Differential temporal profile of lowered blood glucose levels (3.5 to 6.5 mmol/l versus 5 to 8 mmol/l) in patients with severe traumatic brain injury

Stress hyperglycaemia following trauma - a survival benefit or an outcome detriment?

PURPOSE OF REVIEW

Stress hyperglycaemia occur often in critically injured patients. To gain new consideration about it, this review compile current as well as known immunological and biochemical findings about causes and emergence.

RECENT FINDINGS

Glucose is the preferred energy substrate for fending immune cells, reparative tissue and the cardiovascular system following trauma. To fulfil these energy needs, the liver is metabolically reprogrammed to rebuild glucose from lactate and glucogenic amino acids (hepatic insulin resistance) at the expenses of muscles mass and - to a less extent - fat tissue (proteolysis, lipolysis, peripheral insulin resistance). This inevitably leads to stress hyperglycaemia, which is evolutionary preserved and seems to be an essential and beneficial survival response. It is initiated by damage-associated molecular patterns (DAMPs) and pathogen-associated molecular patterns (PAMPs), intensified by immune cells itself and mainly ruled by tumour necrosis factor (TNF)α and catecholamines with lactate and hypoxia inducible factor (HIF)-1α as intracellular signals and lactate as an energy shuttle. Important biochemical mechanisms involved in this response are the Warburg effect as an efficient metabolic shortcut and the extended Cori cycle.

SUMMARY

Stress hyperglycaemia is beneficial in an acute life-threatening situation, but further research is necessary, to prevent trauma patients from the detrimental effects of persisting hyperglycaemia.

Evidence-based management of adult traumatic brain injury with raised intracranial pressure in intensive critical care unit at resource-limited settings: a literature review

Background

In underdeveloped countries, there is a greater incidence of mortality and morbidity arising from trauma, with traumatic brain injury (TBI) accounting for 50% of all trauma-related deaths. The occurrence of elevated intracranial pressure (ICP), which is a common pathophysiological phenomenon in cases of TBI, acts as a contributing factor to unfavorable outcomes. The aim of this systematic review is to analyze the existing literature regarding the management of adult TBI with raised ICP in an intensive critical care unit, despite limited resources.

Methods

This systematic review was performed in accordance with the Preferred Reporting Items for Systematic Review and Meta-Analysis protocol. Search engines such as PubMed, the Cochrane database, and Google Scholar were utilized to locate high-level evidence that would facilitate the formation of sound conclusions.

Result

A total of 11 715 articles were identified and individually assessed to determine their eligibility for inclusion or exclusion based on predetermined criteria and outcome variables. The methodological quality of each study was evaluated using recommended criteria. Ultimately, the review consisted of 51 articles.

Conclusion

Physical examination results and noninvasive assessments of the optic nerve sheath diameter (ONSD) via sonography are positively associated with elevated ICP, and are employed as diagnostic and monitoring tools for elevated ICP in resource-limited settings. Management of elevated ICP necessitates an algorithmic approach that utilizes prophylactic measures and acute intervention treatments to mitigate the risk of secondary brain injury.

Cerebral microdialysis and glucopenia in traumatic brain injury: A review

Traditionally, intracranial pressure (ICP) and partial brain tissue oxygenation (PbtO₂) have been the primary invasive intracranial measurements used to guide management in patients with severe traumatic brain injury (TBI). After injury however, the brain develops an increased metabolic demand which may require an increment in the oxidative metabolism of glucose. Simultaneously, metabolic, and electrical dysfunction can lead to an inability to meet these demands, even in the absence of ischemia or increased intracranial pressure. Cerebral microdialysis provides the ability to accurately measure local concentrations of various solutes including lactate, pyruvate, glycerol and glucose. Experimental and clinical data demonstrate that such measurements of cellular metabolism can yield critical missing information about a patient's physiologic state and help limit secondary damage. Glucose management in traumatic brain injury is still an unresolved question. As cerebral glucose metabolism may be uncoupled from systemic glucose levels due to the metabolic dysfunction, measurement of cerebral extracellular glucose concentrations could provide more predictive information and prove to be a better biomarker to avoid secondary injury of at-risk brain tissue. Based on data obtained from cerebral microdialysis, specific interventions such as ICP-directed therapy, blood glucose increment, seizure control, and/or brain oxygen optimization can be instituted to minimize or prevent secondary insults. Thus, microdialysis measurements of parenchymal metabolic function provides clinically valuable information that cannot be obtained by other monitoring adjuncts in the standard ICU setting.

Traumatic Brain Injury as a Potential Risk Factor for Diabetes Mellitus in the Veteran Population

This review examines various aspects of traumatic brain injury (TBI) and its potential role as a causative agent for type 2 diabetes mellitus (T2DM) in the veteran population. The pituitary glands and the hypothalamus, both housed in the intracranial space, are the most important structures for the homeostatic regulation of almost every hormone in the human body. As such, TBI not only causes psychological and cognitive impairments but can also disrupt the endocrine system. It is well established that in addition to having a high prevalence of chronic traumatic encephalopathy (CTE), veterans have a very high risk of developing various chronic medical conditions. Unfortunately, there are no measures or prophylactic agents that can have a meaningful impact on this medically complex patient population. In this review, we explore several important factors pertaining to both acute and chronic TBI that can provide additional insight into why veterans tend to develop T2DM later in life. We focus on the unique combination of risk factors in this population not typically found in civilians or other individuals with a non-military background. These include post-traumatic stress disorder, CTE, and environmental factors relating to occupation and lifestyle.

Glycemic targets in critically ill adults: A mini-review

Illness-induced hyperglycemia impairs neutrophil function, increases pro-inflammatory cytokines, inhibits fibrinolysis, and promotes cellular damage. In turn, these mechanisms lead to pneumonia and surgical site infections, prolonged mechanical ventilation, prolonged hospitalization, and increased mortality. For optimal glucose control, blood glucose measurements need to be done accurately, frequently, and promptly. When choosing glycemic targets, one should keep the glycemic variability < 4 mmol/L and avoid targeting a lower limit of blood glucose < 4.4 mmol/L. The upper limit of blood glucose should be set according to casemix and the quality of glucose control. A lower glycemic target range (i.e., blood glucose 4.5-7.8 mmol/L) would be favored for patients without diabetes mellitus, with traumatic brain injury, or who are at risk of surgical site infection. To avoid harm from hypoglycemia, strict adherence to glycemic control protocols and timely glucose measurements are required. In contrast, a higher glycemic target range (i.e., blood glucose 7.8-10 mmol/L) would be favored as a default choice for medical-surgical patients and patients with diabetes mellitus. These targets may be modified if technical advances for blood glucose measurement and control can be achieved.

Fine Tuning of Traumatic Brain Injury Management in Neurointensive Care-Indicative Observations and Future Perspectives

Neurointensive care (NIC) has contributed to great improvements in clinical outcomes for patients with severe traumatic brain injury (TBI) by preventing, detecting, and treating secondary insults and thereby reducing secondary brain injury. Traditional NIC management has mainly focused on generally applicable escalated treatment protocols to avoid high intracranial pressure (ICP) and to keep the cerebral perfusion pressure (CPP) at sufficiently high levels. However, TBI is a very heterogeneous disease regarding the type of injury, age, comorbidity, secondary injury mechanisms, etc. In recent years, the introduction of multimodality monitoring, including, e.g., pressure autoregulation, brain tissue oxygenation, and cerebral energy metabolism, in addition to ICP and CPP, has increased the understanding of the complex pathophysiology and the physiological effects of treatments in this condition. In this article, we will present some potential future approaches for more individualized patient management and fine-tuning of NIC, taking advantage of multimodal monitoring to further improve outcome after severe TBI.

High Arterial Glucose is Associated with Poor Pressure Autoregulation, High Cerebral Lactate/Pyruvate Ratio and Poor Outcome Following Traumatic Brain Injury

Background

Arterial hyperglycemia is associated with poor outcome in traumatic brain injury (TBI), but the pathophysiology is not completely understood. Previous preclinical and clinical studies have indicated that arterial glucose worsens pressure autoregulation. The aim of this study was to evaluate the relationship of arterial glucose to both pressure reactivity and cerebral energy metabolism.

Method

This retrospective study was based on 120 patients with severe TBI treated at the Uppsala University hospital, Sweden, 2008–2018. Data from cerebral microdialysis (glucose, pyruvate, and lactate), arterial glucose, and pressure reactivity index (PRx55-15) were analyzed the first 3 days post-injury.

Results

High arterial glucose was associated with poor outcome/Glasgow Outcome Scale-Extended at 6-month follow-up (r = − 0.201, p value = 0.004) and showed a positive correlation with both PRx55-15 (r = 0.308, p = 0.001) and cerebral lactate/pyruvate ratio (LPR) days 1–3 (r = 0. 244, p = 0.014). Cerebral lactate-to-pyruvate ratio and PRx55-15 had a positive association day 2 (r = 0.219, p = 0.048). Multivariate linear regression analysis showed that high arterial glucose predicted poor pressure autoregulation on days 1 and 2.

Conclusions

High arterial glucose was associated with poor outcome, poor pressure autoregulation, and cerebral energy metabolic disturbances. The latter two suggest a pathophysiological mechanism for the negative effect of arterial hyperglycemia, although further studies are needed to elucidate if the correlations are causal or confounded by other factors.

Updates in Glycemic Management in the Hospital

PURPOSE OF REVIEW

To provide an update of glycemic management during metabolic stress related to surgery or critical illness.

RECENT FINDINGS

There is a clear association between severe hyperglycemia, hypoglycemia, and high glycemic variability and poor outcomes of postoperative or critically ill patients. However, the impressive beneficial effects of tight glycemic management (TGM) by intensive insulin therapy reported in one study were never reproduced. Hence, the recommendation of TGM is now replaced by more liberal blood glucose (BG) targets (< 180 mg/dL or 10 mM). Recent data support the concept of targeting individualized blood glucose (BG) values according to the presence of diabetes mellitus/chronic hyperglycemia, the presence of brain injury, and the time from injury. A more liberal glycemic management goal is currently advised during metabolic stress and could be switched to individualized glycemic management once validated by prospective trials.

[Neuroprotection in neurocritical care]

In intensive care medicine neuroprotection is understood mostly as various measures to avoid secondary brain damage after initial trauma, as in stroke, intracranial hemorrhage and resuscitation. Every brain trauma differs in the damage pattern and dynamics depending on the primary form of injury. Therefore, there are targeted treatment approaches depending on the pathophysiology of the medical condition. In addition, neuroprotective methods are desirable that are effective in the majority of patients with acute brain injury. In actual fact, in all forms of acute brain injury certain pathophysiological courses are encountered, which can lead to secondary brain damage depending on the intensity, e.g. reperfusion injury, damage to the blood-brain barrier and excitotoxicity. There is evidence to suggest that the creation of physiologically normal conditions leads to a favorable situation for the damaged brain. This article firstly describes the relevance of neuroprotective measures in neurocritical care medicine. Subsequently, general pathophysiological mechanisms in brain trauma are described. Following this, the pathophysiology and treatment options in brain pressure crises (reduction of intracranial pressure), anemia (transfusion management), hyperglycemia and hypoglycemia (adjustment of the blood sugar level) are dealt with. Finally, the use and benefits of therapeutic hypothermia are discussed. This has a special position as the only clinically effective individual measure for neuroprotection. The focus here is on the application following circulatory and cardiac arrest and resuscitation.

Magnetic Resonance Imaging Pilot Study of Intravenous Glyburide in Traumatic Brain Injury

Pre-clinical studies of traumatic brain injury (TBI) show that glyburide reduces edema and hemorrhagic progression of contusions. We conducted a small Phase II, three-institution, randomized placebo-controlled trial of subjects with TBI to assess the safety and efficacy of intravenous (IV) glyburide. Twenty-eight subjects were randomized and underwent a 72-h infusion of IV glyburide or placebo, beginning within 10 h of trauma. Of the 28 subjects, 25 had Glasgow Coma Scale (GCS) scores of 6-10, and 14 had contusions. There were no differences in adverse events (AEs) or severe adverse events (ASEs) between groups. The magnetic resonance imaging (MRI) percent change at 72-168 h from screening/baseline was compared between the glyburide and placebo groups. Analysis of contusions (7 per group) showed that lesion volumes (hemorrhage plus edema) increased 1036% with placebo versus 136% with glyburide (p = 0.15), and that hemorrhage volumes increased 11.6% with placebo but decreased 29.6% with glyburide (p = 0.62). Three diffusion MRI measures of edema were quantified: mean diffusivity (MD), free water (FW), and tissue MD (MDt), corresponding to overall, extracellular, and intracellular water, respectively. The percent change with time for each measure was compared in lesions (n = 14) versus uninjured white matter (n = 24) in subjects receiving placebo (n = 20) or glyburide (n = 18). For placebo, the percent change in lesions for all three measures was significantly different compared with uninjured white matter (analysis of variance [ANOVA], p < 0.02), consistent with worsening of edema in untreated contusions. In contrast, for glyburide, the percent change in lesions for all three measures was not significantly different compared with uninjured white matter. Further study of IV glyburide in contusion TBI is warranted.

Early dysglycemia and mortality in traumatic brain injury and subarachnoid hemorrhage

BACKGROUND

Traumatic brain injury (TBI) and subarachnoid hemorrhage (SAH) are the most common causes of severe acute brain injury in younger Intensive Care Unit (ICU) patients. Dysglycemia (abnormal peak glycemia, glycemic variability, mean glycemia, nadir glycemia) is common in these patients but its comparative outcome associations are unclear.

METHODS

In a retrospective, cross-sectional, study of adults admitted to Australian and New Zealand ICUs with TBI and SAH from 2005 to 2015, we studied the relationship between multiple aspects of early (first 24 hours) dysglycemia and mortality and compared TBI and SAH patients with the general ICU population and with each other.

RESULTS

Among 670,301 patients, 11,812 had TBI and 6,098 had SAH. After adjustment for illness severity, we found that the mortality rate increased with each quintile of glycemia for each aspect of early dysglycemia (peak glycemia, glycemic variability, mean glycemia, nadir glycemia; P<0.0001 for all). This increased risk of death was greater in TBI and SAH patients than in the general ICU population. Moreover, it was stronger for mean glycemia (increase in mortality from 9.2% in the lowest quintile to 15.1% in general ICU patients compared with an increase in mortality from 4.4% to 49.0% for TBI and SAH patients; P<0.0001). Finally, in TBI patients, this relationship was significantly stronger than in SAH patients (P<0.0001).

CONCLUSIONS

In TBI and SAH patients, greater dysglycemia is associated with greater mortality. This association is significantly stronger than in the general population and it is significantly stronger in patients with TBI compared with SAH.

Update on glucose in critical care

The aim of this review is to summarize recent developments on the mechanisms involved in stress hyperglycemia associated with critical illness. Different aspects of the consequences of stress hyperglycemia as well as the therapeutic approaches tested so far are discussed: the physiological regulations of blood glucose, the mechanisms underlying stress hyperglycemia, the clinical associations, and the results of the prospective trials and meta-analyses to be taken into consideration when interpreting the available data. Current recommendations, challenges, and technological hopes for the future are be discussed.

A systematic scoping review on the consequences of stress-related hyperglycaemia

Background

Stress-related hyperglycaemia (SHG) is commonly seen in acutely ill patients and has been associated with poor outcomes in many studies performed in different acute care settings. We aimed to review the available evidence describing the associations between SHG and different outcomes in acutely ill patients admitted to an ICU. Study designs, populations, and outcome measures used in observational studies were analysed.

Methods

We conducted a systematic scoping review of observational studies following the Joanna Briggs methodology. Medline, Embase, and the Cochrane Library were searched for publications between January 2000 and December 2015 that reported on SHG and mortality, infection rate, length of stay, time on ventilation, blood transfusions, renal replacement therapy, or acquired weakness.

Results

The search yielded 3,063 articles, of which 43 articles were included (totalling 536,476 patients). Overall, the identified studies were heterogeneous in study conduct, SHG definition, blood glucose measurements and monitoring, treatment protocol, and outcome reporting. The most frequently reported outcomes were mortality (38 studies), ICU and hospital length of stay (23 and 18 studies, respectively), and duration of mechanical ventilation (13 studies). The majority of these studies (40 studies) compared the reported outcomes in patients who experienced SHG with those who did not. Fourteen studies (35.9%) identified an association between hyperglycaemia and increased mortality (odds ratios ranging from 1.13 to 2.76). Five studies identified hyperglycaemia as an independent risk factor for increased infection rates, and one identified it as an independent predictor of increased ICU length of stay.

Discussion

SHG was consistently associated with poor outcomes. However, the wide divergences in the literature mandate standardisation of measuring and monitoring SHG and the creation of a consensus on SHG definition. A better comparability between practices will improve our knowledge on SHG consequences and management.

Comparison of intensive versus conventional insulin therapy in traumatic brain injury: a meta-analysis of randomized controlled trials

OBJECTIVE

To compare intensive insulin therapy (IIT) and conventional insulin therapy (CIT) on clinical outcomes of patients with traumatic brain injury (TBI).

METHODS

MEDLINE, EMBASE, Google Scholar, ISI Web of Science, and Cochrane Library were systematically searched for randomized controlled trials (RCTs) comparing IIT to CIT in patients with TBI. Study-level characteristics, intensive care unit (ICU) events, and long-term functional outcomes were extracted from the articles. Meta-analysis was performed with random-effect models.

RESULTS

Seven RCTs comprising 1070 patients were included. Although IIT was associated with better neurologic outcome (GOS > 3) (RR=0.87, 95% CI=0.78-0.97; P=0.01; I²=0%), sensitivity analysis revealed that one study influenced this overall estimate (RR=0.90, 95% CI=0.80-1.01, P=0.07; I²=0%). IIT was strongly associated with higher risk of hypoglycaemia (RR=5.79, 95% CI=3.27-10.26, P<0.01; I²=38%). IIT and CIT did not differ in terms of early or late mortality (RR=0.96, 95% CI=0.79-1.17, P=0.7; I²=0%), infection rate (RR=0.82, 95% CI=0.59-1.14, P=0.23; I²=68%), or ICU length of stay (SMD= -0.14, 95% CI=-0.35 to 0.07, P=0.18; I²=45%0.) Conclusions: IIT did not improve long-term neurologic outcome, mortality, or infection rate and was associated with increased risk of hypoglycaemia. Additional well-designed RCTs with defined TBI subgroups should be performed to generate more powerful conclusions.

Update on the Treatment of Spontaneous Intraparenchymal Hemorrhage: Medical and Interventional Management

PURPOSE OF REVIEW

Spontaneous intraparenchymal hemorrhage (IPH) is a prominent challenge faced globally by neurosurgeons, neurologists, and intensivists. Over the past few decades, basic and clinical research efforts have been undertaken with the goal of delineating biologically and evidence-based practices aimed at decreasing mortality and optimizing the likelihood of meaningful functional outcome for patients afflicted with this devastating condition. Here, the authors review the medical and surgical approaches available for the treatment of spontaneous intraparenchymal hemorrhage, identifying areas of recent progress and ongoing research to delineate the scope and scale of IPH as it is currently understood and treated.

RECENT FINDINGS

The approaches to IPH have broadly focused on arresting expansion of hemorrhage using a number of approaches. Recent trials have addressed the effectiveness of rapid blood pressure lowering in hypertensive patients with IPH, with rapid lowering demonstrated to be safe and at least partially effective in preventing hematoma expansion. Hemostatic therapy with platelet transfusion in patients on anti-platelet medications has been recently demonstrated to have no benefit and may be harmful. Hemostasis with administration of clotting complexes has not been shown to be effective in reducing hematoma expansion or improving outcomes although correcting these abnormalities as soon as possible remains good practice until further data are available. Stereotactically guided drainage of IPH with intraventricular hemorrhage (IVH) has been shown to be safe and to improve outcomes. Research on new stereotactic surgical methods has begun to show promise. Patients with IPH should have rapid and accurate diagnosis with neuroimaging with computed tomography (CT) and computed tomography angiography (CTA). Early interventions should include control of hypertension to a systolic BP in the range of 140 mmHg for small hemorrhages without intracranial hypertension with beta blockers or calcium channel blockers, correction of any coagulopathy if present, and assessment of the need for surgical intervention. IPH and FUNC (Functional Outcome in Patients with Primary Intracerebral Hemorrhage) scores should be assessed. Patients should be dispositioned to a dedicated neurologic ICU if available. Patients should be monitored for seizures and intracranial pressure issues. Select patients, particularly those with intraventricular extension, may benefit from evacuation of hematoma with a ventriculostomy or stereotactically guided catheter. Once stabilized, patients should be reassessed with CT imaging and receive ongoing management of blood pressure, cerebral edema, ICP issues, and seizures as they arise. The goal of care for most patients is to regain capacity to receive multidisciplinary rehabilitation to optimize functional outcome.

Temporal Patterns and Influential Factors of Blood Glucose Levels During the First 10-Day Critical Period After Brain Injury

This study was conducted to document temporal patterns of blood glucose level changes during the first 10-day critical period and to identify factors that influence stress-induced hyperglycemia development in brain injury patients. The medical records of 190 brain injury patients were retrospectively reviewed. Blood glucose levels in the poor recovery group were significantly higher than in the good recovery group, particularly during the first 72 hr (158-172 mg/dl). The poor recovery group showed persistent, fluctuating hyperglycemia, whereas the good recovery group exhibited hyperglycemic peaks during the first 3 days that subsequently reduced linearly to normal. Gender, preexisting hypertension, disease severity at admission, total calorie intake, and steroid use were found to influence stress-induced hyperglycemia development significantly. In conclusion, close monitoring and adjustment are required to maintain safe blood glucose levels and the development of protocols for safe glycemic management is essential to improve critical care in brain injury patients.

Continuous glucose monitoring in the ICU: clinical considerations and consensus

Glucose management in intensive care unit (ICU) patients has been a matter of debate for almost two decades. Compared to intermittent monitoring systems, continuous glucose monitoring (CGM) can offer benefit in the prevention of severe hyperglycemia and hypoglycemia by enabling insulin infusions to be adjusted more rapidly and potentially more accurately because trends in glucose concentrations can be more readily identified. Increasingly, it is apparent that a single glucose target/range may not be optimal for all patients at all times and, as with many other aspects of critical care patient management, a personalized approach to glucose control may be more appropriate. Here we consider some of the evidence supporting different glucose targets in various groups of patients, focusing on those with and without diabetes and neurological ICU patients. We also discuss some of the reasons why, despite evidence of benefit, CGM devices are still not widely employed in the ICU and propose areas of research needed to help move CGM from the research arena to routine clinical use.

Review: Traumatic brain injury and hyperglycemia, a potentially modifiable risk factor

Hyperglycemia after severe traumatic brain injury (TBI) occurs frequently and is associated with poor clinical outcome and increased mortality. In this review, we highlight the mechanisms that lead to hyperglycemia and discuss how they may contribute to poor outcomes in patients with severe TBI. Moreover, we systematically review the proper management of hyperglycemia after TBI, covering topics such as nutritional support, glucose control, moderated hypothermia, naloxone, and mannitol treatment. However, to date, an optimal and safe glycemic target range has not been determined, and may not be safe to implement among TBI patients. Therefore, there is a mandate to explore a reasonable glycemic target range that can facilitate recovery after severe TBI.

Glucose and the injured brain-monitored in the neurointensive care unit

Brain has a continuous demand for energy that is met by oxidative metabolism of oxygen and glucose. This demand is compromised in the injured brain and if the inadequate supply persists it will lead to permanent tissue damage. Zero values of cerebral glucose have been associated with infarction and poor neurological outcome. Furthermore, hyperglycemia is common in patients with neurological insults and associated with poor outcome. Intensive insulin therapy (IIT) to control blood glucose has been suggested and used in neurointensive care with conflicting results. This review covers the studies reporting on monitoring of cerebral glucose with microdialysis in patients with traumatic brain injury (TBI), subarachnoid hemorrhage (SAH) and ischemic stroke. Studies investigating IIT are also discussed. Available data suggest that low cerebral glucose in patients with TBI and SAH provides valuable information on development of secondary ischemia and has been correlated with worse outcome. There is also indication that the location of the catheter is important for correlation between plasma and brain glucose. In conclusion considering catheter location, monitoring of brain glucose in the neurointensive care not only provides information on imminent secondary ischemia it also reveals the effect of peripheral treatment on the injured brain.

Glycemic control after brain injury: boon and bane for the brain

Hyperglycemia is a common phenomenon in the early phase of brain injury (BI). The management of blood glucose levels after BI, however, is subject of a growing debate. The occurrence of elevated blood glucose concentrations is linked to increased mortality and worse neurologic outcomes indicating the necessity for therapeutic glucose-lowering. Intensive glucose-lowering therapy, on the other hand, inevitably results in an increased rate of hypoglycemic episodes with detrimental effects on the injured brain. In this review, we give an overview on the current knowledge about causes and pathophysiological consequences of dysglycemia in patients with BI and offer some suggestions for clinical glucose management.

Rubiano A, Moscote-Salazar LR. Effects of Glycemic Level on Outcome of Patients with Traumatic Brain Injury: A Retrospective Cohort Study

OBJECTIVE

To determine the effects of glycemic level on outcome patients with traumatic brain injury.

METHODS

 From September 2010 to December 2012, all medical records of adult patients with TBI admitted to the Emergency Room of Laura Daniela Clinic in Valledupar City, Colombia, South America were enrolled. Both genders between 18 and 85 years who referred during the first 48 hours after trauma, and their glucose level was determined in the first 24 hours of admission were included. Adults older than 85 years, with absence of Glasgow Coma Scale (GCS) score and a brain Computerized Tomography (CT) scans were excluded. The cut-off value was considered 200 mg/dL to define hyperglycemia. Final GCS, hospital admission duration and complications were compared between normoglycemic and hyperglycemic patients.

RESULTS

Totally 217 patients were identified with TBI. Considering exclusion criteria, 89 patients remained for analysis. The mean age was 43.0±19.6 years, the mean time of remission was 5.9±9.4 hours, the mean GCS on admission was 10.5±3.6 and the mean blood glucose level in the first 24 hours was 138.1±59.4 mg/dL. Hyperglycemia was present in 13.5% of patients. The most common lesions presented by patients with TBI were fractures (22.5%), hematoma (18.3%), cerebral edema (18.3%) and cerebral contusion (16.2%). Most of patients without a high glucose level at admission were managed only medically, whereas surgical treatment was more frequent in patients with hyperglycemia (p=0.042). Hyperglycemia was associated with higher complication (p=0.019) and mortality rate (p=0.039). GCS was negatively associated with on admission glucose level (r=0.11; p=0.46).

CONCLUSION

Hyperglycemia in the first 24-hours of TBI is associated with higher rate of surgical intervention, higher complication and mortality rates. So hyperglycemia handling is critical to the outcome of patients with traumatic brain injury.

Frequency and impact of intensive care unit complications on moderate-severe traumatic brain injury: early results of the Outcome Prognostication in Traumatic Brain Injury (OPTIMISM) Study

BACKGROUND

Known predictors of adverse outcomes in patients with moderate-severe TBI (msTBI) explain only a relatively small proportion of patient-related outcomes. The frequency and impact of intensive care unit complications (ICU-COMPL) on msTBI-associated outcomes are poorly understood.

METHODS

In 213 consecutive msTBI patients admitted to a Level I Trauma Center neuro trauma ICU, twenty-eight ICU-COMPL (21 medical and 7 neurological) were prospectively collected and adjudicated by group consensus, using pre-defined criteria. We determined frequencies, and explored associations of ICU-COMPL and hospital discharge outcomes using multivariable logistic regression.

RESULTS

The average age of the study sample was 53 years, and the median presenting Glasgow Coma Scale and Injury Severity Scores were 5 and 27, respectively. Hyperglycemia (79%), fever (62%), systemic inflammatory response syndrome (60%), and hypotension requiring vasopressors (42%) were the four most common medical ICU-COMPL. Herniation (39%), intracranial rebleed (39%), and brain edema requiring osmotherapy (37%) were the three most common neurological ICU-COMPL. After adjusting for admission variables, duration of ventilation, and ICU length-of-stay, patients with brain edema (OR 5.8; 95% CI 2, 16.7) had a significantly increased odds for dying during hospitalization whereas patients with hospital-acquired urinary tract infection (UTI) had a decreased odds (OR 0.05; 95% CI 0.005, 0.6). Sensitivity analysis revealed that UTI occurred later, suggesting a non-causal association with survival. Brain herniation (OR 15.7; 95% CI 2.6, 95.4) was associated with an unfavorable functional status (GOS 1-3).

CONCLUSION

ICU-COMPL are very common after msTBI, have a considerable impact on short-term outcomes, and should be considered in the prognostication of these high risk patients. Survival associations of time-dependent complications warrant cautious interpretation.

Intensive care and traumatic brain injury after the introduction of a treatment protocol: a prospective study

BACKGROUND

Traumatic brain injury (TBI) treatment protocols have been introduced in the intensive care unit (ICU) to avoid secondary brain injury. In this study, we aimed to evaluate the deviations from such a treatment protocol and the frequency of extracranial complications, and relate these findings to outcome.

METHODS

During a 5-year period (2004-2009), 133 patients with severe TBI [Glasgow Coma Scale (GCS) score ≤ 8] were prospectively included. The following deviations from treatment goals were studied: intracranial pressure (ICP), blood pressure, haemoglobin, blood glucose, serum sodium, serum albumin, body temperature and extracranial complications during the ICU stay. Outcome was assessed using Glasgow Outcome Scale Extended score at 12 months.

RESULTS

The frequencies of deviations from the treatment goals were: episodes of intracranial hypertension 69.5% (of monitored patients), hypotension 20.3%, anaemia 77.4%, hyperglycaemia 42.9%, hyponatremia 34.6%, hypoalbuminemia 30.8% and hyperthermia 54.9%. Pulmonary complications were common (pneumonia 72.2%, acute respiratory distress syndrome/acute lung injury 31.6%). Thrombocytopenia (4.5%), severe sepsis (3.0%), renal failure (0.8%) and liver failure (0.8%) were infrequent. Twenty-six (19.5%) patients died within the first 12 months due to the head injury. Age, GCS score, pupil dilation, Injury Severity Score (ISS), ICP > 25 mmHg, hyperglycaemia and pneumonia predicted a worse outcome.

CONCLUSIONS

Deviations from the TBI treatment protocol were frequent. Pneumonia was the most frequent extracranial complication. Age, GCS score, pupil dilation, ISS, high ICP, hyperglycaemia and pneumonia predicted a worse outcome.

"Moderate intensive insulin therapy" is associated with remission of high intracranial pressure in patients with vascular or infectious central nervous system diseases

Intensive insulin therapy (IIT), targeting blood glucose between 80 mg/dL and 110 mg/dL ("strict IIT"), has been associated with rapid remission of high intracranial pressure (ICP), but its use is limited due to a high risk of hypoglycemia. The aim of this retrospective study was to assess whether "moderate IIT" (target range for blood glucose: 80-140 mg/dL) could have the same beneficial effect on ICP with a lower risk of hypoglycemia. We retrospectively analyzed the records of 64 patients with high ICP due to vascular or infectious central nervous system diseases. Patients treated with moderate IIT (n=32) after 2005 were compared with patients treated with a conventional approach (n=32, target <180 mg/dL) before 2005. We assessed daily ICP during the first 14 days. Secondary endpoints were the rate of hypoglycemic events and outcome. ICP was significantly lower during the second week in patients treated with moderate IIT (mean±standard deviation [SD] daily ICP on days 8-14: 16±5 mmHg compared to 12±4 mmHg, p<0.001). The risk of hypoglycemic events (<40 mg/dL) did not differ significantly between the groups (0 vs. 1 patient, p=0.5). Moderate IIT is associated with remission of high ICP. In contrast to strict IIT, its use seems not to be limited by an increased risk of severe hypoglycemia.

Perioperative glucose control in neurosurgical patients

Many neurosurgery patients may have unrecognized diabetes or may develop stress-related hyperglycemia in the perioperative period. Diabetes patients have a higher perioperative risk of complications and have longer hospital stays than individuals without diabetes. Maintenance of euglycemia using intensive insulin therapy (IIT) continues to be investigated as a therapeutic tool to decrease morbidity and mortality associated with derangements in glucose metabolism due to surgery. Suboptimal perioperative glucose control may contribute to increased morbidity, mortality, and aggravate concomitant illnesses. The challenge is to minimize the effects of metabolic derangements on surgical outcomes, reduce blood glucose excursions, and prevent hypoglycemia. Differences in cerebral versus systemic glucose metabolism, time course of cerebral response to injury, and heterogeneity of pathophysiology in the neurosurgical patient populations are important to consider in evaluating the risks and benefits of IIT. While extremes of glucose levels are to be avoided, there are little data to support an optimal blood glucose level or recommend a specific use of IIT for euglycemia maintenance in the perioperative management of neurosurgical patients. Individualized treatment should be based on the local level of blood glucose control, outpatient treatment regimen, presence of complications, nature of the surgical procedure, and type of anesthesia administered.

Contemporary view on neuromonitoring following severe traumatic brain injury

Evolving brain damage following traumatic brain injury (TBI) is strongly influenced by complex pathophysiologic cascades including local as well as systemic influences. To successfully prevent secondary progression of the primary damage we must actively search and identify secondary insults e.g. hypoxia, hypotension, uncontrolled hyperventilation, anemia, and hypoglycemia, which are known to aggravate existing brain damage. For this, we must rely on specific cerebral monitoring. Only then can we unmask changes which otherwise would remain hidden, and prevent adequate intensive care treatment. Apart from intracranial pressure (ICP) and calculated cerebral perfusion pressure (CPP), extended neuromonitoring (SjvO₂, ptiO₂, microdialysis, transcranial Doppler sonography, electrocorticography) also allows us to define individual pathologic ICP and CPP levels. This, in turn, will support our therapeutic decision-making and also allow a more individualized and flexible treatment concept for each patient. For this, however, we need to learn to integrate several dimensions with their own possible treatment options into a complete picture. The present review summarizes the current understanding of extended neuromonitoring to guide therapeutic interventions with the aim of improving intensive care treatment following severe TBI, which is the basis for ameliorated outcome.

Critical care management of severe traumatic brain injury in adults

Traumatic brain injury (TBI) is a major medical and socio-economic problem, and is the leading cause of death in children and young adults. The critical care management of severe TBI is largely derived from the "Guidelines for the Management of Severe Traumatic Brain Injury" that have been published by the Brain Trauma Foundation. The main objectives are prevention and treatment of intracranial hypertension and secondary brain insults, preservation of cerebral perfusion pressure (CPP), and optimization of cerebral oxygenation. In this review, the critical care management of severe TBI will be discussed with focus on monitoring, avoidance and minimization of secondary brain insults, and optimization of cerebral oxygenation and CPP.

Glucose control and mortality in patients with severe traumatic brain injury

INTRODUCTION

The optimal glucose range in patients with severe traumatic brain injury (TBI) remains unclear. The goal of this study was to examine the association of serum glucose levels on mortality in patients with severe TBI. As a secondary endpoint, we determined the risk of hyperglycemic and hypoglycemic events, and their association with mortality.

METHODS

We conducted a retrospective cohort study of patients admitted to the ICU between May 2000 and March 2006 with severe TBI (Glasgow Coma Scale ≤ 8) who survived at least 12 h. Average daily morning glucose levels for the first 10 days of admission were calculated and divided into quintiles.

RESULTS

A total of 170 patients were included in the analysis. We found no association between quintiles of mean daily morning glucose and hospital mortality. Episodes of hyperglycemia ( ≥ 11.1 mmol/l or 200 mg/dl) during the first 10 days occurred in 65% of patients (5.4% of all glucose measurements). Using multivariable regression, a single episode of hyperglycemia was associated with 3.6-fold increased risk of hospital mortality (95%CI: 1.2-11.2, P = 0.02). Hypoglycemia ( ≤ 4.4 mmol/l or 80 mg/dl) was present in 48% of patients (4.3% of all glucose measurements), and was not associated with mortality.

CONCLUSION

Any episode of hyperglycemia ( ≥ 11.1 mmol/l or 200 mg/dl) was associated with 3.6-fold increased risk of hospital mortality in patients with severe TBI and thus, should be avoided. Maintaining serum glucose ≤ 10 mmol/l appears to be a reasonable balance to avoid extremes of glucose control, but further studies are needed to determine the optimal glucose range.

Treating hyperglycemia in neurocritical patients: benefits and perils

There is growing debate over the value of intensive insulin therapy (IIT) in critically ill patients. Available trials have been performed in general medical or surgical intensive care units, and the results may not be directly applicable to patients with severe acute brain disease because these patients may have heightened susceptibility to hyperglycemia (HyperG) and hypoglycemia. Our objective was to review the pathophysiology and effects of HyperG and hypoglycemia in neurocritical patients and to analyze the potential role of IIT in this population. Source data were obtained from a PubMed search of the medical literature combining the terms HyperG, hypoglycemia, insulin, stroke, intracerebral hemorrhage (ICH), subarachnoid hemorrhage (SAH), traumatic brain injury (TBI), spinal cord injury (SCI), and related diagnoses. Brain metabolism is highly dependent on constant supply of glucose. As a consequence, the acutely injured brain is particularly sensitive to hypoglycemia, which can induce a state of energy failure (metabolic crisis). Meanwhile, neurocritical patients have a high prevalence of HyperG, and its occurrence is associated with poor outcome after acute ischemic stroke, ICH, SAH, and TBI. It is unclear whether this association is due to direct detrimental effects exerted by HyperG or simply represents a marker of severe brain injury. Insulin has been shown to have various potentially pleiotropic neuroprotective properties in experimental models. However, the safety and efficacy of IIT in patients with critical brain disease have not been well studied. Available results do not support the use of IIT to maintain strict normoglycemia in this population. Patients with critical brain disease should have frequent glucose monitoring because severe HyperG and even modest hypoglycemia may be detrimental. Careful use of insulin infusion protocols appears advisable, but maintenance of strict normoglycemia cannot be recommended. Rigorous studies must be conducted to assess the value of insulin therapy and to determine the optimal blood glucose targets in patients with the most common acute vascular and traumatic brain insults.

Propensity scores in intensive care and anaesthesiology literature: a systematic review

INTRODUCTION

Propensity score methods have been increasingly used in the last 10 years. However, the practical use of the propensity score (PS) has been reported as heterogeneous in several papers reviewing the use of propensity scores and giving some advice. No precedent work has focused on the specific application of PS in intensive care and anaesthesiology literature.

OBJECTIVES

After a brief development of the theory of propensity score, to assess the use and the quality of reporting of PS studies in intensive care and anaesthesiology, and to evaluate how past reviews have influenced the quality of the reporting.

STUDY DESIGN AND SETTING

Forty-seven articles published between 2006 and 2009 in the intensive care and anaesthesiology literature were evaluated. We extracted the characteristics of the report, the type of analysis, the details of matching procedures, the number of patients in treated and control groups, and the number of covariates included in the PS models.

RESULTS

Of the 47 articles reviewed, 26 used matching on PS, 12 used stratification on PS and 9 used adjustment on PS. The method used was reported in 81% of the articles, and the choice to conduct a paired analysis or not was reported in only 15%. The comparison with the previously published reviews showed little improvement in reporting in the last few years.

CONCLUSION

The quality of reporting propensity scores in intensive care and anaesthesiology literature should be improved. We provide some recommendations to the investigators in order to improve the reporting of PS analyses.

Increasing hematocrit above 28% during early resuscitative phase is not associated with decreased mortality following severe traumatic brain injury

BACKGROUND

To prevent iatrogenic damage, transfusions of red blood cells should be avoided. For this, specific and reliable transfusion triggers must be defined. To date, the optimal hematocrit during the initial operating room (OR) phase is still unclear in patients with severe traumatic brain injury (TBI). We hypothesized that hematocrit values exceeding 28%, the local hematocrit target reached by the end of the initial OR phase, resulted in more complications, increased mortality, and impaired recovery compared to patients in whom hematocrit levels did not exceed 28%.

METHODS

Impact of hematocrit (independent variable) reached by the end of the OR phase on mortality and morbidity determined by the extended Glasgow outcome scale (eGOS; dependent variables) was investigated retrospectively in 139 TBI patients. In addition, multiple logistic regression analysis was performed to identify additional important variables.

FINDINGS

Following severe TBI, mortality and morbidity were neither aggravated by hematocrit above 28% reached by the end of the OR phase nor worsened by the required transfusions. Upon multiple logistic regression analysis, eGOS was significantly influenced by the highest intracranial pressure and the lowest cerebral perfusion pressure values during the initial OR phase.

CONCLUSIONS

Based on this retrospective observational analysis, increasing hematocrit above 28% during the initial OR phase following severe TBI was not associated with improved or worsened outcome. This questions the need for aggressive transfusion management. Prospective analysis is required to determine the lowest acceptable hematocrit value during the OR phase which neither increases mortality nor impairs recovery. For this, a larger caseload and early monitoring of cerebral metabolism and oxygenation are indispensable.

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.

Brain metabolism is significantly impaired at blood glucose below 6 mM and brain glucose below 1 mM in patients with severe traumatic brain injury

INTRODUCTION

The optimal blood glucose target following severe traumatic brain injury (TBI) must be defined. Cerebral microdialysis was used to investigate the influence of arterial blood and brain glucose on cerebral glucose, lactate, pyruvate, glutamate, and calculated indices of downstream metabolism.

METHODS

In twenty TBI patients, microdialysis catheters inserted in the edematous frontal lobe were dialyzed at 1 microl/min, collecting samples at 60 minute intervals. Occult metabolic alterations were determined by calculating the lactate- pyruvate (L/P), lactate- glucose (L/Glc), and lactate- glutamate (L/Glu) ratios.

RESULTS

Brain glucose was influenced by arterial blood glucose. Elevated L/P and L/Glc were significantly reduced at brain glucose above 1 mM, reaching lowest values at blood and brain glucose levels between 6-9 mM (P < 0.001). Lowest cerebral glutamate was measured at brain glucose 3-5 mM with a significant increase at brain glucose below 3 mM and above 6 mM. While L/Glu was significantly increased at low brain glucose levels, it was significantly decreased at brain glucose above 5 mM (P < 0.001). Insulin administration increased brain glutamate at low brain glucose, but prevented increase in L/Glu.

CONCLUSIONS

Arterial blood glucose levels appear to be optimal at 6-9 mM. While low brain glucose levels below 1 mM are detrimental, elevated brain glucose are to be targeted despite increased brain glutamate at brain glucose >5 mM. Pathogenity of elevated glutamate appears to be relativized by L/Glu and suggests to exclude insulin- induced brain injury.

Year in review 2008: Critical Care--trauma

Eleven papers on trauma published in Critical Care during 2008 addressed traumatic brain injury (TBI), burns, diagnostic concerns and immunosuppression. In regard to TBI, preliminary results indicate the utility of either magnetic resonance imaging (MRI) or ultrasound in measuring optic nerve sheath diameter to identify elevated intracranial pressure (ICP) as well as the potential benefit of thiopental for refractory ICP. Another investigaticc7960on demonstrated that early extubation of TBI patients whose Glasgow Coma Scale score was 8 or less did not result in additional incidence of nosocomial pneumonia. Another study indicated that strict glucose control resulted in worse outcomes during the first week after TBI, but improved outcomes after the second week. Another paper showed the prolonged neuroprotective advantages of proges-terone administration in TBI patients. There was also guidance on improved classifications of renal complications in burn patients. Another study found that patients with inhalation injuries and increased interleukin-6 (IL-6) and IL-10 and decreased IL-7 had increased mortality rates. One literature review described the disadvantages of prolonged immobilization or additional use of MRI for ruling out cervical spine injuries in obtunded TBI patients already cleared by computerized tomography scans. Other investigators found that higher N-terminal pro B-type natriuretic peptide (NT-proBNP) levels may be useful markers for post-traumatic cardiac impairment. Finally, an experimental model showed that both splenic apoptosis and lymphocytopenia may occur shortly after severe hemorrhage, thus increasing the threat of immunosuppression in those with severe blood loss.

Optimum serum glucose levels for patients with severe traumatic brain injury

Tight glucose control during the acute care of patients with severe traumatic brain injury has recently been advocated based on experimental concerns about deleterious effects of presenting the injured brain with a high glucose load, however, there is little or no clinical evidence that hyperglycemia worsens neurologic injury. The majority of the clinical studies of tight glucose control find that it is associated with an increased risk of hypoglycemic episodes and cellular injury, when compared to conventional glucose control protocols.

Differential influence of arterial blood glucose on cerebral metabolism following severe traumatic brain injury

INTRODUCTION

Maintaining arterial blood glucose within tight limits is beneficial in critically ill patients. Upper and lower limits of detrimental blood glucose levels must be determined.

METHODS

In 69 patients with severe traumatic brain injury (TBI), cerebral metabolism was monitored by assessing changes in arterial and jugular venous blood at normocarbia (partial arterial pressure of carbon dioxide (paCO2) 4.4 to 5.6 kPa), normoxia (partial arterial pressure of oxygen (paO2) 9 to 20 kPa), stable haematocrit (27 to 36%), brain temperature 35 to 38 degrees C, and cerebral perfusion pressure (CPP) 70 to 90 mmHg. This resulted in a total of 43,896 values for glucose uptake, lactate release, oxygen extraction ratio (OER), carbon dioxide (CO2) and bicarbonate (HCO3) production, jugular venous oxygen saturation (SjvO2), oxygen-glucose index (OGI), lactate-glucose index (LGI) and lactate-oxygen index (LOI). Arterial blood glucose concentration-dependent influence was determined retrospectively by assessing changes in these parameters within pre-defined blood glucose clusters, ranging from less than 4 to more than 9 mmol/l.

RESULTS

Arterial blood glucose significantly influenced signs of cerebral metabolism reflected by increased cerebral glucose uptake, decreased cerebral lactate production, reduced oxygen consumption, negative LGI and decreased cerebral CO2/HCO3 production at arterial blood glucose levels above 6 to 7 mmol/l compared with lower arterial blood glucose concentrations. At blood glucose levels more than 8 mmol/l signs of increased anaerobic glycolysis (OGI less than 6) supervened.

CONCLUSIONS

Maintaining arterial blood glucose levels between 6 and 8 mmol/l appears superior compared with lower and higher blood glucose concentrations in terms of stabilised cerebral metabolism. It appears that arterial blood glucose values below 6 and above 8 mmol/l should be avoided. Prospective analysis is required to determine the optimal arterial blood glucose target in patients suffering from severe TBI.

Intensive glycemic control in traumatic brain injury: what is the ideal glucose range?

Intensive glycemic control has become standard practice. Existing data, however, suggest this practice may have adverse consequences for traumatic brain injury. The recent paper by Meier and colleagues suggests that intensive glycemic control may be deleterious. The present article explores existing literature surrounding this controversy, and outlines the literature that raises concern. Finally, I suggest an alternative course of action that may enable control of glucose in an optimal range.