Neonatal Hypoglycaemia

Abstract

Aim Neonatal hypoglycaemia is common and a preventable cause of neurological impairment, but the best way to detect and manage it remains unclear. The aim of the studies in this thesis was to provide the basis for a more rational approach to the clinical management of neonatal hypoglycaemia. Method To determine the relationship between neurological function, blood glucose concentrations and alternative cerebral fuels, we induced hypoglycaemia in newborn lambs and conducted an observational study in at-risk babies (the BABIES study). Neurological function was measured using continuous amplitude integrated electroencephalography (aEEG) and glucose concentrations were measured using standard blood glucose measurements (glucose oxidase) and continuous interstitial glucose monitoring. We assessed current management of neonatal hypoglycaemia by a survey of the Australian and New Zealand Neonatal Network. We then undertook a randomised trial (The Sugar Babies) to determine whether 40% dextrose gel was more effective than feeding alone to treat neonatal hypoglycaemia. Findings We did not find changes in the aEEG related to glucose concentrations. Continuous glucose monitoring showed moderate agreement with blood glucose concentrations in lambs and better agreement in babies. However, 81% of episodes of low interstitial glucose concentrations were not detected by blood glucose measurement. Most survey respondents would treat babies with a blood glucose concentration of <2.6 mmol/L. However, respondents reported a wide variation in treatment thresholds and interventions. In the Sugar Babies Study, half of babies in all at risk groups became hypoglycaemic, in a timeframe that did not correspond to current screening guidelines. Babies who received dextrose gel were less likely to remain hypoglycaemic or be admitted to the Newborn Intensive Care Unit for hypoglycaemia, received fewer formula feeds and were less likely to be formula fed at two weeks of age. Conclusion The aEEG is not clinically useful in monitoring neonatal hypoglycaemia. Continuous interstitial glucose monitoring is safe and reliable, but not yet appropriate for widespread clinical use. Dextrose gel should be considered for first line treatment of hypoglycaemia in late-preterm and term babies. These studies have substantially increased the understanding of neonatal hypoglycaemia, and are likely to alter clinical management.