The incidence of neonatal hypoglycemia--a completed survey

Strategies to improve neurodevelopmental outcomes in babies at risk of neonatal hypoglycaemia

Neonatal hypoglycaemia is associated with adverse development, particularly visual-motor and executive function impairment, in childhood. As neonatal hypoglycaemia is common and frequently asymptomatic in at-risk babies-ie, those born preterm, small or large for gestational age, or to mothers with diabetes, it is recommended that these babies are screened for hypoglycaemia in the first 1-2 days after birth with frequent blood glucose measurements. Neonatal hypoglycaemia can be prevented and treated with buccal dextrose gel, and it is also common to treat babies with hypoglycaemia with infant formula and intravenous dextrose. However, it is uncertain if screening, prophylaxis, or treatment improves long-term outcomes of babies at risk of neonatal hypoglycaemia. This narrative review assesses the latest evidence for screening, prophylaxis, and treatment of neonates at risk of hypoglycaemia to improve long-term neurodevelopmental outcomes.

Comparison of risk-of-bias assessment approaches for selection of studies reporting prevalence for economic analyses

OBJECTIVES

Within cost-effectiveness models, prevalence figures can inform transition probabilities. The methodological quality of studies can inform the choice of prevalence figures but no single obvious candidate tool exists for assessing quality of the observational epidemiological studies for selecting prevalence estimates. We aimed to compare different tools to assess the risk of bias of studies reporting prevalence, and develop and compare possible numerical scoring systems using these tools to set a threshold for inclusion of reports of prevalence in an economic analysis of neonatal hypoglycaemia.

DESIGN

Assessments of bias using two tools (Joanna Briggs Institute (JBI) Checklist for Prevalence Studies and a modified version of Risk Of Bias In Non-randomised Studies-of Interventions (ROBINS-I)) were compared for 18 studies relevant to a single setting (neonatal hypoglycaemia). Inclusions of studies for use in a decision analysis model were considered based on summary scores derived from these tools.

RESULTS

Both tools were considered easy to use and produced dispersed scores for each of the 40 study-outcome combinations. The modified ROBINS-I scores were more skewed than the JBI scores, particularly at higher thresholds. The studies selected for inclusion are generally the same using either tool; if 50% was used as the cut-off threshold using the Applicable Score both tools would yield the same results. However, the JBI tool is shorter and may be easier to interpret and apply to studies that do not involve a control group, while the modified ROBINS-I tool assesses more methodological detail in studies that include a control group.

CONCLUSION

Both tools performed well for systematically assessing studies that report on outcome prevalence and provided similar discrimination between studies for risk of bias. This convergent validity supports use of both tools for the purpose of assessing risk of bias and selecting studies that report prevalence for inclusion in economic analyses.

Glucose Gel as a Treatment Strategy for Transient Neonatal Hypoglycemia

BACKGROUND

Transient asymptomatic neonatal hypoglycemia (TANH) is common as infants transition from their mother's energy stores to their own. There is little evidence supporting the blood glucose threshold that indicates a need for treatment although sustained hypoglycemia has been correlated with negative neurodevelopmental consequences. Treatment of TANH includes a stepwise approach from supplemental enteral feedings, buccal glucose gel, intravenous dextrose infusion, and/or transfer to special care units including neonatal intensive care units.

PURPOSE

The purpose of this evidence-based practice brief is to review current evidence on 40% buccal glucose gel administration as a treatment strategy for TANH.

METHODS/SEARCH STRATEGY

CINAHL, Cochrane, Google Scholar, and PubMed were searched using the key words and restricted to English language over the last 7 years.

FINDINGS/RESULTS

The use of buccal dextrose gel for TANH may reduce neonatal intensive care unit admissions, reduce hospital length of stay and cost, support the mother-infant dyad through reduced separation, support exclusive breastfeeding, and improve parental satisfaction without adverse neurodevelopmental consequences.

IMPLICATIONS FOR PRACTICE

Timely collection of blood glucose levels following intervention is critical to support clinical decisions. Clinicians should offer family education regarding the rationale for serial glucose monitoring and treatment indications including buccal glucose administration. Clinical protocols can be revised to include use of buccal dextrose gel.

IMPLICATIONS FOR RESEARCH

There is a need for rigorous long-term studies comparing treatment thresholds and neurodevelopmental outcomes among various treatment strategies for TANH.

Oral dextrose gel for the treatment of hypoglycaemia in newborn infants

BACKGROUND

Neonatal hypoglycaemia, a common condition, can be associated with brain injury. It is frequently managed by providing infants with an alternative source of glucose, given enterally with formula or intravenously with dextrose solution. This often requires that mother and baby are cared for in separate environments and may inhibit breast feeding. Dextrose gel is simple and inexpensive and can be administered directly to the buccal mucosa for rapid correction of hypoglycaemia, in association with continued breast feeding and maternal care.

OBJECTIVES

To assess the effectiveness of dextrose gel in correcting hypoglycaemia and in reducing long-term neurodevelopmental impairment.

SEARCH METHODS

We searched MEDLINE, EMBASE, the Cochrane Central Register of Controlled Trials (CENTRAL), the Cumulative Index to Nursing and Allied Health Literature (CINAHL) and Web of Science from inception of the database to February 2016. We also searched international clinical trials networks and handsearched proceedings of specific scientific meetings.

SELECTION CRITERIA

Randomised and quasi-randomised studies comparing dextrose gel versus placebo, no treatment or other therapies for treatment of neonatal hypoglycaemia.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial quality and extracted data and did not assess publications for which they themselves were study authors.

MAIN RESULTS

We included two trials involving 312 infants. No data were available for correction of hypoglycaemia for each hypoglycaemic event. We found no evidence of a difference between dextrose gel and placebo gel for major neurosensory disability at two-year follow-up (risk ratio (RR) 6.27, 95% confidence interval (CI) 0.77 to 51.03; one trial, n = 184; quality of evidence very low). Dextrose gel compared with placebo gel or no gel did not alter the need for intravenous treatment for hypoglycaemia (typical RR 0.78, 95% CI 0.46 to 1.32; two trials, 312 infants; quality of evidence very low). Infants treated with dextrose gel were less likely to be separated from their mothers for treatment of hypoglycaemia (RR 0.54, 95% CI 0.31 to 0.93; one trial, 237 infants; quality of evidence moderate) and were more likely to be exclusively breast fed after discharge (RR 1.10, 95% CI 1.01 to 1.18; one trial, 237 infants; quality of evidence moderate). Estimated rise in blood glucose concentration following dextrose gel was 0.4 mmol/L (95% CI -0.14 to 0.94; one trial, 75 infants). Investigators in one trial reported no adverse outcomes (n = 237 infants).

AUTHORS' CONCLUSIONS

Treatment of infants with neonatal hypoglycaemia with 40% dextrose gel reduces the incidence of mother-infant separation for treatment and increases the likelihood of full breast feeding after discharge compared with placebo gel. No evidence suggests occurrence of adverse effects during the neonatal period or at two years' corrected age. Oral dextrose gel should be considered first-line treatment for infants with neonatal hypoglycaemia.

Update on neonatal hypoglycemia

PURPOSE OF REVIEW

Neonatal hypoglycemia is one of the most common biochemical abnormalities encountered in the newborn. However, controversy remains surrounding its definition and management especially in asymptomatic patients.

RECENT FINDINGS

New information has been published that describes the incidence and timing of low glucose concentrations in the groups most at risk for asymptomatic neonatal hypoglycemia. Furthermore, one large prospective study failed to find an association between repetitive low glucose concentrations and poor neurodevelopmental outcomes in preterm infants. But hypoglycemia due to hyperinsulinism, especially genetic causes, continued to be associated with brain injury. New advances were made in the diagnosis and management of hyperinsulinism, including acquired hyperinsulinism in small for gestational age infants and others. Continuous glucose monitoring remains an attractive strategy for future research in this area.

SUMMARY

The fundamental question of how best to manage asymptomatic newborns with low glucose concentrations remains unanswered. Balancing the risks of overtreating newborns with low glucose concentrations who are undergoing a normal transition following birth against the risks of undertreating those in whom low glucose concentrations are pathological, dangerous, and/or a harbinger of serious metabolic disease remains a challenge.

Incidence of neonatal hypoglycemia in babies identified as at risk

OBJECTIVES

Routine blood glucose screening is recommended for babies at risk of neonatal hypoglycemia. However, the incidence of hypoglycemia in those screened is not well described. We sought to determine the incidence of hypoglycemia in babies identified as being at risk, and also to determine differences in incidence between at risk groups.

STUDY DESIGN

Infants (n = 514) were recruited who were born in a tertiary hospital, ≥35 weeks gestation and identified as at risk of hypoglycemia (small, large, infant of a diabetic, late-preterm, and other). Blood glucose screening used a standard protocol and a glucose oxidase method of glucose measurement in the first 48 hours after birth.

RESULTS

One-half of the babies (260/514, 51%) became hypoglycemic (<2.6 mM), 97 (19%) had severe hypoglycemia (≤2.0 mM), and 98 (19%) had more than 1 episode. The mean duration of an episode was 1.4 hours. Most episodes (315/390, 81%) occurred in the first 24 hours. The median number of blood glucose measurements for each baby was 9 (range 1-22). The incidence and timing of hypoglycemia was similar in all at risk groups, but babies with a total of 3 risk factors were more likely to have severe hypoglycemia.

CONCLUSIONS

Hypoglycemia is common amongst babies recommended for routine blood glucose screening. We found no evidence that screening protocols should differ in different at risk groups, but multiple risk factors may increase severity. The significance of these hypoglycemic episodes for long-term outcome remains undetermined.

Plasma glucose concentrations in profound neonatal hypoglycemia

The study goal was to define low thresholds of plasma glucose concentrations that constitute profound hypoglycemia. Population analysis was performed on research publications on neonatal hypoglycemia ascertained by a Medline search. Eligible patients had neurological sequelae associated directly and primarily with hypoglycemia (profound hypoglycemia). Of 89 infants, more than 95% had plasma glucose levels of less than 25 mg/dL that were first detected at more than 10 hours of age. A breakdown of study patients according to those with or without neurological sequelae, who were exposed to a similar degree of hypoglycemia, showed a combined incidence of neurological injury of 21%, with 95% confidence interval from 14% to 27%.

Hypoglycemia and the full-term newborn: how well does birth weight for gestational age predict risk?

OBJECTIVE

To determine whether anthropometric characteristics could be used to accurately predict risk of hypoglycemia in full-term newborns during the early post-birth period.

DESIGN

Descriptive, utilizing newborn anthropometric measurements singly and in combination to determine risk of neonatal hypoglycemia. The following measurements were obtained twice for each newborn: weight, head circumference, chest circumference, abdominal circumference, mid-arm circumference, thigh circumference, and length. The investigator was blind to all measurements except weight.

SETTING

Mothers' rooms or the newborn nursery in a community hospital.

INTERVENTIONS

All measurements were obtained twice, and a physical examination was completed on each newborn by the principal investigator. These newborns were classified as large-, average-, and small-for-gestational age, using a tool typically used in many newborn nurseries.

SAMPLE

One hundred fifty-seven full-term newborns (94 White and 63 African American).

MAIN OUTCOME MEASURES

The differences in anthropometric measurements by race and gender were calculated using two-way analysis of variance. The risk of hypoglycemia was calculated using logistic regression modeling.

RESULTS

There were significant differences in measurements by race and by gender. Additionally, there was a subset of newborns classified as average for gestational age who had an increased risk of hypoglycemia (OR = 4.17, 95% CI = 1.33-13.08). Newborns with a mid-arm circumference/head circumference ratio that varied from .26 to .29 have an odds ratio of 6.10 (95% CI = 1.89-19.66) for risk of hypoglycemia. Plotting a newborn's birth weight on a published fetal growth curve clearly did not accurately predict his or her risk of hypoglycemia.

CONCLUSIONS

These findings indicate that extremes in newborn birth weight are not always correctly defined, may vary by race and ethnic group, and may not be the best method for determining under- or overnourishment and risk of neonatal hypoglycemia.

Hypoglycemic brain injury

Hypoglycemia frequently occurs in newborn infants who previously have suffered asphyxia, who are offspring of diabetic mothers, or who are low birthweight for gestational age (IUGR). Many infants who are hypoglycemic do not exhibit clinical manifestations, while others are symptomatic and at risk for the occurrence of permanent brain damage. This review emphasizes the clinical, neuropathologic, and neuro-imaging features of hypoglycemia in newborn infants, especially those who are symptomatic. Neurologic morbidity occurs particularly in those infants who have suffered severe, protracted, or recurrent symptomatic hypoglycemia. Experimental observations emphasize the resistance of the immature brain to the damaging effect of hypoglycemia; such resistance occurs as a consequence of compensatory increases in cerebral blood flow, lower energy requirements, higher endogenous carbohydrate stores, and an ability to incorporate and consume alternative organic substrates to spare glucose for energy production. Hypoglycemia combined with hypoxia-ischemia (asphyxia) is more deleterious to the immature brain than either condition alone.

Hypoglycemia in the neonate

After a brief history of the development of neonatal hypoglycemia, this review emphasizes the current approach to the anticipation, diagnosis, and management of the neonate with a low plasma glucose concentration. Current techniques for studying the neurophysiological and endocrine-metabolic effects of significant hypoglycemia provide new approaches for establishing relevant definitions of significant hypoglycemia, its prognosis, and pathogenesis. The inadequacy of glucose oxidase strips for screening, the definition of high-risk infants, new definitions for low plasma glucose concentrations, and their treatment are presented as well as the ability of the neonate to respond to significantly low glucose values. New data concerning the hereditary aspects of hyperinsulinemia (Glaser, this issue), hereditary defects in branched-chain amino acid, 3-methylglutaconic aciduria and mitochondrial betaoxidation, and degradation of fatty acids (Ozand, this issue), the role of glucose transporters (Vannucci and Vannucci, this issue), and the newer computed tomography and magnetic resonance imaging techniques (Kinnala, this issue) to study neonatal hypoglycemia are reviewed elsewhere in this issue.

Adverse neurodevelopmental outcome of moderate neonatal hypoglycaemia

There has been considerable debate over whether asymptomatic neonatal hypoglycaemia results in neurological damage. In a detailed multicentre study of 661 preterm infants hypoglycaemia was found to be common. Moderate hypoglycaemia (plasma glucose concentration less than 2.6 mmol/l) occurred in 433 of the infants and in 104 was found on three to 30 separate days. There was considerable variation among the centres, implying differences in decisions to intervene. The number of days on which moderate hypoglycaemia occurred was strongly related to reduced mental and motor development scores at 18 months (corrected age), even after adjustment for a wide range of factors known to influence development. When hypoglycaemia was recorded on five or more separate days adjusted mental and motor developmental scores at 18 months (corrected age) were significantly reduced by 14 and 13 points respectively, and the incidence of neurodevelopmental impairment (cerebral palsy or developmental delay) was increased by a factor of 3.5 (95% confidence interval 1.3 to 9.4). These data suggest that, contrary to general belief, moderate hypoglycaemia may have serious neurodevelopmental consequences, and reappraisal of current management is urgently required.

Carbohydrate metabolism in the fetus and neonate and altered neonatal glucoregulation

Altered glucose homeostasis in the neonate often results from antecedent events during fetal life. This article describes the normal and altered development of glucoregulatory capabilities during perinatal life and relates it to problems of hypo- and hyperglycemia in the neonate.

Perioperative care of the surgical neonate

This article provides an overview of perinatal physiology and common pathophysiologic events that are likely to complicate the clinical course of neonates requiring surgical procedures. The special needs and problems of the premature newborn are emphasized. References are provided for a more detailed analysis of the normal and abnormal transition from fetus to newborn.

Cerebral carbohydrate metabolism during hypoglycemia and anoxia in newborn rats

The cerebral metabolic responses to perinatal hypoglycemia and anoxia were studied in newborn rats given regular insulin (30 units per kilogram of body weight). Animals were observed for up to 2 hours with no apparent ill effects in spite of blood glucose concentrations of 0.75 mmol per liter. When exposed to 100% nitrogen at 37 degrees C, hypoglycemic animals survived only one-tenth as long as littermate controls with normal blood glucose levels (4.7 mmol/L). Pretreatment of hypoglycemic rats with glucose (10 mmol/kg) 10 and 30 minutes prior to nitrogen exposure nearly completely reversed the anoxic vulnerability. Hypoglycemia led to progressive reductions in cerebral glycogen and glucose; however, only glucose reverted to normal levels 20 minutes after systemic glucose administration. The glycolytic intermediates glucose 6-phosphate and lactate were also lower during hypoglycemia. Brain glucose levels below 0.1 mmol per kilogram were associated with a disrupted cerebral energy state, reflected by declines in phosphocreatine (33%) and adenosine triphosphate (ATP) (10%). Cerebral energy utilization (metabolic rate) was minimally reduced (-7.2%) by hypoglycemia and returned to the control value (2.36 mmol approximately P/kg/min) with glucose treatment. The cerebral energy reserves ATP, adenosine diphosphate, and phosphocreatine declined more rapidly and to a lower level in hypoglycemic rats subjected to 2 1/2 minutes of anoxia than in normoglycemic animals rendered similarly hypoxic. The findings suggest that decreased anoxic resistance of hypoglycemic newborn rats is not primarily a function of reduced brain glycogen or altered cerebral metabolic rate. The presence of endogenous cerebral glucose stores combined with continued circulating glucose (cerebrovascular perfusion) appear to be critical factors for maintaining perinatal hypoxic survival.

Development of glucagon sensitivity in neonatal rat liver

The ontogenesis of the hepatic glucagon-sensitive adenylate cyclase system has been studied in the rat. With a partially purified liver membrane preparation, fetal adenylate cyclase was less responsive to glucagon than the enzyme from neonatal or adult livers. Similar results were obtained in gently prepared liver homogenates, suggesting that destruction of essential components of the fetal liver membrane did not account for the relative unresponsiveness of the adenylate cyclase enzyme to glucagon. Investigation of other factors that might account for diminished fetal hepatic responsiveness to glucagon indicate (a) minimal glucagon degradation by fetal membranes relative to 8-day or adult tissue; and (b) available adenylate cyclase enzyme, as suggested by a 13-fold increase over basal cyclic AMP formation with NaF in fetal liver membranes. These results indicate that neither enhanced glucagon degradation nor adenylate cyclase enzyme deficiency accounts for the relative insensitivity of the fetal hepatic adenylate cyclase system to glucagon. In early neonatal life, hepatic adenylate cyclase responsiveness to glucagon rapidly developed and was maximal 6 days after birth. These changes were closely paralleled by a fivefold increase in glucagon binding and the kinetically determined Vmax for cyclic AMP formation. These observations suggest that (a) fetal hepatic unresponsiveness to glucagon may be explained by a limited number of glucagon receptor sites; (b) during the neonatal period, the development of glucagon binding is expressed primarily as an increase in adenylate cyclase Vmax; (c) the ontogenesis of hepatic responsiveness to glucagon may be important in the resolution of neonatal hypoglycemia.

Neonatal hypoglycemia and hyperglycemia: two unique perinatal metabolic problems

Hypoglycemia is a frequent, potentially morbid disease in the newborn. Most infants who are at risk can be identified either prior to or immediately after birth. A knowledge of those factors that cause or potentiate the development of hypoglycemia can alert the physician as to which infants require close observation and frequent monitoring of blood glucose. Care in interpretation of laboratory data is important in establishing the diagnosis. Prompt treatment can prevent permanent damage and promote intact survival in these infants. Hyperglycemia has been reported with the use of parenteral glucose in infants of very low birth weight. Rate of glucose infusion appears to be a critical factor in the development of hyperglycemia in these infants. The hazards of allowing fasting hypoglycemia to develop by inappropriate withholding of early calories and of causing hyperglycemia by injudicious use of parenteral glucose infusions in the tiny neonate show the critical need for constant monitoring of blood glucose both by screening techniques and by laboratory determinations.

Response to glucagon in small-for-dates hypoglycaemic and non-hypoglycaemic newborn infants

32 glucagon tests with insulin studies have been performed in hypoglycaemic and non-hypoglycaemic small-for-dates infants. The results suggest that glycogen depletion is an important factor in neonatal hypoglycaemia, and varies with the degree of hypoglycaemia. Hyperinsulinism was found in a proportion of hypoglycaemic infants, though there did not appear to be any correlation between the degree of hyperinsulinism and the severity of the glycogen depletion. Glucagon is not recommended as a therapeutic tool in neonatal hypoglycaemia.