Score For Neonatal Acute Physiology Research Articles

First Month Physiologic Instability is Associated with Neurodevelopmental Morbidity at Two Years in Extremely Premature Infants. ♦ 1211

Extreme prematurity is associated with adverse neurodevelopmental outcomes, which may be due to chronic physiologic instability. We correlated 28 day cumulative scores for neonatal acute physiology (SNAP) with 1 and 2 yr developmental outcomes in infants ≤ 30 weeks gestational age (GA). Daily SNAP scores were summed over the first 28 days in 96 infants (mean GA 27.3± 1.6 wks and birthweight 1085 ± 271g). The mental and psychomotor indices (MDI and PDI) of the Bayley Scales of Infant Development(II) were administered at 1 and 2 yrs of age; the Receptive-Expressive Emergent Language Scale (REEL) was administered at 2 yrs of age. Infants were ranked by 28 day SNAP scores and grouped by quartiles. Outcomes were compared using ANOVA. Higher 28 day SNAP scores were associated (p<0.05) with lower MDI (1 and 2 yrs), PDI (1 and 2 yrs), and increased incidence of combined neurodevelopmental morbidity (see table). REEL and 28 day SNAP scores were not correlated. Using stepwise regression analyses, 28 day SNAP and intracranial anomalies (ICA), but not GA, were predictors of 1 yr MDI and 1 and 2 yr PDI. For 2 yr MDI, only 28 day SNAP scores were a significant predictor. GA was not a significant cofactor in any analysis.

EFFECT OF NEONATAL LYMPHOCYTES UPON THE GROWTH OF CANDIDA ALBICANS. † 1343

In critically ill preterm infants, fungal infections produce significant morbidity and mortality. Human adult lymphocytes activated by interleukin-2(IL-2) inhibit the growth of the hyphal form of Candida albicans. We hypothesized that activated lymphocytes from infants with higher severity of illness scores would be less effective in suppressing candidal growth. Methods: Lymphocytes were isolated from adult peripheral blood and cord blood of term and preterm infants by differential centrifugation and placed in RPMI-1640 medium with IL-2 (1000 u/ml) for 5 days. The lymphocytes were then incubated with the hyphal form of C. albicans for 3 hrs. Growth inhibition of the fungal hyphae was assessed by [3H]uridine incorporation. Severity of illness was determined within the first 24 hrs of admission to the NICU by use of the Score for Neonatal Acute Physiology(SNAP). Results: Lymphocytes obtained from 36 preterm and term infants demonstrated less (P<0.05) growth inhibition of C. albicans than did lymphocytes from adult blood. In addition, cord blood from female infants had a greater (P<0.05) inhibitory effect than did that from male infants. An inverse relationship (r=-0.412; P<0.02) was found between SNAP and lymphocyte inhibition of candidal growth (i.e., infants with higher SNAPs had the least antifungal activity). Conclusion: We conclude that neonatal lymphocytes are deficient in anti-candidal activity compared to adult lymphocytes. Further, the most severely ill infants were the least capable of mounting effective lymphocyte mediated antifungal activity. This deficiency may contribute to the increased susceptibility to candidal infections in critically ill preterm infants. Supported by: AI-31127 and NR-00085.

Mortality Prediction in Very Low Birth Weight Infants At Days 3 and 14.• 1154

Objective: Prediction of subsequent mortality among very low birth weight infants (<1500 grams) on days of life 3 and 14 using the Score for Neonatal Acute Physiology (SNAP) and traditional risk factors.

Neonatal Sepsis: Effect on Protein and Energy Metabolism † 1405

Protein catabolism and oxygen consumption are increased in septic adults in proportion to degree of illness. Inflammatory cytokines are thought to mediate proteolysis to maintain synthesis of acute phase proteins (e.g. C-reactive protein [CRP]) during sepsis. Septic neonates have immature immunologic responses characterized by elevated IL-6, but not tumor necrosis factor (TNF) levels. To study the impact of sepsis on cytokines and protein metabolism in neonates, we studied 25 newborns (36±3 wks EGA; 2910±840g) divided into three groups: Group 1 (septic, positive blood culture [BC]), Group 2 (sick, negative BC), Group 3 (healthy, rule out sepsis). Infants had oxygen consumption (VO2 [mL/kg/min]), 6 hour nitrogen balance (N Bal[g/kg/d]), urinary 3-methyl Histidine/Creatinine (3MH/Cr), serum TNF & IL-6 (pg/mL), CRP (mg/dL), and Score for Neonatal Acute Physiology (SNAP) measured at 12-36 hours after onset of illness. Data are mean±SD.Table

Effect of maternal depression on premature infant health during initial hospitalization

This study evaluates the effect of maternal depression on neonatal health status in premature infants during their initial hospitalization. Infants younger than 34 weeks' gestation born to nondrug abusing mothers were enrolled in the study. Thirty-one mother-infant pairs were identified. Maternal depression was evaluated by the Center for Epidemiologic Studies-Depression Scale (CES-D). Scores > or = 16 defined maternal depression. Initial infant physiologic health status was determined by the Score for Neonatal Acute Physiology (SNAP). In-hospital health status was assessed by the following variables: days receiving supplemental oxygen, days on mechanical ventilation (VENT), and days not on enteral feeding (NPO). Health status variables evaluated for long-term outcome included bronchopulmonary dysplasia at 28 days (BPD), BPD at 34 weeks' postmenstrual age (BPD-34), and intraventricular hemorrhage (IVH). Seventeen (55%) of 31 mothers manifested depression on the CES-D. No epidemiologic differences were found between this group and the nondepressed mothers. No differences in gestation or birth weight was detected between the preterm infants of depressed versus nondepressed mothers. The CES-D scores correlated significantly with SNAP (r = .36, P < .02). Infants of depressed mothers experienced significantly worse outcomes in the occurrence of BPD (P = .015), BPD-34 (P = .049), and IVH (P = .055). This study confirms that maternal depression occurs frequently in mothers of preterm infants and adversely affects the presenting neonatal health status of their babies during the initial hospitalization. Maternal depression was related to the severity of the initial neonatal illness and was significantly related to IVH and BPD. These factors may have long-term consequences for subsequent growth, neurodevelopment, and recurrence of related health problems.

Score for Neonatal Acute Physiology and Phlebotomy Blood Loss Predict Erythrocyte Transfusions in Premature Infants

To test the hypothesis that utilization of a previously described measure of acuity (ie, the score for neonatal acute physiology [SNAP]) during the first 7 postnatal days predicts which infants with a birth weight of 1500 g or less received erythrocyte transfusion during the initial hospitalization. Retrospective chart review. A regional tertiary care newborn intensive care unit at the Arizona Health Sciences Center, University Medical Center, Tucson. Medical records of premature infants (birth weight, < or = 1500 g) who were admitted from October 1993 to January 1995. Occurrence or nonoccurrence of erythrocyte transfusion was determined in 47 infants who were compared for demographic information, phlebotomy blood loss, diagnoses, medications, and the SNAP at 0, 1, 2, and 7 days of life. Infants with a birth weight of 1500 g or less received a mean +/- SD of 1.9 +/- 2.9 transfusions with 22 (47%) of the infants given transfusions Infants who were given transfusions vs those who were not given transfusions were of a lower mean +/- SD birth weight (971 +/- 238 g vs 1272 +/- 144 g; P < .001) and a lower gestational age (27.7 +/- 1.6 weeks vs 30.7 +/- 2.8 weeks; P < .001), and they had a greater mean phlebotomy blood loss (3.3 +/- 1.6 mL/kg per day vs 1.4 +/- 0.5 mL/kg per day; P < .001) during the first postnatal week. The SNAP indexes in those who received transfusions were higher at 1, 2, and 7 days of life (P = .03, P = .001, and P < .001, respectively). Using stepwise logistic regression, phlebotomy blood loss and the SNAP at 7 days of life were significant predictors of the number of transfusions. The logistic model predicted which infants had been administered transfusions with 86% sensitivity and 88% specificity. The efficacy and cost-effectiveness of recombinant human erythropoietin therapy in premature infants remain under study. As earlier treatment with recombinant human erythropoietin may be more efficacious, early identification of which infants currently undergo transfusion may identify those who will receive the greatest benefit from recombinant human erythropoietin therapy. The SNAP distinguished those infants who were given transfusions from those who did not receive transfusions, even after adjusting for phlebotomy blood loss.

PERINATAL EVENTS EXPLAIN VARIATIONS IN NICU ADMISSION ILLNESS SEVERITY† 1643

Methods: The Score for Neonatal Acute Physiology (SNAP) measures illness severity and is highly predictive of mortality. Perinatal events might explain inter-NICU differences in admission SNAP. We prospectively abstracted 583 inborn babies <1500g in six NICUs and compared admission risk profiles by NICU using χ2 and ANOVA. Linear regression identified perinatal factors affecting SNAP and if these explained differences between NICUs.

INFANTS OF ADOLESCENTS AND NEED FOR NEONATAL SPECIAL CARE. † 1593

Infants of adolescent mothers may have increased neonatal complications, but the reasons for this phenomenon are not well understood. We undertook a survey of neonatal morbidity among infants of adolescent mothers at a regional perinatal center. During Oct. `94 - Sept. `95, 8920 live births and 162 infant transports were recorded. 803 (8.8%) of these were born to mothers 2500 g, infants of teen mothers were not more likely to require SCN care than were infants of adult mothers. Severity of illness scores (Score for Neonatal Acute Physiology, SNAP) were calculated for the population of highest risk preterm infants (BW<1500 g), for all SCN-admitted teen births, and for a matched sample of SCN-admitted adult births. No differences were found between teen and adult infant groups for SNAP on day 1 or day 3, nor was there a significant difference in length of stay. We conclude that the increased utilization of neonatal special care services by infants of adolescent mothers is due to the increased risk of low birth weight within the adolescent group. Larger infants of adolescent mothers were neither sicker nor more likely to require SCN care than infants of adult mothers.Table

Bronchoalveolar oxyradical inflammatory elements herald bronchopulmonary dysplasia.

To quantify oxyradical inflammatory markers in serial endotracheal tube aspirates obtained from premature neonates at risk for developing bronchopulmonary dysplasia, and to correlate these parameters with clinical manifestations of the disease. Prospective cohort study. Tertiary neonatal intensive care unit. Twenty-eight intubated, premature infants, with 15 infants displaying simple respiratory distress syndrome and 13 infants eventually developing bronchopulmonary dysplasia. Endotracheal tube aspirates were collected and clinical severity scores were calculated longitudinally from an inception cohort during the first week of life. Diagnosis of bronchopulmonary dysplasia by standard criteria was recorded at 30 days of life. Various biochemical analyses related to pulmonary oxyradical stress were determined on endotracheal tube aspirates and were normalized according to the magnitude of serum/aspirate urea ratios. The demographic, illness severity, and biochemical characteristics of infants with simple respiratory distress syndrome and those characteristics of infants developing bronchopulmonary dysplasia were evaluated by masked comparison. Populations of respiratory distress syndrome and bronchopulmonary dysplasia infants could be differentiated during the first week of life by means of the following parameters: gestational age; birth weight; Score of Neonatal Acute Physiology; Neonatal Therapeutic Intervention Scoring System; epithelial lining fluid leukocytes; elastase; myeloperoxidase; xanthine oxidase and catalase enzyme activities; and total sulfhydryls. Infants with simple respiratory distress syndrome could be segregated from those infants who developed bronchopulmonary dysplasia by the magnitude of the epithelial lining fluid oxyradical inflammation markers. While infants developing bronchopulmonary dysplasia typically exhibited increased concentrations of these markers during the first week of life, those infants with simple respiratory distress syndrome displayed low, uniform, or decreasing values of these markers over this interval. Infants developing bronchopulmonary dysplasia demonstrate an early pulmonary inflammatory response, and one key aspect of this response involves various oxyradical-generating systems.

Time of first stool in premature infants: Effect of gestational age and illness severity

Objective: To assess the effect of gestational age and illness severity, and the effect of antenatal exposure to magnesium sulfate and glucocorticosteroids, on the timing of the first stool in preterm infants. Methods: Medical records of all preterm infants (born at ≤36 weeks of gestational age) admitted to the neonatal intensive care unit at Georgetown University Hospital between April 1993 and March 1994 were reviewed. We studied the time of the first stool in 221 infants after removing from the investigation the 45 infants who met the exclusion criteria. Results: The median age of the infants at the time of the first stool was 18 hours, and 90% of the infants passed stool by 100 hours after birth. Both the gestational age and the illness severity, as measured by the Score for Neonatal Acute Physiology (SNAP), independently correlated with the timing of first stool ( r = 0.31 and p <0.0001 for gestational age; r = 0.33 and p <0.0001 for SNAP). Of the 221 infants, 172 (78%) passed stool before the initiation of enteral feeding. Antenatal exposure to magnesium sulfate for tocolysis had no effect on the timing of the first stool, whereas infants whose mothers received glucocorticosteroids for enhancing fetal lung maturity passed their first stool significantly earlier than nonexposed infants of identical gestational age ( p = 0.005). Conclusion: Delayed passage of first stool is a function of both illness severity and gestational immaturity. Antenatal betamethasone exposure leads to earlier stool passage, whereas antenatal exposure to magnesium sulfate does not affect the timing of first stool in premature infants. (J P EDIATR 1995;127:971-4)

Score for Neonatal Acute Physiology: Validation in Three Kaiser Permanente Neonatal Intensive Care Units

Measurement of the severity of illness is a research area of growing importance in neonatal intensive care. Most severity of illness scales have been developed in tertiary care settings. Their applicability in community neonatal intensive care units has not been tested. Our goal was to assess the operational characteristics of the score for neonatal acute physiology (SNAP): the relationship to birth weight, the length of total hospital stay, and in-hospital mortality. We assigned SNAP scores prospectively to all inborn admissions at three community neonatal intensive care units during an 11-month period. Data on other neonatal predictors (eg, birth weight and the presence of congenital heart disease) were also collected. We measured in-hospital mortality, the experience of interhospital transport to a higher level of care, and total hospital stay. We found that the SNAP's relationship to birth weight was similar to previous reports. The SNAP's perinatal extension is a reliable predictor of newborn in-hospital mortality, with an area under the receiver operator characteristic curve of 0.95. The SNAP is also a good predictor of total hospital length of stay, whether by itself (by which it can explain 31% of the total stay) or in combination with other variables. Its predictive ability is better among infants of low birth weight (<2500 g) than among those of normal birth weight (> or = 2500 g). The SNAP's predictive power was most limited among infants admitted to rule out sepsis. The predictive ability of a model containing birth weight, the SNAP, and transport status was not improved by the inclusion of two major diagnostic categories, the presence of congenital heart disease or complex illness. Although it has definite limitations among infants who weight 2500 g or more, the SNAP is a potent tool for outcomes research. Modification of some of its parameters could result in a multifunctional scale suitable for use with all birth weights.

Developmental Care for Very Low-Birth-Weight Infants-Reply

<h3>In Reply.</h3> —We thank those who wrote for their vigorous criticism and feedback, which has provided us with an opportunity to further explore our conclusions. Groups did not differ in severity of initial illness, as reconfirmed by analysis of variance of score for neonatal acute physiology¹(<i>P</i>&lt;.42) and background variable MANOVA (<i>P</i>&lt;.59). All eligible infants meeting the initial 3-hour criteria also met the 48-hour criteria. Only two control group infants were unavailable for study; one died at 8 months, the other moved out of state. Outcome measures were predetermined and directionality was hypothesized, calling for one-tailed tests.^2(p14)Only three of the 11 "significant" outcome variables narrowly miss the two-tailed.05 level. Considering that all our infants weighed 1250 g or less and were aged 29 weeks or less, control group IVH incidence of 55.56% compares favorably with other estimates of overall incidence (51.13%^{3(Table 5)}) for infants

Coagulase-Negative Staphylococcal Bacteremia Among Very Low Birth Weight Infants: Relation to Admission Illness Severity, Resource Use, and Outcome

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. 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. 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. 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.

Estimating Neonatal Mortality Risk: An Analysis of Clinicians' Judgments

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. 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. 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. 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. 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.

CRIB and SNAP: assessing the risk of death for preterm neonates

The performance of three scoring systems for assessing mortality risk for neonates—clinical risk index for babies (CRIB), score for neonatal acute physiology (SNAP), and SNAP's perinatal extension (SNAP-PE)—were tested in the same set of patients. In 222 neonates weighing less than 1500 g at birth, CRIB scores were significantly better for assessing mortality risk than SNAP (p=0 017) or SNAP-PE (p<0·001), areas under receiver operating characteristic curves being 0·89 (SE 0·02), 0·82 (0·03), and 0 79 (0·03) respectively. Male sex was independently associated with poor prognosis after taking the CRIB score into account with a risk ratio of 2·75. We conclude that CRIB is the most useful score for comparing the performance of neonatal intensive-care units. New treatment methods, however, may require modifications to the system.

Birth Weight and Illness Severity

Richardson, Douglas K.; Phibbs, Ciaran S.; Gray, James E.; McCormick, Marie C.; Workman-Daniels, Kathryn; Goldmann, Donald A. Author Information

Birth Weight and Illness Severity: Independent Predictors of Neonatal Mortality

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. 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. 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). 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. This simplified clinical score provides accurate mortality risk estimates for application in a broad array of clinical and research settings.

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.