Molecular mechanisms behind clinical benefits of intensive insulin therapy during critical illness: glucose versus insulin

C-reactive protein rise in response to macronutrient deficit early in critical illness: sign of inflammation or mediator of infection prevention and recovery

PURPOSE

Withholding parenteral nutrition (PN) early in critical illness, late-PN, has shown to prevent infections despite a higher peak C-reactive protein (CRP). We investigated whether the accentuated CRP rise was caused by a systemic inflammatory effect mediated by cytokines or arose as a consequence of the different feeding regimens, and whether it related to improved outcome with late-PN.

METHODS

This secondary analysis of the EPaNIC-RCT first investigated, with multivariable linear regression analyses, determinants of late-PN-induced CRP rise and its association with cytokine responses (IL-6, IL-10, TNF-α) in matched early-PN and late-PN patients requiring intensive care for ≥ 3 days. Secondly, with multivariable logistic regression and Cox proportional-hazard analyses, we investigated whether late-PN-induced CRP rises mediated infection prevention and enhanced recovery or reflected an adverse effect counteracting such benefits of late-PN.

RESULTS

CRP peaked on day 3, higher with late-PN [216(152-274)mg/l] (n = 946) than with early-PN [181(122-239)mg/l] (n = 946) (p < 0.0001). Independent determinants of higher CRP rise were lower carbohydrate and protein intakes (p ≤ 0.04) with late-PN, besides higher blood glucose and serum insulin concentrations (p ≤ 0.01). Late-PN did not affect cytokines. Higher CRP rises were independently associated with more infections and lower likelihood of early ICU discharge (p ≤ 0.002), and the effect size of late-PN versus early-PN on these outcomes was increased rather than reduced after adjusting for CRP rise, not confirming a mediating role.

CONCLUSIONS

The higher CRP rise with late-PN, explained by the early macronutrient deficits, did not relate to cytokine responses and thus did not reflect more systemic inflammation. Instead of mediating clinical benefit on infection or recovery, the accentuated CRP rise appeared an adverse effect reducing such late-PN benefits.

Estimating Increased EGP During Stress Response in Critically Ill Patients

BACKGROUND

Stress-induced hyperglycemia is frequently experienced by critically ill patients and the use of glycemic control (GC) has been shown to improve patient outcomes. For model-based approaches to GC, it is important to understand and quantify model parameter assumptions. This study explores endogenous glucose production (EGP) and the use of a population-based parameter value in the intensive care unit context.

METHOD

Hourly insulin sensitivity (SI) was fit to clinical data from 145 patients on the Specialized Relative Insulin and Nutrition Titration GC protocol for at least 24 hours. Constraint of SI at a lower bound was used to explore likely EGP variability due to stress response. Minimum EGP was estimated during times when the model SI was constrained, and time and duration of events were examined.

RESULTS

Constrained events occur for 1.6% of patient hours. About 70% of constrained events occur in the first 12 hours and most events (~80%) occur when there is no exogenous nutrition given. Enhanced EGP values ranged from 1.16 mmol/min (current population value) to 2.75 mmol/min, with most being below 1.5 mmol/min (21% increase).

CONCLUSION

The frequency of constrained events is low and the current population value of 1.16 mmol/min is sufficient for more than 98% of patient hours, however, some patients experience significantly raised EGP probably due to an extreme stress response early in patient stay.

Increased insulin resistance in intensive care: longitudinal retrospective analysis of glycaemic control patients in a New Zealand ICU

BACKGROUND

Critical care populations experience demographic shifts in response to trends in population and healthcare, with increasing severity and/or complexity of illness a common observation worldwide. Inflammation in critical illness impacts glucose-insulin metabolism, and hyperglycaemia is associated with mortality and morbidity. This study examines longitudinal trends in insulin sensitivity across almost a decade of glycaemic control in a single unit.

METHODS

A clinically validated model of glucose-insulin dynamics is used to assess hour-hour insulin sensitivity over the first 72 h of insulin therapy. Insulin sensitivity and its hour-hour percent variability are examined over 8 calendar years alongside severity scores and diagnostics.

RESULTS

Insulin sensitivity was found to decrease by 50-55% from 2011 to 2015, and remain low from 2015 to 2018, with no concomitant trends in age, severity scores or risk of death, or diagnostic category. Insulin sensitivity variability was found to remain largely unchanged year to year and was clinically equivalent (95% confidence interval) at the median and interquartile range. Insulin resistance was associated with greater incidence of high insulin doses in the effect saturation range (6-8 U/h), with the 75th percentile of hourly insulin doses rising from 4-4.5 U/h in 2011-2014 to 6 U/h in 2015-2018.

CONCLUSIONS

Increasing insulin resistance was observed alongside no change in insulin sensitivity variability, implying greater insulin needs but equivalent (variability) challenge to glycaemic control. Increasing insulin resistance may imply greater inflammation and severity of illness not captured by existing severity scores. Insulin resistance reduces glucose tolerance, and can cause greater incidence of insulin saturation and resultant hyperglycaemia. Overall, these results have significant clinical implications for glycaemic control and nutrition management.

Hyperglycemia, Insulin, and Insulin Resistance in Sepsis

Critically ill patients frequently have hyperglycemia. This event may reflect severe stress with an imbalance between anabolic hormones and catabolic hormones. Alternatively, it may reflect alterations in either insulin levels or insulin function. Insulin is a pleiotropic hormone with multiple important metabolic effects. In patients with sepsis, insulin levels are increased but insulin sensitivity is decreased. However, there is variability in insulin sensitivity, and this creates variability in glucose levels and insulin requirements and increases the frequency of hypo- and hyperglycemia. The factors that influence insulin sensitivity are complex and include inhibition of tyrosine kinase activity of the beta subunit, increased proteolytic activity resulting in loss of receptors from the plasma membrane, and possibly the transfer of insulin receptors into the nucleus where they bind to gene promoters. Better understanding of the role of insulin in critically ill patients requires prospective studies measuring insulin levels in various patient groups and the development of a simple measure of insulin sensitivity.

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.

Surgical and immune reconstitution murine models in bone marrow research: Potential for exploring mechanisms in sepsis, trauma and allergy

Bone marrow, the vital organ which maintains lifelong hemopoiesis, currently receives considerable attention, as a source of multiple cell types which may play important roles in repair at distant sites. This emerging function, distinct from, but closely related to, bone marrow roles in innate immunity and inflammation, has been characterized through a number of strategies. However, the use of surgical models in this endeavour has hitherto been limited. Surgical strategies allow the experimenter to predetermine the site, timing, severity and invasiveness of injury; to add or remove aggravating factors (such as infection and defects in immunity) in controlled ways; and to manipulate the context of repair, including reconstitution with selected immune cell subpopulations. This endows surgical models overall with great potential for exploring bone marrow responses to injury, inflammation and infection, and its roles in repair and regeneration. We review three different murine surgical models, which variously combine trauma with infection, antigenic stimulation, or immune reconstitution, thereby illuminating different aspects of the bone marrow response to systemic injury in sepsis, trauma and allergy. They are: (1) cecal ligation and puncture, a versatile model of polymicrobial sepsis; (2) egg white implant, an intriguing model of eosinophilia induced by a combination of trauma and sensitization to insoluble allergen; and (3) ectopic lung tissue transplantation, which allows us to dissect afferent and efferent mechanisms leading to accumulation of hemopoietic cells in the lungs. These models highlight the gain in analytical power provided by the association of surgical and immunological strategies.

Usefulness of the plasma glucose concentration-to-HbA1c ratio in predicting clinical outcomes during acute illness with extreme hyperglycaemia

AIMS

To evaluate the correlation between the plasma glucose-to-glycated haemoglobin ratio (GAR) and clinical outcome during acute illness.

METHODS

This retrospective observational cohort study enrolled 661 patients who visited the emergency department of our hospital between 1 July 2008 and 30 September 2010 with plasma glucose concentrations>500mg/dL. Systolic blood pressure, heart rate, white blood cells, neutrophils, haematocrit, blood urea nitrogen, serum creatinine, liver function and plasma glucose concentration were recorded at the initial presentation to the emergency department. Data on glycated haemoglobin over the preceding 6 months were reviewed from our hospital database. The glucose-to-HbA_1c ratio (GAR) was calculated as the plasma glucose concentration divided by glycated haemoglobin.

RESULTS

The GAR of those who died was significantly higher than that of the survivors (81.0±25.9 vs 67.6±25.0; P<0.001). There was a trend towards a higher 90-day mortality rate in patients with higher GARs (log-rank test P<0.0001 for trend). On multivariate Cox regression analysis, the GAR was significantly related to 90-day mortality (hazard ratio [HR] for 1 standard deviation [SD] change: 1.41, 95% confidence interval [CI]: 1.22-1.63; P<0.001), but not to plasma glucose (HR: 0.89, 95% CI: 0.70-1.13; P=0.328). Rates of intensive care unit (ICU) admission and mechanical ventilator use were also higher in those with higher GARs.

CONCLUSION

GAR independently predicted 90-day mortality, ICU admission and use of mechanical ventilation. It was also a better predictor of patient outcomes than plasma glucose alone in patients with extremely high glucose levels.

Assessment of Blood Glucose and Electrolytes during Cardiopulmonary Bypass in Diabetic and Non-Diabetic Patients of Pakistan

Introduction:

Perioperative hyperglycemia has been shown to be related to higher levels of morbidity and mortality in patients on cardiopulmonary bypass (CPB) undergoing coronary artery bypass grafting (CABG), both diabetic and non-diabetic. Blood electrolytes, like sodium, potassium, calcium, and chloride play a very important role in the normal functioning of the body and can lead to a variety of clinical disorders if they become deficient. A minimal number of studies have been conducted on the simultaneous perioperative changes in both blood glucose and electrolyte levels during CPB in Pakistan. Therefore, our aim is to record and compare the changes in blood glucose and electrolyte levels during CPB in diabetic and non-diabetic patients.

Materials and Methods:

This was a prospective, observational study conducted on 200 patients who underwent CABG with CPB, from October 2014 to March 2015. The patients were recruited from the Cardiac Surgery Ward, Civil Hospital Karachi after they complied with the inclusion criteria. Repeated-measures analysis of variance (ANOVA) was used to compare the trend of the changes perioperatively for the two groups.

Results:

There was no significant difference in changes in blood glucose between the two groups (P = 0.62). The only significant difference detected between the two groups was for PaCO₂ (P = 0.001). Besides, further analysis revealed insignificant group differences for the trend changes in other blood electrolytes (P > 0.05).

Conclusion:

Our findings highlighted that there is no significant difference in blood electrolytes changes and the increase in blood glucose levels between diabetic and non-diabetic patients.

Impact of post-procedural hyperglycemia on acute kidney injury after transcatheter aortic valve implantation

BACKGROUND

Post-operative hyperglycemia, in individuals with and without diabetes, has been identified as a predictor of acute kidney injury (AKI) in patients following cardiac surgery. Whether or not this is also true for patients undergoing transcatheter aortic valve implantation (TAVI) is unknown.

OBJECTIVES

To evaluate whether post-procedural glucose levels are associated with AKI after TAVI.

METHODS AND RESULTS

A total of 422 consecutive patients undergoing transfemoral TAVI were included in the analysis. For each patient, plasma glucose levels were assessed at hospital admission, 4h after the procedure and daily during hospitalization. Post-procedural hyperglycemia was defined as 2 consecutive blood glucose readings ≥150mg/dL in the 72-hour period following TAVI. AKI was defined according to the VARC consensus report regarding standardized endpoint definitions. Overall, 137 (32.5%) patients developed post-procedural hyperglycemia and 138 (33%) patients developed AKI. Hyperglycemia was associated with a 2-fold higher incidence of AKI than in patients without hyperglycemia (48% vs. 25%, p<0.001). In-hospital mortality was higher in patients with hyperglycemia than in those without hyperglycemia (9.6% vs. 1.8%, p<0.001). In-hospital mortality rate was also higher in patients who developed AKI (12.7% vs. 2.7%, p<0.001). Patients with acute hyperglycemia that developed AKI had the highest in-hospital and long-term mortality rate (15% and 38%). Post-procedural hyperglycemia was an independent predictor of AKI.

CONCLUSIONS

Post-procedural hyperglycemia is associated with a higher incidence of AKI and mortality after TAVI. Randomized controlled trials are needed to determine whether meticulous post-procedural glycemic control following TAVI impacts upon clinical outcomes.

Admission hyperglycemia is associated with poor outcome after emergent coronary bypass grafting surgery

PURPOSE

Hyperglycemia during or after cardiac surgery is a common finding that is associated with poor outcome. Very few data, however, are available regarding a correlation between admission blood glucose and outcomes after coronary artery bypass grafting (CABG). Thus, the goal of the current study was to examine the relationship between admission blood glucose and outcome after emergency CABG surgery.

MATERIALS AND METHODS

A retrospective analysis to evaluate whether admission hyperglycemia associated with increased morbidity or mortality was performed in patients after emergency CABG surgery. The records of all the patients undergoing emergency CABG surgery between January 1999 and December 2010 at the University of Virginia Health System were reviewed. Postoperative in-hospital mortality and complications were considered as study end points.

RESULTS

A total of 240 patients met the final inclusion criteria. Overall mortality was 14.1%. The median admission blood glucose in patients who died 7.4 (interquartile range, 5.9-10.1) mmol/L was significantly higher compared with survivors 6.1 (interquartile range, 5.4-7.2; P<.01). Furthermore, 59% of the patients who died had admission blood glucose levels higher than 6.6 mmol/L, whereas only 35% of the patients who survived had similar blood glucose levels (P=.01). On multivariable analysis, admission blood glucose was identified as an independent risk factor for death after emergency CABG (P=.01; odds ratio, 1.16; 95% confidence interval, 1.04-1.29). Admission blood glucose was further identified as independently associated with increased risk for a composite outcome of death, postoperative renal failure or stroke (P=.01; odds ratio, 1.14; 95% confidence interval, 1.03-1.27).

CONCLUSIONS

Our study shows for the first time that admission blood glucose is correlated with increased morbidity and mortality among patients undergoing emergency CABG surgery.

The Sick and the Weak: Neuropathies/Myopathies in the Critically Ill

Critical illness polyneuropathies (CIP) and myopathies (CIM) are common complications of critical illness. Several weakness syndromes are summarized under the term intensive care unit-acquired weakness (ICUAW). We propose a classification of different ICUAW forms (CIM, CIP, sepsis-induced, steroid-denervation myopathy) and pathophysiological mechanisms from clinical and animal model data. Triggers include sepsis, mechanical ventilation, muscle unloading, steroid treatment, or denervation. Some ICUAW forms require stringent diagnostic features; CIM is marked by membrane hypoexcitability, severe atrophy, preferential myosin loss, ultrastructural alterations, and inadequate autophagy activation while myopathies in pure sepsis do not reproduce marked myosin loss. Reduced membrane excitability results from depolarization and ion channel dysfunction. Mitochondrial dysfunction contributes to energy-dependent processes. Ubiquitin proteasome and calpain activation trigger muscle proteolysis and atrophy while protein synthesis is impaired. Myosin loss is more pronounced than actin loss in CIM. Protein quality control is altered by inadequate autophagy. Ca(2+) dysregulation is present through altered Ca(2+) homeostasis. We highlight clinical hallmarks, trigger factors, and potential mechanisms from human studies and animal models that allow separation of risk factors that may trigger distinct mechanisms contributing to weakness. During critical illness, altered inflammatory (cytokines) and metabolic pathways deteriorate muscle function. ICUAW prevention/treatment is limited, e.g., tight glycemic control, delaying nutrition, and early mobilization. Future challenges include identification of primary/secondary events during the time course of critical illness, the interplay between membrane excitability, bioenergetic failure and differential proteolysis, and finding new therapeutic targets by help of tailored animal models.

Deceased donor hyperglycemia and liver graft dysfunction

CONTEXT

Hyperglycemia is common in deceased donors, and provokes numerous adverse events in hepatocytic mitochondria.

OBJECTIVE

To determine whether hyperglycemia in deceased donors is associated with graft dysfunction after orthotopic liver transplant.

METHODS

Charts on 572 liver transplants performed at the Cleveland Clinic between January 2005 and October 2010 were reviewed. The primary measure was time-weighted averages of donors' glucose measurements. Liver graft dysfunction was defined as (1) primary nonfunction as indicated by death or retransplant or (2) liver graft dysfunction as indicated by an aspartate amino transferase level greater than 2000 U/L or prothrombin time greater than 16 seconds during the first postoperative week. The relationship of interest was estimated by using a multivariable logistic regression.

RESULTS

The incidence of graft dysfunction was 25%. No significant relationship was found between the range of donor glucose measurements and liver graft dysfunction after donor characteristics were adjusted for (P= .14, Wald test, adjusted odds ratio [95% CI] for liver graft dysfunction corresponding to a relative doubling in time-weighted average for donor glucose of 1.43 [0.89-2.30]). The results thus do not suggest that strict glucose control in donors is likely to improve graft quality.

Glucose control in non-critically ill inpatients with diabetes: towards closed-loop

Inpatient glycaemic control remains an important issue due to the increasing number of patients with diabetes admitted to hospital. Morbidity and mortality in hospital are associated with poor glucose control, and cost of hospitalization is higher compared to non-diabetes patients. Guidelines for inpatient glycaemic control in the non-critical care setting have been published. Current recommendations include basal-bolus insulin therapy, regular glucose monitoring, as well as enhancing healthcare provider's role and knowledge. In spite of growing focus, implementation in practice is limited, mainly due to increasing workload burden on staff and fear of hypoglycaemia. Advances in healthcare technology may contribute to an improvement of inpatient diabetes care. Integration of glucose measurements with healthcare records and computerized glycaemic control protocols are currently being used in some institutions. Recent interests in continuous glucose monitoring have led to studies assessing its utilization in inpatients. Automation of glucose monitoring and insulin delivery may provide a safe and efficacious tool for hospital staff to manage inpatient hyperglycaemia, whilst reducing staff workload. This review summarizes the evidence on current approaches to managing inpatient glycaemic control; its utility and limitations. We conclude by discussing the evidence from feasibility studies to date, on the potential use of closed loop in the non-critical care setting and its implication for future studies.

Nutrition Monitoring in the PICU

The ideal set of variables for nutritional monitoring that may correlate with patient outcomes has not been identified. This is particularly difficult in the PICU patient because many of the standard modes of nutritional monitoring, although well described and available, are fraught with difficulties. Thus, repeated anthropometric and laboratory markers must be jointly analyzed but individually interpreted according to disease and metabolic changes, in order to modify and monitor the nutritional treatment. In addition, isotope techniques are neither clinically feasible nor compatible with the multiple measurements needed to follow progression. On the other hand, indirect alternatives exist but may have pitfalls, of which the clinician must be aware. Risks exist for both overfeeding and underfeeding of PICU patients so that an accurate monitoring of energy expenditure, using targeted indirect calorimetry, is necessary to avoid either extreme. This is very important, since the monitoring of the nutritional status of the critically ill child serves as a guide to early and effective nutritional intervention.

Does tight glycemic control improve outcomes in pediatric patients undergoing surgery and/or those with critical illness?

This literature review examines the current evidence regarding the potential usefulness of tight glycemic control in pediatric surgical patients. In adults, fluctuations in glucose levels and/or prolonged hyperglycemia have been shown to be associated with poor outcomes with respect to morbidity and mortality. This review begins by summarizing the findings of key papers in adult patients and continues by investigating whether or not similar results have been seen in pediatric patients by performing a comprehensive literature review using Medline (OVID). A database search using the OVID interface and including the search terms (exp glucose) AND (exp surgery) AND (exp Paediatric/pediatric) AND (exp Hypoglycaemia/hypoglycemia) AND (exp Hyperglycaemia/hyperglycemia) yielded a total of 150+ papers, of which 24 fulfilled our criteria. We isolated papers utilizing pediatric patients who were hospitalized due to illness and/or surgery. Our review highlights several difficulties encountered in addressing this potentially useful clinical intervention. An absence of scientifically robust and randomized trials and the existence of several small-powered trials yielding conflicting results mean we cannot recommend tight glycemic control in these patients. Differences in study design and disagreements concerning the crucial stage of surgery where hyperglycemia becomes important are compounded by an over-reliance on the discretion of clinicians in the absence of well described treatment protocols. Closer inspection of key papers in adult patients identified fundamental discrepancies between exact definitions of both hyperglycemia and hypoglycemia. This lack of consensus, along with a fear of inducing iatrogenic hypoglycemia in pediatric patients, has resulted in professional bodies advising against this form of intervention. In conclusion, we cannot recommend use of tight glycemic control in pediatric surgical patients due to unclear glucose definitions, unclear thresholds for treatment, and the unknown long-term effects of iatrogenic hypoglycemia on the developing body and brain.

Performance assessment of a glucose control protocol in septic patients with an automated intermittent plasma glucose monitoring device

BACKGROUND & AIMS

The optimal level and modality of glucose control in critically ill patients is still debated. A protocolized approach and the use of nearly-continuous technologies are recommended to manage hyperglycemia, hypoglycemia and glycemic variability. We recently proposed a pato-physiology-based glucose control protocol which takes into account patient glucose/carbohydrate intake and insulin resistance. Aim of the present investigation was to assess the performance of our protocol with an automated intermittent plasma glucose monitoring device (OptiScanner™ 5000).

METHODS

OptiScanner™ was used in 6 septic patients, providing glucose measurement every 15' from a side-port of an indwelling central venous catheter. Target level of glucose was 80-150 mg/dL. Insulin infusion and kcal with nutritional support were also recorded.

RESULTS

6 septic patients were studied for 319 h (1277 measurements); 58 [45-65] hours for each patient (measurements/patient: 231 [172-265]). Blood glucose was at target for 93 [90-98]% of study time. Mean plasma glucose was 126 ± 11 mg/dL. Only 3 hypoglycemic episodes (78, 78, 69 mg/dL) were recorded. Glucose variability was limited: plasma glucose coefficient of variation was 11.7 ± 4.0% and plasma glucose standard deviation was 14.3 ± 5.5 mg/dL.

CONCLUSIONS

The local glucose control protocol achieved satisfactory glucose control in septic patients along with a high degree of safeness. Automated intermittent plasma glucose monitoring seemed useful to assess the performance of the protocol.

Increasing glucose load while maintaining normoglycemia does not evoke neuronal damage in prolonged critically ill rabbits

BACKGROUND & AIMS

Preventing severe hyperglycemia with insulin reduced the neuropathological alterations in frontal cortex during critical illness. We investigated the impact of increasing glucose load under normoglycemia on neurons and glial cells.

METHODS

Hyperinflammatory critically ill rabbits were randomized to fasting or combined parenteral nutrition containing progressively increasing amounts of glucose (low, intermediate, high) within the physiological range but with a similar amount of amino acids and lipids. In all groups, normoglycemia was maintained with insulin. On day 7, we studied the neuropathological alterations in frontal cortex neurons, astrocytes and microglia, and MnSOD as marker of oxidative stress.

RESULTS

The percentage of damaged neurons was comparable among all critically ill and healthy rabbits. Critical illness induced an overall 1.8-fold increase in astrocyte density and activation status, largely irrespective of the nutritional intake. The percentage of microglia activation in critically ill rabbits was comparable with that in healthy rabbits, irrespective of glucose load. Likewise, MnSOD expression was comparable in critically ill and healthy rabbits without any clear impact of the nutritional interventions.

CONCLUSIONS

During prolonged critical illness, increasing intravenous glucose infusion while strictly maintaining normoglycemia appeared safe for neuronal integrity and did not substantially affect glial cells in frontal cortex.

Real-time continuous glucose monitoring in an intensive care unit: better accuracy in patients with septic shock

OBJECTIVE

This study assessed the accuracy of real-time continuous glucose monitoring system (RTCGMS) devices in an intensive care unit (ICU) to determine whether the septic status of the patient has any influence on the accuracy of the RTCGMS.

SUBJECTS AND METHODS

In total, 41 patients on insulin therapy were included. Patients were monitored for 72 h using RTCGMS. Arterial blood glucose (ABG) samples were obtained following the protocol established in the ICU. The results were evaluated using paired values (excluding those used for calibration) with the performance assessed using numerical accuracy. Nonparametric tests were used to determine statistically significant differences in accuracy.

RESULTS

In total, 956 ABG/RTCGMS pairs were analyzed. The overall median relative absolute difference (RAD) was 13.5%, and the International Organization for Standardization (ISO) criteria were 68.1%. The median RADs reported for patients with septic shock, with sepsis, and without sepsis were 11.2%, 14.3%, and 16.3%, respectively (P<0.05). Measurements meeting the ISO criteria were 74.5%, 65.6%, and 63.7% for patients with septic shock, with sepsis, and without sepsis, respectively (P<0.05).

CONCLUSIONS

The results showed that the septic status of patients influenced the accuracy of the RTCGMS in the ICU. Accuracy was significantly better in patients with septic shock in comparison with the other patient cohorts.

Understanding glycemic control in the critically ill: 2011 update

Intensive monitoring of blood glucose concentrations in critically ill patients has become a standard of care in intensive care units over the past 10 years, following the publication of a single-center randomized trial targeting euglycemia in postoperative patients. This article summarizes the literature describing the relationship between hyperglycemia and mortality in the critically ill, the main findings of the major interventional trials of intensive insulin therapy, the association between hypoglycemia and increased glycemic variability with adverse outcomes, and the impact of a preexisting diagnosis of diabetes. A framework for understanding dysglycemia in the critically ill, an approach that recognizes disturbances in the "3 domains" of glycemic control--hyperglycemia, hypoglycemia, and increased glycemic variability--is presented. Finally, practical considerations relating to the implementation of glycemic management protocols are discussed.

Increased protein-energy intake promotes anabolism in critically ill infants with viral bronchiolitis: a double-blind randomised controlled trial

OBJECTIVE

The preservation of nutritional status and growth is an important aim in critically ill infants, but difficult to achieve due to the metabolic stress response and inadequate nutritional intake, leading to negative protein balance. This study investigated whether increasing protein and energy intakes can promote anabolism. The primary outcome was whole body protein balance, and the secondary outcome was first pass splanchnic phenylalanine extraction (SPE(Phe)).

DESIGN

This was a double-blind randomised controlled trial. Infants (n=18) admitted to the paediatric intensive care unit with respiratory failure due to viral bronchiolitis were randomised to continuous enteral feeding with protein and energy enriched formula (PE-formula) (n=8; 3.1 ± 0.3 g protein/kg/24 h, 119 ± 25 kcal/kg/24 h) or standard formula (S-formula) (n=10; 1.7 ± 0.2 g protein/kg/24 h, 84 ± 15 kcal/kg/24 h; equivalent to recommended intakes for healthy infants <6 months). A combined intravenous-enteral phenylalanine stable isotope protocol was used on day 5 after admission to determine whole body protein metabolism and SPE(Phe).

RESULTS

Protein balance was significantly higher with PE-formula than with S-formula (PE-formula: 0.73 ± 0.5 vs S-formula: 0.02 ± 0.6 g/kg/24 h) resulting from significantly increased protein synthesis (PE-formula: 9.6 ± 4.4, S-formula: 5.2 ± 2.3 g/kg/24 h), despite significantly increased protein breakdown (PE-formula: 8.9 ± 4.3, S-formula: 5.2 ± 2.6 g/kg/24 h). SPE(Phe) was not statistically different between the two groups (PE-formula: 39.8 ± 18.3%, S-formula: 52.4 ± 13.6%).

CONCLUSIONS

Increasing protein and energy intakes promotes protein anabolism in critically ill infants in the first days after admission. Since this is an important target of nutritional support, increased protein and energy intakes should be preferred above standard intakes in these infants. Dutch Trial Register number: NTR 515.