Diabetes and hyperglycemia: strict glycemic control

Impact of stress hyperglycemia ratio on mortality in patients with cardiac arrest: insight from American MIMIC-IV database

Background

Stress hyperglycemia ratio (SHR) has shown a predominant correlation with transient adverse events in critically ill patients. However, there remains a gap in comprehensive research regarding the association between SHR and mortality among patients experiencing cardiac arrest and admitted to the intensive care unit (ICU).

Methods

A total of 535 patients with their initial ICU admission suffered cardiac arrest, according to the American Medical Information Mart for Intensive Care (MIMIC)-IV database. Patients were stratified into four categories based on quantiles of SHR. Multivariable Cox regression models were used to evaluate the association SHR and mortality. The association between SHR and mortality was assessed using multivariable Cox regression models. Subgroup analyses were conducted to determine whether SHR influenced ICU, 1-year, and long-term all-cause mortality in subgroups stratified according to diabetes status.

Results

Patients with higher SHR, when compared to the reference quartile 1 group, exhibited a greater risk of ICU mortality (adjusted hazard ratio [aHR] = 3.029; 95% CI: 1.802-5.090), 1-year mortality (aHR = 3.057; 95% CI: 1.885-4.958), and long-term mortality (aHR = 3.183; 95% CI: 2.020-5.015). This association was particularly noteworthy among patients without diabetes, as indicated by subgroup analysis.

Conclusion

Elevated SHR was notably associated with heightened risks of ICU, 1-year, and long-term all-cause mortality among cardiac arrest patients. These findings underscore the importance of considering SHR as a potential prognostic factor in the critical care management of cardiac arrest patients, warranting further investigation and clinical attention.

Continuous ex vivo glucose sensing in human physiological fluids using an enzymatic sensor in a vein replica

Managing blood glucose can affect important clinical outcomes during the intraoperative phase of surgery. However, currently available instruments for glucose monitoring during surgery are few and not optimized for the specific application. Here we report an attempt to exploit an enzymatic sensor in a vein replica that could continuously monitor glucose level in an authentic human bloodstream. First, detailed investigations of the superficial venous systems of volunteers were carried out using ocular and palpating examinations, as well as advanced ultrasound measurements. Second, a tubular glucose-sensitive biosensor mimicking a venous system was designed and tested. Almost ideal linear dependence of current output on glucose concentration in phosphate buffer saline was obtained in the range 2.2-22.0 mM, whereas the dependence in human plasma was less linear. Finally, the developed biosensor was investigated in whole blood under homeostatic conditions. A specific correlation was found between the current output and glucose concentration at the initial stage of the biodevice operation. However, with time, blood coagulation during measurements negatively affected the performance of the biodevice. When the experimental results were remodeled to predict the response without the influence of blood coagulation, the sensor output closely followed the blood glucose level.

Metal-Based Nanozymes with Multienzyme-Like Activities as Therapeutic Candidates: Applications, Mechanisms, and Optimization Strategy

Most nanozymes in development for medical applications only exhibit single-enzyme-like activity, and are thus limited by insufficient catalytic activity and dysfunctionality in complex pathological microenvironments. To overcome the impediments of limited substrate availabilities and concentrations, some metal-based nanozymes may mimic two or more activities of natural enzymes to catalyze cascade reactions or to catalyze multiple substrates simultaneously, thereby amplifying catalysis. Metal-based nanozymes with multienzyme-like activities (MNMs) may adapt to dissimilar catalytic conditions to exert different enzyme-like effects. These multienzyme-like activities can synergize to realize "self-provision of the substrate," in which upstream catalysts produce substrates for downstream catalytic reactions to overcome the limitation of insufficient substrates in the microenvironment. Consequently, MNMs exert more potent antitumor, antibacterial, and anti-inflammatory effects in preclinical models. This review summarizes the cellular effects and underlying mechanisms of MNMs. Their potential medical utility and optimization strategy from the perspective of clinical requirements are also discussed, with the aim to provide a theoretical reference for the design, development, and therapeutic application of their catalytic effects.

Association of Diabetes and Other Clinical and Sociodemographic Factors With Guideline-concordant Breast Cancer Treatment for Breast Cancer

BACKGROUND

Women with breast cancer have worse health outcomes with co-occurring type 2 diabetes, possibly due to suboptimal breast cancer treatment.

METHODS

We created a cohort of women ages 66 to 85 y with stage I to III breast cancer from 1993 to 2012 from an integrated health care delivery system (n=1612) and fee-for-service Medicare beneficiaries (n=98,915), linked to Surveillance, Epidemiology, and End Results (SEER) data (total n=100,527). We evaluated associations between type 2 diabetes and other factors with undergoing guideline-concordant cancer treatment. We estimated χ tests for univariate analysis and relative risks (RRs) using multivariable log-binomial models for outcomes of (1) overall guideline-concordant treatment, (2) definitive surgical therapy (mastectomy or lumpectomy with radiation), (3) chemotherapy if indicated, and (4) endocrine therapy.

RESULTS

Our cohort included 60% of subjects with stage 1 tumors, one quarter below 70 years old, 23% had diabetes, 35% underwent overall guideline-concordant treatment, 24% chemotherapy, and 83% endocrine therapy. Women with diabetes were less likely to undergo overall guideline-concordant treatment (RR: 0.96; 95% confidence interval: 0.94-0.98), and only slightly less likely to undergo guideline-concordant definitive surgical therapy (RR: 0.99; 95% confidence interval: 0.99-1.00). No differences were found for chemotherapy or endocrine therapy. Other factors significantly associated with a lower risk of guideline-concordant care were cancer stages II to III (vs. I; RR=0.47-0.69, P<0.0001), older age (vs. 66 to 69 y; RR=0.56-0.90, P<0.0001), higher comorbidity burden, and Medicaid dual-eligibility.

CONCLUSIONS

Diabetes was associated with lower adherence to overall guideline-concordant breast cancer treatment. However, higher stage, older age, higher comorbidity burden, and Medicaid insurance were more strongly associated with lower use of guideline-concordant treatment. Given the heavy burden of breast cancer and diabetes, long-term outcomes analysis should consider guideline-concordant treatment.

IMPACT

Other factors besides diabetes are more strongly associated with guideline-concordant breast cancer treatment.

Postoperative Day 1 Glucose May Be Associated With Wound Complications in Sarcomas Treated With Preoperative Radiation

BACKGROUND

Uncontrolled blood glucose impacts key phases of the wound healing process. Various factors have been associated with postoperative wound complications in soft tissue sarcomas; however, the association of postoperative early morning blood glucose with wound complications, if any, remains to be determined. Because blood glucose levels may be modified, understanding whether glucose levels are associated with wound complications has potential therapeutic importance.

QUESTIONS/PURPOSES

The purposes of this study were (1) to evaluate if postoperative early morning blood glucose is associated with the development of wound complications in soft tissue sarcomas; (2) to determine a blood glucose cutoff that may be associated with an increased risk of wound complications; and (3) to evaluate if patients with diabetes have higher postoperative blood glucose and an associated increased risk of wound complications.

METHODS

From 2000 to 2015, 298 patients with Stage I to III soft tissue sarcomas of the extremity or chest wall were treated with preoperative radiation ± chemotherapy followed by limb-sparing resection. Of those, 191 (64%) patients had demographic, treatment, and postoperative variables and wound outcomes available; these patients' results were retrospectively evaluated. None of the 191 patients were lost to followup. Early morning blood glucose levels on postoperative day (POD) 1 were available in all patients. Wound complications were defined as those resulting in an operative procedure or prolonged wound care for 6 months postresection. Variables that may be associated with wound complications were evaluated using logistic regression for multivariate analysis. Receiver operative curve (ROC) analysis was used to assess the early morning blood glucose level that best was associated postoperative wound complications.

RESULTS

After controlling for potentially relevant confounding variables such as patient comorbidities, tumor size, and location, lower extremity soft tissue sarcomas (p = 0.002, odds ratio [OR], 6.4; 95% confidence interval [CI], 1.97-20.84) and elevated POD 1 early morning blood sugars (p < 0.001; OR, 1.1; 95% CI, 1.04-1.11) were associated with increased wound complications postoperatively. ROC analysis revealed that early morning POD 1 blood glucose of > 127 mg/dL was associated with postoperative wound complications with a sensitivity of 89% (area under the curve 0.898, p < 0.001). Median POD 1 early morning blood glucose in patients without diabetes was 118 mg/dL and 153 mg/dL in patients with diabetes (p = 0.023). However, with the numbers available, there was no increase in wound complications in patients with diabetes compared with those without it.

CONCLUSIONS

Our study provides preliminary information suggesting that POD 1 early morning blood glucose in patients with soft tissue sarcomas may be associated with a slightly increased risk of postoperative wound complications. An early morning blood glucose of > 127 mg/dL may be a threshold associated with this outcome. Although patients with diabetes had higher POD 1 early morning blood glucose levels, diabetes itself was not associated with the development of wound complications. We cannot conclude that better glycemic control will reduce wound complications in patients who receive preoperative radiation, but our data suggest this should be further studied in a larger, prospective study.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Glycemic management in critically ill patients

Hyperglycemia associated with critical illness, also called “stress hyperglycemia” or “stress diabetes”, is a consequence of many pathophysiologic hormonal responses including increased catecholamines, cortisol, glucagon, and growth hormone. Alterations in multiple biochemical pathways result in increased hepatic and peripheral insulin resistance with an uncontrolled activation of gluconeogenesis and glycogenolysis. Hyperglycemia has a negative impact on the function of the immune system, on the host response to illness or injury, and on infectious and overall outcomes. The degree of glucose elevation is associated with increased disease severity. Large randomized controlled trials including the Van den Berghe study, the NICE-SUGAR trial, VISEP and GLUCONTROL have shown that the control of glucose levels in critically ill patients has implications on outcome and that both hyperglycemia and hypoglycemia are detrimental and should be avoided. Glucose variability has also been shown to be detrimental. Aggressive glucose control strategies have changed due to the concerns of hypoglycemia and therefore intermediate target glucose control strategies are most often adopted. Different patient populations may vary with regards to optimal glucose targets, timing and approach for glucose control, and with regards to the prognostic significance of glucose excursions and variability. Medical, surgical, and trauma patients may benefit at different rates from glucose control and the approach may need to be adapted to various medical settings and to correspond to the workflow of health providers. Effect modifiers for the success of insulin therapy for hyperglycemia include the methods of nutritional supplementation and exogenous glucose administration. Further research is required to improve insulin protocols for glucose control, to further define glucose targets, and to enhance the accuracy of glucose measuring technologies.

Glycemic Status and Infection Risk in Nondiabetic Autologous Hematopoietic Cell Transplantation Recipients

BACKGROUND

Patients undergoing hematopoietic cell transplantation (HCT) for hematological malignancies experience a number of challenges during treatment. There is growing evidence that malglycemia (hyperglycemia, hypoglycemia, and/or increased glycemic variability) contributes to HCT-related complications, even in patients without preexisting diabetes. The purpose of this pilot study was to investigate factors influencing glycemic status and associated infection occurrences in nondiabetic autologous HCT recipients.

METHODS

Oncology patients without preexisting diabetes treated with autologous HCT at a National Cancer Institute-designated cancer center were followed from admission through discharge or 28 days post-HCT. Patients had morning fasting laboratory tests. Descriptive statistics and Cox proportional hazards models were used to examine associations between BG levels and risk for infection while adjusting for baseline covariates including age, body mass index (BMI), cumulative glucocorticoid dose, and diagnosis.

RESULTS

The sample included 28 female and 25 male predominately non-Hispanic White patients (mean age 55.7 years, SD = 11.32). Blood glucose (BG) range was 35-325 mg/dl. Twenty-three patients incurred at least one infection. BMI ≥ 25 kg/m(2) was associated with high BG and infections. In the multivariate Cox model, an increase of 1 interquartile range in BG 2 days before infection was associated with a moderately increased risk of infection (hazard ratio = 1.44, p = .008).

CONCLUSIONS

Understanding the contributors to and consequences of malglycemic events can lead to better protocols for identifying patients at greater risk for infection. Further investigation is warranted for interventions to mitigate BG events for improved outcomes.

Burn intensive care

As a result of continuous development in the treatment of burns, the LD50 (the burn size lethal to 50% of the population) for thermal injuries has risen from 42% total body surface area (TBSA) during the 1940s and 1950s to more than 90% TBSA for young thermally injured patients. This vast improvement in survival is due to simultaneous developments in critical care, advancements in resuscitation, control of infection through early excision, and pharmacologic support of the hypermetabolic response to burns. This article reviews these recent advances and how they influence modern intensive care of burns.

Malglycemia and cancer: introduction to a conceptual model

PURPOSE/OBJECTIVES

To introduce a conceptual model detailing the physiologic contributions of malglycemia to cancer formation and increased morbidity and mortality.

DATA SOURCES

A literature search was conducted using the PubMed, CINAHL®, and Cochrane databases, as well as Surveillance, Epidemiology and End Results (SEER) cancer statistics.

DATA SYNTHESIS

Multiple complex factors are associated with malignancy formation, proliferation, and outcomes for each individual. The authors present a model, termed the Malglycemia Orbit Model, that is analogous to an atom, centered on a core of individual factors, and surrounded by "orbits" containing cancer and related factors. Highlighted in this model is the role of malglycemia.

CONCLUSIONS

Cancer formation and sequelae involve numerous multifaceted factors. One factor not well described or understood within the context of malignancies is glycemic status, most notably how malglycemia impacts cancer formation and risks for adverse outcomes. The atomic-structured malglycemia model describes this process.

IMPLICATIONS FOR NURSING

Among the many uncontrollable factors that contribute to cancer formation and adverse outcomes, malglycemia is one that is modifiable. Nurses are in a prime position to conduct research to enhance understanding and ultimately improve protocols for better glycemic control and, in effect, better outcomes for individuals with cancer.

Insulin inhibits hepatocyte iNOS expression induced by cytokines by an Akt-dependent mechanism

Hepatocyte inducible nitric oxide synthese (iNOS) expression is a tightly controlled pathway that mediates hepatic inflammation and hepatocyte injury in a variety of disease states. We have shown that cyclic adenosine monophosphate (cAMP) regulates cytokine-induced hepatocyte iNOS expression through mechanisms that involve protein kinase B/Akt. We hypothesized that insulin, which activates Akt signaling in hepatocytes, as well as signaling through p38 and MAPK p42/p44, would regulate iNOS expression during inflammation. In primary rat hepatocytes, insulin inhibited cytokine-stimulated nitrite accumulation and iNOS expression in a dose-dependent manner. Inhibition of MAPK p42/p44 with PD98059 had no effect on iNOS activation, whereas SB203580 to block p38 reversed insulin's inhibitory effect. However, insulin did not increase p38 activation and inhibition of p38 signaling with a dominant negative p38 plasmid had no effect on cytokine- or insulin-mediated effects on iNOS. We found that SB203580 blocked insulin-induced Akt activation. Inhibition of Akt signaling with LY294002 or a dominant negative Akt plasmid increased cytokine-stimulated nitrite production and iNOS protein expression and blocked the inhibitory effects of insulin. NF-κB induces iNOS expression and can be regulated by Akt, but insulin had no effect on cytokine-mediated IκBα levels or NF-κB p65 translocation. Our data demonstrate that insulin inhibits cytokine-stimulated hepatocyte iNOS expression and does so through effects on Akt-mediated signaling.

The role of hyperglycemia in burned patients: evidence-based studies

Severely burned patients typically experience a systemic response expressed as increased metabolism, inflammation, alteration of cardiac and immune function, and associated hyperglycemia. Hyperglycemia has been associated with an increased risk of morbidity and mortality in critically ill patients. Until recently and for many years, hyperglycemia has been expectantly managed and considered a normal and desired response of an organism to stress. However, findings reported from recent studies now suggest beneficial effects of intensive insulin treatment of critically ill patients. The literature on the management of hyperglycemia in severely burned patients is sparse, with most of the available studies involving only small numbers of burned patients. The purpose of this article is to describe the pathophysiology of hyperglycemia after severe burns and to review the available literature on the outcome of intensive insulin treatment and other anti-hyperglycemic modalities in burned patients in an evidence-based medical approach.

Glycemic control in critically ill patients before and after institution of an intensive insulin infusion protocol: circadian rhythm and the quality duration calculator

INTRODUCTION

A circadian rhythm of blood glucose values has been recently reported in critically ill patients, but there are no reports of how this rhythm is altered by a continuous intensive insulin infusion therapy protocol (IIT). We wished to examine the effect of IIT on this rhythm as well as to describe the use of the quality duration calculator (QDC) for the evaluation of glycemic control before and after IIT.

METHODS

This was a retrospective multihospital observational study that took place in the medical and surgical intensive care units (ICUs) of 2 tertiary care hospitals. Cohorts of consecutively admitted critically ill patients from 2-year periods before and after institution of an IIT protocol were examined. Laboratory, demographic, and outcome data were extracted from hospital databases.

RESULTS

We studied 167,645 blood glucose measurements from 8,327 patients. We observed a circadian rhythm of blood glucose control in the pre-IIT cohort that was greatly attenuated in the post-IIT cohort. The difference between the morning and the average daily blood glucose in the pre-IIT cohort was 3.53 mg/dL (P < .001), and the difference between these values in the post-IIT cohort was 1.10 mg/dL (P = .031). In addition, the circadian nature of hyperglycemia incidence observed in the pre-IIT cohort was not seen in the post-IIT cohort. The amount of time spent in goal glycemic range increased from 23.69% (95% CI 23.01-24.38) in the pre-IIT cohort to 29.67% (95% CI 29.04-30.31) in the post-IIT cohort as estimated by the QDC. The amount of time spent in the hyperglycemic decreased from 20.17% (95% CI 19.33-20.99) in the pre-IIT cohort to 14.80% (95% CI 14.15-15.39) in the post-IIT cohort.

CONCLUSIONS

The circadian rhythm of blood glucose control confirmed in our pre-IIT cohort was lost after institution of IIT. The morning blood glucose value appears to be a reasonable surrogate of overall glycemic control in a critically ill population on IIT, although this may vary based on the degree of control achieved. The QDC method is useful for analyzing glycemic control in patients on IIT.

Hyperinsulinemia predicts survival in a hyperglycemic mouse model of critical illness

OBJECTIVES

: The mechanisms by which correcting hyperglycemia with exogenous insulin improves mortality and morbidity in critically ill patients remain unclear. We designed this study to test the hypothesis that relative endogenous insulin deficiency is associated with adverse outcomes in critical illness related to hyperglycemia.

DESIGN

: Prospective controlled animal study.

SETTING

: University research laboratory.

SUBJECTS

: Male C57BL/6J mice, 8-12 wks old.

INTERVENTIONS

: Spontaneously breathing mice were instrumented with chronic indwelling arterial and venous catheters. After a postoperative recovery period, endotoxemia was initiated with intra-arterial lipopolysaccharide (1 mg/kg) in the presence of dextrose infusion (100 microL/hr). Insulin secretion was blocked with diazoxide (2.5-30 mg/kg/day). Mice were monitored continuously for 48 hrs with blood sampled serially for blood glucose and plasma insulin determinations.

MEASUREMENTS AND MAIN RESULTS

: In both saline- and glucose-infused mice, lipopolysaccharide administration induced transient hemodynamic instability without significant impact on mortality. In the saline-infused group, lipopolysaccharide administration caused a transient reduction in blood glucose and in circulating insulin. However, in glucose-infused mice, lipopolysaccharide induced a large and unexpected increase in circulating insulin without significant alteration in blood glucose. Blockade of insulin secretion in response to lipopolysaccharide in the presence of exogenous glucose precipitated marked hyperglycemia and resulted in >90% mortality. In a subanalysis of animals matched for the degree of hyperglycemia, nonsurvivors had markedly lower insulin levels compared with survivors (3.5 +/- 0.8 ng/dL vs. 9.3 +/- 1.4 ng/dL; p < .004).

CONCLUSIONS

: Endogenous insulin deficiency in the face of hyperglycemia is associated with mortality in a mouse model of lipopolysaccharide-induced critical illness.

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.

Towards closed-loop glycaemic control

Blood glucose control performed by intensive care unit (ICU) nurses is becoming standard practice for critically ill patients. New algorithms, ranging from basic protocols to elementary computerized protocols to advanced computerized protocols, have been presented during the last years aiming to reduce the workload of the medical team. This paper gives an overview of the different types of algorithms and their features. Performance comparisons between different algorithms are avoided as blood glucose sampling frequencies and protocol durations were not similar among different studies and even within studies. Particularly advanced computerized protocols can potentially be introduced as fully-automated blood glucose algorithms when accurate and reliable near-continuous glucose sensor devices are available. Furthermore, it is surprising to consider in some of the described protocols that the original blood glucose target ranges (80-110 mg/dl) were increased (due to fear of hypoglycaemia) and/or that glycaemia levels were determined in capillary blood samples.

[Mortality risk factors in surgical patients in a tertiary hospital: a study of patient records in the period 2004-2006]

OBJECTIVE

To determine mortality risk factors in surgical patients.

MATERIAL AND METHOD

A cross-sectional study was carried out on all surgical patients who died while in hospital, over a period of three years (2004-2006). Pre, intra and postoperative variables were analysed. Comparisons were made between patients operated on as emergencies and elective surgery patients. Multivariate analysis was performed on the pre, intra and postoperative variables, using chi(2) of Pearson correlation with a confidence interval of 95%.

RESULTS

Surgery was performed on a total of 38 815 patients, of which 6 326 were emergency procedures and 32 489 as elective. There were 479 deaths registered: 36 occurred in the operating theatre and 443 died after the operation. Arterial hypertension, diabetes mellitus and cancer were significant causes of death. Intraoperative complications were associated with mortality during the surgical procedure. Emergency surgery was an independent risk factor (mortality, 5.5% vs. 0.4% for elective surgery). Sepsis, cardiac and respiratory related deaths were the main risk factors for postoperative death.

CONCLUSIONS

Prevention and adequate treatment of perioperative risk factors should significantly reduce morbidity and mortality rates, mainly in those patient operated as emergencies.

Glycemia management in neurocritical care patients: a review

Intensive research investigating the relation between the management of glycemia and outcome in patients receiving neurocritical care has underlined the possible benefits and adverse events related to glucose control. Here, we review experimental and clinical studies investigating the effects of hypoglycemia and hyperglycemia on the brain that advance current knowledge on managing glycemia in patients receiving neurocritical care.

Evaluation of cerebrovascular carbon dioxide reactivity in patients with diabetes mellitus under sedative doses of propofol

The present study compared cerebrovascular CO2 reactivity in diabetic patients on different treatment modalities under sedative doses of propofol. Fifteen patients with diabetes mellitus (on three different antidiabetic treatment modalities) who required mechanical ventilation during intensive care therapy were studied, sedation during mechanical ventilation being maintained using propofol. As controls, 6 patients without diabetes were monitored. A 2.5-MHz pulsed transcranial Doppler probe was attached to the head of the patient at the right temporal window for continuous measurement of mean blood flow velocity in the middle cerebral artery (Vmca). After establishing baseline values of Vmca and cardiovascular hemodynamics, end-tidal CO2 was decreased by increasing ventilatory frequency by 5-8 breaths.min(-1). Values for absolute and relative CO2 reactivity in insulintreated patients were lower than those in the other three groups (absolute CO2 reactivity [means +/- SD]: control, 3.1 +/- 0.6 cm.s(-1).mmHg(-1), diet, 3.8 +/- 1.4 cm.s(-1) x mmHg(-1); oral antidiabetic drug 3.2 +/- 0.9 cm x s(-1) x mmHg(-1); insulin, 1.1 +/- 0.6 cm x s(-1) x mmHg(-1); P = 0.002).The present study shows that insulin-treated diabetic patients probably have lower cerebrovascular CO2 reactivity under propofol anesthesia than control patients or diabetics treated with dietary therapy or oral hypoglycemics.

Glycemic control in the ICU

Glycemic control clearly improves outcome in critically ill patients. Remaining questions are how tight the control must be to obtain the most benefit without increasing the risk for severe hypoglycemia, and whether an acuity level exists in which this benefit is not clearly visualized. In other words, is this benefit only seen in severely ill patients? The authors believe that clinical trials with ICU lengths of stay of 3 days or less make showing a clinical benefit difficult. Rather, they believe that clinical benefit is seen in higher acuity patients whose ICU length of stay is directly related to the reversal of the inflammatory systemic response rather than the disease or injury alone. Finally, the issue remains of how to obtain a TGC in the 80 to 110 mg/dL range without achieving a less-than-acceptable incidence of hypoglycemia. The answer may well lie with the introduction of continuous glucose monitors that will allow measurements to be obtained every 15 to 30 minutes without introducing an increased workload to the nursing staff. Many of these devices, such as the Optiscanner, which measures plasma glucose continuously, are on the horizon and should be approved by the FDA in 2008.

[Glycemic control in sepsis and septic shock: friend or foe?]

INTRODUCTION

Intensive care patients commonly suffer from hyperglycemia. Evidence is growing that strictly maintaining normoglycemia by intensive insulin therapy (IIT) ameliorates outcome in these patients. Whether or not this also holds true for patients with sepsis and septic shock is the issue of this post-hoc analysis of the database (2,748 patients) of 2 recent prospective clinical trials.

MATERIAL AND METHODS

A total of 950 patients suffering from sepsis were identified and of these 462 fulfilled the diagnostic criteria of septic shock upon admission to the intensive care unit (ICU). Patients were treated by either IIT [mean glycemia 5.88 mmol/l (106 mg/dl)] or conventional glucose management [mean glycemia 8.44 mmol/l (152 mg/dl)].

RESULTS

Under IIT the mortality of patients treated for more than 3 days in the ICU was lowered by 7.6% (p=0.03) in septic patients and by 8.7% (p=0.08) in septic shock patients. Polyneuropathy occurred less frequently under IIT compared to conventional glucose management (sepsis -9.8%, septic shock -14%; p<0.001). The incidence of acute renal failure was not affected by either treatment regimen (sepsis -3.3%, septic shock -3.1%; p<0.25). Intensive insulin therapy was associated with an increased risk of hypoglycemia (sepsis +16.7%, septic shock +18.8; p<0.0001) which did not, however, directly affect morbidity nor mortality.

CONCLUSIONS

These data suggest that IIT improves outcome of patients with sepsis or septic shock. Hypoglycemia is a frequent complication, but its clinical relevance remains to be defined.

Tight glycaemic control: a prospective observational study of a computerised decision-supported intensive insulin therapy protocol

INTRODUCTION

A single centre has reported that implementation of an intensive insulin protocol, aiming for tight glycaemic control (blood glucose 4.4 to 6.1 mmol/l), resulted in significant reduction in mortality in longer stay medical and surgical critically ill patients. Our aim was to determine the degree to which tight glycaemic control can be maintained using an intensive insulin therapy protocol with computerized decision support and to identify factors that may be associated with the degree of control.

METHODS

At a general adult 22-bed intensive care unit, we implemented an intensive insulin therapy protocol in mechanically ventilated patients, aiming for a target glucose range of 4.4 to 6.1 mmol/l. The protocol was integrated into the computerized information management system by way of a decision support program. The time spent in each predefined blood glucose band was estimated, assuming a linear trend between measurements.

RESULTS

Fifty consecutive patients were investigated, involving analysis of 7,209 blood glucose samples, over 9,214 hours. The target tight glycaemic control band (4.4 to 6.1 mmol/l) was achieved for a median of 23.1% of the time that patients were receiving intensive insulin therapy. Nearly half of the time (median 48.5%), blood glucose was within the band 6.2 to 7.99 mmol/l. Univariate analysis revealed that body mass index (BMI), Acute Physiology and Chronic Health Evaluation (APACHE) II score and previous diabetes each explained approximately 10% of the variability in tight glycaemic control. BMI and APACHE II score explained most (27%) of the variability in tight glycaemic control in the multivariate analysis, after adjusting for age and previous diabetes.

CONCLUSION

Use of the computerized decision supported intensive insulin therapy protocol did result in achievement of tight glycaemic control for a substantial percentage of each patient's stay, although it did deliver 'normoglycaemia' (4.4 to about 8 mmol/l) for nearly 75% of the time. Tight glycaemic control was difficult to achieve in critically ill patients using this protocol. More sophisticated methods such as continuous blood glucose monitoring with automated insulin and glucose infusion adjustment may be a more effective way to achieve tight glycaemic control. Glycaemia in patients with high BMI and APACHE II scores may be more difficult to control using intensive insulin therapy protocols. Trial registration number 05/Q0505/1.

Stochastic modelling of insulin sensitivity and adaptive glycemic control for critical care

Targeted, tight model-based glycemic control in critical care patients that can reduce mortality 18-45% is enabled by prediction of insulin sensitivity, S(I). However, this parameter can vary significantly over a given hour in the critically ill as their condition evolves. A stochastic model of S(I) variability is constructed using data from 165 critical care patients. Given S(I) for an hour, the stochastic model returns the probability density function of S(I) for the next hour. Consequently, the glycemic distribution following a known intervention can be derived, enabling pre-determined likelihoods of the result and more accurate control. Cross validation of the S(I) variability model shows that 86.6% of the blood glucose measurements are within the 0.90 probability interval, and 54.0% are within the interquartile interval. "Virtual Patients" with S(I) behaving to the overall S(I) variability model achieved similar predictive performance in simulated trials (86.8% and 45.7%). Finally, adaptive control method incorporating S(I) variability is shown to produce improved glycemic control in simulated trials compared to current clinical results. The validated stochastic model and methods provide a platform for developing advanced glycemic control methods addressing critical care variability.

Intensive insulin therapy after severe traumatic brain injury: a randomized clinical trial

INTRODUCTION

To investigate the risks and possible benefits of routine versus intensive insulin therapy, assessed by the frequency of hypoglycemic events defined as a glucose concentration less than 80 mg/dl (<4.44 mmol/l) in patients admitted to the intensive care unit (ICU) after severe traumatic brain injury (TBI).

METHODS AND RESULTS

Ninety-seven patients admitted after severe TBI, were enrolled and randomly assigned to two groups of target glycemia. Insulin was infused at conventional rates when blood glucose levels exceeded 220 mg/dl (12.22 mmol/l) or at intensive rates, to maintain glycemia at 80-120 mg/dl (4.44-6.66 mmol/l). The following primary and outcome variables were measured during follow-up: hypoglycemic episodes, duration of ICU stay, infection rate, and 6-month mortality and neurologic outcome measured using the Glasgow Outcome Scale (GOS). Episodes of hypoglycemia (defined as blood glucose <80 mg/dl or 4.44 mmol/l) were significantly higher in patients receiving intensive insulin therapy: median (min-max) conventional insulin therapy 7 (range 0-11) vs. intensive insulin therapy 15 (range 6-33); P<0.0001. Duration of ICU stay was shorter in patients receiving intensive insulin therapy (7.3 vs. 10.0 days; P < 0.05); while infection rates during ICU stay (25.0% vs. 38.8%, P = 0.15), and GOS scores and mortality at 6 months were similar in the two groups.

CONCLUSIONS

Intensive insulin therapy significantly increases the risk of hypoglycemic episodes. Even though patients receiving intensive insulin therapy have shorter ICU stays and infection rates similar to those receiving conventional insulin therapy, both groups have similar follow-up mortality and neurologic outcome. Hence if intensive insulin therapy is to be used, great effort must be taken to avoid hypoglycemia.

Glucose control in the intensive care unit: how it is done

Hyperglycaemia occurs in the majority of critically-ill patients, partly because patients are hypercatabolic and consequently have increased glucose levels and partly because of insulin resistance. Hyperglycaemia is associated with increased mortality in critical illness. In 2001 it was shown that mortality and other complications of critical illness can be decreased by adopting 'tight' glycaemic control (4.1-6.4 mmol/l). The critical care world adopted tight glycaemic control enthusiastically, until it became apparent that profound life-threatening hypoglycaemia could result. Most clinicians, currently, have adopted regimens aiming to control glucose between 4 and 8 mmol/l. Practising this regimen safely requires attention to detail. Patients must be provided with energy as well as insulin; preferably via the enteral route, but parenterally if necessary. Insulin is administered according to a relatively simple scale that is adjustable by nursing staff according to patients' glucose results. Frequent glucose measurement is essential to success, along with using visual charting that makes sudden changes in blood glucose levels obvious. There are several 'champions' of safe implementation of glucose control in the intensive care unit at the Royal Liverpool University Hospital who are educators and who feed results back to staff regularly. Further studies will clarify the ultimate role of tight glycaemic control, but it can be done safely with meticulous attention to detail.

Glycemic control and critical illness: is the kidney involved?

The pathophysiology, consequences, and management of hyperglycemia during critical illness is an important clinical issue. Uncontrolled hyperglycemia in this setting is associated with a variety of adverse events, including mortality. The kidneys have a major role in glucose and insulin metabolism, and emerging evidence suggests that they both are actively involved in the development, maintenance, and resolution of hyperglycemia. The development of acute kidney injury is also a risk in this setting. This article discusses potential approaches for efficient and effective management of hyperglycemia.

Circadian rhythm of blood glucose values in critically ill patients

OBJECTIVE

To test whether there is a circadian rhythm of blood glucose control in critically ill patients and whether morning blood glucose is an accurate surrogate of overall blood glucose control.

DESIGN

Retrospective multiple-center observational study.

SETTING

Intensive care units of three tertiary hospitals and one affiliated private hospital.

PATIENTS

Cohort of 8,307 consecutive critically ill patients.

INTERVENTIONS

Extraction of blood glucose values from electronically stored measurements. Extraction of demographic and outcome data from unit and hospital databases. Statistical assessment of variations in blood glucose control over each 24-hr cycle.

MEASUREMENTS AND MAIN RESULTS

We studied 208,362 blood glucose measurements in 8,307 patients (5.5 measurements/day/person). In each hospital, there was a circadian rhythm of blood glucose control (p<.0001). The differences between highest and lowest blood glucose concentration in different time periods in each hospital were 0.27, 0.28, 0.95, and 0.22 mmol/L. There was also significant variation in the incidence and notional duration of hyperglycemia. The differences between the lowest and highest incidence of hyperglycemia in different time periods were 3.3, 2.7, 9.9, and 2.6% in each hospital. In all four hospitals, the average blood glucose value from 5:30 am to 6:30 am was significantly lower than the 24-hr average.

CONCLUSIONS

Blood glucose values and the incidence of hyperglycemia have a circadian rhythm in critically ill patients. Morning blood glucose may not be an accurate surrogate of blood glucose control over the daily cycle.

Glycemic control, diabetic status, and mortality in a heterogeneous population of critically ill patients before and during the era of intensive glycemic management: six and one-half years experience at a university-affiliated community hospital

Hyperglycemia occurs commonly in acutely and critically ill patients and has been associated with adverse clinical consequences. An emerging body of literature describes the beneficial effects of intensive glycemic monitoring and treatment (tight glycemic control, or "TGC"). This manuscript reviews the experience of a cohort of 5365 non-cardiac surgery patients admitted to the adult intensive care unit of a university-affiliated community hospital before and after implementation of TGC. Significant decreases in mortality occurred among medical and surgical patients during the TGC era, but not among trauma patients. Non-diabetics who sustained hyperglycemia had an especially high risk of mortality, and benefited greatly from treatment. Further investigations will be needed to identify the most appropriate glycemic targets for different populations of patients.