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.

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.

Normal birth weight intensive care unit survivors: outcome assessment.

UNLABELLED: 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.

Neonatal therapeutic intervention scoring system: a therapy-based severity-of-illness index.

Severity-of-illness scales have proven valuable in assessing clinical outcomes and resource consumption in adult and pediatric intensive care, but they have been less extensively developed for neonatal care. The National Therapeutic Intervention Scoring System (NTISS) was created by modifying the Therapeutic Intervention Scoring System (TISS). From the 76 original TISS items, 42 were deleted and 28 added to form the NTISS. Like TISS, NTISS assigns score points from 1 to 4 for various intensive care therapies. Admission-day NTISS scores were calculated for 1643 newborns admitted to three neonatal intensive care units (NICUs) between November 1, 1989, and September 30, 1990. NTISS scores ranged from 0 to 47 with a mean of 12.3 +/- 8.7 (SD). There was little correlation with birth weight (r = -.11) or gestational age (r = -.17), but NTISS scores were highly correlated with expected markers of illness severity, including mortality risk estimates by neonatal attending physicians (r = .70, P < .0001), in-hospital mortality rates (P < .05), and a measure of nursing acuity (Medicus) (r = .69, P < .0001). In addition, admission-day NTISS scores were found to be predictive of both NICU length of stay (r = .37, P < .0001) and total hospital charges for survivors (r = .65, P < .0001). It is concluded that NTISS is a valid measure of therapeutic intensity that is independent of birth weight and can be used as an indicator of neonatal illness severity and resource utilization. Further validation in other NICUs is required.

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.

Score for Neonatal Acute Physiology: a physiologic severity index for neonatal intensive care.

The substantial variation in birth weight-adjusted mortality among neonatal intensive care units (NICUs) may reflect differences in population illness severity. Development of an illness severity measure is essential for comparisons of outcomes. The Score for Neonatal Acute Physiology (SNAP) was developed and validated prospectively on 1643 admissions (114 deaths) in three NICUs. SNAP scores the worst physiologic derangements in each organ system in the first 24 hours. SNAP showed little correlation with birth weight and was highly predictive of neonatal mortality even within narrow birth weight strata. It was capable of separating patients into groups with 2 to 20 times higher mortality risk. It also correlated highly with other indicators of severity including nursing workload (r = .59), therapeutic intensity (r = .78), physician estimates of mortality risk (r = .65), and length of stay (R2 = .59). SNAP is an important new tool for NICU research.

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.

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: 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.

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."

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.

Birth weight and illness severity: independent predictors of neonatal mortality.

BACKGROUND: Low birth weight is a major determinant of neonatal mortality. Yet birth weight, even in conjunction with other demographic markers, is inadequate to explain the large variations in neonatal mortality between intensive care units. This variation probably reflects differences in admission severity. The authors have recently developed the Score for Neonatal Acute Physiology (SNAP), an illness severity index specific for neonatal intensive care, and demonstrated illness severity to be a major determinant of neonatal mortality. OBJECTIVE: To define the relative contributions of birth weight and illness severity to the risk of neonatal mortality and to identify other significant independent risk factors. METHODS: Logistic regression was used to analyze data from a cohort of 1621 consecutive admissions to three neonatal intensive care units (92 deaths), to test six alternative predictive models. The best logistic model was then used to develop a simple additive clinical score, the SNAP Perinatal Extension (SNAP-PE). RESULTS: These analyses demonstrated that birth weight and illness severity are powerful independent predictors across a broad range of birth weights and that their effects are additive. Below 750 g, there is an interaction between birth weight and SNAP. Other factors that showed independent predictive power were low Apgar score at 5 minutes and small size for gestational age. Separate derivation and test samples were used to demonstrate that the SNAP-PE is comparable to the best logistic model and has a sensitivity and specificity superior to either birth weight or SNAP alone (receiver-operator characteristic area .92 +/- .02) as well as excellent goodness of fit. CONCLUSION: This simplified clinical score provides accurate mortality risk estimates for application in a broad array of clinical and research settings.

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.

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.

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.

Insulin response in skeletal muscle and fat cells of the genetically obese Zucker rat.

Isolated fat cells derived from 10-wk-old Zucker obese rats utilized substantially greater amounts of glucose per cell in the presence or absence of insulin than those from lean rats. Initial rates of deoxyglucose or 3-0-methylglucose uptake in fat cells from Zucker obese rats were also 5--10 times greater than those observed in cells from lean rats. However, while 240 microU/ml insulin elicited a maximal response in fat cells from lean rats, this dose of hormone was only about 50% as effective as 24 microU/ml insulin in stimulating glucose metabolism or hexose transport in obese rat cells. This apparent rightward shift in the dose response-relationship could not be adequately explained on the basis of decreased insulin receptors since (125I-) insulin binding per fat cell was increased 2.5--3-fold in obesity, while receptor density on the cell surface in obesity was decreased only slightly. Soleus muscles from obese Zucker rats exhibited decreased basal rates of D(5-3H)glucose conversion to glycogen and H2O compared to those of lean controls. While the percent increase in glucose metabolism due to a supermaximal dose of insulin was similar in soleus muscles of lean and obese Zucker rats, a blunted response to a submaximal insulin dose was observed in muscles from the latter animals. This rightward shift in the dose-response relationship was also observed when deoxyglucose uptake was monitored in soleus muscles from obese rats. Binding of (1251-) insulin to soleus muscles at a medium concentration of 57 microU/ml was significantly decreased in obese compared to lean rats. We conclude that (1) fat cells do not contribute to the insulin resistance of 10-wk obese Zucer rats since glucose utilization is higher in these cells at all concentrations of insulin tested, (2) obese Zucker rat soleus muscle metabolism is defective in two respects--imparied basal glucose utilization and a rightward shift in the insulin dose-response relationship with respect to hexose transport, and (3) this latter defect involving decreased sensitivity of muscle to insulin appears to result from a marked decrease in cell surface receptors for the hormone.

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.

Decision analysis of high-risk patient referral.

Decisions to refer obstetric patients are often complicated by social and financial considerations as well as medical risks. To study such decisions, 600 Fellows of the American College of Obstetricians and Gynecologists were studied using a new decision analysis technique. It was found that obstetricians base their referrals predominantly on medical factors, but that other considerations can affect a close decision. Physicians differed on their indications to refer, as well as on the weight placed on some factors. Such differences could not be explained by age, training, or practice characteristics. Studying the referral process is important because successful regionalization depends on appropriate referral.

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.