The impact of low birth weight, perinatal conditions, and sociodemographic factors on educational outcome in kindergarten.

OBJECTIVE: To assess the relative effects and the impact of perinatal and sociodemographic risk factors on long-term morbidity within a total birth population in Florida. METHODS: School records for 339 171 children entering kindergarten in Florida public schools in the 1992-1993, 1993-1994, or 1994-1995 academic years were matched with Florida birth records from 1985 to 1990. Effects on long-term morbidity were assessed through a multivariate analysis of an educational outcome variable, defined as placement into 9 mutually exclusive categories in kindergarten. Of those categories, 7 were special education (SE) classifications determined by statewide standardized eligibility criteria, 1 was academic problems, and the reference category was regular classroom. Generalized logistic regression was used to simultaneously estimate the odds of placement in SE and academic problems. The impact of all risk factors was assessed via estimated attributable excess/deficit numbers, based on the multivariate analysis. RESULTS: Educational outcome was significantly influenced by both perinatal and sociodemographic factors. Perinatal factors had greater adverse effects on the most severe SE types, with birth weight <1000 g having the greatest effect. Sociodemographic predictors had greater effects on the mild educational disabilities. Because of their greater prevalence, the impact attributable to each of the factors (poverty, male gender, low maternal education, or non-white race) was between 5 and 10 times greater than that of low birth weight and >10 times greater than that of very low birth weight, presence of a congenital anomaly, or prenatal care. CONCLUSIONS: Results are consistent with the hypothesis that adverse perinatal conditions result in severe educational disabilities, whereas less severe outcomes are influenced by sociodemographic factors. Overall, sociodemographic factors have a greater total impact on adverse educational outcomes than perinatal factors.

Educational disabilities of neonatal intensive care graduates.

OBJECTIVE: To determine the relationship between perinatal and sociodemographic factors in low birth weight and sick infants hospitalized at regional neonatal intensive care units (NICUs) and subsequent educational disabilities. METHOD: NICU graduates born between 1980 and 1987 at nine statewide regionalized level III centers were located in Florida elementary schools (kindergarten through third grade) during academic year 1992-1993 (n = 9943). Educational disability was operationalized as placement into eight mutually exclusive types of special education (SE) classifications determined by statewide standardized eligibility criteria: physically impaired, sensory impaired (SI), profoundly mentally handicapped, trainable mentally handicapped, educable mentally handicapped, specific learning disabilities, emotionally handicapped, and speech and language impaired (SLI). Logistic regression was used to estimate the odds of placement in SE for selected perinatal and sociodemographic variables. RESULTS: Placement into SE ranged from .8% for SI to 9.9% for SLI. Placement was related to four perinatal factors (birth weight, transport, medical conditions [congenital anomalies, seizures or intraventricular hemorrhage] and ventilation), and five sociodemographic factors (child's sex, mother's marital status, mother's race, mother's educational level, and family income). Perinatal factors primarily were associated with placement in physically impaired, SI, profoundly mentally handicapped, and trainable mentally handicapped. Perinatal and sociodemographic factors both were associated with placement in educable mentally handicapped and specific learning disabilities whereas sociodemographic factors primarily were associated with placement in emotionally handicapped and SLI. CONCLUSIONS: Educational disabilities of NICU graduates are influenced differently by perinatal and sociodemographic variables. Researchers must take into account both sets of these variables to ascertain the long-term risk of educational disability for NICU graduates. Birth weight alone should not be used to assess NICU morbidity outcomes.

Changes in survival patterns of very low-birth-weight infants from 1980 to 1993.

OBJECTIVE: To determine changes in survival patterns among very low-birth-weight ( < 1500 g) infants between 1980 and 1993. METHODS: The records of 12,960 infants treated in nine perinatal intensive care centers in Florida were analyzed on the basis of survival (discharged alive from hospital) according to four independent variables: birth weight, race, sex, and transport status. Survival curves were generated using log linear regression techniques for each race by sex by transport status group. RESULTS: Race, sex, and transport status correlated significantly with survival: survival percentages were higher among black infants, female infants, and infants transported to the perinatal intensive care centers than among white infants, male infants, and those admitted initially to the tertiary care centers. After 1985, 95% of neonates with birth weights between 1200 and 1500 g survived. In addition, survival of 500- to 500-g transported black male infants increased from zero to near 80% during the 13-year period; that of 500- to 550-g inborn white female infants rose from 35% to 70%. CONCLUSIONS: These results illustrate the value of taking into account race, sex, and transport status in efforts to understand the contribution that neonatal intensive care of extremely low-birth-weight infants makes to the lowering of infant mortality, and of using multivariable statistical procedures to generate predicted survival probabilities for different subpopulations. These probabilities can be applied to (1) predicting survival for specific subgroups of extremely low-birth-weight infants, and (2) helping physicians develop clinical guidelines for extending care to infants at the threshold of viability.

Multicenter controlled trial comparing high-frequency jet ventilation and conventional mechanical ventilation in newborn infants with pulmonary interstitial emphysema.

One hundred forty-four newborn infants with pulmonary interstitial emphysema were stratified by weight and severity of illness, and randomly assigned to receive treatment with high-frequency jet ventilation (HFJV) or rapid-rate conventional mechanical ventilation (CV) with short inspiratory time. If criteria for treatment failure were met, crossover to the alternate ventilatory mode was permitted. Overall, 45 (61%) of 74 infants met treatment success criteria with HFJV compared with 26 (37%) of 70 treated with CV (p less than 0.01). Eighty-four percent of patients who crossed over from CV to HFJV initially responded to the new treatment, and 45% ultimately met success criteria on HFJV. In contrast, only 9% of those who crossed over from HFJV to CV responded well to CV (p less than 0.01), and the same 9% ultimately met success criteria (p less than 0.05). Therapy with HFJV resulted in improved ventilation at lower peak and mean airway pressures, as well as more rapid radiographic improvement of pulmonary interstitial emphysema, in comparison with rapid-rate CV. Survival by original assignment was identical. When survival resulting from rescue by the alternate therapy in crossover patients was excluded, the survival rate was 64.9% for HFJV, compared with 47.1% for CV (p less than 0.05). The incidence of chronic lung disease, intraventricular hemorrhage, patent ductus arteriosus, airway obstruction, and new air leak was similar in both groups. We conclude that HFJV, as used in this study, is safe and is more effective than rapid-rate CV in the treatment of newborn infants with pulmonary interstitial emphysema.

Effects of birth weight and sociodemographic variables on mental development of neonatal intensive care unit survivors.

Neonatal intensive care unit survivors (N = 494) from 10 tertiary care centers were evaluated over the first 4 to 5 years of life to determine the relative contributions of birth weight and sociodemographic factors to mental development. Six sociodemographic factors were studied: sex, race, family income, and mother's marital status, age, and educational level; the last five factors also are known to be associated with premature birth. Mental development was measured with the Bayley Scales of Infant Development (12 to 24 months) and the Stanford Binet Intelligence Test (4 to 5 years). Each factor's influence was assessed by multivariate analysis. Birth weight had limited long-term implications; at 4 to 5 years, only infants with birth weights less than 1000 gm had significantly lower scores than those in other birth weight categories. Sociodemographic variables had a greater impact on mental development, with age-dependent differences found between nonwhite and white children and between children with mothers of low, medium, and high educational levels.

Perspectives on respiratory distress syndrome of the newborn.

In summary, strategies for the metabolic and respiratory support of premature infants with HMD have been developed over the last 30 years. Most infants with a birth weight over 1000 g survive with supportive care. Surfactant treatments are an important addition that should decrease the need for respiratory support. Other problems of prematurity remain, although an improvement in respiratory care appears to simplify the care overall. Many practical aspects of the treatment of infants with surfactant must yet be evaluated. If surfactant therapy proves to be efficacious and safe, it may ultimately be a major advance in the care of premature infants with HMD.

Effect of fenoldopam on preconstricted isolated salt-perfused rat lungs.

Using an in situ isolated salt-perfused rat lung preparation, we investigated the pulmonary vascular response to fenoldopam (a highly selective dopamine (DA1) agonist) infused at six different doses ranging from 0.1 to 10,000 micrograms/kg, during prostaglandin F2 alpha- (PGF2 alpha) induced pulmonary vasoconstriction. These experiments were repeated after selective DA1-blockade with SCH 23390. Twelve experiments were performed to evaluate the effect of fenoldopam on base-line hemodynamics. Sixty experiments were performed after PGF2 alpha vasoconstriction. Thirty lung preparations were pretreated with SCH 23390. PGF2 alpha was infused into the pulmonary inflow catheter at 2.5 micrograms.kg-1.min-1 to give a sustained rise in mean pulmonary arterial pressure (5.0 +/- 1.0 mmHg). Fenoldopam, at doses of 0.1, 1, 10, 100, 1,000, or 10,000 micrograms/kg, was injected into the pulmonary artery (n = 5 blocked and n = 5 unblocked at each dose). Fenoldopam had no effect on hemodynamics in the absence of PGF2 alpha. In the unblocked group, after PGF2 alpha vasoconstriction, fenoldopam infusion resulted in a dose-dependent decrease in the mean pulmonary arterial pressure with a dose-response curve characteristic for a drug-receptor interaction [Response = -1.0 (log Dose) -1.6]. In the DA1-blocked group after PGE2 alpha vasoconstriction, the dose-response curve was shifted to the right but parallel to the unblocked group, indicating competitive receptor blockade [Response -0.8 (log Dose) -0.05]. We conclude that vasodilatory DA1-receptors are responsible for the observed results.

Effect of birth weight, race, and sex on survival of low-birth-weight infants in neonatal intensive care.

Survival for low-birth-weight infants has traditionally been analyzed by birth weight categories spanning considerable ranges of weight. We developed a finer description of survival rates to allow estimation of survival percentages for infants of any specific birth weight between 500 and 2500 gm. Our sample consisted of 16,183 infants treated in tertiary neonatal intensive care between 1980 and 1987. Their survival data were analyzed by 50 gm increments between 500 and 2500 gm, and a continuous survival curve was constructed by log linear regression methods. Mortality differences between males and females and blacks and whites were analyzed. Survival for females was higher than males between 500 and 1500 gm and higher for blacks than whites between 650 and 1500 gm. Between 1500 and 2500 gm, no significant effects of birth weight, race, or sex were observed, with survival remaining stable at approximately 95% across all combinations of variables.

Determination of extracellular fluid volume using impedance measurements.

Currently, accurate determination of body fluid compartments depends on the sodium bromide method (NaBr), an invasive measurement requiring venipuncture with infusion of a foreign substance. Impedance (Z) measurements may provide a practical noninvasive alternative for estimating fluid compartments in sick, premature neonates. To validate the impedance method, we compared it with the NaBr technique in nine anesthetized rabbits. Electrodes were placed for impedance measurement. Vascular catheters were inserted into the femoral artery and vein. Baseline impedance data were collected at 1.0 kHz and blood samples were drawn for NaBr standard assay. Using conventional assay techniques for determination of extracellular fluid volume (ECFV), we correlated NaBr data with impedance measurements. A linear relationship between ECFV by NaBr assay and the previously developed impedance equation rho L2/Z1.0 was established using regression analysis. A correlation value of r = .95 was obtained. These data suggest the potential for impedance to estimate ECFV.

Comparison of airway pathologic lesions after high-frequency jet or conventional ventilation.

High-frequency jet ventilation in neonates has been associated with airway damage ranging from focal necrosis to complete airway obstruction with mucus and severe necrotizing tracheobronchitis. However, studies have lacked consistent criteria for assessment, and jet ventilation systems have varied widely. We compared autopsy and histopathologic findings in six neonates who died after prolonged jet ventilatory support with findings in six matched controls who died after receiving conventional ventilatory support. Jet ventilation consisted of a pressure-limited, time-cycled, flow-interrupter-type system. The airways of all patients were assessed by the histopathologic scoring system of Ophoven et al. No differences were observed between neonates who received jet ventilation or conventional ventilation. We believe that the risk of airway damage should not preclude the use of jet ventilation, although further monitoring is imperative.

Prospective pricing model for neonatologists and obstetricians in tertiary care centers.

According to the new federal diagnosis-related group (DRG) system, hospitals are reimbursed fixed sums based on discharge diagnoses, rather than variable sums that depend on specific goods and services consumed and number of days hospitalized. The government is now exploring DRGs as a potential mechanism for reimbursing physicians. In Florida, two DRG-type reimbursement systems were developed for neonatal and obstetrical hospitalizations in tertiary care settings, as departures from the federal DRG system. Called neonatal care groups (NCGs) and obstetrical care groups (OBCGs), both classification systems predicted hospital charges in these settings more accurately than did federal DRGs. The feasibility of a prospective pricing system for neonatologists and obstetricians based on NCGs and OBCGs was investigated. The data showed that neonatologists' charges had a high correlation with hospital charges (r = .90) and that increasing levels of intensity of care as defined by the NCGs were reflected by consistent increases in reimbursement to neonatologists. If the NCG system were to be applied, neonatologists would receive compensation equivalent to that which they currently earn according to the fee-for-service system. In contrast, obstetricians' charges bore almost no relationship to hospital charges. However, modest differences in obstetrician's charges did emerge as a reflection of number of complications, which are incorporated into the OBCG categories; this suggests that a reimbursement system based on hospital OBCG categories might be applied to obstetricians.

Developmental intervention for low birth weight infants: improved early development outcome.

This prospective longitudinal study was designed to evaluate the effects of a multidisciplinary infant development program (IDP) on the mental and physical development of low birth weight infants (less than 1,800 g). Infants in the neonatal intensive care were randomly assigned to the IDP or to traditional care (control group). IDP infants received developmental interventions in the hospital and at home through the first 2 years of life. Counseling and parenting education were provided to their parents during this same period. The control group received all the postnatal care and referrals customarily given in traditional care. Both IDP and control infants were enrolled in an independent follow-up program, which used the Bayley Scales of Infant Development in a blind evaluation design. The IDP group had a significantly lower incidence of developmental delay (P less than .05) and scored significantly higher than the control group (P less than .05) on mean mental and physical indices at 12 and 24 months of adjusted age.

Prospective pricing system by diagnosis-related groups: comparison of federal diagnosis-related groups with high-risk obstetric care groups.

Of 468 diagnosis-related groups identified by the federal government for Medicaid reimbursement, 15 are related to obstetric hospital care. Each diagnosis-related group is considered a distinct group in which cases are homogeneous with respect to resource consumption. Because the diagnosis-related group system is based primarily on data from community and secondary care hospitals, it does not differentiate sufficiently among high-risk obstetric patients seen at tertiary care institutions, such as Florida's Regional Perinatal Intensive Care Centers. We developed an alternative scheme for diagnosis-related groups, called obstetric care groups, using the federal diagnosis-related groups as the model from which to depart. Data collected for 4192 women during a 2 1/2-year period indicate that obstetric care groups provide more homogeneous groups than diagnosis-related groups for our population of high-risk patients. The obstetric care groups differentiate between no complications, one complication, and two or more complications, while the diagnosis-related groups differentiate only between no complications and one or more complications. Also, complications for obstetric care groups are based on only 19 diagnoses that contribute significantly to resource consumption, while the list of possible complications exceeds 200 for diagnosis-related groups. Although the obstetric care group classification system is simpler than that for diagnosis-related groups, it results in a more accurate reimbursement of hospitalization charges for high-risk obstetric care.

Partitioning the respiratory effects of airway citric acid and normal saline in lambs.

Aspiration is common in the intubated human neonate. Thus, the ventilatory and blood gas responses to citric acid and saline instillation into different airway sites were studied in ten awake, unanesthetised lambs, breathing spontaneously via a tracheostomy tube. With a system of balloons, 1 ml of saline or citric acid was placed selectively into the midtrachea, the laryngeal area, or the lower trachea (lower tr). Changes in minute ventilation (VE), after a 30 sec baseline period, were measured 30 sec and 1 and 2 min after the challenge. Arterial blood gas changes were measured at 30 sec and 2 min. Major increases in VE were seen only when saline or citric acid was instilled into the lower tr, the citric acid responses exceeding saline ones. The arterial oxygen tension (PaO2) fell after lower tr saline, whereas the arterial CO2 tension (PaCO2) fell with midtracheal saline instillation. A rise in pH and a fall in PaCO2 accompanied citric acid given into the lower tr. An initial rise in PaO2 after citric acid into the lower tr was followed by a return to baseline despite hyperventilation. The ventilatory and blood gas changes with saline and citric acid depend on the site of airway instillation.

Lack of effect of Lactobacillus on gastrointestinal bacterial colonization in premature infants.

Studies were carried out on premature infants in the neonatal intensive care unit to determine the effect of feeding of lactobacilli on colonization of the gastrointestinal tract by antibiotic-resistant gram-negative enteric organisms. Thirty premature infants were matched by birth weight and gestational age, randomized and fed double blind either lactobacilli-containing formula or non-lactobacilli-containing formula within 72 hours of delivery. The two study groups were screened weekly by culture for stool lactobacilli, for gram-negative bacteria and for antibiotic resistance of these bacteria. Lactobacilli were cultured from the stools of 13 of 15 patients receiving lactobacilli and from 3 of 15 patients not receiving lactobacilli (P less than 0.001). Gram-negative enteric organisms were isolated during 40 of the 86 weeks (47%) of hospitalization for patients receiving lactobacilli and during 28 of 57 weeks (49%) for patients not receiving lactobacilli. There was no significant difference between the study groups in the number of resistant organisms or in the proportion of resistant organisms per gram-negative enteric isolates (4 of 40 vs. 0 of 28). These results suggest that facultative gram-negative enteric bacterial colonization, with either total or aminoglycoside-resistant strains, is not decreased by oral feedings of Lactobacillus acidophilus in premature infants.

Synergy between penicillins and low concentrations of gentamicin in the killing of group B streptococci.

Antimicrobial sensitivity, synergy, and timed-killing assays were determined for 20 strains of group B streptococci isolated from cultures of blood and cerebrospinal fluid (CSF) of infected neonates. The mean minimal inhibitory concentrations by the tube-dilution method were as follows: penicillin, 0.02 microgram/ml; ampicillin, 0.05 microgram/ml; and gentamicin, 4.5 micrograms/ml. No synergy was detected with any combination of penicillin or ampicillin and gentamicin by the checkerboard titration method. Killing kinetics were determined for combinations of penicillin or ampicillin and gentamicin at low concentrations of these antibiotics comparable to those attained in the CSF following systemic administration of these antibiotics. Addition of 0.1 microgram and 0.5 microgram of gentamicin/ml to penicillin or ampicillin significantly accelerated the killing of group B streptococci. Despite the "poor" permeation of gentamicin into the CSF, the accelerated killing of streptococci at low concentrations of this antibiotic provides a rationale for the initial use of a combination of penicillin or ampicillin and gentamicin in the treatment of group B streptococcal meningitis.

New approach to management of unilateral tension pulmonary interstitial emphysema in premature infants.

Conservative management of unilateral tension pulmonary interstitial emphysema is reported. Treatment consisted of (1) positioning the infant on his or her side with the emphysematous lung dependent, (2) minimal chest physiotherapy and endotracheal suctioning, and (3) appropriate ventilator management. Conservative therapy is effective and appears to be safer than selective bronchial intubation or surgical therapy.

Oxygen consumption of infants with respiratory distress syndrome.

The objective of this research was to determine the oxygen consumption of newborn infants with respiratory distress syndrome in the first 4 days of life. Serial determinations of oxygen consumption were made in 14 infants with respiratory distress syndrome receiving positive end-expiratory pressures. The mean (+/- SE) oxygen consumption determined at 24, 48, 72, and 96 h postnatal age were 8.3 +/- 0.9, 6.5 +/- 0.8, 5.5 +/- 0.5, and 5.3 +/- 0.6 ml/min/kg, respectively. The level of oxygen consumption at 24 h postnatal age was significantly greater than the levels determined at 48, 72, and 96 h (p less than 0.03). The oxygen levels found at 72 and 96 h of age were comparable to those determined for healthy preterm infants. A linear regression of serial oxygen consumption and weight loss yielded a 'fair' (r = 0.5) correlation with a significant inference (p less than 0.01).