Active Precipitation of Radiation Belt Electrons Using Rocket Exhaust Driven Amplification (REDA) of Man-Made Whistlers

Ground-based very low frequency (VLF) transmitters located around the world generate signals that leak through the bottom side of the ionosphere in the form of whistler mode waves. Wave and particle measurements on satellites have observed that these man-made VLF waves can be strong enough to scatter trapped energetic electrons into low pitch angle orbits, causing loss by absorption in the lower atmosphere. This precipitation loss process is greatly enhanced by intentional amplification of the whistler waves using a newly discovered process called rocket exhaust driven amplification (REDA). Satellite measurements of REDA have shown between 30 and 50 dB intensification of VLF waves in space using a 60 s burn of the 150 g/s thruster on the Cygnus satellite that services the International Space Station. This controlled amplification process is adequate to deplete the energetic particle population on the affected field lines in a few minutes rather than the multi-day period it would take naturally. Numerical simulations of the pitch angle diffusion for radiation belt particles use the UCLA quasi-linear Fokker Planck model to assess the impact of REDA on radiation belt remediation of newly injected energetic electrons. The simulated precipitation fluxes of energetic electrons are applied to models of D-region electron density and bremsstrahlung X-rays for predictions of the modified environment that can be observed with satellite and ground-based sensors.

Cumulative illness severity and progression from moderate to severe retinopathy of prematurity

OBJECTIVE

To test cumulative neonatal illness severity (IS) and IS fluctuation as predictors of progression from moderate to severe retinopathy of prematurity (ROP).

METHODS

Data from research databases and medical record review were collected for infants from four neonatal intensive care unit (NICUs) admitted between 1995 and 2001 and diagnosed with prethreshold ROP. Cumulative neonatal IS measured using daily Scores for Neonatal Acute Physiology (SNAP) for the first 28 days of life, and IS fluctuation as assessed by summing changes between daily SNAP scores, were tested as predictors of progression to threshold ROP using logistic regression.

RESULTS

Infants progressing to threshold (n=79), compared to those not progressing to threshold (n=130), had significantly (P<0.05) lower gestational ages (25.2+/-1.1 versus 25.8+/-1.4 weeks), higher cumulative neonatal SNAP (255+/-77 versus 224+/-63 weeks) and had more severe hospitalizations as indicated by diagnoses and medical management. In regression analysis, gestational age, chronological age and presence of plus disease at first diagnosis of prethreshold were associated with development of threshold. After adjusting for these factors, cumulative neonatal SNAP was significantly associated with progression to threshold. However, addition of cumulative SNAP to the model only increased receiver-operating characteristic curve area from 0.77 to 0.78 (NS). Other factors, including SNAP fluctuation, were not associated with progression to threshold after adjustment using this model.

CONCLUSIONS

Cumulative neonatal IS, as measured by cumulative SNAP, is an independent risk factor for progression from moderate to severe ROP. However, cumulative IS does not enhance assessment of risk for ROP progression after adjusting for simpler clinical factors.

The primary amine metabolite of sibutramine stimulates lipolysis in adipocytes isolated from lean and obese mice and in isolated human adipocytes

Sibutramine is a satiety-inducing serotonin-noradrenaline reuptake inhibitor that acts predominantly via its primary and secondary metabolites. This study investigates the possibility that sibutramine and/or its metabolites could act directly on white adipose tissue to increase lipolysis. Adipocytes were isolated by a collagenase digestion procedure from homozygous lean (+/+) and obese-diabetic OB/OB mice, and from lean nondiabetic human subjects. The lipolytic activity of adipocyte preparations was measured by the determination of glycerol release over a 2-hour incubation period. The primary amine metabolite of sibutramine M2, caused a concentration-dependent stimulation of glycerol release by murine lean and obese adipocytes (maximum increase by 157+/-22 and 245+/-16%, respectively, p<0.05). Neither sibutramine nor its secondary amine metabolite M1 had any effect on lipolytic activity. Preliminary studies indicated that M2-induced lipolysis was mediated via a beta-adrenergic action. The non-selective beta-adrenoceptor antagonist propranolol (10 (-6) M) strongly inhibited M2-stimulated lipolysis in lean and obese murine adipocytes. M2 similarly increased lipolysis by isolated human omental and subcutaneous adipocytes (maximum increase by 194+/-33 and 136+/-4%, respectively, p<0.05) with EC50 values of 12 nM and 3 nM, respectively. These results indicate that the sibutramine metabolite M2 can act directly on murine and human adipose tissue to increase lipolysis via a pathway involving beta-adrenoceptors.

Association between variants in the genes for adiponectin and its receptors with insulin resistance syndrome (IRS)-related phenotypes in Mexican Americans

AIMS/HYPOTHESIS

The aim of this study was to examine whether genetic variation in ADIPOQ, ADIPOR1 and ADIPOR2 may contribute to increased susceptibility to components of the insulin resistance syndrome (IRS).

MATERIALS AND METHODS

We genotyped single-nucleotide polymorphisms (SNPs) in ADIPOQ, ADIPOR1 and ADIPOR2 in Mexican American subjects (N=439) and performed an association analysis of IRS-related traits.

RESULTS

Of the eight SNPs examined in the ADIPOQ gene, rs4632532 and rs182052 exhibited significant associations with BMI (p=0.029 and p=0.032), fasting specific insulin (p=0.023 and p=0.026), sum of skin folds (SS) (p=0.0089 and p=0.0084) and homeostasis model assessment of insulin sensitivity (HOMA-%S) (p=0.015 and p=0.016). Two other SNPs, rs266729 and rs2241767, were significantly associated with SS (p=0.036 and p=0.013). SNP rs7539542 of ADIPOR1 was significantly associated with BMI, SS and waist circumference (p=0.025, p=0.047 and p=0.0062). Fourteen of the ADIPOR2 SNPs were found to be significantly (p<0.05) associated with fasting plasma triglyceride concentrations. Four of these SNPs (rs10848569, rs929434, rs3809266 and rs12342) were in high pairwise linkage disequilibrium (r (2)=0.99) and were strongly associated with fasting triglyceride levels (p=0.00029, p=0.00016, p=0.00027 and p=0.00021). Adjusting for the effects of BMI and HOMA-%S on triglyceride concentrations increased significance to p=0.000060 for SNP rs929434. Bayesian quantitative trait nucleotide analysis was used to examine all possible models of gene action. Again, SNP rs929434 provided the strongest statistical evidence of an effect on triglyceride concentrations.

CONCLUSIONS/INTERPRETATION

These results provide evidence for association of SNPs in ADIPOQ and its receptors with multiple IRS-related phenotypes. Specifically, several genetic variants in ADIPOR2 were strongly associated with decreased triglyceride levels.

Moderately premature infants at Kaiser Permanente Medical Care Program in California are discharged home earlier than their peers in Massachusetts and the United Kingdom

OBJECTIVE

To compare gestational age at discharge between infants born at 30-34(+6) weeks gestational age who were admitted to neonatal intensive care units (NICUs) in California, Massachusetts, and the United Kingdom.

DESIGN

Prospective observational cohort study.

SETTING

Fifty four United Kingdom, five California, and five Massachusetts NICUs.

SUBJECTS

A total of 4359 infants who survived to discharge home after admission to an NICU.

MAIN OUTCOME MEASURES

Gestational age at discharge home.

RESULTS

The mean (SD) postmenstrual age at discharge of the infants in California, Massachusetts, and the United Kingdom were 35.9 (1.3), 36.3 (1.3), and 36.3 (1.9) weeks respectively (p = 0.001). Compared with the United Kingdom, adjusted discharge of infants occurred 3.9 (95% confidence interval (CI) 1.4 to 6.5) days earlier in California, and 0.9 (95% CI -1.2 to 3.0) days earlier in Massachusetts.

CONCLUSIONS

Infants of 30-34(+6) weeks gestation at birth admitted and cared for in hospitals in California have a shorter length of stay than those in the United Kingdom. Certain characteristics of the integrated healthcare approach pursued by the health maintenance organisation of the NICUs in California may foster earlier discharge. The California system may provide opportunities for identifying practices for reducing the length of stay of moderately premature infants.

Unstudied infants: outcomes of moderately premature infants in the neonatal intensive care unit

BACKGROUND

Newborns of 30-34 weeks gestation comprise 3.9% of all live births in the United States and 32% of all premature infants. They have been studied much less than very low birthweight infants.

OBJECTIVE

To measure in-hospital outcomes and readmission within three months of discharge of moderately premature infants.

DESIGN

Prospective cohort study including retrospective chart review and telephone interviews after discharge.

SETTING

Ten birth hospitals in California and Massachusetts.

PATIENTS

Surviving moderately premature infants born between October 2001 and February 2003.

MAIN OUTCOME MEASURES

(a) Occurrence of assisted ventilation during the hospital stay after birth; (b) adverse in-hospital outcomes-for example, necrotising enterocolitis; (c) readmission within three months of discharge.

RESULTS

With the use of prospective cluster sampling, 850 eligible infants and their families were identified, randomly selected, and enrolled. A total of 677 families completed a telephone interview three months after hospital discharge. During the birth stay, these babies experienced substantial morbidity: 45.7% experienced assisted ventilation, and 3.2% still required supplemental oxygen at 36 weeks. Readmission within three months occurred in 11.2% of the cohort and was higher among male infants and those with chronic lung disease.

CONCLUSIONS

Moderately premature infants experience significant morbidity, as evidenced by high rates of assisted ventilation, use of oxygen at 36 weeks, and readmission. Such morbidity deserves more research.

[Assessing the impact of delivery unit size on neonatal survival: estimation of potentially avoidable deaths in Hessen, Germany, 1990-2000]

BACKGROUND AND OBJECTIVE

There are only few analyses from Germany on the impact of delivery unit size on neonatal outcome. The objective of this study was to evaluate the influence of delivery unit size on neonatal survival in Germany.

PATIENTS AND METHODS

Data from the perinatal birth register for Hessen for 1990-2000 comprising 640554 births, and the Neonatal Survey for 1989-1997 in Hessen were used. Potentially avoidable deaths were assessed according to delivery unit size and birth weight category. Additionally trend analyses and an extrapolation to potentially avoidable deaths in all of Germany were performed.

RESULTS

Compared to large delivery units, smaller ones showed higher risk adjusted mortality rates. Calculation of potentially avoidable deaths gave an estimate of 257 early neonatal deaths in 11 years. Although trend analyses revealed a decline of potentially avoidable deaths, an extrapolation of such deaths for all of Germany still yielded an estimate of more than 300 potentially avoidable deaths per year using data from 1997-2000 only.

CONCLUSION

A valid inference as to the magnitude of the observed effect remains even in the face of a very cautious interpretation of our results. During the study period of 11 years, more than 200 neonatal deaths could be attributed to the fact that births in Hessen are dispersed among many small hospitals. If this pattern of births in small units is common throughout Germany, it suggests that several hundred neonatal deaths per year may be attributed to this risk factor when extrapolating these results nationally. Further research is necessary to describe the nation-wide magnitude of this problem and to identify the role of underlying causal risk factors more precisely. Additionally policy discussions regarding structural changes in obstetrical care should be undertaken in the meantime, aimed at reducing the observed mortality rates.

Inter-neonatal intensive care unit variation in discharge timing: influence of apnea and feeding management

BACKGROUND

Premature infants need to attain both medical stability and maturational milestones (specifically, independent thermoregulation, resolution of apnea of prematurity, and the ability to feed by mouth) before safe discharge to home. Current practice also requires premature infants to be observed in hospital before discharge for several days (margin of safety) after physiologic maturity is recognized.

OBJECTIVE

To compare postmenstrual age (PMA) at discharge in a homogeneous population of premature infants cared for in different neonatal intensive care units (NICUs) and to assess the impact on hospital stay of the recognition and recording of physiologic maturity and the required margin of safety.

METHODS

We studied premature infants delivered at 30 to 34 6/7 weeks gestational age (GA), free of significant medical or surgical complications. Medical records of 30 eligible infants consecutively discharged from the hospital before July 1997 from each of 15 NICUs in Massachusetts (9 level 2 and 6 level 3) were reviewed.

RESULTS

A total of 435 infants were included in the study sample. Mean (+/- standard deviation) GA and birth weight of the study population were 33.2 +/- 1.2 weeks and 2024 +/- 389 g, respectively. Infants were discharged at a similar PMA regardless of GA at birth. Considerable variation in the PMA at discharge between hospital sites was observed (range, 35.2 +/- 0.5 weeks to 36.5 +/- 1.2 weeks). Despite the homogeneous study population, hospitals in which infants had the latest PMA at discharge also recorded mature cardiorespiratory and feeding behavior at an older age. Longer duration of pulse oximetry use was associated with later resolution of apnea. Differences in the duration of the margin of safety between sites did not contribute to variation in hospital stay.

CONCLUSION

NICUs vary widely in length of hospital stay for healthy premature infants. We speculate that this variation results in part from differences in monitoring for and documentation of apnea of prematurity and feeding behavior.

Variations in prevalence of hypotension, hypertension, and vasopressor use in NICUs

OBJECTIVE

Very low birth weight infants are vulnerable to hypotension and its associated complications. Vasopressors are used to raise blood pressure (BP), but indications for use are uncertain. Our objectives were (1) to study variations in BP stability among NICUs, (2) to investigate inter-NICU differences in vasopressor use, and (3) to address the association between intraventricular hemorrhage (IVH) and abnormal BPs.

STUDY DESIGN

A total of 1288 infants with birth weight <1500 g were admitted to six NICUs in Massachusetts and Rhode Island over 21 months. The lowest and highest mean BPs were collected within the first 12 hours. Also recorded were the use of vasopressors within the first 24 hours and the occurrence of IVH. Logistic regressions were used to model outcomes, controlling for gestational age and illness severity using the Score for Neonatal Acute Physiology.

RESULTS

Two of the six NICUs had significantly higher percentages of infants with at least one hypotensive BP, with prevalences of 24% to 45%. Percentages of infants treated with vasopressors ranged from 4% to 39%. This range of vasopressor use could not be explained by inter-NICU differences in birth weight, illness severity, or rates of hypotension. We found a borderline association between severe IVH and hypotension (odds ratio 1.6, p=0.055), but not between severe IVH and hypertension.

CONCLUSION

Wide differences exist in the prevalence of hypotension, hypertension, and vasopressor use among NICUs. We also found an association between hypotension and IVH, but not between hypertension and IVH.

SNAP-II and SNAPPE-II: Simplified newborn illness severity and mortality risk scores

OBJECTIVES

Illness severity scores for newborns are complex and restricted by birth weight and have dated validations and calibrations. We developed and validated simplified neonatal illness severity and mortality risk scores. The primary outcome was in-hospital mortality.

STUDY DESIGN

Thirty neonatal intensive care units in Canada, California, and New England collected data on all admissions during the mid 1990s; patients moribund at birth or discharged to normal newborn care in <24 hours were excluded. Starting with the 34 data elements of the Score for Neonatal Acute Physiology (SNAP), we derived the most parsimonious logistic model for in-hospital mortality using 10,819 randomly selected Canadian cases. SNAP-II includes 6 physiologic items; to this are added points for birth weight, low Apgar score, and small for gestational age to create a 9-item SNAP-Perinatal Extension-II (SNAPPE-II). We validated SNAPPE-II on the remaining 14,610 cases and optimized the calibration.

RESULTS

In all birth weights, SNAPPE-II had excellent discrimination and goodness of fit. Area under the receiver operator characteristic curve was .91 +/- 0.01. Goodness of fit (Hosmer-Lemeshow) was 0.90.

CONCLUSIONS

SNAP-II and SNAPPE-II are empirically validated illness severity and mortality risk scores for newborn intensive care. They are simple, accurate, and robust across populations.

A critical review of cost reduction in neonatal intensive care. II. Strategies for reduction

Neonatal intensive care is extremely expensive; there is both a financial and an ethical obligation to practice efficiently. In the current era of intense cost containment in hospital care, neonatologists and hospital administrators are under pressure to find strategies for cost reduction for neonatal services. In this review, we address reducing discretionary admissions, the high costs of low-cost testing, minimizing use of selected high-cost technologies (ventilators and parenteral nutrition), shortening length of stay, and optimizing nursing allocation.

A critical review of cost reduction in neonatal intensive care. I. The structure of costs

Neonatal intensive care is expensive. In the current era of intense cost containment in hospital care, neonatologists and hospital administrators are under intense pressure to find strategies for cost reduction for neonatal services. Few neonatal clinicians are trained in economics, management, or accounting, and few hospital administrators are familiar with neonatal intensive care. In this review, we describe the structure and sources of hospital costs and the accounting systems needed to isolate and measure such costs. We discuss where efficiencies might be found and consider specific issues in capitated settings such as health maintenance organizations in the United States, the Canadian health care system and the National Health System in the United Kingdom.

Relationship of race and severity of neonatal illness

OBJECTIVE

Our goal was to determine whether there are racial differences in the severity of illness on admission for premature newborn infants independent of gestational age.

STUDY DESIGN

The study population consisted of all African American and Caucasian singleton infants with gestational ages <34 weeks who were admitted to the neonatal intensive care unit at Brigham and Women's Hospital between December 1994 and November 1995. Illness severity was measured with a neonatal severity of illness score, the SNAP score (Score for Neonatal Acute Physiology). The SNAP score is a physiologic scoring system that ranks the worst physiologic derangements in each organ system in the first 12 hours of life. It is an objective measure of neonatal illness severity with scores ranging from 0 (healthy) to 42 (most severely ill). Student t tests, chi(2) analysis, and Fisher exact tests were used to assess statistical significance. Linear and logistic regression analyses were used to examine associations while confounding factors were controlled for.

RESULTS

There were 129 (79%) Caucasian and 36 (22%) African American newborns included in the analysis. Caucasian newborns had significantly higher mean SNAP scores than African American newborns (8.8 vs. 6.3; P <.05). Compared with African American newborns, Caucasian newborns were more than twice as likely to have a SNAP score >10 (33% vs. 14%; P <.05). In a linear regression analysis in which we controlled for gestational age, birth weight, preterm premature rupture of membranes, preterm labor, preeclampsia, intrapartum fever > or =100.4 degrees F, route of delivery, and other maternal and fetal factors, African American newborns were predicted to have a SNAP score that was on average 3.0 points lower than that of Caucasian newborns (P =.005). In a logistic regression in which we controlled for the above-mentioned confounders, African American newborns were only 14% as likely to have a SNAP score >10 when compared with Caucasian newborns (odds ratio, 0.14; 95% confidence interval, 0.04-0.51).

CONCLUSIONS

Over a broad range of prematurity, Caucasian newborns were more ill than African American newborns on admission to the neonatal intensive care unit.

SNAP-II and SNAPPE-II: Simplified newborn illness severity and mortality risk scores

OBJECTIVES

Illness severity scores for newborns are complex and restricted by birth weight and have dated validations and calibrations. We developed and validated simplified neonatal illness severity and mortality risk scores. The primary outcome was in-hospital mortality.

STUDY DESIGN

Thirty neonatal intensive care units in Canada, California, and New England collected data on all admissions during the mid 1990s; patients moribund at birth or discharged to normal newborn care in <24 hours were excluded. Starting with the 34 data elements of the Score for Neonatal Acute Physiology (SNAP), we derived the most parsimonious logistic model for in-hospital mortality using 10,819 randomly selected Canadian cases. SNAP-II includes 6 physiologic items; to this are added points for birth weight, low Apgar score, and small for gestational age to create a 9-item SNAP-Perinatal Extension-II (SNAPPE-II). We validated SNAPPE-II on the remaining 14,610 cases and optimized the calibration.

RESULTS

In all birth weights, SNAPPE-II had excellent discrimination and goodness of fit. Area under the receiver operator characteristic curve was .91 +/- 0.01. Goodness of fit (Hosmer-Lemeshow) was 0.90.

CONCLUSIONS

SNAP-II and SNAPPE-II are empirically validated illness severity and mortality risk scores for newborn intensive care. They are simple, accurate, and robust across populations.

Economics of prematurity in the era of managed care

Both the acute intensive care of premature infants and the management of their long-term medical and educational sequelae are costly. Because neonatal intensive care is very effective in reducing mortality, however, its cost effectiveness as described previously is actually quite favorable when compared with other well-accepted medical interventions, such as coronary artery bypass grafting and renal dialysis. This article has highlighted the relatively scant literature on which those estimates of costs and cost effectiveness of both neonatal intensive care and its component interventions rest. This is particularly true with respect to long-term resource use by graduates of NICUs. Without such information, we cannot hope to allocate resources in a way that ensures optimal care of this vulnerable population.

Cost-effectiveness and implications of newborn screening for prolongation of QT interval for the prevention of sudden infant death syndrome

OBJECTIVE

To determine the cost-effectiveness of universal and high-risk neonatal electrocardiographic (ECG) screening for QT prolongation as a predictor of sudden infant death syndrome (SIDS) risk in a theoretical group of neonates.

STUDY DESIGN

Incremental cost-effectiveness analysis with decision analytic modeling. A hypothetical cohort of healthy, term infants was modeled, comparing options of no screening, high-risk neonate screening, and universal screening. The high-risk strategy is speculative, because no currently accepted methodology is known for identifying infants at high risk for SIDS. Given the uncertain mechanisms of association between prolonged corrected QT interval (QTc) and SIDS, analyses were repeated under different assumptions. Sensitivity analyses were also performed on all input variables for both costs and effectiveness.

RESULTS

Under the assumption that neonatal electrocardiographic screening detects long QT syndrome responsive to conventional therapy, the cost-effectiveness of high-risk screening was $3403 per life year gained, whereas universal screening cost $18,465 per additional life year gained. However, if the effectiveness of SIDS therapy falls below 10%, the cost-effectiveness deteriorates to $28,376 per life year saved for the high-risk strategy and $118,900 for universal screening. The analyses were robust to a broad array of sensitivity analyses.

CONCLUSIONS

The acceptability of the cost-effectiveness of neonatal electrocardiographic screening is heavily dependent on the pathophysiologic mechanism of SIDS and on the efficacy of monitoring and antiarrhythmic treatment. The nature of this association must be elucidated before routine neonatal electrocardiographic screening is warranted.

Variation in the use of alternative levels of hospital care for newborns in a managed care organization

OBJECTIVE(S)

To assess the extent to which variation in the use of neonatal intensive care resources in a managed care organization is a consequence of variation in neonatal health risks and/or variation in the organization and delivery of medical care to newborns.

STUDY DESIGN

Data were collected on a cohort of all births from four sites in Kaiser Permanente by retrospective medical chart abstraction of the birth admission. Likelihood of admission into a neonatal intensive care unit (NICU) is estimated by logistic regression. Durations of NICU stays and of hospital stay following birth are estimated by Cox proportional hazards regression.

RESULTS

The likelihood of admission into NICU and the duration of both NICU care and hospital stay are proportional to the degree of illness and complexity of diagnosis. Adjusting for variation in health risks across sites, however, does not fully account for observed variation in NICU admission rates or for length of hospital stay. One site has a distinct pattern of high rates of NICU admissions; another site has a distinct pattern of low rates of NICU admission but long durations of hospital stay for full-term newborns following NICU admission as well as for all newborns managed in normal care nurseries.

CONCLUSIONS

Substantial variations exist among sites in the risk-adjusted likelihood of NICU admission and in durations of NICU stay and hospital stay. Hospital and NICU affiliation (Kaiser Permanente versus contract) or affiliation of the neonatologists (Kaiser Permanente versus contract) could not explain the variation in use of alternative levels of hospital care. The best explanation for these variations in neonatal resource use appears to be the extent to which neonatology and pediatric practices differ in their policies with respect to the management of newborns of minimal to moderate illness.

Intrapartum maternal fever and neonatal outcome

OBJECTIVE

Much of fever during term labor may not be infectious but rather a consequence of the use of epidural analgesia. Therefore, we investigated the association of elevated maternal intrapartum temperature with neonatal outcome when the infant does not develop an infection.

METHODS

We studied 1218 nulliparous women with singleton, term pregnancies in a vertex presentation and spontaneous labor. Women were excluded if their temperature was >99.5 degrees F at admission for delivery, if they were diabetic or had an active genital herpes infection or if their infant developed a neonatal infection, had a congenital infection, or had a major malformation. Maximum intrapartum temperature was categorized as: </=100.4 degrees F (afebrile), 100.5 degrees F to 101 degrees F, and >101 degrees F.

RESULTS

During labor, 123 women (10.1%) developed a fever >100.4 degrees F; 62 (5.1%) women had a maximum temperature of 100.5 degrees F to 101 degrees F and 61 (5.0%) women had a maximum temperature >101 degrees F. Of febrile women, 97.6% had received epidural analgesia for pain relief. Infants of women developing a fever >100.4 degrees F were more likely to have a 1-minute Apgar score <7 (22.8% for >100.4 degrees F vs 8.0% for afebrile) and to be hypotonic after delivery (4.8% for >100.4 degrees F vs.5% for afebrile). Compared with infants of afebrile women, infants whose mothers' maximum temperature was >101 degrees F were more likely to require bag and mask resuscitation (11.5% vs 3.0%) and to be given oxygen therapy in the nursery (8.2% vs 1.3%). We also found a higher rate of neonatal seizure with fever (3.3% vs.2%), but the number of infants with seizure was small (n = 4). All associations remained essentially the same after controlling for confounding in logistic regression analyses.

CONCLUSIONS

Intrapartum maternal fever, particularly if >101 degrees F, was associated with a number of apparently transient adverse effects in the newborn. Larger studies are needed to investigate the association of intrapartum fever with neonatal seizures and to determine whether any lasting injury to the fetus may occur.

Occurrence of nosocomial bloodstream infections in six neonatal intensive care units

BACKGROUND

Nosocomial bloodstream infections (NBSIs) occur frequently in neonatal intensive care units (NICUs) and are associated with substantial morbidity and mortality. Little has been published regarding variation in NBSI among institutions.

OBJECTIVE

To determine NBSI incidence among six NICUs and to explore how much variation is explained by patient characteristics and NICU practice patterns.

METHODS

From October, 1994, to June, 1996, six regional NICUs prospectively abstracted clinical records of all neonates weighing <1,500 g. Occurrence of NBSI, defined as first positive culture occurring >48 h after admission, was analyzed in relation to baseline patient characteristics and several common therapeutic interventions. Variables significant in univariate analyses were analyzed by Cox proportional hazards regression.

RESULTS

There were 258 NBSIs (incidence, 19.1%) among 1,354 inborn first admissions. Incidence varied significantly by site, from 8.5 to 42%. Birth weight, Broviac catheter use and parenteral nutrition were significantly associated with NBSI (P < 0.05). When controlling for these variables interinstitutional variation in NBSI occurrence decreased but remained significant.

CONCLUSIONS

Neonatal NBSI incidence varies substantially among institutions despite adjustment for length of stay and some known risk factors. The uses of Broviac catheters and especially intravenous nutrition supplements were significant determinants of NBSI risk.

Responsibilities, roles & staffing patterns of nurse practitioners in the neonatal intensive care unit

PURPOSE

To describe the unique contribution of the NP in caring for critically ill infants through the study of NP responsibilities, roles, staffing patterns, and patient profiles.

DESIGN

This prospective descriptive study was conducted in conjunction with a regional multi-site outcomes study.

METHODS

Data were collected at five regional level II/III NICUs in Massachusetts and Rhode Island. Twenty-two NPs were surveyed. Existing data on outcomes of 2,146 very low birth weight infants were used to describe patient profiles. NP care was defined as assignment to an NP at admission. Illness severity was measured using the Score of Neonatal Acute Physiology (SNAP).

RESULTS

NP roles included all levels of NICU care as well as antepartal consultation, delivery room management, transport, and outpatient follow-up. NPs were equally involved with patients of all degrees of complexity and birthweights. Patient assignments were most often made by a rotational system with the resident/fellow or by complexity of infant with the NP in some NICUs caring for sicker smaller babies.

CLINICAL IMPLICATIONS

This study documents a blended model of NP MD care in the NICU with each provider bringing unique strengths to the team. Nurse practitioners working in the NICU provide an invaluable contribution in terms of parent support and teaching, post NICU follow-up care, and professional education and research. The NP role in the NICU should not be viewed as a substitution for resident physicians.

Perinatal risk and severity of illness in newborns at 6 neonatal intensive care units

OBJECTIVES

This multisite study sought to identify (1) any differences in admission risk (defined by gestational age and illness severity) among neonatal intensive care units (NICUs) and (2) obstetric antecedents of newborn illness severity.

METHODS

Data on 1476 babies born at a gestational age of less than 32 weeks in 6 perinatal centers were abstracted prospectively. Newborn illness severity was measured with the Score for Neonatal Acute Physiology. Regression models were constructed to predict scores as a function of perinatal risk factors.

RESULTS

The sites differed by several obstetric case-mix characteristics. Of these, only gestational age, small for gestational age. White race, and severe congenital anomalies were associated with higher scores. Antenatal corticosteroids, low Apgar scores, and neonatal hypothermia also affected illness severity. At 2 sites, higher mean severity could not be explained by case mix.

CONCLUSIONS

Obstetric events and perinatal practices affect newborn illness severity. These risk factors differ among perinatal centers and are associated with elevated illness severity at some sites. Outcomes of NICU care may be affected by antecedent events and perinatal practices.

Characterization of the triage process in neonatal intensive care

OBJECTIVE

Despite intense interest in allocation of resources to neonatal intensive care, no description exists of resource use by the large numbers of newborns admitted for triage, the process of short-term evaluation and management of infants after delivery. This study characterized the triage phase of neonatal care with respect to infant demographics, risk factors for illness, and the course of the hospital admission. We hypothesized that triage infants were responsible for a significant fraction of total intensive care resource utilization, and that patterns of use were predictable.

DESIGN

Cross-sectional cost analysis of prospectively collected data.

PARTICIPANTS

Data were collected prospectively on 2486 inborn infants admitted to two neonatal intensive care units (NICUs) for <24 hours and subsequently discharged to routine care. Over the 11-month study period, these two hospitals delivered 15 097 live births and admitted a further 1837 infants for nontriage NICU care.

INTERVENTIONS

On a 50% random subsample, we calculated severity of illness using the Score for Neonatal Acute Physiology (SNAP) and applied a NICU resource checklist. Daily NICU workload was estimated according to the number and labor intensity of NICU admissions using Medicus and SNAP. Charges were obtained from patient-level item charge records and converted to costs using Medicare ratios of costs to charges. Length of stay (LOS) and costs for triage were correlated with diagnoses, perinatal descriptors, severity of illness, and markers of concurrent NICU workload using stepwise regression.

RESULTS

Mean birth weight for triage infants was 3367 g (standard deviation, 600 g) and mean gestational age 39.1 weeks (standard deviation, 1.8 weeks). The predominant reasons for evaluation were exclusion of sepsis (34%), birth complications including meconium aspiration, perinatal depression and trauma (24%), and transitional respiratory distress (23%). Severity illness, as measured by SNAP, was minimal, with 70% having scores of 0, indicating no derangement. Only 6% experienced depressed 5-minute Apgar scores (<7), and 80% required no delivery room resuscitation. The most frequent forms of resource use were antibiotic administration (34%), placement of a peripheral intravenous line (40%), cardiac monitoring (53%) and external warming (26%). Median LOS was 102 minutes, corresponding over the study period to 2% of total NICU hours but 7% of NICU days charged. Median cost was $870, with aggregate costs accounting for a total of 9.5% of total NICU costs. In the multivariate model, LOS was increased by respiratory diagnosis or hypoglycemia, severity of illness, lower gestational age, the need for intravenous placement, daytime shift, hospital, and lower acuity of concurrent NICU admissions (R2 = 0.24).

CONCLUSIONS

Neonatal triage is a low-acuity but time-intensive process that contributes significantly to total resource use by newborns because of the large numbers of infants involved. Both LOS and costs are affected not only by infant medical characteristics but also by nonmedical markers of unit structure, which may be amenable to change. This source of resource consumption should be recognized in future assessments of costs associated with neonatal intensive care.

Variations in blood transfusions among newborn intensive care units. SNAP II Study Group

OBJECTIVES

Very low birth weight (< 1500 g) infants frequently require packed red blood cell transfusions, and transfusion rates vary among neonatal intensive care units (NICUs). We analyzed transfusions and compared outcomes among NICUs.

STUDY DESIGN

In a 6-site prospective study, we abstracted all newborns weighing < 1500 g (total = 825) born between October 1994 and September 1995. Transfusion frequency and volume and phlebotomy number were analyzed by site and adjusted for birth weight and illness severity. We compared rates of intraventricular hemorrhage, necrotizing enterocolitis, bronchopulmonary dysplasia, growth, and length of stay between the high and low transfuser NICUs.

RESULTS

Sites differed significantly in mean birth weight, illness severity, number of transfusions, pretransfusion hematocrit, blood draws, and donor number. Multivariate adjustment for these risks showed that the highest transfusing NICU transfused an additional 24 cc/kg per baby during the first 14 days and 47 cc/kg per baby after 15 days, relative to the lowest transfusing NICU. The presence of arterial catheters increased the frequency of blood transfusions. The rates of intraventricular hemorrhage, necrotizing enterocolitis, and bronchopulmonary dysplasia were not higher in the 2 lowest transfusing NICUs, nor were there differences in 28-day weight gain or length of stay.

CONCLUSIONS

Major differences in transfusion practices for very low birth weight infants exist among NICUs. Because clinical outcomes were no different in lower transfuser NICUs, it is likely that transfusion and phlebotomy guidelines could result in fewer transfusions, fewer complications, and reduced cost.

Declining severity adjusted mortality: evidence of improving neonatal intensive care

OBJECTIVES

Declines in neonatal mortality have been attributed to neonatal intensive care. An alternative to the "better care" hypothesis is the "better babies" hypothesis; ie, very low birth weight infants are delivered less ill and therefore have better survival.

DESIGN

We ascertained outcomes of all live births <1500 g in two prospective inception cohorts. We estimated mortality risk from birth weight and illness severity on admission and measured therapeutic intensity. We calculated logistic regression models to estimate the changing odds of mortality between cohorts.

PATIENTS AND SETTING

Two cohorts in the same two hospitals, 5 years apart (1989-1990 and 1994-1995) (total n = 739).

RESULTS

Neonatal intensive care unit mortality declined from 17.1% to 9.5%, and total mortality declined from 31.6% to 18.4%. Cohort 2 had lower risk (higher birth weight, gestational age, and Apgar scores and lower admission illness severity for newborns >/=750 g). Risk-adjusted mortality declined (odds ratio, 0.52; confidence interval, 0.29-0. 96). One third of the decline was attributable to "better babies" and two thirds to "better care." Use of surfactant, mechanical ventilation, and pressors became more aggressive, but decreases in monitoring, procedures, and transfusions resulted in little change in therapeutic intensity.

CONCLUSIONS

Mortality decreased nearly 50% for infants <1500 g in 5 years. One third of this decline is attributable to improved condition on admission that reflects improving obstetric and delivery room care. Two thirds of the decline is attributable to more effective newborn intensive care, which was associated with greater aggressiveness of respiratory and cardiovascular treatments. Attribution of improved birth weight specific mortality solely to neonatal intensive care may underestimate the contribution of high-risk obstetric care in providing "better babies."

Neonatal risk scoring systems. Can they predict mortality and morbidity?

Physiology-based illness severity scores are proving their value through a wide variety of practical applications. The theoretical disadvantages noted in Table 1 have not turned out to be major problems, whereas the advantages have been quite real. Numerous studies have reported insightful comparisons between treatment groups, between NICUs, between countries, between eras, and over the course of care. Many institutions have implemented routine collection of physiology-based newborn scores. The answer to the question posed in the title is yes; neonatal risk scoring systems can predict some mortality and some morbidity. However, it is clear that this function is much less important than their application as a means of improving quality and cost. Future development will depend on commercially viable applications.

Variation among neonatal intensive care units in narcotic administration

OBJECTIVES

To compare rates of narcotic administration for medically treated neonates in different neonatal intensive care units (NICUs) and to compare treated and untreated neonates to assess whether narcotics provided advantages or disadvantages for short-term outcomes, such as cardiovascular stability (ie, blood pressure and heart rate), hyperbilirubinemia, duration of respiratory support, growth, and the incidence of intraventricular hemorrhage.

STUDY DESIGN

The medical charts of neonates weighing less than 1500 g, admitted to 6 NICUs (A-F), were abstracted. Neonates who had a chest tube or who had undergone surgery were excluded from the study, leaving the records of 1171 neonates. We modeled outcomes by linear or logistic regression, controlling for birth weight (<750, 750-999, and 1000-1499 g) and illness severity (low, 0-9; medium, 10-19; high, > or =20) using the Score for Neonatal Acute Physiology (SNAP), and adjusted for NICU.

RESULTS

Narcotic use varied by birth weight (<750 g, 21%; 750-999 g, 13%; and 1000-1499 g, 8%), illness severity (low, 9%; medium, 19%; and high, 37%), day (1, 11%; 3, 6%; and 14, 2%), and NICU. We restricted analyses to the 1018 neonates who received mechanical ventilation on day 1. Logistic regression, adjusting for birth weight and SNAP, confirmed a 28.6-fold variation in narcotic administration (odds ratios, 4.1-28.6 vs NICU A). Several short-term outcomes also were associated with narcotic use, including more than 33 g of fluid retention on day 3 and a higher direct bilirubin level (6.8 micromol/L higher [0.4 mg/dL higher], P = .03). There were no differences in weight gain at 14 and 28 days or mechanical ventilatory support on days 14 and 28. Narcotic use was not associated with differences in worst blood pressure or heart rate or with increased length of hospital stay.

CONCLUSIONS

Our study found a 28.6-fold variation among NICUs in narcotic administration in very low-birth-weight neonates. We were unable to detect any major advantages or disadvantages of narcotic use. We did not assess iatrogenic abstinence syndrome or long-term outcomes. These results indicate the need for randomized trials to rationalize these widely differing practices.

Outcome prediction in Greek neonatal intensive care units using a score for neonatal acute physiology (SNAP)

OBJECTIVES

This study was undertaken to evaluate the performance of the score for neonatal acute physiology (SNAP) in Greece, to examine the predictive power of SNAP calculated during the 12 hours after admission in comparison with customarily calculated SNAP during the first 24 hours, and to assess SNAP during the second 12 hours from admission as a measure of response to treatment.

METHODOLOGY

A total of 579 newborns admitted to three neonatal intensive care units (NICUs) from two cities in Greece were enrolled in the study; SNAP was determined during the first 12 hours, the second 12 hours, and the first 24 hours from admission to the NICU and calculated using an algorithm based on deviations from normal values of 26 physiologic parameters.

RESULTS

All three variants of SNAP were powerful predictors of vital status at discharge, as well as of duration of stay among survivors. A five-point increase in SNAP in the first 12 hours corresponds to a more than twofold ratio in the odds for death, whereas a five-unit difference in SNAP from the second 12 hours corresponds to a more than threefold ratio. The combined 24-hour score was similar to that for the first 12 hours. A considerable advantage of SNAP was its independence from more traditional predictors of neonatal death, notably gestational age, birth weight, and Apgar score. The combination of all of these predictors improved further the overall predictive potential.

CONCLUSIONS

SNAP is a useful tool in medical research and can be applied in different population groups. Its independence from birth weight underlines its added value to predict fatality ratios. Moreover, the results of the present study indicate that SNAP can be estimated without loss of predictive efficiency during the first 12 hours from admission to the NICU, whereas SNAP during the second 12 hours adequately reflects the effectiveness of early medical interventions.

Variations in transfusion practice in neonatal intensive care

OBJECTIVE

To compare the transfusion practices between two neonatal intensive care units (NICUs) to assess the impact of local practice styles on the timing, number, and total volume of packed red cell transfusions in very low birth weight infants. To derive multivariate models to describe practice and to identify potential areas for improvement in the future.

METHODOLOGY

We reviewed phlebotomy losses and transfusion rates between two NICUs (A and B) for 270 consecutive admissions of birth weight < 1500 g. We stratified for birth weight and for illness severity by the Score for Neonatal Acute Physiology (SNAP). Measures of short-term outcome were compared. We derived multivariate models to describe and compare the practices in the two NICUs.

RESULTS

Patients in NICU A had smaller phlebotomy losses than those in NICU B. A lower percentage of the patients in NICU A (65% vs 87%) received transfusions, but they tended to receive a greater total volume per kg per patient (67 mL/kg vs 54.8 mL/kg). Transfusion timing differed between the NICUs; in NICU A only approximately one-half of their transfusions occurred in the first 2 weeks, whereas in NICU B almost 70% of the transfusions were given in this time period. Multivariate models showed that phlebotomy losses were significantly related to lower gestational age (GA) and higher SNAP. Hospitalization in NICU B resulted in 10.7 cc of additional losses relative to NICU A for a comparable GA and illness severity score. The volume of blood transfused per kilogram of body weight was a function of GA, SNAP, and hospital. Care practices in NICU A added an additional 19 cc of transfused volume in the first 14 days of life, and an additional 26 cc thereafter when adjusted for GA and SNAP. These differences in phlebotomy and transfusion were not associated with differences in the days of oxygen therapy or mechanical ventilation, the oxygen requirement at 28 days, the incidence of chronic lung disease, or the rate of growth by day 28.

CONCLUSIONS

We identified significant differences in phlebotomy and transfusion practices between two NICUs. We found no differences in short-term outcome, suggesting that the additional use of blood in one of the NICUs was discretionary rather than necessary. Our multivariate models can be used to characterize and quantify transfusion and phlebotomy practices. By predicting which patients are likely to require multiple transfusions, clinicians can target patients for erythropoietin therapy and identify those patients for whom donor exposure can be reduced by a unit of blood for multiple use. The models may help in monitoring changes in practice as they occur.

Intravenous lipid emulsions are the major determinant of coagulase-negative staphylococcal bacteremia in very low birth weight newborns

BACKGROUND

Intravenous lipid emulsions and the i.v. catheters through which they were administered were the major risk factors for nosocomial coagulase-negative staphylococcal (CONS) bacteremia among newborns in our neonatal intensive care units a decade ago. However, medical practice is changing, and these and other interventions may have different effects in the current setting.

OBJECTIVES

We determined the independent risk factors for CONS bacteremia in current very low birth weight newborns after adjusting for severity of underlying illness.

METHODS

We surveyed 590 consecutively admitted newborns with birth weights < 1500 g hospitalized in 2 neonatal intensive care units and conducted a case-control study in a sample of 74 cases of CONS bacteremia and 74 pairs of matched controls. Adjusted relative odds of bacteremia were estimated for a number of attributes and therapeutic interventions in 2 time intervals before CONS bacteremia: any time before bacteremia and the week before bacteremia.

RESULTS

Using conditional logistic regression to adjust for indicators of severity of illness, two procedures were independently associated with subsequent risk of CONS bacteremia at any time during hospitalization: i.v. lipids, odds ratio (OR) = 9.4 [95% confidence interval (CI) 1.2 to 74.2]; and any surgical or percutaneously placed central venous catheter, OR = 2.0 (95% CI 1.1 to 3.9). Considering only the week immediately preceding bacteremia, the independent risk factors were: mechanical ventilation, OR = 3.2 (95% CI 1.3 to 7.6); and short peripheral venous catheters, OR = 2.6 (95% CI 1.0 to 6.5).

CONCLUSIONS

During the last decade exposure to i.v. lipids any time during hospitalization has become an even more important risk factor for CONS bacteremia (OR = 9.4). Of these bacteremias 85% are now attributable to lipid therapy. In contrast the relative importance of intravenous catheters as independent risk factors has declined. Mechanical ventilation in the week before bacteremia has emerged as a risk factor for bacteremia.

Cost-effectiveness of fetal lung maturity testing in preterm labor

OBJECTIVE

To determine the marginal cost-effectiveness of two strategies for preventing respiratory distress syndrome (RDS) resulting from preterm birth: 1) tocolysis with beta-mimetic agonists and treatment with corticosteroids (TREATALL), and 2) amniocentesis and testing for fetal lung maturity, with treatment based on test results (TESTALL), compared with no treatment.

METHODS

We used a Markov decision analytic model to estimate the outcomes of each strategy, from a hospital-based perspective. Probability variables were obtained from the literature, whereas cost variables came from the Beth Israel-Deaconess Medical Center. Sensitivity analysis was performed on all variables.

RESULTS

The most cost-effective strategy varied with the probability of RDS. TREATALL was the most cost-effective strategy above a probability of 17% (before 34 weeks' gestation), TESTALL was most cost-effective from 17% to 2% (34-36 weeks), and it was most cost-effective to use no treatment at probabilities less than 2% (after 36 weeks). TREATALL and TESTALL were both cost-saving compared with no treatment at probabilities of RDS above 2%. TREATALL was more highly favored as the costs of RDS and preterm birth increased, whereas TESTALL was more favored as the specificity of the test and the cost of maternal hospitalization increased.

CONCLUSION

Although testing for fetal lung maturity is useful in many clinical situations, the cost-effectiveness of such testing in the setting of idiopathic preterm labor from a tertiary medical center perspective depends primarily on the probability and costs of RDS and the costs of non-RDS-related morbidity. At our institution, such testing is cost-effective between 34 and 36 weeks' gestation.

Physician variations and the ancillary costs of neonatal intensive care

OBJECTIVE

To determine to what degree attending physicians contribute to cost variations in the care of ventilator-dependent newborns.

DATA SOURCES

Clinical data were merged with hospital financial data describing daily ancillary care costs during the first two weeks of life for 132 extremely low-birthweight newborns. In addition, each patient's chart was reviewed and illness severity graded using both SNAP and CRIB scores.

STUDY DESIGN

This was a retrospective cohort of infants with birth weights of less than 1,001 grams and respiratory distress syndrome requiring mechanical ventilation in the first day of life. From birth up to two weeks of life, each received care directed by only one of 11 faculty neonatologists in a single university hospital. Data were analyzed stratified by these physicians. t-Test, ANOVA, and chi-square were used to assess bivariate data. For continuous data, log linear regressions were used.

PRINCIPAL FINDINGS

After controlling for illness severity, when stratified by physicians, there were significant variances in the costs of ancillary resources for the study infants (p < .0001). Twenty-nine percent of the variance was attributable to whether or not the hospital day included the use of a ventilator. Physician identity explained only 5.6 percent (p < .0001).

CONCLUSIONS

Physician identity was significant but explained less than 6 percent of the total variance in ancillary costs. Whether or not a ventilator was used during care was far more important. We conclude that for very sick babies during the first two weeks of care, reducing variations in ancillary services utilization among neonatologists will yield only modest savings.

Epidural analgesia, intrapartum fever, and neonatal sepsis evaluation

OBJECTIVE

Although several studies have documented an increase in maternal temperature associated with use of epidural analgesia during labor, none have investigated the impact of epidural use on the rate of intrapartum fever or the consequences for the fetus and newborn of this elevated maternal temperature. This study evaluates the impact of epidural analgesia use during labor on the rate of intrapartum fever and the performance of neonatal sepsis evaluations and treatment with antibiotics.

METHODS

We studied 1657 nulliparous women with term pregnancies and singleton vertex fetuses who were afebrile at admission for delivery. The rates of maternal intrapartum fever >100.4 degrees F, neonatal sepsis evaluation, and neonatal antibiotic treatment according to use of epidural analgesia during labor were determined. Rate ratios and 95% confidence intervals (CI) were calculated. Multiple logistic regression was used to examine associations while controlling for confounding factors.

RESULTS

Intrapartum fever >100.4 degrees F occurred in 14.5% of women receiving an epidural but only 1.0% of women not receiving an epidural (adjusted odds ratio (OR) = 14.5, 95% CI = 6.3, 33.2). Without epidural, the rate of fever remained low regardless of length of labor; with epidural, the rate of fever increased from 7% for labors < or = 6 hours to 36% for labors >18 hours. Neonates whose mothers received epidurals were more often evaluated for sepsis (34.0% vs 9.8%; adjusted OR = 4.3, 95% CI = 3.2, 5.9) and treated with antibiotics (15.4% vs 3.8%; adjusted OR = 3.9, 95% CI = 2.1, 6.1). Although 63% of women received epidurals, 96.2% of intrapartum fevers, 85.6% of neonatal sepsis evaluations, and 87.5% of neonatal antibiotic treatment occurred in the epidural group.

CONCLUSIONS

Use of epidural analgesia during labor is strongly associated with the occurrence of maternal intrapartum fever, neonatal sepsis evaluations, and neonatal antibiotic treatment.

Racial differences in the predictive value of the TDx fetal lung maturity assay

OBJECTIVE

Black newborns have lower rates of neonatal respiratory distress syndrome compared with nonblack newborns. This has been attributed to accelerated lung maturation. Previous studies have demonstrated a difference in the predictive value of the lecithin/sphingomyelin ratio, a test for lung maturity, between races. Our study examines the predictive value of the newer TDx Fetal Lung Maturity Surfactant-to-Albumin assay.

STUDY DESIGN

We reviewed the records of 393 nonblack and 87 black infants delivered within 72 hours of the TDx FLM S/A assay testing. We compared the rates of neonatal respiratory distress syndrome by race, stratified by results.

RESULTS

In our study population black newborns had less than one half the rate of respiratory distress syndrome compared with nonblack newborns (4.6% vs 10.4%). To adjust for possible differences in the timing of lung maturation, the results were stratified by the TDx FLM S/A assay result. Black race had a protective effect (Mantel-Haenszel weighted odds ratio 0.30, 95% confidence interval 0.06 to 0.93, p < 0.05). This significant racial difference remained when both TDx FLM S/A assay result and gestational age were controlled in a multiple logistic regression analysis.

CONCLUSIONS

There are differences in the predictive value of the TDx FLM S/A assay among races. Black fetuses are less likely to have respiratory distress syndrome. The difference in rates of respiratory distress syndrome between races must be due to either a qualitative difference in the surfactant or to an anatomic difference in fetal lungs. Consideration should be given to a lower cutoff value for a mature test result in black women.

Normal birth weight intensive care unit survivors: outcome assessment

RATIONALE/OBJECTIVE: Although the short- and long-term outcome of low birth weight neonatal intensive care unit (NICU) survivors has been extensively studied, much less information is available for normal birth weight (NBW) infants (greater than or equal to 2500 g) who require NICU care.

METHODS

To address this issue, we retrospectively examined the neonatal hospitalizations and 6-month health status of 521 consecutive NBW admissions to a single NICU. Information on the neonatal hospitalization was obtained from a review of medical records. Postdischarge health status was collected by using telephone survey techniques.

RESULTS

NBW infants comprised 88.1% of births in this hospital and 35.4% of NICU admissions during the study period. The in-hospital mortality rate for this group was 2%. The median length of stay was 7.7 days (range 1 to 110 days) with median hospital charges of $5222 (range $565 to $317,820). Only 59% of infants required active intensive care therapy; the remainder received only intensive monitoring. The need for intensive therapy on admission day along with the presence of prematurity and congenital anomalies were significant predictors of hospital charges (R2 = 0.31, P < .01). After initial discharge, 10.1% of these infants required rehospitalization in the first 6 to 8 months of life. The rate of readmission among infants with congenital anomalies was over 30%. In addition to its association with neonatal resource consumption, the presence of congenital anomalies along with low 5-minute Apgar scores was associated with higher postdischarge resource use, as measured by frequency of physician visits, need for special medical items, and rate of rehospitalization (P < .05).

CONCLUSIONS

NBW infants represent a significant percentage of NICU admissions, but for many of these patients NICU admission could be avoided if alternative care settings that provided intensive monitoring were available. In addition, these infants also incur higher rates of postdischarge use of medical care.

Prediction of respiratory distress syndrome by the novel dipalmitoyl phosphatidylcholine test

OBJECTIVE

To determine the accuracy of a new test that measures the concentration in amniotic fluid (AF) of dipalmitoyl phosphatidylcholine (DPPC) in predicting respiratory distress syndrome (RDS).

METHODS

The neonatal respiratory status of 176 newborns delivered within 72 hours of sampling was correlated with the concentration of DPPC, fluorescence polarization (TDx-FLM), lecithin-sphingomyelin ratio (L/S), and phosphatidyl-glycerol (Amniostat-FLM) in AF.

RESULTS

Thirty infants developed RDS (17%), all correctly predicted with DPPC values less than 12 micrograms/mL (sensitivity 100%). Only six of the 146 cases with no RDS had DPPC values less than 12 micrograms/mL (specificity 96%). The overall accuracy of the DPPC test was 98% compared with 70% for TDx-FLM, 71% for the L/S, and 67% for Amniostat-FLM. Receiver operating characteristic analysis area was 0.98 +/- 0.01, indicating that the DPPC test is superior to both the TDx-FLM and L/S tests.

CONCLUSION

The DPPC test is an accurate predictor of RDS and fetal lung maturity.

Outcomes of severely abnormal umbilical artery doppler velocimetry in structurally normal singleton fetuses

OBJECTIVE

To construct a management guide for preterm pregnancies complicated by severely abnormal umbilical artery Doppler velocimetry.

METHODS

A retrospective chart review was conducted on all cases of absent or reversed end-diastolic flow umbilical artery Doppler velocimetry identified through an ultrasound data base. Maternal and perinatal outcome variables were retrospectively reviewed and analyzed using both parametric and nonparametric statistical techniques. Seventy-one cases were identified over a 5-year period. After excluding multiple gestations, anomalous fetuses, and two cases that were terminated before 24 weeks' gestation, 56 singleton gestations remained for analysis.

RESULTS

Among the 56 subjects, there were 45 survivors and 11 deaths (five fetal and six neonatal deaths). Nonsurvivors had a significantly lower gestational age at diagnosis and delivery. Nonsurviving live-born neonates had lower Apgar scores and were significantly smaller; however, there were no differences in proportion or severity of fetal growth restriction in survivors and nonsurvivors. There were no differences in last biophysical profile before delivery or interval from diagnosis of reversed end-diastolic flow to delivery. Predictors of nonsurvival were the presence of reversed end-diastolic flow and oligohydramnios. Perinatal mortality for reversed end-diastolic flow was 333/1000 and 94/1000 for absent end-diastolic flow. Risk for perinatal death was highly gestational age dependent. For delivery at less than 26 weeks, survival was one of four; at 26-27.9 weeks, survival was seven of 12; and at 28 weeks or greater, survival was 37 of 40.

CONCLUSION

Whereas severely abnormal umbilical artery blood flow poses significant risk for pregnancy, perinatal mortality is dominated by gestational age at diagnosis and delivery. This may reflect the severity of the disease or the low survival of very immature gestations. Interventions on behalf of the fetus at very early gestational ages should be undertaken with caution.

Prediction of fetal lung maturity in infants of diabetic mothers using the FLM S/A and disaturated phosphatidylcholine tests

The authors evaluated the performance of the amniotic fluid surfactant to albumin ratio (FLM S/A), and disaturated phosphatidylcholine (DSPC) tests in assessing fetal lung maturity in infants of mothers with insulin-dependent diabetes mellitus antedating pregnancy. The distribution of the study population (n = 180) by class of diabetes was class B (27%); class C (28%); class D (29%); class F, FR and T (8%); and class R patients (8%). The diagnosis of respiratory distress syndrome (RDS) was the standard for evaluating the performance of FLM S/A and DSPC. The mean estimated gestational age was 37.4 weeks. Three infants (1.7%) were diagnosed with RDS. All three were delivered before 36 weeks. FLM S/A at the cut-off for "maturity" of > or = 70 mg/g, had a sensitivity of 66.6%, specificity of 94.9%, positive predictive value (PPV) of 18.2%, and negative predictive value (NPV) of 99.4%. DSPC at the cut-off for "maturity" of 1,000 micrograms/dL, had identical sensitivity and NPV, but lower specificity (89.2%) and PPV (9.5%) than FLM S/A. Both tests mispredicted maturity in the same case of RDS. The false "mature" rate of FLM S/A was 0.6% (95% confidence interval 0.0%-3.2%). The FLM S/A result of > or = 70 mg/g, obtained at or near-term, is a reliable predictor of the absence of RDS in infants of mothers with diabetes mellitus antedating pregnancy.

Perinatal regionalization versus hospital competition: the Hartford example

OBJECTIVES

The increasingly competitive health care environment may undermine effective traditional regional organizations. It is urgent to document the benefits of perinatal regionalization for the emerging health care system. We present a case study that illustrates many of the challenges to and benefits of perinatal regionalization in the 1990s.

BACKGROUND

The controversy in Hartford was sparked by a proposed merger of two major pediatric services into a full-service children's hospital. Community hospitals reacted with plans to upgrade their obstetrics/neonatal facilities toward level II (intermediate) or II+ (intensive) neonatal intensive care units (NICUs). The fear that unrestricted competition would drive up overall health care costs prompted the hospital association and Chamber of Commerce to retain consultants to evaluate the number and location of regional NICU beds.

METHODS

The consultant team interviewed stake-holders in area hospitals, health maintenance organizations, insurance companies, businesses, state agencies, and community groups, and analyzed quantitative data on newborn discharges.

RESULTS

The existing system worked remarkably well for clinical care, training, referrals, and provider and patient satisfaction. There was a high level of inter-hospital collaboration and regional leadership in obstetrics and pediatrics, but strong and growing competition between their hospitals. Hospital administrators enumerated the competitive threats that obligated them to compete and the financial disincentives to support the regional structures. Business leaders and insurance executives emphasized the need to control costs. Analysis of discharge data showed marginal adequacy of NICU beds but maldistribution between NICUs, particularly between level III and level II units. The consultants recommended no new beds based on population projections, declining lengths of stay nationally, and substantial gains available from aggressive back-transport of convalescing infants. The consultants emphasized the need for all stakeholders to support the regional infrastructure (referral, transport, education, evaluation, quality assurance) and to modify competition when it impaired effective regionalization.

CONCLUSIONS

Regionalization permits better care at lower cost, yet competition may disrupt this effective system. Active cooperation by stakeholders is vital. Substantial new research is required to define optimal regional organization.

Management of infection and occlusion associated with vascular access devices

OBJECTIVE

To provide an overview of the etiology, assessment, diagnosis, and management of infections and occlusions that occur with venous access devices (VADs).

CONCLUSIONS

The two major complications of VADs are infections and occlusions. Several strategies have been attempted to prevent and treat infections and occlusions; however, one specific method has yet to be determined. As a result, major controversies exist regarding the best method to manage these complications. Controlled randomized studies are needed to examine each type of VAD in relation to preventive and treatment strategies.

IMPLICATIONS FOR NURSING PRACTICE

Preservation of VADs demands the development of and adherence to specific guidelines for maintenance care as well as an awareness of the incidence, presentation, and management of complications. Clearly, prevention is the key to effective management of infection and occlusion associated with VADs. Nurses must be familiar with institutional policies and procedures for the care of VADs.

Coagulase-negative staphylococcal bacteremia among very low birth weight infants: relation to admission illness severity, resource use, and outcome

OBJECTIVE

To examine the impact of admission-day illness severity on nosocomial bacteremia risk after consideration of traditional risk determinants such as birth weight and length of stay.

METHODS

The hospital courses for 302 consecutive very low birth weight (less than 1500 g) infants admitted to two neonatal intensive care units were examined for the occurrence of nosocomial coagulase-negative staphylococcal bacteremia. Using both cumulative incidence and incidence density as measures of bacteremia risk, we explored the relation between illness severity (as measured by the Score for Neonatal Acute Physiology [SNAP]) and bacteremia both before and after birth weight adjustment. In addition, the effect of bacteremia on hospital resource use was estimated.

RESULTS

Coagulase-negative staphylococcus was the most common pathogen noted in blood cultures drawn at 48 hours after admission or later. It was isolated on at least one occasion in 53 patients (cumulative incidence of 17.5 first episodes per 100 patients). These episodes occurred during 7652 days at risk, giving an incidence density of 6.9 initial bacteremias per 1000 patient-days at risk. As expected, when compared with the nonbacteremic group, bacteremic patients were of lower birth weight (888 +/- 231 vs 1127 +/- 258 g; P < .01) and gestational age (26.4 +/- 2.1 vs 28.9 +/- 2.8 weeks; P < .01). In addition, these patients were more severely ill on admission (SNAP 17.3 +/- 6.5 vs 12.2 +/- 5.8; P < .01). Even after birth weight stratification, the risk of bacteremia by both measures increased with higher SNAP scores. For example, among infants with birth weights greater than 1 kg, 25% of the most severely ill patients (SNAP 20 and higher) experienced at least one bacteremic episode, whereas the rates seen in infants with intermediate (SNAP 10 to 19) and low illness severity (SNAP 0 to 9) were 8.6% and 3.0%, respectively (chi 2 for trend = 7.25; P < .01). Multivariate linear regression showed that bacteremia was associated with a prolongation of neonatal intensive care unit stay of 14.0 +/- 4.0 days (P < .01) and an increase in hospital charges of $25,090 +/- 12,051 (P < .05), even after adjustment for birth weight and admission-day SNAP.

CONCLUSIONS

Nosocomial coagulase-negative bacteremia is an important complication among very low birth weight infants. Assessment of illness severity with SNAP provides information regarding nosocomial infection risk beyond that available from birth weight alone.

Access to neonatal intensive care

The birth of a high-risk infant is still a relatively rare, not totally predictable event; and the management of high-risk newborns requires highly skilled personnel and sophisticated technology. In the early days of neonatal intensive care, scarce resources led to regionalized systems of neonatal and, later, perinatal services, generally based on voluntary agreements but sometimes reinforced by planning legislation. At present, a vastly increased pool of skilled professionals and technical resources is available in the context of a rapidly changing medical care system characterized by intense competition, coalescence of services under large managed care plans, and substantial cost pressures. The evidence suggests that, in many areas, these forces have led to the dismantling of regional networks; however, the full potential for these changes to hinder or facilitate access to neonatal intensive care remains to be assessed.

Estimating neonatal mortality risk: an analysis of clinicians' judgments

BACKGROUND

Clinicians' estimates of mortality risk in the neonatal intensive care unit (NICU) have implications for patient triage, transfer, initiation and termination of life support, and allocation of medical resources. The accuracy of these judgments has not been studied, nor the differences between nurses and attending physicians.

OBJECTIVES

1) evaluate the accuracy of subjective judgments of NICU unit mortality risk, 2) identify the key components of clinician judgments, 3) compare accuracy between attending physicians and nurses, and 4) examine the utility of combining an objectively computed risk and clinician judgments to improve predictions.

METHODS

We obtained estimates of mortality risk on 544 admissions to two NICUs on the day of admission from the attending physician and primary nurse. These were compared with an objective computed mortality risk based on birth weight and the Score for Neonatal Acute Physiology (SNAP) using a linear judgment analysis model, as well as with actual outcomes.

RESULTS

Physicians and nurses had good discriminating power with actual mortality rates ranging from 0% among low risk patients to 67% among those with the highest mortality estimates. Physicians had a tendency to overestimate mortality risk. Clinicians base their estimates on the same factors and similar judgment weights as the empiric mortality risk model (22% birth weight, 62% illness severity (SNAP), 13% low Apgar, and 3% for intrauterine growth restriction). Clinicians place additional emphasis on therapeutic as well as physiologic factors. When the computed risk and physician judgment were combined, both made significant contributions in a logistic mortality risk model.

CONCLUSIONS

Clinician judgments of mortality risk are fairly accurate and similar to an objective illness severity index. This simple method provides insight into clinical decision making and has important applications in improving direct patient care, appropriate allocation of medical resources, and medical training.

Racial differences in predictive value of the lecithin/sphingomyelin ratio

OBJECTIVE

Blacks are known to have lower rates of respiratory distress syndrome when rates are adjusted for gestational age and to be more responsive to antenatal glucocorticoid administration compared with nonblacks. These observations have been attributed to acceleration of the timing of lung maturation. An alternative hypothesis is that there are qualitative differences in the surfactants between races.

STUDY DESIGN

We reviewed the medical records of a cohort of 702 nonblack and 135 black infants delivered within 72 hours of lecithin/sphingomyelin ratio testing from the presurfactant era and compared respiratory outcome stratified by lecithin/sphingomyelin ratio.

RESULTS

Black newborns had less than one third the rate of respiratory distress syndrome (2.2% vs 8.0%, p < 0.01). To adjust for possible differences in maturational timing between races, the results were stratified by lecithin/sphingomyelin ratio. There were no cases of respiratory distress syndrome among black infants with a lecithin/sphingomyelin ratio > 1.2. The protective effect was evident across all strata of lecithin/sphingomyelin ratios (odds ratio 0.25, p = 0.04). Parallel, highly significant reductions in non-respiratory distress syndrome pulmonary morbidity were also noted across all strata of lecithin/sphingomyelin ratios (odds ratio 0.35, p = 0.02).

CONCLUSIONS

These differences in the predictive value of the lecithin/sphingomyelin ratio suggest that protection from respiratory distress syndrome must depend on factors independent of the ratio and that these factors differ between races. They also suggest that clinical interpretation of test results may be different between races.