently available amino acid solutions are likely to be suboptimal in their supply of phenylalanine, tyrosine, or both for these infants.

Late-onset sepsis in very low birth weight neonates: the experience of the NICHD Neonatal Research Network.

OBJECTIVE: Late-onset sepsis (occurring after 3 days of age) is an important problem in very low birth weight (VLBW) infants. To determine the current incidence of late-onset sepsis, risk factors for disease, and the impact of late-onset sepsis on subsequent hospital course, we evaluated a cohort of 6956 VLBW (401-1500 g) neonates admitted to the clinical centers of the National Institute of Child Health and Human Development Neonatal Research Network over a 2-year period (1998-2000). METHODS: The National Institute of Child Health and Human Development Neonatal Research Network maintains a prospective registry of all VLBW neonates admitted to participating centers within 14 days of birth. Expanded infection surveillance was added in 1998. RESULTS: Of 6215 infants who survived beyond 3 days, 1313 (21%) had 1 or more episodes of blood culture-proven late-onset sepsis. The vast majority of infections (70%) were caused by Gram-positive organisms, with coagulase-negative staphylococci accounting for 48% of infections. Rate of infection was inversely related to birth weight and gestational age. Complications of prematurity associated with an increased rate of late-onset sepsis included patent ductus arteriosus, prolonged ventilation, prolonged intravascular access, bronchopulmonary dysplasia, and necrotizing enterocolitis. Infants who developed late-onset sepsis had a significantly prolonged hospital stay (mean length of stay: 79 vs 60 days). They were significantly more likely to die than those who were uninfected (18% vs 7%), especially if they were infected with Gram-negative organisms (36%) or fungi (32%). CONCLUSIONS: Late-onset sepsis remains an important risk factor for death among VLBW preterm infants and for prolonged hospital stay among VLBW survivors. Strategies to reduce late-onset sepsis and its medical, social, and economic toll need to be addressed urgently.

Whole-body hypothermia for neonatal encephalopathy: animal observations as a basis for a randomized, controlled pilot study in term infants.

OBJECTIVE: Modest reduction in brain temperature is a promising therapy to reduce brain damage after neonatal encephalopathy as a result of acute perinatal asphyxia. The efficacy of modest hypothermia may in part be dependent on the stability of the desired brain temperature. The objective of this study was 1) to evaluate in newborn animals a commercially available cooling system (Blanketrol II Hyperthermia-Hypothermia system) to control brain temperature during whole-body hypothermia and 2) to use the results of the animal experiments to perform a pilot study evaluating the feasibility of whole-body hypothermia as a neuroprotective therapy for newborns with encephalopathy at birth. METHODS: In the animal investigation, 3 miniature swine were instrumented and ventilated, and temperature probes were placed in the esophagus and the brain (1 cm and 2 cm beneath the parietal cortical surface and the dura). Body cooling was achieved using the automatic control mode (servo) of the cooling system. In the human investigation, 19 term infants with moderate or severe encephalopathy were randomized to either normothermia (n = 10) or hypothermia (n = 9) within 6 hours of birth. Whole-body hypothermia was achieved using the hyperthermia-hypothermia cooling system with servo control of esophageal temperature to 34.5 degrees C for 72 hours followed by slow rewarming. RESULTS: In the animal investigation, body cooling with the animal lying on a single blanket resulted in rapid cooling of the body within 90 minutes. Repetitive cyclical swings in esophageal temperature of 1.7 +/- 0.2 degrees C (mean +/- standard deviation) around the set point of 33.5 degrees C were reduced to 0.7 +/- 0.2 degrees C when a second, larger blanket was attached and suspended. Esophageal temperature was a good marker of deep brain temperature (esophageal to 2-cm brain difference: 0.1 +/- 0.3 degrees C). In the human investigation, the infants were randomized at 4.1 +/- 1.3 hours (mean +/- standard deviation) after birth. Age at randomization was similar in the 2 groups. Cooling was initiated at an average age of 5.3 hours. Target temperature of 34.5 degrees C was achieved within 30 minutes and remained constant throughout the intervention period. Heart rate decreased to 108 +/- 14 beats per minute (bpm) at 60 minutes and remained between 115 and 130 bpm for the duration of cooling compared with 130 to 145 bpm in the normothermia group. Blood pressure was similar in the 2 groups. No adverse events occurred during 72 hours of cooling. The mortality rate and frequency of persistent pulmonary hypertension, renal failure, hepatic dysfunction, and need for pressor support were similar in both groups. CONCLUSIONS: Animal studies showed that a simple modification of a commercially available cooling system (2 blankets attached, subject lying on 1 and the second hanging freely) results in stable core body and brain temperature when used in the automatic control mode. The pilot study in term infants with encephalopathy using this cooling system demonstrates feasibility of initiating whole-body hypothermia at <6 hours of age to a constant esophageal temperature using servo control and provides no evidence that hypothermia involved greater hazard than benefit.

Changes in pathogens causing early-onset sepsis in very-low-birth-weight infants.

BACKGROUND: It is uncertain whether the rates and causes of early-onset sepsis (that occurring within 72 hours after birth) among very-low-birth-weight infants have changed in recent years, since antibiotics have begun to be used more widely during labor and delivery. METHODS: We studied 5447 very-low-birth-weight infants (those weighing between 401 and 1500 g) born at centers of the Neonatal Research Network of the National Institute of Child Health and Human Development between 1998 and 2000 who had at least one blood culture in the first three days of life and compared them with 7606 very-low-birth-weight infants born at centers in the network between 1991 and 1993. RESULTS: Early-onset sepsis (as confirmed by positive blood cultures) was present in 84 infants in the more recent birth cohort (1.5 percent). As compared with the earlier birth cohort, there was a marked reduction in group B streptococcal sepsis (from 5.9 to 1.7 per 1000 live births of infants weighing 401 to 1500 g, P<0.001) and an increase in Escherichia coli sepsis (from 3.2 to 6.8 per 1000 live births, P=0.004); the overall rate of early-onset sepsis was not significantly changed. Most E. coli isolates from the recent birth cohort (85 percent) were resistant to ampicillin, and mothers of infants with ampicillin-resistant E. coli infections were more likely to have received intrapartum ampicillin than were those with ampicillin-sensitive strains (26 of 28 with sensitivity data vs. 1 of 5, P=0.01). Infants with early-onset sepsis were more likely to die than uninfected infants (37 percent vs. 13 percent, P<0.001), especially if they were infected with gram-negative organisms. CONCLUSIONS: Early-onset sepsis remains an uncommon but potentially lethal problem among very-low-birth-weight infants. The change in pathogens over time from predominantly gram-positive to predominantly gram-negative requires confirmation by ongoing surveillance.

Neurodevelopmental outcome of premature infants after antenatal phenobarbital exposure.

OBJECTIVE: We previously demonstrated that antenatal phenobarbital does not decrease the risk of intracranial hemorrhage or early death in premature infants. The objective of the present study was to evaluate the impact of antenatal phenobarbital exposure on the neurodevelopmental outcome of premature infants born to women who were participating in the randomized clinical trial of antenatal phenobarbital exposure. STUDY DESIGN: Infants were evaluated at 18 to 22 months corrected age with a standard neurologic examination and the Bayley scales of infant development measuring the mental developmental index and the psychomotor developmental index. RESULTS: Of the 578 infants <34 weeks of gestational age who were born to women who were enrolled in the primary study, 7 infants died after discharge from the neonatal intensive care unit, and 135 infants were lost to follow-up. Infants who were lost to follow-up had a higher mean birth weight and gestational age and a lower maternal education, but the rates of intracranial hemorrhage were comparable to those infants who were evaluated. Among the infants who were evaluated (n = 436; 76%), the mean birth weight and gestational age, maternal education, and frequency and distribution of intracranial hemorrhage were similar in the antenatal phenobarbital exposed and placebo groups. Eighteen infants (8%) in the antenatal phenobarbital exposed group and 21 infants (11%) in the placebo group had cerebral palsy (P = not significant). There was no difference between the 2 groups in either the median Bayley II mental developmental index (85 in the antenatal phenobarbital and 86 in the placebo group) or the Psychomotor Developmental Index (91 in the antenatal phenobarbital and 91 in the placebo group). Infants with intracranial hemorrhage (23%) had significantly lower mental developmental index and psychomotor developmental index scores than infants with no intracranial hemorrhage, independent of antenatal phenobarbital exposure. In the total cohort of 436 infants, the presence of intracranial hemorrhage or periventricular leukomalacia was associated with lower mental developmental index and psychomotor developmental index scores; the presence of increasing birth weight, maternal education, and a complete course of antenatal steroids was associated with a higher mental developmental index score. CONCLUSION: Antenatal phenobarbital exposure did not favorably or adversely affect the neurodevelopmental outcome of premature infants at 18 to 22 months of age.

Efficacy and safety of tolazoline for treatment of severe hypoxemia in extremely preterm infants.

OBJECTIVE: To determine the efficacy of tolazoline as a rescue treatment for hypoxemia in preterm infants with respiratory distress syndrome. METHODS: Retrospective chart review on case series of infants weighing < 750 g at birth who received tolazoline during a severe hypoxemic episode while receiving maximal ventilator support for respiratory distress syndrome. A slow bolus infusion of low dose tolazoline (0.5 mg-2 mg/kg) mixed with plasmanate or normal saline (10 mL/kg) was administered. Outcome measures evaluated included an increase in PaO(2) > or =20 mm Hg from pretreatment value and an increase in oxygen saturation to > or =90%. RESULTS: Forty-three infants with a mean gestational age and birth weight of 24 weeks and 581 g, respectively, received tolazoline. All infants were mechanically ventilated and required a fraction of inspired oxygen of 1.0. Oxygenation improved in 72% (31/43) of infants with a tolazoline dose of 0.5 to 1.0 mg/kg. Of those who responded, PaO(2) values (mean +/- standard deviation) pretolazoline and posttolazoline were 32 +/- 7.5 mm Hg and 156 +/- 114.9 mm Hg, respectively. In all responders, oxygen saturation increased to > or =90% within 30 minutes of tolazoline administration. Improvement in pH, pCO(2), oxygenation index, and mean airway pressure was also noted. Among nonresponders, pH decreased and pCO(2) increased after tolazoline. Minimal change in blood pressure was noted in both responders and nonresponders. Heart rate decreased by 19 beats per minute among nonresponders compared with an increase of 3 beats per minute in those who responded to tolazoline. CONCLUSION: Tolazoline is an effective treatment of severe resistant hypoxemia in preterm infants who are already on vigorous ventilatory support.

Risk factors for early death among extremely low-birth-weight infants.

OBJECTIVE: The purposes of this study were to compare the clinical characteristics of extremely low birth-weight infants (501-1000 g birth weight) who die early (<12 hours of age) with those of infants who die >12 hours after birth and infants who survive to neonatal intensive care unit discharge and to develop a model of risk for early death. STUDY DESIGN: Perinatal data were prospectively collected on 5986 infants in the 12 participating centers of the National Institute of Child Health and Human Development Neonatal Research Network from March 1993 through December 1997. Maternal and neonatal characteristics of infants who died early were compared with infants who survived and infants who died beyond 12 hours of age. A model for risk for early death was developed by logistic regression analysis, with results expressed as odds ratio with 95% CI. RESULTS: Mothers of infants who died early were more likely to be delivered in an inborn setting and experience labor and were less likely to have hypertension or preeclampsia, to receive antenatal corticosteroids, or to be delivered by cesarean birth than mothers of infants who died >12 hours after birth or infants who survived. Infants who died early were more likely to have lower Apgar scores and lower gestational age/birth weight and were less likely to be intubated at birth and to receive mechanical ventilation and surfactant therapy than infants who died >12 hours after birth or infants who survived. Greater risk for early death versus survival to neonatal intensive care unit discharge was associated with the lack of surfactant administration (odds ratio, 8.6; 95% CI, 6.3-11.9), lack of delivery room intubation (odds ratio, 5.3; 95% CI, 3.5-8.1), lack of antenatal corticosteroid use (odds ratio, 2.3; 95% CI, 1.6-3.2), lower 1-minute Apgar score (odds ratio, 2.0; 95% CI, 1.8-2.2), male sex (odds ratio, 1.7; 95% CI, 1.3-2.3), multiple gestation (odds ratio, 1.7; 95% CI, 1.2-2.5), no tocolytics (odds ratio, 1.7; 95% CI, 1.2-2.3), lower gestational age per week (odds ratio, 1.4; 95% CI, 1.3-1.6), and lower birth weight per 50 g (95% CI, 1.2-1.4). CONCLUSION: Early death (<12 hours of age) among extremely low-birth-weight infants may reflect an assessment of non-viability by obstetricians and neonatologists.

Cerebrovasodilatory contribution of endogenous carbon monoxide during seizures in newborn pigs.

Carbon monoxide (CO) and the excitatory amino acid glutamate both dilate cerebral arterioles in newborn pigs. The key enzyme in CO synthesis is heme oxygenase, which is highly expressed in neurons with glutamatergic receptor activity as well as cerebral microvessels. During seizures the extracellular level of glutamate is increased, which results in excessive depolarization of neurons. We hypothesized that CO is a mediator of excitatory amino acid-induced dilation of the cerebral microvasculature during seizures. Three groups of piglets were examined: 1) i.v. normal saline (sham control), 2) topical chromium mesoporphyrin (Cr-MP, 15 x 10(-6) M), and 3) i.v. tin-protoporphyrin (Sn-PP, 4 mg/kg). Synthetic metalloporphyrins (Cr-MP and Sn-PP) are heme oxygenase inhibitors, thereby reducing CO synthesis. Implanted closed cranial windows were used to monitor changes in pial arteriolar diameters. Seizures were induced by administration of i.v. bicuculline. Changes in pial arteriolar diameters were monitored during 30 min of status epilepticus. The percent increase in pial arteriolar dilation in the saline group during seizures was 68 +/- 3%. In the metalloporphyrin groups, the pial arteriolar dilation was markedly reduced (35 +/- 3% and 13 +/- 1%, for Cr-MP and Sn-PP, respectively; p < 0.05, compared with the saline group). We conclude that metalloporphyrins by inhibition of heme oxygenase and prevention of CO synthesis attenuate pial arteriolar dilation during seizures. Therefore, CO appears to be involved in cerebral vasodilation caused by glutamatergic seizures.

Neurobiologic risk score and long-term developmental outcomes of premature infants, birth weight less than 1,250 grams.

OBJECTIVE: To determine whether neurobiologic risk score (NBRS) would continue to correlate with developmental outcomes. METHOD: An observational cohort consisting of 258 surviving infants who returned to the follow-up clinic with a mean age 22 months' corrected age. Both univariate and multivariate analysis were performed to identify risk factors and to assess the predictive value of NBRS. RESULTS: Forty-eight to 53 per cent of these infants had growth parameters < 25th percentile for age. Seventeen and 18 per cent respectively had mental developmental index (MDI) and psychomotor developmental index (PDI) on the Bayley Scales less than 70 and 14 per cent developed cerebral palsy (CP). NBRS demonstrated a significant correlation with the outcome (p < 0.001). In infants with NBRS > or = 8, 48 per cent had MDI < 70 and 68 per cent, had PDI < 70. At a similar NBRS cutoff, specificity and negative predictive value (NPV) were 86 and 96 per cent, respectively. Logistic regression indicated that birth weight and gestational age were the most significant, independent variables for predicting poor outcomes. CONCLUSION: Very preterm infants in the present study were at risk for abnormal developmental outcomes. NBRS demonstrated a very high specificity and NPV and may be a useful index to identify those who need early intervention.