Glucose variability and mortality in patients with sepsis

A diabetes-specific enteral formula improves glycemic variability in patients with type 2 diabetes

BACKGROUND

Well-controlled studies have demonstrated that inpatient hyperglycemia is an indicator of poor clinical outcomes, but the use of diabetes-specific enteral formulas in hospitalized patients remains a topic of great debate.

METHODS

In two different protocols, postprandial glycemia and insulinemia were measured in 22 subjects with diabetes fed a diabetes-specific or standard formula (protocol 1). Continuous glucose monitoring was used to assess glucose levels in 12 enterally fed patients with diabetes receiving the standard formula followed by the diabetes-specific formula continuously for 5 days each (protocol 2). End points included postprandial glycemia and insulinemia, glycemic variability (mean amplitude of glycemic excursions [MAGE]), mean glucose, and insulin use.

RESULTS

In the postprandial response protocol, the diabetes-specific formula resulted in lower positive areas under the postprandial curve (P < 0.001) and peak glucose (P < 0.001) and insulin (P = 0.017) levels. In the protocol using continuous glucose monitoring, glycemic variability (as measured by MAGE) was lower with continuous administration of the diabetes-specific than the standard formula (64.6 +/- 6.8 mg/dL vs. 110.6 +/-15.3 mg/dL, P = 0.003). Also, administration of the diabetes-specific formula resulted in lower mean glucose concentrations during feeding (171.1 +/- 16.1 vs. 202.1 +/- 17.4 mg/dL, P = 0.024) and insulin requirements (7.8 +/- 2.3 vs. 10.9 +/- 3.3 units/day, P = 0.039) than the standard formula.

CONCLUSIONS

Relative to the standard formula, the diabetes-specific formula reduced postprandial glycemia, mean glucose, glycemic variability, and short-acting insulin requirements. These results suggest potential clinical usefulness of a diabetes-specific enteral formula for minimizing glycemic excursions in hospitalized patients.

Tight Glucose Control versus Intermediate Glucose Control: A Quasi-Experimental Study

Intensive insulin treatment is associated with an increased risk of hypoglycaemia. The purpose of this study was to evaluate two different strategies: tight glucose control (TGC) versus intermediate glucose control (IGC). In this quasi-experimental study, 130 critically ill patients were assigned to receive either the TGC protocol (n=65), according to which blood glucose levels were maintained between 4.4 and 6.1 mmol/l, or the IGC protocol (n=65), according to which blood glucose levels were maintained between 4.4 and 8.0 mmol/l. A total of 52 subjects (40%) were diabetic and 63 (49%) were septic. In the IGC group, glucose levels were stabilised in the target range for a longer period of time when compared to the TGC group (63 vs 41%, P <0.001). The median capillary blood glucose level was 6.7 mmol/l in the TGC group (6.2 to 7.2) and 7.9 mmol/l (7.0 to 8.5) in the IGC group (P <0.001). The incidence of hypoglyacemia less than 2.2 mmol/l was 21.5% in the TGC group and 1.5% in the IGC group (P <0.001), and the incidence of hypoglycaemia less than 3.3 mmol/l was 67.7 and 26.2% (P <0.001) in the two groups, respectively. Diabetes (odds ratio 2.88, CI 1.22 to 6.84) and the TGC protocol (odds ratio 7.39, CI 3.15 to 17.35) were identified as independent risk factors for hypoglycaemia less than 3.3 mmol/l. Mechanical ventilation (odds ratio 4.33, CI 1.16 to 16.13), medical illness (odds ratio 2.88, CI 1.20 to 6.99) and hypoglycaemia (<3.3 mmol/l) (odds ratio 2.99, CI 1.21 to 7.41) were independent factors associated with mortality. TGC is difficult to accomplish in routine intensive care unit settings and is associated with a significant increase in the incidence of hypoglycaemia. Hypoglycaemia <3.3 mmol/l is an independent risk factor for in-hospital mortality.

Dynamic characteristics of blood glucose time series during the course of critical illness: effects of intensive insulin therapy and relative association with mortality

OBJECTIVES

To assess the effect of intensive insulin therapy on blood glucose amplitude variation and pattern irregularity in critically ill patients. To assess the association of these blood glucose signal characteristics with hospital mortality, independent of blood glucose level.

DESIGN

Retrospective analysis of the databases of two previously published randomized controlled trials.

SETTING

University hospital, 56-bed adult surgical intensive care unit and 17-bed medical intensive care unit.

PATIENTS

One thousand five-hundred forty-eight surgical intensive care unit patients, admitted between February 2000 and January 2001, and 1200 medical intensive care unit patients, admitted between March 2002 and May 2005.

INTERVENTIONS

In the two randomized controlled trials, patients were randomized to receive either intensive insulin therapy (targeting normoglycemia, between 4.4 and 6.1 mmol/L) or conventional insulin therapy (infusing insulin when blood glucose levels were >12 mmol/L and stopping at 10 mmol/L).

MEASUREMENTS AND MAIN RESULTS

Intensive insulin therapy significantly lowered mean blood glucose (5.8 vs. 8.4 mmol/L), hyperglycemic index (0.8 vs. 3.2 mmol/L), and glycemic penalty index (26 vs. 53), but it increased the mean daily difference between minimum and maximum blood glucose (mean daily delta blood glucose; 4.0 vs. 3.3 mmol/L). There was no significant effect on the standard deviation of the blood glucose measurements or on jack-knifed approximate entropy. In multivariable logistic regression analysis, corrected for baseline risk factors, blood glucose levels outside the normoglycemic range, higher mean daily delta blood glucose, higher standard deviation blood glucose, and higher jack-knifed approximate entropy were independently associated with hospital mortality.

CONCLUSIONS

The Leuven intensive insulin therapy strategy increased mean daily delta blood glucose while not affecting standard deviation blood glucose and jack-knifed approximate entropy. Increased blood glucose amplitude variation and pattern irregularity were associated with mortality, irrespective of blood glucose level. The reduced mortality observed with intensive insulin therapy in the Leuven trials cannot be attributed to an effect on blood glucose amplitude variation or entropy. Reducing amplitude variation and entropy of the blood glucose signal, irrespective of blood glucose concentration, may produce clinical benefits.

Association of hypoglycemia with mortality for subjects hospitalized with pneumonia

BACKGROUND

Previous research has shown that hypoglycemia is associated with worse outcomes for the elderly, in sepsis, and in children with pneumonia. The purpose of this study was to examine whether hypoglycemia (<70 mg/dL) is associated with increased 30-day mortality, after adjusting for potential confounders, for adults hospitalized with pneumonia.

METHODS

A retrospective cohort study conducted at 2 tertiary teaching hospitals. Eligible subjects were admitted with a diagnosis of, and had a chest x-ray consistent with, community-acquired pneumonia. Our primary analysis was a multivariable logistic regression with the dependent variable of 30-day mortality and with independent variable of hypoglycemia, diabetes, severity of illness determined using the pneumonia severity index, and pneumonia-related processes of care.

RESULTS

Data were abstracted on 787 subjects at the 2 hospitals. Mortality was 8.1% at 30 days. At presentation, 55% of subjects were at low risk, 33% were at moderate risk, and 12% were at high risk. In our cohort, 2.8% (n = 22) had hypoglycemia at presentation. Unadjusted mortality for those who were hypoglycemic was 27.3% versus 8.6% for those who were not (P = 0.0003). In the multivariable analysis, hypoglycemia (odds ratio: 4.1, 95% confidence interval: 1.4-11.7) was significantly associated with 30-day mortality.

CONCLUSIONS

After adjusting for severity of illness and other potential confounders, hypoglycemia is significantly associated with 30-day mortality for patients hospitalized with pneumonia. Patients with hypoglycemia should be placed in closely monitored settings even when by pneumonia specific risk systems they would normally be discharged.

How to weigh the current evidence for clinical practice

This article presents a template for judging trials of tight glucose control in critically ill patients. It reviews threats to both internal validity and generalisability using examples from the current literature. When judging internal validity, it is important to consider factors specific to trials of glucose control (particularly the methods of glucose control, measurement and reporting) in addition to factors common to all randomised controlled trials (such as treatment allocation, losses to follow-up and protocol violations). Judging generalisability requires the identification of differences between the trial population and the population for whom the intervention is being considered. These may relate to the setting, the patients or the practical delivery of tight glucose control or other interventions. Once identified, a judgement must be made for each difference of whether it is likely to modify the effect of tight glucose control.

Scientific principles and clinical implications of perioperative glucose regulation and control

Development of hyperglycemia after major operations is very common and is modulated by many factors. These factors include perioperative metabolic state, intraoperative management of the patient, and neuroendocrine stress response to surgery. Acute insulin resistance also develops perioperatively and contributes significantly to hyperglycemia. Hyperglycemia is associated with poor outcomes in critically ill and postsurgical patients. A majority of the investigations use the term "hyperglycemia" very loosely and use varying thresholds for initiating treatment. Initial studies demonstrated improved outcomes in critically ill, postsurgical patients who received intensive glycemic control (IGC) (target serum glucose <110 mg/dL). These results were quickly extrapolated to other clinical areas, and IGC was enthusiastically recommended in the perioperative period. However, there are few studies investigating the value of intraoperative glycemic control. Moreover, recent prospective trials have not been able to show the benefit of IGC; neither an appropriate therapeutic glycemic target nor the true efficacy of perioperative glycemic control has been fully determined. Practitioners should also appreciate technical nuances of various glucose measurement techniques. IGC increases the risk of hypoglycemia significantly, which is not inconsequential in critically ill patients. Until further specific data are accumulated, it is prudent to maintain glucose levels <180 mg/dL in the perioperative period, and glycemic control should always be accompanied by close glucose monitoring.

Glucose variability is associated with high mortality after severe burn

BACKGROUND

Hyperglycemia is associated with increased mortality in the severely injured; intensive insulin protocols reduce mortality, improve wound healing, and decrease susceptibility to infection. High glucose variability creates challenges to glycemic control and may be a marker of poor outcome. We wondered whether glycemic variability alone might identify patients at higher risk of death.

METHODS

Burn patients admitted in 2005 with >20% total body surface area burned, >or=100 glucose measurements, and one hypo- and hyperglycemic event were included in the analysis; all were treated with intensive insulin (glycemic target: 80-110 mg/dL). Glycemic variability was the sum of percent excursions (defined as values <80 mg/dL or >110 mg/dL); variability above the mean was considered high.

RESULTS

Individual average variability in the 49 subjects was 50% +/- 8% (range, 30-65%); the average number of glucose measurements per patient was 840 (range, 103-5314). Percent excursions in those with high (n = 26) compared with low (n = 23) variability scores was 56% +/- 6% and 43% +/- 5% (p < 0.001), respectively. No difference was found between groups in injury severity score, age, total body surface area burned, full thickness burns, gender, or inhalation injury. Both groups were similar for days of ventilator support, intensive care unit stay, and hospital stay. Mortality in the highly variable group was twice that of the less variable group (50% vs. 22%, p = 0.041).

CONCLUSIONS

High glucose variability (>50% of values outside 80-110 mg/dL) is associated with increased mortality in the severely burned. Individuals with frequent excursions outside the glucose target range of 80 mg/dL to 110 mg/dL are at greater risk of death.

Toward understanding tight glycemic control in the ICU: a systematic review and metaanalysis

BACKGROUND

Following publication of the Leuven Intensive Insulin Therapy Trial in 2001, tight glycemic control became the standard of care in ICUs around the world. Recent studies suggest that this approach may be flawed. The goal of this systematic review was to determine the benefits and risks of tight glycemic control in ICU patients and to explain the differences in outcomes among reported trials.

METHODS

Prospective, randomized controlled clinical trials (RCTs) that studied the impact of tight glycemic control (blood glucose 80-110 mg/dL) on mortality in ICU patients were identified through a search of MEDLINE, EMBASE, and the Cochrane Database of Systematic Reviews, and a citation review of relevant primary and review articles. Data were abstracted on study design, study size, and patient characteristics, as well as on the mean (or median) and SD of the ICU blood glucose level, mean daily dose of insulin administered, average daily caloric intake, percentage of calories given intravenously (parenteral nutrition), incidence of hypoglycemia, need for dialysis, and 28-day/hospital mortality. Metaanalytic techniques were used to analyze the data; subgroup analysis and metaregression were used to explain differences in the treatment effect.

RESULTS

We identified seven RCT studies that included 11,425 patients. Overall, tight glycemic control did not reduce the 28-day mortality (odds ratio [OR] 0.95; 95% CI, 0.87-1.05), the incidence of blood stream infections (OR 1.04; 95% CI, 0.93-1.17), or the requirement for renal replacement therapy (OR 1.01; 95% CI, 0.89-1.13). The incidence of hypoglycemia was significantly higher in patients randomized to tight glycemic control (OR 7.7; 95% CI, 6.0-9.9; P < .001). Metaregression demonstrated a significant relationship between the treatment effect (28-day mortality) and the proportion of calories provided parenterally (P = .005). This suggests that the difference in outcome between the two Leuven Intensive Insulin Therapy Trials and the subsequent trials could be related to the use of parenteral nutrition. When the two Leuven Intensive Insulin Therapy Trials were excluded from the metaanalysis, mortality was lower in the control patients (OR 0.90; 95% CI, 0.81-0.99; P = .04; I(2) = 0%).

CONCLUSIONS

There is no evidence to support the use of intensive insulin therapy in general medical-surgical ICU patients who are fed according to current guidelines. Tight glycemic control is associated with a high incidence of hypoglycemia and an increased risk of death in patients not receiving parenteral nutrition.

Increased inflammation, impaired bacterial clearance, and metabolic disruption after gram-negative sepsis in Mkp-1-deficient mice

MAPKs are crucial for TNF-alpha and IL-6 production by innate immune cells in response to TLR ligands. MAPK phosphatase 1 (Mkp-1) deactivates p38 and JNK, abrogating the inflammatory response. We have previously demonstrated that Mkp-1(-/-) mice exhibit exacerbated inflammatory cytokine production and increased mortality in response to challenge with LPS and heat-killed Staphylococcus aureus. However, the function of Mkp-1 in host defense during live Gram-negative bacterial infection remains unclear. We challenged Mkp-1(+/+) and Mkp-1(-/-) mice with live Escherichia coli i.v. to examine the effects of Mkp-1 deficiency on animal survival, bacterial clearance, metabolic activity, and cytokine production. We found that Mkp-1 deficiency predisposed animals to accelerated mortality and was associated with more robust production of TNF-alpha, IL-6 and IL-10, greater bacterial burden, altered cyclooxygenase-2 and iNOS expression, and substantial changes in the mobilization of energy stores. Likewise, knockout of Mkp-1 also sensitized mice to sepsis caused by cecal ligation and puncture. IL-10 inhibition by neutralizing Ab or genetic deletion alleviated increased bacterial burden. Treatment with the bactericidal antibiotic gentamicin, given 3 h after Escherichia coli infection, protected Mkp-1(+/+) mice from septic shock but had no effect on Mkp-1(-/-) mice. Thus, during Gram-negative bacterial sepsis Mkp-1 not only plays a critical role in the regulation of cytokine production but also orchestrates the bactericidal activities of the innate immune system and controls the metabolic response to stress.

Glucose control and its implications for the general surgeon

In the face of these conflicting data, how should the practicing surgeon approach the issue of tight glucose control in their critically ill surgical patients? The answer to that question may well change over time as new data emerge. For now, however, it seems reasonable to conclude that tight glucose control to the normal range (80-110 mg/dL) in critically ill general surgery patients (i.e., the Van den Berghe model) is an intriguing but unproven hypothesis that needs to be confirmed by prospective randomized trials in different ICUs and in a relevant patient population. It is quite possible, and probably likely, that levels of hyperglycemia that were previously thought to be inconsequential (180-200 mg/dL) may be harmful when sustained over prolonged periods of time and that better glucose control in the ICU than previously practiced is merited. However, given the detrimental effects of hypoglycemia, great care must be exercised in trying to achieve better glucose control so as not to induce harm. Technical considerations such as differences in glucose measuring systems, use of morning versus all glucose values, and nutritional regimens all need to be considered. The ICU is by definition a complex environment involving multiple teams of consulting specialists whose orders for medications, dialysis treatments, radiographic studies, and interruptions of enteral nutrition may all disrupt the ability to establish stable blood glucose levels. These factors need to be accounted for in daily clinical practice and their roles need to be better understood in future clinical trials. At present, it seems reasonable to attempt to control blood glucose levels in critically ill general surgery patients to moderate levels that avoid deleterious hypoglycemia but have been associated with encouraging clinical results until better data emerge. Until that time, the clinician will need to attempt to balance the potentially detrimental effects of hyperglycemia with the risk of hypoglycemia carefully until future trials involving general surgery patients are completed to clarify this issue.

Reducing glycemic variability in intensive care unit patients: a new therapeutic target?

Acute hyperglycemia is common in critically ill patients. Strict control of blood glucose (BG) concentration has been considered important because hyperglycemia is associated independently with increased intensive care unit mortality. After intensive insulin therapy was reported to reduce mortality in selected surgical critically ill patients, lowering of BG levels was recommended as a means of improving patient outcomes. However, a large multicenter multination study has found that intensive insulin therapy increased mortality significantly. A difference in variability of BG control may be one possible explanation why the effect of intensive insulin therapy varied from beneficial to harmful. Several studies have confirmed significant associations between variability of BG levels and patient outcomes. Decreasing the variability of the BG concentration may be an important dimension of glucose management. If reducing swings in the BG concentration is a major biologic mechanism behind the putative benefits of glucose control, it may not be necessary to pursue lower glucose levels with their attendant risk of hypoglycemia.

Glycemic variability and mortality in critically ill patients: the impact of diabetes

BACKGROUND

Glycemic variability (GV) has recently been associated with mortality in critically ill patients. The impact of diabetes or its absence on GV as a risk factor for mortality is unknown.

METHODS

A total of 4084 adult intensive care unit (ICU) patients admitted between October 15, 1999, and June 30, 2009, with at least three central laboratory measurements of venous glucose samples during ICU stay were studied retrospectively. The patients were analyzed according to treatment era and presence or absence of diabetes: 1460 admitted before February 1, 2003, when there was no specific treatment protocol for hyperglycemia ("PRE") and 2624 patients admitted after a glycemic control protocol was instituted ("GC"). 3142 were patients without diabetes ("NON"), and 942 were patients with diabetes ("DM"). The coefficient of variation (CV) [standard deviation (SD)/mean glucose level (MGL)] of each patient was used as a measure of GV. Patients were grouped by MGL (mg/dl) during ICU stay (70-99, 100-119, 120-139, 140-179, and 180+) as well as by CV (<15%, 15-30%, 30-50%, and 50%+).

RESULTS

Patients with diabetes had higher MGL, SD, and CV than did NON (p < .0001 for all comparisons). Mean glucose level was lower among both GC groups compared to their corresponding PRE groups (p < .0001), but CV did not change significantly between eras. Multivariable logistic regression analysis demonstrated that low CV was independently associated with decreased risk of mortality and high CV was independently associated with increased risk of mortality among NON PRE and GC patients, even after exclusion of patients with severe (<40 mg/dl) or moderate (40-59 mg/dl) hypoglycemia. There was no association between CV and mortality among DM using the same multivariable model. Mortality among NON from the entire cohort, with MGL 70-99 mg/dl during ICU stay, was 10.2% for patients with CV < 15% versus 58.3% for those with CV 50%+; for NON with MGL 100-119 mg/dl, corresponding rates were 10.6% and 55.6%.

CONCLUSIONS

Low GV during ICU stay was associated with increased survival among NON, and high GV was associated with increased mortality, even after adjustment for severity of illness. There was no independent association of GV with mortality among DM. Attempts to minimize GV may have a significant beneficial impact on outcomes of critically ill patients without diabetes.

Glycemic control in the burn intensive care unit: focus on the role of anemia in glucose measurement

Glycemic control with intensive insulin therapy (IIT) has received widespread adoption secondary to findings of improved clinical outcomes and survival in the burn population. Severe burn as a model for trauma is characterized by a hypermetabolic state, hyperglycemia, and insulin resistance. In this article, we review the findings of a burn center research facility in terms of understanding glucose management. The conferred benefits from IIT, our findings of poor outcomes associated with glycemic variability, advantages from preserved diurnal variation of glucose and insulin, and impacts of glucometer error and hematocrit correction factor are discussed. We conclude with direction for further study and the need for a reliable continuous glucose monitoring system. Such efforts will further the endeavor for achieving adequate glycemic control in order to assess the efficacy of target ranges and use of IIT.

Perioperative and critical illness dysglycemia--controlling the iceberg

Patients with dysglycemia related to known or unrecognized diabetes, stress hyperglycemia, or hypoglycemia in the presence or absence of exogenous insulin routinely require care during the perioperative period or critical illness. Recent single and multicenter studies, a large multinational study, and three meta-analyses evaluated the safety of routine tight glycemic control (80-110 mg/dl) in critically ill adults. Results led to a call for more modest treatment goals (initiation of insulin at a blood glucose >180 mg/dl with a goal of approximately 150 mg/dl). In this symposium, an international group of multidisciplinary experts discusses the role of tight glycemic control, glucose measurement technique and its accuracy, glucose variability, hypoglycemia, and innovative methods to facilitate glucose homeostasis in this heterogeneous patient population.

[Supportive and adjunctive sepsis therapy]

Severe sepsis and septic shock have an increasing incidence but an unchanged mortality. It has been demonstrated that the time until the start of supportive therapy affects the progress of multiorgan failure and patient outcome. Early goal-directed therapy guided by central venous oxygen saturation is associated with a significant reduction in mortality, as is the use of lung-protective mechanical ventilation and recombinant activated protein C (rhAPC) in eligible patients. The use of starches for volume resuscitation, low-dose dopamine and hydrocortison as well as an intensive insulin protocol for restoration of euglycemia is not recommended. The German Competence Network Sepsis (SepNet) is currently studying further relevant questions.

Year in review 2008: Critical Care--metabolism

In 2008, the interest in metabolic and endocrine issues and their consequences in critically ill patients was high. A large proportion of the research papers related to these issues was related to the metabolism of glucose and its control and to the changes in body composition, including muscular weakness. In Critical Care, original reports from investigations of glucose physiology and clinical data from observational and interventional studies were published. Important reports of the effects of hormone analogues, such as vasopressin and hydrocortisone, and early antioxidants in selected subpopulations were also available in 2008.

When less is more in the intensive care unit; lessons learned

In parallel to technological advances in late twentieth century, medical diagnostics and therapeutic options greatly improved. A surge of evidence-based research in intensive care medicine provided additional opportunities and the "best" medical practice has been changing rapidly. However, the primary focus of Hippocrates: "Primum non nocere" (first do no harm) is often neglected at the bedside. It became apparent that lesser intervention in the ICU may actually mean more for the patient. Multiple examples of the concept "when less is more in the ICU" are described here in an ABC format. Critical care providers have an obligation to keenly and closely follow the results of new investigative studies and to carefully incorporate those into our practice. However, they have to be sensitive to individual circumstances, patient and family preferences, and avoidance of harm.

Blood glucose control in patients with severe sepsis and septic shock

The main pathophysiological feature of sepsis is the uncontrollable activation of both pro- and anti-inflammatory responses arising from the overwhelming production of mediators such as pro- and anti-inflammatory cytokines. Such an uncontrollable inflammatory response would cause many kinds of metabolic derangements. One such metabolic derangement is hyperglycemia. Accordingly, control of hyperglycemia in sepsis is considered to be a very effective therapeutic approach. However, despite the initial enthusiasm, recent studies reported that tight glycemic control with intensive insulin therapy failed to show a beneficial effect on mortality of patients with severe sepsis and septic shock. One of the main reasons for this disappointing result is the incidence of harmful hypoglycemia during intensive insulin therapy. Therefore, avoidance of hypoglycemia during intensive insulin therapy may be a key issue in effective tight glycemic control. It is generally accepted that glycemic control aimed at a blood glucose level of 80-100 mg/dL, as initially proposed by van den Berghe, seems to be too tight and that such a level of tight glycemic control puts septic patients at increased risk of hypoglycemia. Therefore, now many researchers suggest less strict glycemic control with a target blood glucose level of 140-180 mg/dL. Also specific targeting of glycemic control in diabetic patients should be considered. Since there is a significant correlation between success rate of glycemic control and the degree of hypercytokinemia in septic patients, some countermeasures to hypercytokinemia may be an important aspect of successful glycemic control. Thus, in future, use of an artificial pancreas to avoid hypoglycemia during insulin therapy, special consideration of septic diabetic patients, and control of hypercytokinemia should be considered for more effective glycemic control in patients with severe sepsis and septic shock.

Blood glucose control among critically ill patients with brain injury

OBJECTIVE

To evaluate the incidence of hypoglycemia, hyperglycemia and blood glucose (BG) variability in brain-injured patients and their association with clinical outcomes.

METHODS

Retrospective cohort study of brain-injured patients admitted to an 11-bed neurosciences intensive care unit (ICU) from January 1 to December 31, 2003.

RESULTS

We included 606 patients. Mean age was 52.3 years, 60.6% were male, 11.9% had diabetes mellitus, and 64% were post-operative. Seventy-five (12.4%) received intensive insulin therapy (IIT) for a median (IQR) 72 (24-154) hours. Hypoglycemia and hyperglycemia occurred in 4.6% (96.4% receiving IIT) and 9.6% (77.6% receiving IIT). Median number of episodes per patient was 3 (75% with > or = 2) and 4 (81% with > or = 2) for hypoglycemia and hyperglycemia. Variable glycemic control occurred in 3.8% (100% receiving IIT) with median number of 13 episodes per patient. In-hospital mortality was 16.7%, median (IQR) ICU and hospital lengths of stay were 2 (1-5) and 8 (3-19) days. Hypoglycemia, hyperglycemia and BG variability showed non-significant but consistent associations with hospital mortality and prolonged lengths of ICU and hospital stay. The rate of recurrence of episodes showed stronger and significant associations with outcome, in particular for BG variability and hyperglycemia.

CONCLUSIONS

Hypoglycemia, hyperglycemia and BG variability are relatively common in brain-injured patients and are associated with IIT. An increased frequency of episodes, in particular for BG variability and hyperglycemia, was associated with greater risk of both hospital death and prolonged duration of stay.

The impact of early hypoglycemia and blood glucose variability on outcome in critical illness

Introduction

In critical illness, the association of hypoglycemia, blood glucose (BG) variability and outcome are not well understood. We describe the incidence, clinical factors and outcomes associated with an early hypoglycemia and BG variability in critically ill patients.

Methods

Retrospective interrogation of prospectively collected data from the Australia New Zealand Intensive Care Society Adult Patient Database on 66184 adult admissions to 24 intensive care units (ICUs) from 1 January 2000 to 31 December 2005. Primary exposure was hypoglycemia (BG < 4.5 mmol/L) and BG variability (BG < 4.5 and ≥ 12.0 mmol/L) within 24 hours of admission. Primary outcome was all-cause mortality.

Results

The cumulative incidence of hypoglycemia and BG variability were 13.8% (95% confidence interval (CI) = 13.5 to 14.0; n = 9122) and 2.9% (95%CI = 2.8 to 3.0, n = 1913), respectively. Several clinical factors were associated with both hypoglycemia and BG variability including: co-morbid disease (P < 0.001), non-elective admissions (P < 0.001), higher illness severity (P < 0.001), and primary septic diagnosis (P < 0.001). Hypoglycemia was associated with greater odds of adjusted ICU (odds ratio (OR) = 1.41, 95% CI = 1.31 to 1.54) and hospital death (OR = 1.36, 95% CI = 1.27 to 1.46). Hypoglycemia severity was associated with 'dose-response' increases in mortality. BG variability was associated with greater odds of adjusted ICU (1.5, 95% CI = 1.4 to 1.6) and hospital (1.4, 95% CI = 1.3 to 1.5) mortality, when compared with either hypoglycemia only or neither.

Conclusions

In critically ill patients, both early hypoglycemia and early variability in BG are relatively common, and independently portend an increased risk for mortality.

Stress hyperglycaemia

Results of randomised controlled trials of tight glycaemic control in hospital inpatients might vary with population and disease state. Individualised therapy for different hospital inpatient populations and identification of patients at risk of hyperglycaemia might be needed. One risk factor that has received much attention is the presence of pre-existing diabetes. So-called stress hyperglycaemia is usually defined as hyperglycaemia resolving spontaneously after dissipation of acute illness. The term generally refers to patients without known diabetes, although patients with diabetes might also develop stress hyperglycaemia-a fact overlooked in many studies comparing hospital inpatients with or without diabetes. Investigators of several studies have suggested that patients with stress hyperglycaemia are at higher risk of adverse consequences than are those with pre-existing diabetes. We describe classification of stress hyperglycaemia, mechanisms of harm, and management strategies.

Stress hyperglycaemia

Results of randomised controlled trials of tight glycaemic control in hospital inpatients might vary with population and disease state. Individualised therapy for different hospital inpatient populations and identification of patients at risk of hyperglycaemia might be needed. One risk factor that has received much attention is the presence of pre-existing diabetes. So-called stress hyperglycaemia is usually defined as hyperglycaemia resolving spontaneously after dissipation of acute illness. The term generally refers to patients without known diabetes, although patients with diabetes might also develop stress hyperglycaemia-a fact overlooked in many studies comparing hospital inpatients with or without diabetes. Investigators of several studies have suggested that patients with stress hyperglycaemia are at higher risk of adverse consequences than are those with pre-existing diabetes. We describe classification of stress hyperglycaemia, mechanisms of harm, and management strategies.

Severe intraoperative hyperglycemia is independently associated with surgical site infection after liver transplantation

BACKGROUND

Surgical site infection (SSI) is a common postoperative complication associated with increased morbidity and mortality in patients undergoing liver transplantation (LT). Although intraoperative hyperglycemia has been shown to be associated with adverse postoperative outcomes including overall infection rate in LT patients, a relationship between intraoperative hyperglycemia and SSI in LT has not been established. We sought to determine if intraoperative hyperglycemia was associated with SSI after LT.

METHODS

Patients undergoing LT at our medical center between January 2004 and November 2007 were included in the study. Recipient, donor, and intraoperative variables including a variety of glucose indices were retrospectively analyzed. Independent risk factors of SSI were identified using a multivariate logistic regression model.

RESULTS

Of 680 patients, 76 (11.2%) experienced postoperative SSIs. Among all intraoperative glucose indices analyzed, severe hyperglycemia (>or= 200 mg/dL) was independently associated with postoperative SSI (odds ratio [OR] 2.25, 95% confidence interval [CI] 1.26-4.03, P=0.006). Other independent risk factors include repeat surgery (OR 6.58, 95% CI 3.41-12.69, P<0.001), intraoperative administration of vasopressor (OR 3.14, 95% CI 1.65-5.95, P<0.001), preoperative mechanical ventilation (OR 3.01, 95% CI 1.70-5.33, P<0.001), and combined liver and kidney transplantation (OR 2.95, 95% CI 3.41-12.69, P<0.001).

CONCLUSIONS

Severe, but not mild or moderate, intraoperative hyperglycemia is independently associated with postoperative SSI and should be avoided during LT surgery.

NICE-SUGAR: the end of a sweet dream?

The results of the NICE-SUGAR (Normoglycaemia in Intensive Care Evaluation Survival Using Glucose Algorithm Regulation) trial were released last March. The primary outcome variable, 90-day mortality, was actually increased in patients randomly assigned to intensive insulin therapy, as compared with an intermediate target range for blood glucose. These findings, reflecting data collected in a set of more than 6,000 patients, clearly refute the external validity of tight glucose control. Future research will probably focus on several questions raised by the divergent results reported from investigations in the field of glucose control in the critically ill.

Glucose control in the intensive care unit

OBJECTIVE

Hyperglycemia, be it secondary to diabetes, impaired glucose tolerance, impaired fasting glucose, or stress-induced is common in the critically ill. Hyperglycemia and glucose variability in intensive care unit (ICU) patients has some experts calling for routine administration of intensive insulin therapy to normalize glucose levels in hyperglycemic patients. Others, however, have raised concerns over the optimal glucose level, the accuracy of measurements, the resources required to attain tight glycemic control (TGC), and the impact of TGC across the heterogeneous ICU population in patients with diabetes, previously undiagnosed diabetes or stress-induced hyperglycemia. Increased variability in glucose levels during critical illness and the therapeutic intervention thereof have recently been reported to have a deleterious impact on survival, particularly in nondiabetic hyperglycemic patients. The incidence of hypoglycemia (<40 mg/dL or 2.2 mmol) associated with TGC is reported to be as high as 18.7%, by Van den Berghe in a medical ICU, although application of various approaches and computer-based algorithms may improve this. The impact of hypoglycemia, particularly in patients with septic shock and those with neurologic compromise, warrants further evaluation. This review briefly discusses the epidemiology of hyperglycemia in the acutely ill and glucose metabolism in the critically ill. It comments on present limitations in glucose monitoring, outlines current glucose management approaches in the critically ill, and the transition from the ICU to the intermediate care unit or ward. It closes with comment on future developments in glycemic care of the critically ill.

METHODS

The awareness of the potential deleterious impact of hyperglycemia was heightened after Van den Berghe et al presented their prospective trial in 2001. Therefore, source data were obtained from PubMed and Cochrane Analysis searches of the medical literature, with emphasis on the time period after 2000. Recent meta-analyses were reviewed, expert editorial opinion collated, and the Web site of the Normoglycemia in Intensive Care Evaluation and Survival Using Glucose Algorithm Regulation Trial investigated.

SUMMARY AND CONCLUSIONS

Hyperglycemia develops commonly in the critically ill and impacts outcome in patients with diabetes but, even more so, in patients with stress-induced hyperglycemia. Despite calls for TGC by various experts and regulatory agencies, supporting data remain somewhat incomplete and conflicting. A recently completed large international study, Normoglycemia in Intensive Care Evaluation and Survival Using Glucose Algorithm Regulation, should provide information to further guide best practice. This concise review interprets the current state of adult glycemic management guidelines to provide a template for care as new information becomes available.

Is reducing variability of blood glucose the real but hidden target of intensive insulin therapy?

Since the first report that intensive insulin therapy reduced mortality in selected surgical critically ill patients, lowering of blood glucose levels has been recommended as a means of improving patient outcomes. In this initial Leuven trial, blood glucose control by protocol using insulin was applied to 98.7% of patients in the intensive group but to only 39.2% (P < 0.0001) of patients in the control group. If appropriately applied, such protocols should decrease both the mean blood glucose concentration and its variability (variation of blood glucose concentration). Thus, it is logically possible that the benefit of intensive insulin therapy in the first Leuven trial was due to a decrease in mean glucose levels, a decrease in their variability, or both. Several recent studies have confirmed significant associations between variability of blood glucose levels and patient outcomes. Decreasing the variability of blood glucose levels might be an important dimension of glucose management, a possible mechanism by which an intensive insulin protocol exerts its putative beneficial effects, and an important goal of glucose management in the intensive care unit. Clinicians need to be aware of this controversy when considering the application of intensive insulin therapy and interpreting future trials.

Intensive glucose control after allogeneic hematopoietic stem cell transplantation: a retrospective matched-cohort study

Some studies have shown that intensive glucose control (IGC) improves outcome in the intensive care unit setting. However, it is the benefit of IGC in hematopoietic SCT (HSCT) that is not well defined. Between June 2006 and May 2007, IGC was maintained prospectively after allogeneic HSCT and clinical outcomes were compared with a cohort matched for conditioning regimen, source of stem cells, age and relation to donor. A stratified Cox regression model was used. There were no significant differences in baseline clinical characteristics. The median age was 43.5 years in both groups. The primary diagnosis was a hematologic malignancy. Patients in the IGC group had a lower glucose level (least-square mean, 116.4 vs 146.8 mg per 100 ml, P<0.001) compared to the standard glucose control group. The incidences of documented infections and bacteremia were significantly lower in the IGC group (14 vs 46%, P=0.004, 9 vs 39%, P=0.002, respectively). IGC tended to reduce the incidence of renal dysfunction (19 vs 37%, P=0.36) and the elevation of C-reactive protein (18 vs 38%, P=0.13). This study suggests that IGC has may have a beneficial effect after HSCT. IGC should be evaluated further in a large prospective, randomized study.

Is reducing variability of blood glucose the real but hidden target of intensive insulin therapy?

Since the first report that intensive insulin therapy reduced mortality in selected surgical critically ill patients, lowering of blood glucose levels has been recommended as a means of improving patient outcomes. In this initial Leuven trial, blood glucose control by protocol using insulin was applied to 98.7% of patients in the intensive group but to only 39.2% (P < 0.0001) of patients in the control group. If appropriately applied, such protocols should decrease both the mean blood glucose concentration and its variability (variation of blood glucose concentration). Thus, it is logically possible that the benefit of intensive insulin therapy in the first Leuven trial was due to a decrease in mean glucose levels, a decrease in their variability, or both. Several recent studies have confirmed significant associations between variability of blood glucose levels and patient outcomes. Decreasing the variability of blood glucose levels might be an important dimension of glucose management, a possible mechanism by which an intensive insulin protocol exerts its putative beneficial effects, and an important goal of glucose management in the intensive care unit. Clinicians need to be aware of this controversy when considering the application of intensive insulin therapy and interpreting future trials.

The severity of sepsis: yet another factor influencing glycemic control

The present commentary provides a brief overview of the evolving literature on glycemic management in critically ill patients. Recent interventional studies have been plagued by high rates of severe hypoglycemia among patients, particularly those with sepsis. The investigation by Waeschle and colleagues adds to our knowledge about the relationship between the severity of sepsis and glycemic dysregulation. The severity of sepsis is shown to correlate with the risk of sustaining hyperglycemia as well as critical hypoglycemia.

The prevention of acute kidney injury: an in-depth narrative review Part 1: volume resuscitation and avoidance of drug- and nephrotoxin-induced AKI

This narrative clinical review in two parts discusses the prevention of clinical acute kidney injury (AKI). The first part focuses on general prevention measures, including identification of individuals at high risk for AKI, and on the role of volume expansion and fluid therapy. The latter discusses the timing, the goals, the selection of the fluids and the haemodynamic management of the patient receiving parenteral fluids for the prevention of AKI. In addition, this part summarizes the interaction of intensivist-nephrologist in the ICU with attention to tight glycaemia control and the use of low doses of corticoids in the septic shock patients. Finally, the avoidance of drug- and nephrotoxin-induced AKI is discussed. The second part of this review will summarize the possible pharmacological interventions in the patient at risk.