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

Argon inhalation attenuates systemic inflammation and rescues lung architecture during experimental neonatal sepsis

PURPOSE

Neonatal sepsis is a systemic inflammatory infection common in premature infants and a leading cause of mortality. Argon is an emerging interest in the field of noble gas therapy. Neonates with severe sepsis are frequently mechanically ventilated creating an opportunity for inhalation therapy. We aimed to investigate argon inhalation as a novel experimental therapy in neonatal sepsis.

METHODS

Sepsis was established in C57BL/6 neonatal mice by a lipopolysaccharide intraperitoneal injection on postnatal day 9. Septic pup mice were exposed to room air as well as non-septic controls. In the argon group, septic pup mice were exposed to argon (70% Ar, 30% O2) for 6 h in a temperature-controlled environment.

RESULTS

At 6 h, survival was significantly enhanced when septic mice received argon compared to septic controls. Serum profiles of cytokine release were significantly attenuated as well as lung architecture restored.

CONCLUSIONS

Our findings suggest that argon inhalation as a novel treatment for neonatal sepsis, reducing mortality and counteracting the acute systemic inflammatory response in the blood and preserving the architecture of the lung. This research can contribute to a paradigm shift in the treatment and outcome of neonates with sepsis.

Model-based subcutaneous insulin for glycemic control of pre-term infants in the neonatal intensive care unit

Hyperglycaemia is a common problem in neonatal intensive care units (NICUs). Achieving good control can result in better outcomes for patients. However, good control is difficult, where poor control and resulting hypoglycaemia reduces outcomes and confounds results. Clinically validated models can provide good control, and subcutaneous insulin delivery can provide more options for insulin therapy for clinicians. However, this combination has only been significantly utilised in adult outpatient diabetes, but could hold benefit for treating NICU infants. This research combines a well-validated NICU metabolic model with subcutaneous insulin kinetics models to assess the feasibility of a model-based approach. Clinical data from 12 very/extremely pre-mature infants was collected for an average study duration of 10.1 days. Blood glucose, interstitial and plasma insulin, as well as subcutaneous and local insulin were modelled, and patient-specific insulin sensitivity profiles were identified for each patient. Modelling error was low, where the cohort median [IQR] mean percentage error was 0.8 [0.3 3.4] %. For external validation, insulin sensitivity was compared to previous NICU cohorts using the same metabolic model, where overall levels of insulin sensitivity were similar. Overall, the combined system model accurately captured observed glucose and insulin dynamics, showing the potential for a model-based approach to glycaemic control using subcutaneous insulin in this cohort. The results justify further model validation and clinical trial research to explore a model-based protocol.

Glucose supply and glycolysis inhibition shape the clinical fate of Staphylococcus epidermidis-infected preterm newborns

Preterm infants are susceptible to bloodstream infection by coagulase-negative staphylococci (CONS) that can lead to sepsis. High parenteral glucose supplement is commonly used to support their growth and energy expenditure, but may exceed endogenous regulation during infection, causing dysregulated immune response and clinical deterioration. Using a preterm piglet model of neonatal CONS sepsis induced by Staphylococcus epidermidis infection, we demonstrate the delicate interplay between immunity and glucose metabolism to regulate the host infection response. Circulating glucose levels, glycolysis and inflammatory response to infection are closely connected across the states of tolerance, resistance and immunoparalysis. Further, high parenteral glucose provision during infection induces hyperglycemia, elevated glycolysis and inflammation, leading to metabolic acidosis and sepsis, whereas glucose restricted individuals are clinically unaffected with increased gluconeogenesis to maintain moderate hypoglycemia. Finally, standard glucose supply maintaining normoglycemia or pharmacological glycolysis inhibition enhances bacterial clearance and dampens inflammation but fails to prevent sepsis. Our results uncover how blood glucose and glycolysis controls circulating immune responses, in turn determining the clinical fate of CONS infected preterm individuals. This questions the current practice of parenteral glucose supply for preterm infants during infection.

Audit of the provision of nutritional support to mechanically ventilated dogs and cats

OBJECTIVES

To evaluate the use of enteral and parenteral nutrition in a population of mechanically ventilated cats and dogs, identify factors associated with implementation of nutrition, and assess the frequency of nutritional support within 72 hours of absent caloric intake.

DESIGN

Retrospective, single-center audit from June 2013 to June 2016.

SETTING

ICU of a veterinary university teaching hospital.

ANIMALS

Fifty-eight animals (50 dogs, 8 cats) that underwent mechanical ventilation for ≥6 hours with complete medical records.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Data collected included nutritional provision, time to initiation of nutrition, period of absent caloric intake, percentage of caloric intake obtained, and possible factors contributing to the delay or failure to implement nutrition. Thirty-one percent of patients (dogs 16/50, 32%; cats 2/8, 25%) received nutritional support during mechanical ventilation with all but 2 dogs receiving parenteral nutrition. Of those patients that did not receive nutrition (dogs 34/50, 68%; cats 6/8, 75%), documented contraindications or notations within the medical record for its omission were present in 16 of 34 dogs (47%) and 4 of 6 cats (66.7%). Thirteen animals (11 dogs, 2 cats) had >72 hours of absent caloric intake with only a small number of these receiving nutrition (dogs 4/11, 36.4%; cats 0/2, 0%).

CONCLUSIONS

Only 18 of 58 (31%) mechanically ventilated dogs and cats at our institution received nutritional support, and the majority of these were fed parenterally (16/18, 88.9%). For animals that did not receive nutrition, there was no clear reason for its absence in many cases. Animals with absent caloric intake >72 hours had poor implementation of nutritional support in contrast to current guidelines. A repeat audit after implementing changes to institutional protocols for nutritional provision is warranted to assess the impact on morbidity and mortality.

Metabolic and Immunological Effects of Intermittent Fasting on a Ketogenic Diet Containing Medium-Chain Triglycerides in Healthy Dogs

In several species, intermittent fasting (IF) has been shown to have beneficial effects, including delayed aging, increased lifespan, increased insulin sensitivity, reduced ischemic tissue damage, delayed onset of neurodegenerative disease and improved neuronal repair following injury. However, the metabolic and immunological effects of IF have not been well-established in dogs. The aim of this study was to examine the effects of a 48 h IF regimen using a low fat and a high fat diet in healthy dogs by quantifying the metabolic, hormonal, and immunological changes. We hypothesized that IF dogs would have higher blood ketone and ghrelin concentrations, lower blood leptin, insulin and glucose concentrations, and signs of immunosuppression compared to dogs eating daily. Ten healthy adult dogs were randomized into three group and underwent three feeding regimes in a 3 × 3 Latin square design: twice a day feeding on a low fat (23% energy from fat; LF) diet, 48 h fasting on a low fat diet, and 48 h fasting on a high fat enriched with medium-chain triglycerides (68% energy from fat; HF) diet. Body weight, food intake, activity, blood glucose, β-hydroxybutyrate, leptin, ghrelin, and insulin were measured. Lymphocyte proliferation and neutrophil/macrophage phagocytosis and respiratory burst were measured as markers of immune function. Nuclear magnetic resonance spectroscopy was used to relatively quantify plasma metabolites. When the dogs were IF on a HF diet, they had the highest concentration of blood ketones (mean 0.061 mmol/L, SD 0.024), whereas they had the lowest concentration (mean 0.018 mmol/L, SD 0.004) when fed daily. Blood glucose and insulin concentrations were lower in IF dogs on a HF diet compared to daily feeding or IF on a LF diet. There was an increase in plasma β-hydroxybutyrate concentrations, and a reduction in glucose and insulin concentrations when dogs were IF on a HF diet. There was only a decline in the immune parameters studied when the dogs were IF on a LF diet, which was not seen when on the HF diet. The results of this study indicate the potential of IF to be further investigated as a potential beneficial feeding regime for dogs.

Childhood Obesity, Endothelial Cell Activation, and Critical Illness

Pediatric obesity is increasing in prevalence and is frequently an antecedent to adult obesity and adult obesity-associated morbidities such as atherosclerosis, type II diabetes, and chronic metabolic syndrome. Endothelial cell activation, one aspect of inflammation, is present in the early stages of atherosclerosis, often prior to the onset of symptoms. Endothelial activation is a pathological condition in which vasoconstricting, pro-thrombotic, and proliferative mediators predominate protective vasodilating, anti-thrombogenic, and anti-mitogenic mediators. Many studies report poor outcomes among obese children with systemic endothelial activation. Likewise, the link between childhood obesity and poor outcomes in critical illness is well-established. However, the link between obesity and severity of endothelial activation specifically in the setting of critical illness is largely unstudied. Although endothelial cell activation is believed to worsen disease in critically ill children, the nature and extent of this response is poorly understood due to the difficulty in measuring endothelial cell dysfunction and destruction. Based on the data available for the obese, asymptomatic population and the obese, critically ill population, the authors posit that obesity, and obesity-associated chronic inflammation, including oxidative stress and insulin resistance, may contribute to endothelial activation and associated worse outcomes among critically ill children. A research agenda to examine this hypothesis is suggested.

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.

Overfeeding-associated hyperglycemia and injury-response homeostasis in critically ill neonates

BACKGROUND

Injury severity induces a proportionate acute metabolic stress response, associated with increased risk of hyperglycemia. We hypothesized that excess caloric delivery (overfeeding) during high stress states would increase hyperglycemia and disrupt response homeostasis.

METHODS

Gestational age, daily weight, total daily caloric intake, serum C-reactive protein (CRP), prealbumin, and blood glucose concentrations in all acutely-injured premature NICU infants requiring TPN over the past 3years were reviewed. Injury severity was based on CRP and patients were divided into high (CRP ≥50mg/L) versus low (CRP <50mg/L) stress groups. Glycemic variability was used to measure disruption of homeostasis.

RESULTS

Overall sample included N=563 patient days (37 patients; 42 episodes). High stress group pre-albumin levels negatively correlated with CRP levels (R=-0.62, p<0.005). A test of equal variance demonstrated significantly increased high stress glycemic variability (Ha:ratio>1, Pr(F>f)=0.0353). When high stress patients were separated into high caloric intake (≥70kg/kcal/day) versus low caloric intake (<70kg/kcal/day), maximum serum glucose levels were significantly higher with overfeeding (230.33±55.81 vs. 135.71±37.97mg/dL, p<0.004).

CONCLUSION

Higher injury severity induces increased disruption of response homeostasis in critically ill neonates. TPN-associated overfeeding worsens injury-related hyperglycemia in more severely injured infants.

TYPE OF STUDY

Retrospective study.

LEVEL OF EVIDENCE

Level II.

Energy Demands of Early Life Drive a Disease Tolerant Phenotype and Dictate Outcome in Neonatal Bacterial Sepsis

Bacterial sepsis is one of the leading causes of death in newborns. In the face of growing antibiotic resistance, it is crucial to understand the pathology behind the disease in order to develop effective interventions. Neonatal susceptibility to sepsis can no longer be attributed to simple immune immaturity in the face of mounting evidence that the neonatal immune system is tightly regulated and well controlled. The neonatal immune response is consistent with a "disease tolerance" defense strategy (minimizing harm from immunopathology) whereas adults tend toward a "disease resistance" strategy (minimizing harm from pathogens). One major advantage of disease tolerance is that is less energetically demanding than disease resistance, consistent with the energetic limitations of early life. Immune effector cells enacting disease resistance responses switch to aerobic glycolysis upon TLR stimulation and require steady glycolytic flux to maintain the inflammatory phenotype. Rapid and intense upregulation of glucose uptake by immune cells necessitates an increased reliance on fatty acid metabolism to (a) fuel vital tissue function and (b) produce immunoregulatory intermediates which help control the magnitude of inflammation. Increasing disease resistance requires more energy: while adults have fat and protein stores to catabolize, neonates must reallocate resources away from critical growth and development. This understanding of sepsis pathology helps to explain many of the differences between neonatal and adult immune responses. Taking into account the central role of metabolism in the host response to infection and the severe metabolic demands of early life, it emerges that the striking clinical susceptibility to bacterial infection of the newborn is at its core a problem of metabolism. The evidence supporting this novel hypothesis, which has profound implications for interventions, is presented in this review.

Indications and complications of inpatient parenteral nutrition prescribed to children in a large tertiary referral hospital

BACKGROUND

Parenteral Nutrition (PN) is prescribed to children with intestinal failure. Although life saving, complications are common. Recommendations for indications and constituents of PN are made in the 2005 guidelines by the European Society of Paediatric Gastroenterology, Hepatology and Nutrition (ESPGHAN). The aim of this study was to establish if the indications for prescribing PN in a tertiary children's hospital were appropriate, and to identify complications encountered. Data were compared to those published by the National Confidential Enquiry into patient outcome and death (NCEPOD) carried out in the United Kingdom in 2010.

METHODS

Children and newborns receiving inpatient PN over a 6 months period were entered into the study and data was collected prospectively. The appropriate indications for the use of PN were based on the ESPGHAN guidelines. Recorded complications were divided into metabolic, central venous catheter (CVC) related, hepatobiliary and nutritional.

RESULTS

A total of 303 children (67 newborns) were entered into the study. The main indications for the start of PN were critical illness (66/303), surgery (63/303) and bone marrow transplantation (28/303). The ESPGHAN recommendations were followed in 91.7% (278/303) of cases (95.5% of newborns, 90.7% of children). PN was considered inappropriate in 12/303 patients and equivocal in 13. The mean PN duration was 18 days (1-160) and the incidence of complications correlated to the length of PN prescribed. Metabolic, hepatobiliary and CVC related complications affected 74.6, 24.4, 16.4% of newborns and 76.7, 37.7 and 24.6% of children respectively. In relation to the appropriate indications for the start of PN our results mirrored those reported by the NCEPOD audit (92.4% of newborns and 88.6% children). However, the incidence of metabolic disturbances was higher in our cohort (74.6% vs 30.4% in children, 76.7% vs 14.3% in newborns) but CVC related complications lower amongst our newborns (16,4% vs 25%).

CONCLUSIONS

Although the indications for inpatient PN in children is mostly justified, there is still a proportion who is receiving PN unnecessarily. PN related complications remain common. There is a need for better education amongst health professionals prescribing PN and access to nutritional support teams to reduce unwanted side effects.

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.

Nutrition for the Extremely Preterm Infant

With advancements in the care of preterm infants, the goals in nutritional care have expanded from survival and mimicking fetal growth to optimizing neurodevelopmental outcomes. Inadequate nutritional support may be a risk factor for major complications of prematurity; conversely, higher disease burden is a risk for growth restriction. Early complete parenteral nutrition support, including intravenous lipid emulsion, should be adopted, and the next challenge that should be addressed is parenteral nutrition customized to fit the specific needs and metabolism of the extremely preterm infant. Standardized feeding protocols should be adopted.

Does Persistent Inflammatory Catabolic Syndrome Exist in Critically Ill Neonates?

BACKGROUND

Persistent inflammatory catabolic syndrome (PICS) has not been described in the infant population. This study proposes a definition of PICS in critically ill infants.

METHODS

A published adult criterion of PICS was modified using anthropometric and biochemical reference ranges for infants. A prospective chart review of admissions to a tertiary surgical neonatal intensive care unit (NICU) was performed over 65 days. Demographic, anthropometric, biochemical, and other clinical variables such as length of stay and medication use were collected daily throughout admission. Infants were categorized as having or not having PICS.

RESULTS

Twenty percent of admitted infants (n = 15) developed PICS using the proposed criteria. Infants with PICS were more likely to be classified as failure to thrive (53%), meeting only 75% of their anticipated weight gain. Significantly more infants with PICS had undergone surgery (100%; P = .01), received inotropic medication (40%; P = .05), and had longer NICU and total hospital length of stay ( P < .001 and P < .001). Infants with PICS had higher peak glucose levels (11.8 ± 7.3 mmol/L) and elevated urea concentrations (7.9 ± 4.6 mmol/L).

CONCLUSIONS

PICS does exist in a critically ill neonatal population and may be identified using the definition proposed in this study. Infants with PICS displayed metabolic dysregulation, impaired expected growth velocity, and longer length of stay despite no differences in severity scores or diagnosis between the groups. Validation of this work is required, and research into timely identification of infants with PICS is needed to inform whether these infants would benefit from earlier and novel nutrition intervention.

Insulin kinetics and the Neonatal Intensive Care Insulin-Nutrition-Glucose (NICING) model

BACKGROUND

Models of human glucose-insulin physiology have been developed for a range of uses, with similarly different levels of complexity and accuracy. STAR (Stochastic Targeted) is a model-based approach to glycaemic control. Elevated blood glucose concentrations (hyperglycaemia) are a common complication of stress and prematurity in very premature infants, and have been associated with worsened outcomes and higher mortality. This research identifies and validates the model parameters for model-based glycaemic control in neonatal intensive care.

METHODS

C-peptide, plasma insulin, and BG from a cohort of 41 extremely pre-term (median age 27.2 [26.2-28.7] weeks) and very low birth weight infants (median birth weight 839 [735-1000] g) are used alongside C-peptide kinetic models to identify model parameters associated with insulin kinetics in the NICING (Neonatal Intensive Care Insulin-Nutrition-Glucose) model. A literature analysis is used to determine models of kidney clearance and body fluid compartment volumes. The full, final NICING model is validated by fitting the model to a cohort of 160 glucose, insulin, and nutrition data records from extremely premature infants from two different NICUs (neonatal intensive care units).

RESULTS

Six model parameters related to insulin kinetics were identified. The resulting NICING model is more physiologically descriptive than prior model iterations, including clearance pathways of insulin via the liver and kidney, rather than a lumped parameter. In addition, insulin diffusion between plasma and interstitial spaces is evaluated, with differences in distribution volume taken into consideration for each of these spaces. The NICING model was shown to fit clinical data well, with a low model fit error similar to that of previous model iterations.

CONCLUSIONS

Insulin kinetic parameters have been identified, and the NICING model is presented for glycaemic control neonatal intensive care. The resulting NICING model is more complex and physiologically relevant, with no loss in bedside-identifiability or ability to capture and predict metabolic dynamics.

Nutrition: A Primary Therapy in Pediatric Acute Respiratory Distress Syndrome

Appropriate nutrition is an essential component of intensive care management of children with acute respiratory distress syndrome (ARDS) and is linked to patient outcomes. One out of every two children in the pediatric intensive care unit (PICU) will develop malnutrition or have worsening of baseline malnutrition and present with specific micronutrient deficiencies. Early and adequate enteral nutrition (EN) is associated with improved 60-day survival after pediatric critical illness, and, yet, despite early EN guidelines, critically ill children receive on average only 55% of goal calories by PICU day 10. Inadequate delivery of EN is due to perceived feeding intolerance, reluctance to enterally feed children with hemodynamic instability, and fluid restriction. Underlying each of these factors is large practice variation between providers and across institutions for initiation, advancement, and maintenance of EN. Strategies to improve early initiation and advancement and to maintain delivery of EN are needed to improve morbidity and mortality from pediatric ARDS. Both, over and underfeeding, prolong duration of mechanical ventilation in children and worsen other organ function such that precise calorie goals are needed. The gut is thought to act as a "motor" of organ dysfunction, and emerging data regarding the role of intestinal barrier functions and the intestinal microbiome on organ dysfunction and outcomes of critical illness present exciting opportunities to improve patient outcomes. Nutrition should be considered a primary rather than supportive therapy for pediatric ARDS. Precise nutritional therapies, which are titrated and targeted to preservation of intestinal barrier function, prevention of intestinal dysbiosis, preservation of lean body mass, and blunting of the systemic inflammatory response, offer great potential for improving outcomes of pediatric ARDS. In this review, we examine the current evidence regarding dose, route, and timing of nutrition, current recommendations for provision of nutrition to children with ARDS, and the current literature for immune-modulating diets for pediatric ARDS. We will examine emerging data regarding the role of the intestinal microbiome in modulating the response to critical illness.

Quantitative analysis of insulin in total parenteral nutrition bag in Taiwan

Regular insulin can reduce hyperglycemia when directly added to total parenteral nutrition (TPN) solutions. Insulin is not routinely added to all TPN solutions. For patients who require insulin prior to the initiation of TPN supplement, one-third to one-half of the usual total daily dose can be added to the TPN bag as regular human insulin. However, an incorrect dose or an interaction between insulin and the TPN bag material may affect blood sugar control in clinical practice. Therefore, it is important to quantitatively determine the final dose of insulin in the TPN bag. High performance liquid chromatography is a very powerful technique for determining the purity of proteins. The goal of this study was to use high-performance liquid chromatography to perform quantitative analysis of insulin in a TPN bag. The analysis was performed under different light conditions (UV, fluorescent, and darkness) and different temperatures (25°C and 2–8°C). The results show that adsorption of insulin on an ethylene vinyl acetate TPN bag is significantly higher than that on glass. Based on the results, it is evident that regular insulin should be administered separately from TPN to reduce cost and eliminate wasteful disposal of TPN solutions.

Impact of Obesity during Pediatric Acute and Critical Illness

Pediatric overweight and obesity rates have reached epidemic proportions and continue to rise globally. Many long-term complications have been described about the impact of obesity; however, little work has been done in the area of acute and critical illness in children. Available evidence suggests that childhood obesity can impact acute and critical illness when compared with normal weight cohorts. This review will discuss the available literature on the impact of pediatric obesity during acute and critical illness.

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.

Brain mass estimation by head circumference and body mass methods in neonatal glycaemic modelling and control

INTRODUCTION

Hyperglycaemia is a common complication of stress and prematurity in extremely low-birth-weight infants. Model-based insulin therapy protocols have the ability to safely improve glycaemic control for this group. Estimating non-insulin-mediated brain glucose uptake by the central nervous system in these models is typically done using population-based body weight models, which may not be ideal.

METHOD

A head circumference-based model that separately treats small-for-gestational-age (SGA) and appropriate-for-gestational-age (AGA) infants is compared to a body weight model in a retrospective analysis of 48 patients with a median birth weight of 750g and median gestational age of 25 weeks. Estimated brain mass, model-based insulin sensitivity (SI) profiles, and projected glycaemic control outcomes are investigated. SGA infants (5) are also analyzed as a separate cohort.

RESULTS

Across the entire cohort, estimated brain mass deviated by a median 10% between models, with a per-patient median difference in SI of 3.5%. For the SGA group, brain mass deviation was 42%, and per-patient SI deviation 13.7%. In virtual trials, 87-93% of recommended insulin rates were equal or slightly reduced (Δ<0.16mU/h) under the head circumference method, while glycaemic control outcomes showed little change.

CONCLUSION

The results suggest that body weight methods are not as accurate as head circumference methods. Head circumference-based estimates may offer improved modelling accuracy and a small reduction in insulin administration, particularly for SGA infants.

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.

Hyperglycemia and its association with clinical outcomes for patients in the pediatric intensive care unit after abdominal surgery

PURPOSE

We investigated the incidence of hyperglycemia of patients in the pediatric intensive care unit (PICU) after receiving abdominal surgery and its association with clinical outcomes.

METHODS

A retrospective review was performed from November 1, 2010 to November 1, 2011 on all PICU admissions after abdominal surgery. Maximum serum glucose concentrations (Gmax) in PICU, PICU length of stay, total hospital length of stay, deep and systemic infection, wound infection and mortality rates were recorded and analyzed.

RESULTS

A total of 193 children met the inclusion criteria of our research. Maximum glucose levels ranged from 55.7 mg/dL to 415.9 mg/dL (median: 132 mg/dL). Hyperglycemia in PICU was prevalent, with 125 (64.8%) patients having Gmax >110 mg/dL during their PICU stay and 35 (18.8%) having Gmax >200 mg/dL. Average PICU length of stay and total hospital length of stay grew as the maximum glucose levels rose among the four plasma glycemic ranges. The highest serum glucose range patient group also had the highest wound infection rates (14.3% and 11.4%).

CONCLUSIONS

Hyperglycemia was prevalent among patients after major abdominal surgery in PICU and was correlated with increased PICU length of stay, total hospital length of stay. Appropriate glycemic control may improve clinical outcomes for this group of patients.

Impact of variation in patient response on model-based control of glycaemia in critically ill patients

Critically ill patients commonly experience stress-induced hyperglycaemia, and several studies have shown tight glycaemic control (TGC) can reduce patient mortality. However, tight control is often difficult to achieve due to conflicting drug therapies and evolving patient condition. Thus, a number of studies have failed to achieve consistently safe and effective TGC possibly due to the use of fixed insulin dosing protocols over adaptive patient-specific methods. Model-based targeted glucose control can adapt insulin and dextrose interventions to match identified patient insulin sensitivity. This study explores the impact on glycaemic control of assuming patient response to insulin is constant, as many protocols do, versus time-varying. Validated virtual trial simulations of glucose control were performed on adult and neonatal virtual patient cohorts. Results indicate assumptions of constant insulin sensitivity can lead to six-fold increases in incidence of hypoglycaemia, similar to literature reports and a commonly cited issue preventing increased adoption of TGC in critical care. It is clear that adaptive, patient-specific, approaches are better able to manage inter- and intra-patient variability than typical, fixed protocols.

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

Efficacy and safety of a tight glucose control protocol in critically ill term neonates

BACKGROUND

A large single-center randomized trial showed that treating hyperglycemia in critically ill children improved outcome, despite an increased incidence of hypoglycemia, especially in infants.

OBJECTIVES

We evaluated the efficacy and incidence of hypoglycemia using a tight glucose protocol in critically ill term neonates.

METHODS

Term hyperglycemic (>8 mmol·l(-1); >144 mg·dl(-1)) neonates treated with a tight glucose protocol during a 3.5-year period in a tertiary pediatric intensive care unit were retrospectively analyzed.

RESULTS

Seventy-three term hyperglycemic neonates [age 0 days (0-6), weight 3.2 ± 0.8 kg, PRISM 16 (11-20)] were included for analysis. Eighteen neonates died (25%). The initial mean (range) glucose level was 11.1 mmol·l(-1) [9.6-15.2; 200 mg·dl(-1) (173-274)], and normoglycemia (<8 mmol·l(-1); <144 mg·dl(-1)) was reached within 5.3 h (1-25) with an overall treatment duration of 27 h (10-57). Seven hypoglycemic incidents (5 times ≤2.2 mmol·l(-1); 40 mg·dl(-1), and 2 times <1.7 mmol·l(-1); 31 mg·dl(-1)) occurred in 5 (6.7%) infants, without severe clinical signs. Three hypoglycemic incidents were directly explained due to a protocol violation. One hypoglycemic incident occurred with the onset of sepsis, while no apparent cause was identified for three hypoglycemic incidents.

CONCLUSIONS

Our glucose protocol was effective, but hypoglycemia occurred more frequently than in older children reported previously. Potential differences in glucose and insulin metabolism in term neonates appear to justify additional safety approaches, while awaiting further studies assessing the benefits of tight glucose protocols in this population. Meanwhile, we have decreased the initial insulin starting doses in our protocol.

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.

Glucose variability and survival in critically ill children: allostasis or harm?

OBJECTIVES

To assess whether individual blood glucose variability in critically ill children is associated with increased mortality and to define the temporal patterns of blood glucose variability during critical illness in children.

DESIGN

Retrospective cohort study.

SETTING

A 20-bed pediatric intensive care unit in a children's hospital.

PATIENTS

Patients aged 0-20 yrs and with at least 12 blood glucose measurements taken within the first 72 hrs of pediatric intensive care unit admission.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

A total of 101 eligible patients had 3,144 measured blood glucose concentrations with 16% mortality. Nonsurvivors had higher median blood glucose concentrations (129 mg/dL vs. 118 mg/dL, p < .01), more hyperglycemia (blood glucose >200 mg/dL) (88% vs. 59%, p < .05), and more hypoglycemia (blood glucose <60 mg/dL) (56% vs. 15%, p < .01) than survivors. The mean blood glucose range (257 mg/dL vs. 185 mg/dL, p < .01) and the blood glucose variability (63 mg/dL vs. 45 mg/dL, p = .02) were greater in nonsurvivors compared with survivors. Blood glucose variability tertiles were proportionately associated with increasing mortality: 6% vs. 15% vs. 27% (p = .07). Compared with survivors, daily blood glucose variability was significantly higher in nonsurvivors during the first 48 hrs of admission and after 1 wk of admission. After controlling for confounders, individual blood glucose variability was associated with higher pediatric intensive care unit mortality for each mg/dL of blood glucose concentration (adjusted odds ratio, 1.03; 95% confidence interval, 1.01-1.05).

CONCLUSIONS

Glucose variability is common in critically ill children and is associated with increased mortality. Whereas early alterations in blood glucose may represent allostasis, later fluctuations in blood glucose may represent an alteration of autoregulation with resulting higher mortality. Control of variability may need to be incorporated into glycemic control regimens.

A multi-center, randomized, controlled trial of parenteral nutrition titrated to resting energy expenditure in children undergoing hematopoietic stem cell transplantation ("PNTREE"): rationale and design

BACKGROUND

Children undergoing hematopoietic stem cell transplantation (HSCT) frequently require prolonged courses of parenteral nutrition (PN) as a consequence of gastrointestinal dysfunction related to preparative chemotherapy and radiation. PN has been associated with shorter engraftment time and decreased mortality during HSCT, however, it is also linked with complications, including infections, liver disease, and metabolic disturbances. Some of these complications may be a result of providing PN in excess of nutrient requirements. We previously described significant reductions in resting energy expenditure (REE), as measured by indirect calorimetry, over the course of HSCT. We also documented a decline in mid-arm muscle area, suggesting depletion of muscle mass, while triceps skinfold, a marker of fat stores, was unchanged. These results suggested the need for further study of energy expenditure, body composition and nutritional intake in this group of high risk patients.

DESIGN AND HYPOTHESIS

We hypothesize that changes in body composition affect REE during HSCT, and that standard nutritional support may lead to overfeeding. We are performing a randomized controlled trial of parenteral nutrition among children undergoing allogeneic HSCT. Subjects are randomized to receive PN designed to provide 100% of measured REE, or standard PN, i.e., 140% of estimated energy expenditure. The primary outcome variable is change in percent body fat. Secondary outcomes include glycemic control and frequency of infections, changes in REE and body composition.

CONCLUSION

This study will provide unique and comprehensive nutritional data and its results will guide nutritional therapy for children undergoing HSCT and possibly other catabolic patients.

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.

Relationship of serum C-reactive protein and blood glucose levels with injury severity and patient morbidity in a pediatric trauma population

PURPOSE

Serum markers of inflammation and of glucose production are known to reflect the immediate metabolic response to injury. We hypothesized that monitoring of the early C-reactive protein (CRP) and blood glucose (BG) concentrations would correlate with clinical morbidity and outcome measures in pediatric trauma patients.

METHODS

A five-year retrospective chart review of pediatric trauma patients admitted to our Level I pediatric trauma center was conducted to establish the relationships between early (first 3 hospital days) serum CRP and BG concentrations, Injury Severity Score (ISS), and hospital length of stay (HLOS). Statistical significance (P < 0.05) was determined using Student's t-test.

RESULTS

Forty-two trauma patients (8.0 +/- 5.2 years) were evaluated. The early inflammatory response (CRP >or= 10 vs <10 mg/dl) was significantly correlated to the glycemic response (BG;121 +/- 24 vs 97.3 +/- 14.2 mg/dl, P < 0.05). Severely injured patients (ISS >or= 25 vs <25) were significantly more hyperglycemic (BG;156 +/- 56.9 vs 125 +/- 31.6 mg/dL, P = 0.003). Both increased inflammatory response (CRP;8.1 +/- 6.4 vs 2.5 +/- 3.5 mg/dL) and increased glycemic response (BG;111 +/- 15.9 vs 97.4 +/- 11.7 mg/dL) were independently and significantly associated with prolonged hospitalization (HLOS > 7 vs <or=7 days, P < 0.05).

CONCLUSION

This study establishes a significant relationship between the early inflammatory and glycemic injury response and the association of that response with pediatric trauma patient morbidity and outcome measures.

Postoperative hyperglycemia is associated with mediastinitis following pediatric cardiac surgery

INTRODUCTION

Mediastinitis is an infrequent, but significant complication of median sternotomy. Perioperative hyperglycemia is associated with increased morbidity, including infection in pediatric and adult cardiac surgical patients. We hypothesized that perioperative blood glucose levels would be higher in patients who later developed mediastinitis.

METHODS

We examined the medical records of all infants and children diagnosed with poststernotomy mediastinitis (n = 24) from July 2001 to December 2005. Data recorded included postoperative blood glucose levels, age, diagnosis, operation, surgical complexity score, duration of operation and cardiopulmonary bypass, delayed sternal closure, perioperative use of steroids and total parenteral nutrition, and duration of postoperative inotropic and ventilatory support. Records of patients without mediastinitis matched for age, complexity score, and month of operation (control group, n = 32) were also reviewed. Data were analyzed with t-tests and chi-square tests. Variables with P < 0.21 on univariate tests were entered into a multivariate logistic regression model.

RESULTS

Initially, postoperative blood glucose levels were elevated, but similar in both mediastinitis and control groups. The number of subjects having peak blood glucose levels >7.2 mm (>130 mg.dl(-1)) during the first 24 h was greater in the mediastinitis group (P = 0.07). The significant multivariate predictor of mediastinitis was 24 h peak blood glucose >7.2 mM (>130 mg.dl(-1)) (P = 0.039).

CONCLUSION

Our data support the hypothesis that postoperative hyperglycemia is a risk factor for the development of mediastinitis in infants and children following cardiac surgery.

Hyperglycemia and outcome in the pediatric intensive care unit

OBJECTIVE

To identify the frequency of hyperglycemia in children who are nondiabetic and critically ill and assess the independent effect of hyperglycemia on outcome.

STUDY DESIGN

Consecutive admissions to the pediatric intensive care unit (PICU) were reviewed. The Pediatric Risk of Mortality III score (PRISM) measured patient acuity. Because maximum glucose level in the first day of PICU admission (GLFD) >200mg/dL contributes to PRISM, 200 mg/dL was used to differentiate high glucose (HG) from normal glucose.

RESULTS

Of 1550 patients, 221 (14.3%) had HG. GLFD correlated with PRISM (r = 0.39, P < .001). Without controlling for PRISM, the HG group had more mechanical ventilation days (MVD; P < .001), longer PICU length of stay (PLOS; P < .001) and lower percent survival (P < .001) than the normal glucose group. Controlling for PRISM in survivors, GLFD was not associated with PLOS (P = .75) or with MVD (P = .06). GLFD was not significantly associated with survival (P = .76). In nonsurvivors, GLFD was not associated with PLOS (P = .19) or MVD (P = .31).

CONCLUSION

When controlling for disease severity, hyperglycemia within 24 hours of PICU admission was not independently associated with increased mechanical ventilation time, length of stay, or mortality. Prospective evaluation of glycemic control in critically ill children is needed to elucidate its effects on outcome.

Maximizing efficacy from parenteral nutrition in critical care: appropriate patient populations, supplemental parenteral nutrition, glucose control, parenteral glutamine, and alternative fat sources

The gastrointestinal tract is the preferred route for nutritional support in hospitalized patients. Patients with a functioning gastrointestinal tract, including those with pancreatitis or inflammatory bowel disease and those receiving chemotherapy, should be fed enterally. Parenteral nutrition (PN) should be limited to patients with gastrointestinal failure, including those with short gut syndrome, high-output fistula, prolonged ileus, or bowel obstruction. PN is associated with numerous complications, most notably increased risk of serious infection. Emerging data suggest that immunologic complications of PN may result from hyperglycemia and use of n-6 polyunsaturated fatty acids. Safety may be improved with a low-calorie formula and ensuring tight glycemic control with an insulin protocol. A lipid emulsion containing fish oil, olive oil, or both should replace soybean-containing emulsions. Supplemental glutamine, 0.2 g/kg/d to 0.5 g/kg/d, has been shown to reduce the risk of infection and to improve glycemic control.

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.