Continuous insulin infusion in hyperglycaemic very-low-birth-weight infants receiving parenteral nutrition

Administering Parenteral Nutrition in the Neonatal Intensive Care Unit: Logistics, Existing Challenges, and a Few Conundrums

Use of parenteral nutrition (PN) in the neonatal intensive care unit (NICU) requires evaluating the need for central venous catheters, potential drug incompatibilities, unintentional exposures, and suboptimal energy and nutrient intake during the transition to full enteral nutrition. Risks of photooxidation reactions in PN components, refeeding syndrome, and excess early amino acid intake should prompt the reevaluation of routine practices. The goal of this paper is to review the practicalities, challenges, and conundrums of administering PN in the NICU.

Hyperglycemia and prematurity: a narrative review

Hyperglycemia is commonly encountered in extremely preterm newborns and physiologically can be attributed to immaturity in several biochemical pathways related to glucose metabolism. Although hyperglycemia is associated with a variety of adverse outcomes frequently described in this population, evidence for causality is lacking. Variations in definitions and treatment approaches have further complicated the understanding and implications of hyperglycemia on the immediate and long-term effects in preterm newborns. In this review, we describe the relationship between hyperglycemia and organ development, outcomes, treatment options, and potential gaps in knowledge that need further research. IMPACT: Hyperglycemia is common and less well described than hypoglycemia in extremely preterm newborns. Hyperglycemia can be attributed to immaturity in several cellular pathways involved in glucose metabolism in this age group. Hyperglycemia has been shown to be associated with a variety of adverse outcomes frequently described in this population; however, evidence for causality is lacking. Variations in definitions and treatment approaches have complicated the understanding and the implications of hyperglycemia on the immediate and long-term effects outcomes. This review describes the relationship between hyperglycemia and organ development, outcomes, treatment options, and potential gaps in knowledge that need further research.

Insulin for Treatment of Neonatal Hyperglycemia in Premature Infants: Prevalence over Time and Association with Outcomes

OBJECTIVE

 Our objective was to determine the prevalence of insulin treatment in premature infants with hyperglycemia and evaluate the association of length of treatment with outcomes.

STUDY DESIGN

 The study included cohort of 29,974 infants 22 to 32 weeks gestational age (GA) admitted to over 300 neonatal intensive care unit (NICU) from 1997 to 2018 and diagnosed with hyperglycemia.

RESULTS

 Use of insulin significantly decreased during the study period (p = 0.002) among studied NICUs. The percentage of hyperglycemic infants exposed to insulin ranged from 0 to 81%. Infants who received insulin were more likely to have lower GA, birth weight, 5-minute Apgar score, longer duration of stay, and require mechanical ventilation. After adjustment for GA, infants requiring insulin for >14 days were more likely to have treated retinopathy of prematurity (ROP) and develop chronic lung disease (CLD). Insulin treatment of 1 to 7 days had increased odds of death, death/ROP, and death/CLD compared with no exposure.

CONCLUSION

 Insulin use decreased over time, and differing durations of use were associated with adverse outcomes.

KEY POINTS

· Insulin use decreased over time.. · There is a temporal relation between the duration of treatment and adverse outcomes.. · Further studies are needed to determine the efficacy and safety of insulin use..

Hyperglycemia in Extremely Preterm Infants

Hyperglycemia after birth is common in extremely preterm infants (<28 weeks of gestation). Lower gestational age, lower birthweight, presence of severe illness, and higher parenteral glucose intake increase the risk for hyperglycemia, while provision of higher amounts of amino acids and lipids in parenteral nutrition and early initiation and faster achievement of full enteral feeding decrease the risk. Hyperglycemia is associated with increased mortality and morbidity in the neonatal period. Limited data show an association with long-term adverse effects on growth, neurodevelopment, and cardiovascular and metabolic health. Lowering the glucose infusion rate and administration of insulin are the 2 treatment options. Lowering the glucose infusion could lead to calorie deficits and long-term adverse effects on growth and neurodevelopment. Conversely, insulin use increases the risk for hypoglycemia and requires close blood glucose monitoring and frequent adjustments to glucose infusion and insulin dosage. Randomized trials of varying strategies of nutrient provision and/or insulin therapy and long-term follow-up are needed to improve clinical care and overall health of extremely preterm infants with hyperglycemia.

Modelling intestinal glucose absorption in premature infants using continuous glucose monitoring data

BACKGROUND

Model-based glycaemic control protocols have shown promise in neonatal intensive care units (NICUs) for reducing both hyperglycaemia and insulin-therapy driven hypoglycaemia. However, current models for the appearance of glucose from enteral feeding are based on values from adult intensive care cohorts. This study aims to determine enteral glucose appearance model parameters more reflective of premature infant physiology.

METHODS

Peaks in CGM data associated with enteral milk feeds in preterm and term infants are used to fit a two compartment gut model. The first compartment describes glucose in the stomach, and the half life of gastric emptying is estimated as 20 min from literature. The second compartment describes glucose in the small intestine, and absorption of glucose into the blood is fit to CGM data. Two infant cohorts from two NICUs are used, and results are compared to appearances derived from data in highly controlled studies in literature.

RESULTS

The average half life across all infants for glucose absorption from the gut to the blood was 50 min. This result was slightly slower than, but of similar magnitude to, results derived from literature. No trends were found with gestational or postnatal age. Breast milk fed infants were found to have a higher absorption constant than formula fed infants, a result which may reflect known differences in gastric emptying for different feed types.

CONCLUSIONS

This paper presents a methodology for estimation of glucose appearance due to enteral feeding, and model parameters suitable for a NICU model-based glycaemic control context.

Safe and effective glycaemic control in premature infants: observational clinical results from the computerised STAR-GRYPHON protocol

OBJECTIVE

Previous studies examine clinical outcomes of insulin therapy in neonatal intensive care units (NICUs), without first developing safe and effective control protocols. This research quantifies the safety and performance of a computerised model-based control algorithmSTAR-GRYPHON (Stochastic TARgeted Glucose Regulation sYstem to Prevent Hyper- and hypO-glycaemia in Neonates).

DESIGN

Retrospective observational study of glycaemic control in very/extremely low birthweight infants treated with insulin from Christchurch Women's Hospital NICU between January 2013 and June 2017. Blood glucose (BG) outcomes and control performance is compared with retrospective data (n=22) and literature.

INTERVENTIONS

Insulin infusion doses were calculated from 3 to 4 hourly BG measurements using a computerised model-based control algorithm, STAR-GRYPHON.

MAIN OUTCOME MEASURES

Mean BG, time in targeted range and incidence of hypoglycaemia.

RESULTS

STAR-GRYPHON (n=35) had lower mean BG concentration (7.0mmol/L vs 7.9 mmol/L), higher %BG within the 4.0-8.0 mmol/L target range (71.1% vs 50.9%) and lower %BG <4.0 mmol/L (0.6% vs 2.1%). There were only 2 BG <2.6 mmol/L (over n=2, 5.5% of patients, 0.03% of all BG outcomes), one of which may be attributed to clinical error. These results show better control to target and lower incidence of hypoglycaemia than most literature results from intensive insulin therapy protocols or study groups in children and infants.

CONCLUSIONS

Model-based protocols can safely and effectively control BG in very premature infants and should be used in future studies to determine the effect of insulin therapy on clinical outcomes.

Model-based glycaemic control: methodology and initial results from neonatal intensive care

Very/extremely premature infants often experience glycaemic dysregulation, resulting in abnormally elevated (hyperglycaemia) or low (hypoglycaemia) blood glucose (BG) concentrations, due to prematurity, stress, and illness. STAR-GRYPHON is a computerised protocol that utilises a model-based insulin sensitivity parameter to directly tailor therapy for individual patients and their changing conditions, unlike other common insulin protocols in this cohort. From January 2013 to January 2015, 13 patients totalling 16 hyperglycaemic control episodes received insulin under STAR-GRYPHON. A significant improvement in control was achieved in comparison to a retrospective cohort, with a 26% absolute improvement in BG within the targeted range and no hypoglycaemia. This improvement was obtained predominantly due to the reduction of hyperglycaemia (%BG>10.0 mmol/l: 5.6 vs. 17.7%, p<0.001), and lowering of the median per-patient BG [6.9 (6.1-7.9) vs. 7.8 (6.6-9.1) mmol/l, p<0.001, Mann-Witney U test]. While cohort-wide control results show good control overall, there is high intra-patient variability in BG behaviour, resulting in overly conservative treatments for some patients. Patient insulin sensitivity differs between and within patients over time, with some patients having stable insulin sensitivity, while others change rapidly. These results demonstrate the trade-off between safety and performance in a highly variable and fragile cohort.

A C-Peptide-Based Model of Pancreatic Insulin Secretion in Extremely Preterm Neonates in Intensive Care

BACKGROUND

Model-based glycemic control relies on sufficiency of underlying models to describe underlying patient physiology. In particular, very preterm infant glucose-insulin metabolism can differ significantly from adults, and is relatively unstudied. In this study, C-peptide concentrations are used to develop insulin-secretion models for the purposes of glycemic control in neonatal intensive care.

METHODS

Plasma C-peptide, insulin, and blood glucose concentrations (BGC) were retrospectively analyzed from a cohort of 41 hyperglycemic very preterm (median age 27.2 [26.2-28.7] weeks) and very low birth-weight infants (median birth weight 839 [735-1000] g). A 2-compartment model of C-peptide kinetics was used to estimate insulin secretion. Insulin secretion was examined with respect to nutritional intake, exogenous and plasma insulin concentration, and BGC.

RESULTS

Insulin secretion was found to be highly variable between patients and over time, and could not be modeled with respect to age, weight, or protein or dextrose intake. In 13 of 54 samples exogenous insulin was being administered, and insulin secretion was lower. However, low data numbers make this result inconclusive. Insulin secretion was found to increase with BG, with a stronger association in female infants than males (R(2) = .51 vs R(2) = .13, and R(2) = .26 for the combined cohort).

CONCLUSIONS

A sex-based insulin secretion model was created and incorporated into a model-based glycemic control framework. Nutritional intake did not predict insulin secretion, indicating that insulin secretion is a complex function of a number of metabolic factors.

Nasogastric aspiration as an indicator for feed absorption in model-based glycemic control in neonatal intensive care

BACKGROUND

STAR (stochastic targeted) is a glycemic control model-based framework for critically ill neonates that has shown benefits in reducing hypoglycemia and hyperglycemia. STAR uses a stochastic matrix method to forecast future changes in a patient's insulin sensitivity and then applies this result to a physiological model to select an optimal insulin treatment. Nasogastric aspiration may be used as an indicator to suggest periods of care when enteral feed absorption is compromised, improving the performance of glycemic control. An analysis has been carried out to investigate the effect of poorly absorbed feeds on glycemic control.

METHOD

Clinical data were collected from eight patients on insulin therapy and enteral feed, which included large or significantly milky aspirates. Patients had a median gestational age of 25 weeks and postnatal age of 5.5 days. Virtual patients were created using the NICING model, and insulin sensitivity (SI) profiles were fit. Alternative feed profiles were generated whereby enteral feed absorption was redistributed with time to account for poor feed absorption. The effect of poor feed absorption, as indicated by aspirates, is investigated.

RESULTS

The average percentage change of SI 4 h before a significant aspirate was 1.16%, and 1.49% in the 4 h following the aspirate. No distinct relationship was found between the fractional change in SI and the volume of the aspirate. Accounting for aspirates had a clinically negligible impact on glycemic control in virtual trials.

CONCLUSION

Accounting for aspirates by manipulating enteral feed profiles had a minimal influence on both modeling and controlling glycemia in neonates. The impact of this method is clinically insignificant, suggesting that a population constant for the rate of glucose absorption in the gut adequately models feed absorption within the STAR framework.

Extremely low birthweight infants: how neonatal intensive care unit teams can reduce postnatal malnutrition and prevent growth retardation

AIM

To evaluate the impact of an improved nutritional policy for extremely low birthweight (ELBW) infants on nutritional deficits and postnatal growth.

METHOD

We compared two groups of 37 ELBW infants, born before and after the introduction of an improved nutritional policy in April 2006. Group A (born 2005 to early 2006) and group B (born 2009) stayed in a French neonatal intensive care unit (NICU) for at least 7 weeks. Optimal energy and protein intakes were 120 and 3.5 g/kg/day, respectively, and used to calculate cumulative deficits. Delta z-scores for weight, length and head circumference were calculated between birth and 36 weeks of postmenstrual age (PMA). The improved nutritional policy focused on earlier and higher parenteral intake of lipids and proteins, earlier and higher human milk fortification and earlier transition to preterm formula.

RESULTS

The two groups did not differ in gestational age and birthweight. However, protein and energy deficits were significantly reduced in group B. Between birth and 36 weeks of PMA, delta z-scores were significantly reduced for length (p = 0.012) but not for weight (p = 0.09) or head circumference (p = 0.83).

CONCLUSION

Higher parenteral intake and close attention to enteral feeding reduced nutritional deficits and linear growth restriction in infants admitted to a French NICU.

Pilot study of a model-based approach to blood glucose control in very-low-birthweight neonates

Background

Hyperglycemia often occurs in premature, very low birthweight infants (VLBW) due to immaturity of endogenous regulatory systems and the stress of their condition. Hyperglycemia in neonates has been linked to increased morbidities and mortality and occurs at increasing rates with decreasing birthweight. In this cohort, the emerging use of insulin to manage hyperglycemia has carried a significant risk of hypoglycemia. The efficacy of blood glucose control using a computer metabolic system model to determine insulin infusion rates was assessed in very-low-birth-weight infants.

Methods

Initial short-term 24-hour trials were performed on 8 VLBW infants with hyperglycemia followed by long-term trials of several days performed on 22 infants. Median birthweight was 745 g and 760 g for short-term and long-term trial infants, and median gestational age at birth was 25.6 and 25.4 weeks respectively. Blood glucose control is compared to 21 retrospective patients from the same unit who received insulin infusions determined by sliding scales and clinician intuition. This study was approved by the Upper South A Regional Ethics Committee, New Zealand (ClinicalTrials.gov registration NCT01419873).

Results

Reduction in hyperglycemia towards the target glucose band was achieved safely in all cases during the short-term trials with no hypoglycemic episodes. Lower median blood glucose concentration was achieved during clinical implementation at 6.6 mmol/L (IQR: 5.5 – 8.2 mmol/L, 1,003 measurements), compared to 8.0 mmol/L achieved in similar infants previously (p < 0.01). No significant difference in incidence of hypoglycemia during long-term trials was observed (0.25% vs 0.25%, p = 0.51). Percentage of blood glucose within the 4.0 – 8.0 mmol/L range was increased by 41% compared to the retrospective cohort (68.4% vs 48.4%, p < 0.01).

Conclusions

A computer model that accurately captures the dynamics of neonatal metabolism can provide safe and effective blood glucose control without increasing hypoglycemia.

Trial Registration

ClinicalTrials.gov registration NCT01419873

[Does early parenteral protein intake improve extrauterine growth in low birth weight preterms?]

INTRODUCTION

Extrauterine growth restriction affects most premature newborns. Early and higher parenteral protein intake seems to improve postnatal growth and associated comorbidities. We evaluate the impact of a new parenteral nutrition protocol based on early amino acid administration on postnatal growth in premature infants with a birth weight < 1,500 grams.

MATERIAL AND METHODS

A case-control study in 58 premature newborns with a birth weight < 1,500 grams. In the case group we included 29 preterm neonates who received at least 1.5 g/kg/day parenteral amino acid during the first 24 hours after birth, reaching a maximum dose of 3.5 g/kg/day on the 3(rd)-4(th) day after birth. The control group was formed by 29 preterm neonates for whom protein support began on the 2(nd-)3(rd) day after birth with a dose of 1g/kg/day with lower daily increases than the case group. Growth rates and complications were followed until 28 days of life or discharge from NICU.

RESULTS

There were no differences between groups in baseline characteristics. Premature newborns who received higher and earlier doses of proteins had a greater weight gain than the control group, and this difference was statistically significant (423 ± 138 g vs. 315 ± 142 g; P=.005). In addition, they had a higher daily weight gain rate (19.4 ± 3.3 vs. 16.5 ± 4.8; P=.010) and they regained birth weight earlier (11.5 ± 3.3 days vs. 14.5 ± 4.5 days; P=.045). A higher incidence of complications was not observed.

CONCLUSIONS

Early and higher amino acid administration improves growth rate in premature neonates with no apparent increase in risks for the patient.

Interventions for treatment of neonatal hyperglycemia in very low birth weight infants

BACKGROUND

Early neonatal hyperglycemia is common among very low birth weight (VLBW) neonates. Increased risks for death and major morbidities have been observed among VLBW neonates who develop hyperglycemia. It is uncertain whether the hyperglycemia per se is a cause of adverse clinical outcomes or whether the incidence of adverse outcomes can be reduced by treatment.

OBJECTIVES

To assess the effects on clinical outcomes of interventions for treating neonatal hyperglycemia in the VLBW neonate receiving total or partial parenteral nutrition.

SEARCH STRATEGY

We searched The Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 4 of 12, 2011), MEDLINE (1966 to April 2011), EMBASE (1980 to April 2011) and CINAHL (1982 to July 2008). We searched for abstracts submitted for the annual meetings of Pediatric Academic Societies 2000 to 2011 and The European Society for Pediatric Research  2005 to 2010.

SELECTION CRITERIA

Randomized or quasi-randomized trials of interventions for the treatment of hyperglycemia in hyperglycemic VLBW neonates were eligible for inclusion in this review.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected studies for eligibility and extracted data on study design, methodology, clinical features, and treatment outcomes. Additional information on study design and outcomes was obtained from the lead investigator of each of the two included trials. The included trials were assessed for blinding of randomization, blinding of caretakers to the intervention, completeness of follow-up, and blinding of outcome measurement. The treatment effect measures for categorical outcomes were relative risk (RR) and risk difference (RD) with their 95% confidence intervals (CI); for continuous outcomes the measure was mean difference and 95% CI.

MAIN RESULTS

Only two eligible trials were found (Collins 1991; Meetze 1998). Both were randomized but of very small size (24 and 23 neonates randomized in each trial, respectively).No trial compared reduction versus no reduction of glucose infusion.Collins 1991 compared insulin infusion with standard care. Insulin infusion had no significant effect on death or bacterial sepsis; effects on other major morbidities were not assessed. Insulin infusion resulted in significant increases in non-protein energy intake, glucose intake, and short-term weight gain.Meetze 1998 compared insulin infusion with reduction of glucose infusion. Insulin infusion had no significant effects on death, severe intraventricular hemorrhage, retinopathy of prematurity, bacterial sepsis, fungal sepsis, or necrotizing enterocolitis; effects on other major morbidities were not assessed. Insulin infusion resulted in significant increases in glucose intake and total energy intake.

AUTHORS' CONCLUSIONS

Evidence from randomized trials in hyperglycemic VLBW neonates is insufficient to determine the effects of treatment on death or major morbidities. It remains uncertain whether the hyperglycemia per se is a cause of adverse clinical outcomes or how the hyperglycemia should be treated. Much larger randomized trials in hyperglycemic VLBW neonates that are powered on clinical outcomes are needed in order to determine whether, and how, the hyperglycemia should be treated.

Modeling the glucose regulatory system in extreme preterm infants

BACKGROUND

Premature infants represent a significant proportion of the neonatal intensive care population. Blood glucose homeostasis in this group is often disturbed by immaturity of endogenous regulatory systems and the stress of their condition. Hypo- and hyperglycemia are frequently reported in very low birth weight infants, and more mature infants often experience low levels of glycemia. A model capturing the unique fundamental dynamics of the neonatal glucose regulatory system could be used to develop better blood glucose control methods.

METHODS

A metabolic system model is adapted from adult critical care to the unique physiological case of the neonate. Integral-based fitting methods were used to identify time-varying insulin sensitivity and non-insulin mediated glucose uptake profiles. The clinically important predictive ability of the model was assessed by assuming insulin sensitivity was constant over prediction intervals of 1, 2 and 4h forward and comparing model-simulated versus actual clinical glucose values for all recorded interventions. The clinical data included 1091 glucose measurements over 3567 total patient hours, along with all associated insulin and nutritional infusion data, for N=25 total cases. Ethics approval was obtained from the Upper South A Regional Ethics Committee for this study.

RESULTS

The identified model had a median absolute percentage error of 2.4% [IQR: 0.9-4.8%] between model-fitted and clinical glucose values. Median absolute prediction errors at 1-, 2- and 4-h intervals were 5.2% [IQR: 2.5-10.3%], 9.4% [IQR: 4.5-18.4%] and 13.6% [IQR: 6.3-27.6%] respectively.

CONCLUSIONS

The model accurately captures and predicts the fundamental dynamic behaviors of the neonatal metabolism well enough for effective clinical decision support in glycemic control. The adaptation from adult to a neonatal case is based on the data from the literature. Low prediction errors and very low fitting errors indicate that the fundamental dynamics of glucose metabolism in both premature neonates and critical care adults can be described by similar mathematical models.

Development of blood glucose control for extremely premature infants

Extremely premature neonates often experience hyperglycaemia, which has been linked to increased mortality and worsened outcomes. Insulin therapy can assist in controlling blood glucose levels and promoting needed growth. This study presents the development of a model-based stochastic targeted controller designed to adapt insulin infusion rates to match the unique and changing metabolic state and control parameters of the neonate. Long-term usage of targeted BG control requires successfully forecasting variations in neonatal metabolic state, accounting for differences in clinical practices between units, and demonstrating robustness to errors that can occur in everyday clinical usage. Simulation studies were used to evaluate controller ability to target several common BG ranges and evaluate controller sensitivity to missed BG measurements and delays in control interventions on a virtual patient cohort of 25 infants developed from retrospective data. Initial clinical pilot trials indicated model performance matched expected performance from simulations. Stochastic targeted glucose control developed using validated patient-specific virtual trials can yield effective protocols for this cohort. Long-term trials show fundamental success, however clinical interface design appears as a critical factor to ensuring good compliance and thus good control.

Blood glucose prediction using stochastic modeling in neonatal intensive care

Hyperglycemia is a common metabolic problem in premature, low-birth-weight infants. Blood glucose homeostasis in this group is often disturbed by immaturity of endogenous regulatory systems and the stress of their condition in intensive care. A dynamic model capturing the fundamental dynamics of the glucose regulatory system provides a measure of insulin sensitivity (S(I)). Forecasting the most probable future S(I) can significantly enhance real-time glucose control by providing a clinically validated/proven level of confidence on the outcome of an intervention, and thus, increased safety against hypoglycemia. A 2-D kernel model of S(I) is fitted to 3567 h of identified, time-varying S(I) from retrospective clinical data of 25 neonatal patients with birth gestational age 23 to 28.9 weeks. Conditional probability estimates are used to determine S(I) probability intervals. A lag-2 stochastic model and adjustments of the variance estimator are used to explore the bias-variance tradeoff in the hour-to-hour variation of S(I). The model captured 62.6% and 93.4% of in-sample S(I) predictions within the (25th-75th) and (5th-95th) probability forecast intervals. This overconservative result is also present on the cross-validation cohorts and in the lag-2 model. Adjustments to the variance estimator found a reduction to 10%-50% of the original value provided optimal coverage with 54.7% and 90.9% in the (25th-75th) and (5th-95th) intervals. A stochastic model of S(I) provided conservative forecasts, which can add a layer of safety to real-time control. Adjusting the variance estimator provides a more accurate, cohort-specific stochastic model of S(I) dynamics in the neonate.

Blood glucose controller for neonatal intensive care: virtual trials development and first clinical trials

BACKGROUND

Premature neonates often experience hyperglycemia, which has been linked to worsened outcomes. Insulin therapy can assist in controlling blood glucose (BG) levels. However, a reliable, robust control protocol is required to avoid hypoglycemia and to ensure that clinically important nutrition goals are met.

METHODS

This study presents an adaptive, model-based predictive controller designed to incorporate the unique metabolic state of the neonate. Controller performance was tested and refined in virtual trials on a 25-patient retrospective cohort. The effects of measurement frequency and BG sensor error were evaluated. A stochastic model of insulin sensitivity was used in control to provide a guaranteed maximum 4% risk of BG < 72 mg/dl to protect against hypoglycemia as well as account for patient variability over 1-3 h intervals when determining the intervention. The resulting controller is demonstrated in two 24 h clinical neonatal pilot trials at Christchurch Women's Hospital.

RESULTS

Time in the 72-126 mg/dl BG band was increased by 103-161% compared to retrospective clinical control for virtual trials of the controller, with fewer hypoglycemic measurements. Controllers were robust to BG sensor errors. The model-based controller maintained glycemia to a tight target control range and accounted for interpatient variability in patient glycemic response despite using more insulin than the retrospective case, illustrating a further measure of controller robustness. Pilot clinical trials demonstrated initial safety and efficacy of the control method.

CONCLUSIONS

A controller was developed that made optimum use of the very limited available BG measurements in the neonatal intensive care unit and provided robustness against BG sensor error and longer BG measurement intervals. It used more insulin than typical sliding scale approaches or retrospective hospital control. The potential advantages of a model-based approach demonstrated in simulation were applied to initial clinical trials.

Interventions for treatment of neonatal hyperglycemia in very low birth weight infants

BACKGROUND

Early neonatal hyperglycemia is common among very low birth weight (VLBW) neonates. Increased risks for death and major morbidities have been observed among VLBW neonates who develop hyperglycemia. It is uncertain whether the hyperglycemia per se is a cause of adverse clinical outcomes or whether the incidence of adverse outcomes can be reduced by treatment.

OBJECTIVES

To assess the effects on clinical outcomes of interventions for treating neonatal hyperglycemia in the VLBW neonate receiving total or partial parenteral nutrition.

SEARCH STRATEGY

We searched The Cochrane Central Register of Controlled Trials (CENTRAL), The Cochrane Library, Issue 3, 2008; MEDLINE (1966 - July 2008); EMBASE (1980 - July 2008); and CINAHL (1982 - July 2008). We searched for abstracts submitted for the annual meetings of The Society for Pediatric Research 2000 - 2008 and The European Society for Paediatric Research 2005-2007.

SELECTION CRITERIA

Randomized or quasi-randomized trials of interventions for the treatment of hyperglycemia in hyperglycemic VLBW neonates were eligible for inclusion in this review.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected studies for eligibility and extracted data on study design, methodology, clinical features, and treatment outcomes. Additional information on study design and outcomes was obtained from the lead investigator of each of the two included trials. The included trials were assessed for blinding of randomization, blinding of caretakers to the intervention, completeness of follow-up, and blinding of outcome measurement. The treatment effect measures for categorical outcomes were relative risk (RR) and risk difference (RD) with their 95% confidence intervals (CI); for continuous outcomes the measure was mean difference and 95% CI.

MAIN RESULTS

Only two eligible trials were found (Collins 1991; Meetze 1998). Both were randomized but of very small size (24 and 23 neonates randomized in each trial, respectively).No trial compared reduction vs. no reduction of glucose infusion.Collins 1991 compared insulin infusion with standard care. Insulin infusion had no significant effect on death or bacterial sepsis; effects on other major morbidities were not assessed. Insulin infusion resulted in significant increases in non-protein energy intake, glucose intake, and short-term weight gain.Meetze 1998 compared insulin infusion with reduction of glucose infusion. Insulin infusion had no significant effects on death, severe intraventricular hemorrhage, retinopathy of prematurity, bacterial sepsis, fungal sepsis, or necrotizing enterocolitis; effects on other major morbidities were not assessed. Insulin infusion resulted in significant increases in glucose intake and total energy intake.

AUTHORS' CONCLUSIONS

Evidence from randomized trials in hyperglycemic VLBW neonates is insufficient to determine the effects of treatment on death or major morbidities. It remains uncertain whether the hyperglycemia per se is a cause of adverse clinical outcomes or how the hyperglycemia should be treated. Much larger randomized trials in hyperglycemic VLBW neonates that are powered on clinical outcomes are needed in order to determine whether, and how, the hyperglycemia should be treated.

Insulin infusion for the treatment of hyperglycemia in low birth weight infants: examining the evidence

FORTY TO 80 PERCENT OF VERY LOW birth weight (VLBW) (infants <1,500 g) and extremely low birth weight (ELBW) (infants <1,000 g) infants will develop hyperglycemia when provided with glucose infusions adequate to meet basal metabolic needs.1,2 Avoiding hyperglycemia while providing adequate nutrition to promote growth and development is a major challenge for health care providers in the NICU. Some health care providers suggest that the judious use of continuous insulin infusion (CII) may provide the opportunity for increasing nutritional support while maintaining euglycemia. A systematic review of the literature is presented to evaluate the evidence supporting this practice.

Insulin therapy in the pediatric intensive care unit

BACKGROUND & AIMS

Hyperglycemia is a major risk factor for increased morbidity and mortality in the intensive care unit. Insulin therapy has emerged in adult intensive care units and several pediatric studies are currently being conducted. This review discusses hyperglycemia and the effects of insulin on metabolic and non-metabolic pathways, with a focus on pediatric critical illness.

METHODS

A PubMed search was performed by using the following keywords and limits (("hyperglycemia"[MeSH terms] or ("insulin resistance"[MeSH major topic]) and ("critical care"[MeSH terms] or "critical illness"[MeSH terms])) in different combinations with ("metabolism"[MeSH terms] or "metabolic networks and pathways"[MeSH terms]) and ("outcome"[all fields]) and ("infant"[MeSH terms] or "child"[MeSH terms] or "adolescent"[MeSH terms]). Quality assessment of selected studies included clinical pertinence, publication in peer-reviewed journals, objectivity of measurements and techniques used to minimize bias. Reference lists of such studies were included.

RESULTS

The magnitude and duration of hyperglycemia are associated with increased morbidity and mortality in the pediatric intensive care unit (PICU), but prospective, randomized controlled studies with insulin therapy have not been published yet. Evidence concerning the mechanism and the effect of insulin on glucose and lipid metabolism in pediatric critical illness is scarce. More is known about the positive effect on protein homeostasis, especially in severely burned children. The effect in septic children is less clear and seems age dependent. Some non-metabolic properties of insulin such as the modulation of inflammation, endothelial dysfunction and coagulopathy have not been fully investigated in children.

CONCLUSION

Future studies on the effect of insulin on morbidity and mortality as well as on the mechanisms through which insulin exerts these effects are necessary in critically ill children. We propose these studies to be conducted under standardized conditions including precise definitions of hyperglycemia and rates of glucose intake.

Attenuated insulin release and storage in fetal sheep pancreatic islets with intrauterine growth restriction

We determined in vivo and in vitro pancreatic islet insulin secretion and glucose metabolism in fetuses with intrauterine growth restriction (IUGR) caused by chronic placental insufficiency to identify functional deficits in the fetal pancreas that might be caused by nutrient restriction. Plasma insulin concentrations in the IUGR fetuses were 69% lower at baseline and 76% lower after glucose-stimulated insulin secretion (GSIS). Similar deficits were observed with arginine-stimulated insulin secretion. Fetal islets, immunopositive for insulin and glucagon, secreted insulin in response to increasing glucose and KCl concentrations. Insulin release as a fraction of total insulin content was greater in glucose-stimulated IUGR islets, but the mass of insulin released per IUGR islet was lower because of their 82% lower insulin content. A deficiency in islet glucose metabolism was found in the rate of islet glucose oxidation at maximal stimulatory glucose concentrations (11 mmol/liter). Thus, pancreatic islets from nutritionally deprived IUGR fetuses caused by chronic placental insufficiency have impaired insulin secretion caused by reduced glucose-stimulated glucose oxidation rates, insulin biosynthesis, and insulin content. This impaired GSIS occurs despite an increased fractional rate of insulin release that results from a greater proportion of releasable insulin as a result of lower insulin stores. Because this animal model recapitulates the human pathology of chronic placental insufficiency and IUGR, the beta-cell GSIS dysfunction in this model might indicate mechanisms that are developmentally adaptive for fetal survival but in later life might predispose offspring to adult-onset diabetes that has been previously associated with IUGR.

Total parenteral nutrition-associated hyperglycemia correlates with prolonged mechanical ventilation and hospital stay in septic infants

PURPOSE

We studied the effects of total parenteral nutrition (TPN)-associated hyperglycemia on the clinical outcome in premature septic infants in the neonatal intensive care unit.

METHODS

The charts of all premature infants weighing less than 1500 g upon admission to the neonatal intensive care unit between January 1, 2002, and December 31, 2002, with sepsis, ventilator dependence, and feeding intolerance were studied. Maximum serum glucose concentrations were compared with duration of TPN, mechanical ventilation, hospital length of stay, and survival using Pearson regression analysis and Student's t test.

RESULTS

Thirty-seven patients met the search criteria. The average caloric intake for all infants at the time of blood culture-proven sepsis was 83 +/- 19 kcal/kg per day. The maximum serum glucose concentration (milligrams per deciliter) after having positive blood cultures (sepsis) was positively correlated with the duration of TPN (r = 0.45, P = .005), length of dependence on mechanical ventilation (r = 0.45, P = .006), and hospital length of stay (r = 0.36, P = .03). The average maximum serum glucose level was significantly higher in the nonsurviving infants (241 +/- 46 vs 141 +/- 48, P < .0001).

CONCLUSION

Hyperglycemia correlated with prolonged ventilator dependency and increased hospital length of stay in premature septic infants. Avoidance of excessive nutrient delivery and tight glycemic control during periods of acute metabolic stress may improve outcome in this patient population.

Hyperglycaemia and the very preterm baby

Neonatal hyperglycaemia, as usually defined (a whole blood glucose of >7 mmol/L), is common in the first week of life in babies born more than 12 weeks early. However, a review of a cohort of all such births in the north of England suggests that significant glycosuria is uncommon, and that there is no threat of an osmotic diuresis until the urine contains 2% glucose (by which time the blood glucose level almost always exceeds 15 mmol/L). The current statistical or epidemiological definition of hyperglycaemia (derived from data on term babies) needs to be replaced, for clinical purposes, by a more operationally relevant definition.