Glycemia management in neurocritical care patients: a review. J Neurosurg Anesthesiol. 2009;21:2-9. [PMID: 19098617 DOI: 10.1097/ana.0b013e31818f8a5c]

Diffuse Axonal Injury: Clinical Prognostic Factors, Molecular Experimental Models and the Impact of the Trauma Related Oxidative Stress. An Extensive Review Concerning Milestones and Advances

Traumatic brain injury (TBI) is a condition burdened by an extremely high rate of morbidity and mortality and can result in an overall disability rate as high as 50% in affected individuals. Therefore, the importance of identifying clinical prognostic factors for diffuse axonal injury (DAI) in (TBI) is commonly recognized as critical. The aim of the present review paper is to evaluate the most recent contributions from the relevant literature in order to understand how each single prognostic factor determinates the severity of the clinical syndrome associated with DAI. The main clinical factors with an important impact on prognosis in case of DAI are glycemia, early GCS, the peripheral oxygen saturation, blood pressure, and time to recover consciousness. In addition, the severity of the lesion, classified on the ground of the cerebral anatomical structures involved after the trauma, has a strong correlation with survival after DAI. In conclusion, modern findings concerning the role of reactive oxygen species (ROS) and oxidative stress in DAI suggest that biomarkers such as GFAP, pNF-H, NF-L, microtubule associated protein tau, Aβ42, S-100β, NSE, AQP4, Drp-1, and NCX represent a possible critical target for future pharmaceutical treatments to prevent the damages caused by DAI.

Perioperative Glycemia Management in Patients Undergoing Craniotomy for Brain Tumor Resection: A Global Survey of Neuroanesthesiologists' Perceptions and Practices

OBJECTIVE

There is a paucity of clinical evidence that guides perioperative glycemia management in patients undergoing craniotomy for brain tumor resection. The purpose of this study was to better understand global perceptions and practices related to glycemia management in these patients.

METHODS

Neuroanesthesiologists throughout North America, South America, Europe, and Asia filled out a brief online questionnaire related to their perceptions and practices regarding glycemia management in patients undergoing craniotomy for brain tumor resection.

RESULTS

Over 4 weeks, 435 participants practicing in 34 countries across 6 continents participated in this survey. Although responders in North America were found to perceive a higher risk hyperglycemia compared with those practicing in European (P = 0.024) and South Asian (P = 0.007) countries, responders practicing in South Asian countries (P = 0.030), Middle Eastern countries (P = 0.029), and South American (P = 0.005) countries were more likely than those from North America to remeasure glucose after an initial normal glucose measurement at incision. Responders from North America reported that a higher blood glucose threshold was necessary for them to delay or cancel the surgery compared with responders in Slavic (P < 0.001), European (P = 0.002), South American (P = 0.002), and Asian and Pacific (P < 0.001) countries. Responders from North America were more likely to report that they would delay or cancel the surgery because of a higher blood glucose threshold.

CONCLUSIONS

Our survey results suggest that perceptions and practices related to blood glucose management in patients undergoing brain tumor resection are variable. This study highlights the need for stronger clinical evidence and guidelines to help guide decisions for when and how to manage blood glucose derangements in these patients.

Comparison of sevoflurane and propofol anesthesia on the incidence of hyperglycemia in patients with type 2 diabetes undergoing lung surgery

Background

The type and regimen of anesthesia may affect perioperative hyperglycemia following major surgical stress. This study compared the effects of sevoflurane and propofol on the incidence of hyperglycemia and clinical outcomes in diabetic patients undergoing lung surgery.

Methods

This retrospective study included 176 patients with type 2 diabetes mellitus who had undergone lung surgery. Blood glucose levels and clinical outcomes from the preoperative period to the first 2 post-operative days (PODs) were retrospectively examined in patients who received sevoflurane (group S, n= 87) and propofol (group P, n=89) for maintenance of general anesthesia. The primary endpoint was the incidence of persistent hyperglycemia (2 consecutive blood glucose levels >180 mg/dL [10.0 mmol/L]) during the perioperative period. The secondary composite endpoint was the incidence of major postoperative complications and 30-day mortality rate after surgery.

Results

Blood glucose levels similarly increased from the preoperative period to the second POD in both groups (p=0.857). Although blood glucose levels at 2 hours after surgery were significantly lower in group P than in group S (p=0.022; 95% confidence interval for mean difference, -27.154 to -2.090), there was no difference in the incidence of persistent hyperglycemia during the perioperative period (group S, 70%; group P, 69%; p=0.816). The composite of major postoperative complications and all-cause in-hospital and 30-day mortality rates were also comparable between the two groups.

Conclusion

Sevoflurane and propofol were associated with a comparable incidence of perioperative hyperglycemia and clinical outcomes in diabetic patients undergoing lung surgery.

Management of hyperglycemia in the neurosurgery patient

Hyperglycemia is associated with adverse outcomes in patients who are candidates for or underwent neurosurgical procedures. Specific concerns and settings that relate to these patients are preoperative glycemic control, intraoperative control, management in the neurological intensive care unit (NICU), and postoperative control. In each of these settings, physicians have to ensure appropriate glycemic control to prevent or minimize adverse events. The glycemic control is usually managed by a neurohospitalist in co-management with the neurosurgery team pre- and post-operatively, and by the neurocritical care team in the setting of NICU. In this review article, we outline current standards of care for neurosurgery patients with diabetes mellitus and/or and hyperglycemia and discuss results of most recent clinical trials. We highlight specific concerns with regards to glycemic controls in these patients including enteral tube feeding and parenteral nutrition, the issues of the transition to the outpatient care, and management of steroid-induced hyperglycemia. We also note lack of evidence in some important areas, and the need for more research addressing these gaps. Where possible, we provide suggestions how to manage these patients when there is no underlying guideline.

Diffuse Axonal Injury: Epidemiology, Outcome and Associated Risk Factors

Diffuse axonal injury (DAI), a type of traumatic injury, is known for its severe consequences. However, there are few studies describing the outcomes of DAI and the risk factors associated with it. This study aimed to describe the outcome for patients with a primary diagnosis of DAI 6 months after trauma and to identify sociodemographic and clinical factors associated with mortality and dependence at this time point. Seventy-eight patients with DAI were recruited from July 2013 to February 2014 in a prospective cohort study. Patient outcome was analyzed using the Extended Glasgow Outcome Scale (GOS-E) within 6 months of the traumatic injury. The mean Injury Severity Score was 35.0 (SD = 11.9), and the mean New Injury Severity Score (NISS) was 46.2 (SD = 15.9). Mild DAI was observed in 44.9% of the patients and severe DAI in 35.9%. Six months after trauma, 30.8% of the patients had died, and 45.1% had shown full recovery according to the GOS-E. In the logistic regression model, the severity variables - DAI with hypoxia, as measured by peripheral oxygen saturation, and hypotension with NISS value - had a statistically significant association with patient mortality; on the other hand, severity of DAI and length of hospital stay were the only significant predictors for dependence. Therefore, severity of DAI emerged as a risk factor for both mortality and dependence.

Association of increased morbidity with the occurrence of hyperglycemia in the immediate postoperative period after elective pediatric neurosurgery

OBJECTIVE The acute elevation of blood glucose in perioperative pediatric patients subjected to cardiac surgery and in victims of head trauma is associated with higher rates of postoperative complications. Data on the occurrence of hyperglycemia and its association with unfavorable outcomes among patients who have undergone elective neurosurgery are scarce in the literature. This study aimed to determine whether the occurrence of hyperglycemia during the perioperative period of elective neurosurgery for the resection of tumors of the CNS in children is associated with increased morbidity. METHODS This retrospective cohort analysis included 105 children up to 12 years of age who underwent elective neurosurgery for resection of supratentorial and infratentorial CNS tumors between January 2005 and December 2010 at the São Rafael Hospital, a tertiary care medical center in Salvador, Brazil. Demographic data and intraoperative and postoperative information were collected from the medical records. Differences in blood glucose levels during the perioperative period were evaluated with nonparametric tests. RESULTS The patients who developed postoperative complications exhibited higher blood glucose levels on admission to the intensive care unit (ICU) (162.0 ± 35.8 mg/dl vs 146.3 ± 43.3 mg/dl; p = 0.016) and peak blood glucose levels on postoperative Day 1 (171.9 ± 30.2 mg/dl vs 156.1 ± 43.2 mg/dl; p = 0.008). Multivariate analysis showed that peak blood glucose levels on postoperative Day 1 were independently associated with a higher odds ratio for postoperative complication (OR 1.05). The occurrence of hyperglycemia (>150 mg/dl) upon admission to the ICU was associated with longer ICU (p = 0.003) and hospital (p = 0.001) stays. CONCLUSIONS The occurrence of hyperglycemia during the postoperative period after elective pediatric neurosurgery for the resection of CNS tumors was associated with longer hospital and ICU stays. Postoperative complications were associated with higher blood glucose levels upon admission to the ICU and higher peak blood glucose on the first postoperative day.

Insulin infusion therapy in critical care patients: regular insulin vs short-acting insulin. A prospective, crossover, randomized, multicenter blind study

INTRODUCTION

The aim of this multicenter, prospective, randomized, crossover trial is to compare, in critical care patients receiving insulin infusion therapy (IIT), the pharmacodynamic of Humulin insulin (Hlin), currently used as "standard of care," and Humalog insulin (Hlog), a shorter acting insulin formulation. This was measured as extent and duration of the carryover effect of insulin treatment, with the latter calculated as ratio between blood glucose concentration (BGC) reduction during and after IIT.

MATERIALS AND METHODS

Twenty-eight patients treated in an intensive care unit and receiving full nutritional support were randomly assigned to Hlin or Hlog as first treatment. Insulin was infused at a constant rate in patients presenting with BGC greater than or equal to 180 mg/dL (0.04 U/kg per hour) and was discontinued when BGC was less than or equal to 140 mg/dL (therapeutic BGC drop). Further reductions in BGC after discontinuation of insulin infusion were recorded (postinfusional BGC drop). During the study period, whole blood BGC was measured every 30 minutes. A minimal 6-hour washout interval was maintained between treatments with the 2 types of insulin. The primary end point was the extent (calculated as ratio between the therapeutic BGC drop and the postinfusional BGC drop) and duration of the carryover effect.

RESULTS

Treatment with Hlog, as compared with Hlin, was associated with a less profound carryover effect as well as a briefer duration of carryover (median, 0.40 vs 0.62; P < .001; median, 1 vs 1.5 hours; P < .001).

CONCLUSIONS

The use of constant Hlog infusion for IIT, when compared with Hlin at the same dose, is associated with a less profound carryover effect on BGC after discontinuation of IIT, a briefer duration of carryover, a faster BGC drop during infusion, and a quicker BGC rise after discontinuation. These characteristics suggest that Hlog IIT may be preferable for use in critically ill patients.

Short acting insulin analogues in intensive care unit patients

Blood glucose control in intensive care unit (ICU) patients, addressed to actively maintain blood glucose concentration within defined thresholds, is based on two major therapeutic interventions: to supply an adequate calories load and, when necessary, to continuously infuse insulin titrated to patients needs: intensive insulin therapy (IIT). Short acting insulin analogues (SAIA) have been synthesized to improve the chronic treatment of patients with diabetes but, because of the pharmacokinetic characteristics that include shorter on-set and off-set, they can be effectively used also in ICU patients and have the potential to be associated with a more limited risk of inducing episodes of iatrogenic hypoglycemia. Medical therapies carry an intrinsic risk for collateral effects; this can be more harmful in patients with unstable clinical conditions like ICU patients. To minimize these risks, the use of short acting drugs in ICU patients have gained a progressively larger room in ICU and now pharmaceutical companies and researchers design drugs dedicated to this subset of medical practice. In this article we report the rationale of using short acting drugs in ICU patients (i.e., sedation and treatment of arterial hypertension) and we also describe SAIA and their therapeutic use in ICU with the potential to minimize iatrogenic hypoglycemia related to IIT. The pharmacodynamic and pharmachokinetic characteristics of SAIA will be also discussed.

Optimal glycemic control in neurocritical care patients

Currently, the major issue in glycemic control in neurocritical care patients is that tight glycemic control (target range of 80 to 110 mg/dL) using intensive insulin therapy is associated with higher rates of hypoglycemia without an improvement in survival rate. The review by Kramer and colleagues in this issue of Critical Care confirms these data but provides solid evidence about the relationship between hyperglycemia and worsened neurological outcome after acute brain injury. In accordance with the conclusions of Kramer and colleagues, we recommend that a glucose control goal in neurocritical care patients be in the 'moderate' target range (110 to 180 mg/dL). In addition, we recommend adequate nutrition before and during insulin infusion, avoidance of insulin as a bolus, and the use of continuous insulin infusion, beginning with low doses with titration to individual sensitivity. Careful and accurate glycemic monitoring is especially important when insulin is infused.

Glycemia management in critical care patients

Over the last decade, the approach to clinical management of blood glucose concentration (BGC) in critical care patients has dramatically changed. In this editorial, the risks related to hypo, hyperglycemia and high BGC variability, optimal BGC target range and BGC monitoring devices for patients in the intensive care unit (ICU) will be discussed. Hypoglycemia has an increased risk of death, even after the occurrence of a single episode of mild hypoglycemia (BGC < 80 mg/dL), and it is also associated with an increase in the ICU length of stay, the major determinant of ICU costs. Hyperglycemia (with a threshold value of 180 mg/dL) is associated with an increased risk of death, longer length of stay and higher infective morbidity in ICU patients. In ICU patients, insulin infusion aimed at maintaining BGC within a 140-180 mg/dL target range (NICE-SUGAR protocol) is considered to be the state-of-the-art. Recent evidence suggests that a lower BGC target range (129-145 mg/dL) is safe and associated with lower mortality. In trauma patients without traumatic brain injury, tight BGC (target < 110 mg/dL) might be associated with lower mortality. Safe BGC targeting and estimation of optimal insulin dose titration should include an adequate nutrition protocol, the length of insulin infusion and the change in insulin sensitivity over time. Continuous glucose monitoring devices that provide accurate measurement can contribute to minimizing the risk of hypoglycemia and improve insulin titration. In conclusion, in ICU patients, safe and effective glycemia management is based on accurate glycemia monitoring and achievement of the optimal BGC target range by using insulin titration, along with an adequate nutritional protocol.

Intensive insulin therapy in brain injury: a meta-analysis

Many studies have addressed the question of whether intensive insulin therapy (IIT) provides better outcomes for brain-injured patients than does conventional insulin therapy (CIT), with conflicting results. We performed a systematic review and meta-analysis of the literature to estimate the effect of IIT on patients with brain injury. We searched MEDLINE, Embase, Cochrane Central Register of Controlled Trials (CENTRAL), and citations of key articles and selected "all randomized controlled trials" (RCTs) comparing the effect of IIT to CIT among adult patients with acute brain injury (traumatic brain injury, stroke, subarachnoid hemorrhage, and encephalitis). Of the 2807 studies, we identified 9 RCTs with a total of 1160 patients for analysis. IIT did not appear to decrease the risk of in-hospital or late mortality (RR=1.04, 95% CI=0.75, 1.43 and RR=1.07, 95%CI=0.91, 1.27 respectively). No significant heterogeneity was found (I(2)=0.0%). IIT also did not have a protective effect on long-term neurological outcomes (LTNO) (RR=1.10, 95% CI=0.96, 1.27). IIT, however, did decrease the rate of infections (RR=0.76, 95% CI=0.58, 0.98). Heterogeneity was present (I(2)=64%), which was eliminated upon sensitivity analysis bringing the RR to 0.66 (95% CI=0.55, 0.80, I(2)=0%). IIT increased the rate of hypoglycemic episodes (RR=1.72, 95% CI=1.20, 2.46) however there was intractable heterogeneity present (I(2)=89%), which did not resolve upon sensitivity analysis. We found no evidence of publication bias by Egger's test (p=0.50). To conclude, IIT has no mortality or LTNO benefit to patients with brain injury, but is beneficial at decreasing infection rates.

Ghrelin attenuates brain injury after traumatic brain injury and uncontrolled hemorrhagic shock in rats

Traumatic brain injury (TBI) and hemorrhagic shock often occur concomitantly due to multiple injuries. Gastrointestinal dysfunction occurs frequently in patients with TBI. However, whether alterations in the gastrointestinal system are involved in modulating neuronal damage and recovery after TBI is largely neglected. Ghrelin is a "gut-brain" hormone with multiple functions including antiinflammation and antiapoptosis. The purpose of this study was to determine whether ghrelin attenuates brain injury in a rat model of TBI and uncontrolled hemorrhage (UH). To study this, brain injury was induced by dropping a 450-g weight from 1.5 m onto a steel helmet attached to the skull of male adult rats. Immediately after TBI, a midline laparotomy was performed and both lumbar veins were isolated and severed at the junction with the vena cava. At 45 min after TBI/UH, ghrelin (4, 8 or 16 nmol/rat) or 1 mL normal saline (vehicle) was intravenously administered. Brain levels of TNF-α and IL-6, and cleaved PARP-1 levels in the cortex were measured at 4 h after TBI/UH. Beam balance test, forelimb placing test and hindlimb placing test were used to assess sensorimotor and reflex function. In additional groups of animals, ghrelin (16 nmol/rat) or vehicle was subcutaneously (s.c.) administered daily for 10 d after TBI/UH. The animals were monitored for 28 d to record body weight changes, neurological severity scale and survival. Our results showed that ghrelin downregulated brain levels of TNF-α and IL-6, reduced cortical levels of cleaved PARP-1, improved sensorimotor and reflex functions, and decreased mortality after TBI/UH. Thus, ghrelin has a great potential to be further developed as an effective resuscitation approach for the trauma victims with brain injury and severe blood loss.

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.

[Cerebral microdialysis in the current clinical setting]

Cerebral microdialysis, introduced in experimental studies 40 years ago, has been used clinically since 1992 for the neurochemical monitoring of patients in intensive care. The principles underlying this technique are closely related to brain metabolism. The study of the metabolites detected at brain interstitial tissue level, through the semipermeable membrane of the device, allows us to assess different physiological pathways in the brain, analyzing the changes that occur when they become less efficient in terms of energy, and also detecting waste products secondary to tissue damage. Despite its current limitations, this technique provides relevant information for research and the clinical management of critical neurological patients.

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.

Surgical intensive care unit--the trauma surgery perspective

PURPOSE

This review addresses and summarizes the key issues and unique specific intensive care treatment of adult patients from the trauma surgery perspective.

MATERIALS AND METHODS

The cornerstones of successful surgical intensive care management are fluid resuscitation, transfusion protocol and extracorporeal organ replacement therapies. The injury-type specific complications and unique pathophysiologic regulatory mechanisms of the traumatized patients influencing the critical care treatment are discussed.

CONCLUSIONS

Furthermore, the fundamental knowledge of the injury severity, understanding of the trauma mechanism, surgical treatment strategies and specific techniques of surgical intensive care are pointed out as essentials for a successful intensive care therapy.

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.

A review of perioperative glucose control in the neurosurgical population

Significant fluctuations in serum glucose levels accompany the stress response of surgery or acute injury and may be associated with vascular or neurologic morbidity. Maintenance of euglycemia with intensive insulin therapy (IIT) continues to be investigated as a therapeutic intervention to decrease morbidity associated with derangements in glucose metabolism. Hypoglycemia is a common side effect of IIT with potential for significant morbidity, especially in the neurologically injured patient. Differences in cerebral versus systemic glucose metabolism, the time course of cerebral response to injury, and heterogeneity of pathophysiology in 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 specific use of IIT for maintenance of euglycemia in the perioperative management of neurosurgical patients. Existing data are summarized and reviewed in this context.

Year in review 2008: Critical Care--metabolism

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

NICE-SUGAR: the end of a sweet dream?

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