Cerebral metabolic effects of strict versus conventional glycaemic targets following severe traumatic brain injury

Cerebral Glucose Metabolism following TBI: Changes in Plasma Glucose, Glucose Transport and Alternative Pathways of Glycolysis-A Translational Narrative Review

Traumatic brain injury (TBI) is a major public health concern with significant consequences across various domains. Following the primary event, secondary injuries compound the outcome after TBI, with disrupted glucose metabolism emerging as a relevant factor. This narrative review summarises the existing literature on post-TBI alterations in glucose metabolism. After TBI, the brain undergoes dynamic changes in brain glucose transport, including alterations in glucose transporters and kinetics, and disruptions in the blood-brain barrier (BBB). In addition, cerebral glucose metabolism transitions from a phase of hyperglycolysis to hypometabolism, with upregulation of alternative pathways of glycolysis. Future research should further explore optimal, and possibly personalised, glycaemic control targets in TBI patients, with GLP-1 analogues as promising therapeutic candidates. Furthermore, a more fundamental understanding of alterations in the activation of various pathways, such as the polyol and lactate pathway, could hold the key to improving outcomes following TBI.

High-physiological and supra-physiological 1,2-13C2 glucose focal supplementation to the traumatised human brain

How to optimise glucose metabolism in the traumatised human brain remains unclear, including whether injured brain can metabolise additional glucose when supplied. We studied the effect of microdialysis-delivered 1,2-13C2 glucose at 4 and 8 mmol/L on brain extracellular chemistry using bedside ISCUSflex, and the fate of the 13C label in the 8 mmol/L group using high-resolution NMR of recovered microdialysates, in 20 patients. Compared with unsupplemented perfusion, 4 mmol/L glucose increased extracellular concentrations of pyruvate (17%, p = 0.04) and lactate (19%, p = 0.01), with a small increase in lactate/pyruvate ratio (5%, p = 0.007). Perfusion with 8 mmol/L glucose did not significantly influence extracellular chemistry measured with ISCUSflex, compared to unsupplemented perfusion. These extracellular chemistry changes appeared influenced by the underlying metabolic states of patients' traumatised brains, and the presence of relative neuroglycopaenia. Despite abundant 13C glucose supplementation, NMR revealed only 16.7% 13C enrichment of recovered extracellular lactate; the majority being glycolytic in origin. Furthermore, no 13C enrichment of TCA cycle-derived extracellular glutamine was detected. These findings indicate that a large proportion of extracellular lactate does not originate from local glucose metabolism, and taken together with our earlier studies, suggest that extracellular lactate is an important transitional step in the brain's production of glutamine.

An overview of clinical cerebral microdialysis in acute brain injury

Cerebral microdialysis may be used in patients with severe brain injury to monitor their cerebral physiology. In this article we provide a concise synopsis with illustrations and original images of catheter types, their structure, and how they function. Where and how catheters are inserted, their identification on imaging modalities (CT and MRI), together with the roles of glucose, lactate/pyruvate ratio, glutamate, glycerol and urea are summarized in acute brain injury. The research applications of microdialysis including pharmacokinetic studies, retromicrodialysis, and its use as a biomarker for efficacy of potential therapies are outlined. Finally, we explore limitations and pitfalls of the technique, as well as potential improvements and future work that is needed to progress and expand the use of this technology.

Prognostic Significance of Plasma Insulin Level for Deep Venous Thrombosis in Patients with Severe Traumatic Brain Injury in Critical Care

BACKGROUND

Whether insulin resistance underlies deep venous thrombosis (DVT) development in patients with severe traumatic brain injury (TBI) is unclear. In this study, the association between plasma insulin levels and DVT was analyzed in patients with severe TBI.

METHODS

A prospective observational study of 73 patients measured insulin, glucose, glucagon-like peptide 1 (GLP-1), inflammatory factors, and hematological profiles within four preset times during the first 14 days after TBI. Ultrasonic surveillance of DVT was tracked. Two-way analysis of variance was used to determine the factors that discriminated between patients with and without DVT or with and without insulin therapy. Partial correlations of insulin level with all the variables were conducted separately in patients with DVT or patients without DVT. Factors associated with DVT were analyzed by multivariable logistic regression. Neurological outcomes 6 months after TBI were assessed.

RESULTS

Among patients with a mean (± standard deviation) age of 53 (± 16 years), DVT developed in 20 patients (27%) on median 10.4 days (range 4-22), with higher Acute Physiology and Chronic Health Evaluation II scores but similar Sequential Organ Failure Assessment scores and TBI severity. Patients with DVT were more likely to receive insulin therapy than patients without DVT (60% vs. 28%; P = 0.012); hence, they had higher 14-day insulin levels. However, insulin levels were comparable between patients with DVT and patients without DVT in the subgroups of patients with insulin therapy (n = 27) and patients without insulin therapy (n = 46). The platelet profile significantly discriminated between patients with and without DVT. Surprisingly, none of the coagulation profiles, blood cell counts, or inflammatory mediators differed between the two groups. Patients with insulin therapy had significantly higher insulin (P = 0.006), glucose (P < 0.001), and GLP-1 (P = 0.01) levels and were more likely to develop DVT (60% vs. 15%; P < 0.001) along with concomitant platelet depletion. Insulin levels correlated with glucose, GLP-1 levels, and platelet count exclusively in patients without DVT. Conversely, in patients with DVT, insulin correlated negatively with GLP-1 levels (P = 0.016). Age (P = 0.01) and elevated insulin levels at days 4-7 (P = 0.04) were independently associated with DVT. Patients with insulin therapy also showed worse Glasgow Outcome Scale scores (P = 0.001).

CONCLUSIONS

Elevated insulin levels in the first 14 days after TBI may indicate insulin resistance, which is associated with platelet hyperactivity, and thus increasing the risk of DVT.

A Retrospective Analysis of Randomized Controlled Trials on Traumatic Brain Injury: Evaluation of CONSORT Item Adherence

Traumatic brain injury (TBI) contributes to death and disability, resulting in an enormous individual and socio-economic challenges. Despite huge efforts, there are still controversies on treatment strategies and early outcome estimation. We evaluate current randomized controlled trials (RCTs) on TBI according to their fulfillment of the CONSORT (Consolidated Statement of Reporting Trials) statement’s criteria as a marker of transparency and the quality of study planning and realization. A PubMed search for RCTs on TBI (January 2014–December 2019) was carried out. After screening of the abstracts (n = 1.926), the suitable full text manuscripts (n = 72) were assessed for the fulfillment of the CONSORT criteria. The mean ratio of consort statement fulfillment was 59% (±13%), 31% of the included studies (n = 22) complied with less than 50% of the CONSORT criteria. Citation frequency was moderately related to ratio of CONSORT item fulfillment (r = 0.4877; p < 0.0001) and citation frequency per year (r = 0.5249; p < 0.0001). The ratio of CONSORT criteria fulfillment was associated with the impact factor of the publishing journal (r = 0.6428; p < 0.0001). Essential data for study interpretation, such as sample size determination (item 7a), participant flow (item 13a) as well as losses and exclusions (item 13b), were only reported in 53%, 60% and 63%, respectively. Reporting and methodological aspects in RCTs on TBI still may be improved. Thus, the interpretation of study results may be hampered due to methodological weaknesses.

The Japanese Clinical Practice Guidelines for Management of Sepsis and Septic Shock 2020 (J-SSCG 2020)

The Japanese Clinical Practice Guidelines for Management of Sepsis and Septic Shock 2020 (J-SSCG 2020), a Japanese-specific set of clinical practice guidelines for sepsis and septic shock created as revised from J-SSCG 2016 jointly by the Japanese Society of Intensive Care Medicine and the Japanese Association for Acute Medicine, was first released in September 2020 and published in February 2021. An English-language version of these guidelines was created based on the contents of the original Japanese-language version. The purpose of this guideline is to assist medical staff in making appropriate decisions to improve the prognosis of patients undergoing treatment for sepsis and septic shock. We aimed to provide high-quality guidelines that are easy to use and understand for specialists, general clinicians, and multidisciplinary medical professionals. J-SSCG 2016 took up new subjects that were not present in SSCG 2016 (e.g., ICU-acquired weakness [ICU-AW], post-intensive care syndrome [PICS], and body temperature management). The J-SSCG 2020 covered a total of 22 areas with four additional new areas (patient- and family-centered care, sepsis treatment system, neuro-intensive treatment, and stress ulcers). A total of 118 important clinical issues (clinical questions, CQs) were extracted regardless of the presence or absence of evidence. These CQs also include those that have been given particular focus within Japan. This is a large-scale guideline covering multiple fields; thus, in addition to the 25 committee members, we had the participation and support of a total of 226 members who are professionals (physicians, nurses, physiotherapists, clinical engineers, and pharmacists) and medical workers with a history of sepsis or critical illness. The GRADE method was adopted for making recommendations, and the modified Delphi method was used to determine recommendations by voting from all committee members.As a result, 79 GRADE-based recommendations, 5 Good Practice Statements (GPS), 18 expert consensuses, 27 answers to background questions (BQs), and summaries of definitions and diagnosis of sepsis were created as responses to 118 CQs. We also incorporated visual information for each CQ according to the time course of treatment, and we will also distribute this as an app. The J-SSCG 2020 is expected to be widely used as a useful bedside guideline in the field of sepsis treatment both in Japan and overseas involving multiple disciplines.

The Japanese Clinical Practice Guidelines for Management of Sepsis and Septic Shock 2020 (J-SSCG 2020)

The Japanese Clinical Practice Guidelines for Management of Sepsis and Septic Shock 2020 (J-SSCG 2020), a Japanese-specific set of clinical practice guidelines for sepsis and septic shock created as revised from J-SSCG 2016 jointly by the Japanese Society of Intensive Care Medicine and the Japanese Association for Acute Medicine, was first released in September 2020 and published in February 2021. An English-language version of these guidelines was created based on the contents of the original Japanese-language version. The purpose of this guideline is to assist medical staff in making appropriate decisions to improve the prognosis of patients undergoing treatment for sepsis and septic shock. We aimed to provide high-quality guidelines that are easy to use and understand for specialists, general clinicians, and multidisciplinary medical professionals. J-SSCG 2016 took up new subjects that were not present in SSCG 2016 (e.g., ICU-acquired weakness [ICU-AW], post-intensive care syndrome [PICS], and body temperature management). The J-SSCG 2020 covered a total of 22 areas with four additional new areas (patient- and family-centered care, sepsis treatment system, neuro-intensive treatment, and stress ulcers). A total of 118 important clinical issues (clinical questions, CQs) were extracted regardless of the presence or absence of evidence. These CQs also include those that have been given particular focus within Japan. This is a large-scale guideline covering multiple fields; thus, in addition to the 25 committee members, we had the participation and support of a total of 226 members who are professionals (physicians, nurses, physiotherapists, clinical engineers, and pharmacists) and medical workers with a history of sepsis or critical illness. The GRADE method was adopted for making recommendations, and the modified Delphi method was used to determine recommendations by voting from all committee members. As a result, 79 GRADE-based recommendations, 5 Good Practice Statements (GPS), 18 expert consensuses, 27 answers to background questions (BQs), and summaries of definitions and diagnosis of sepsis were created as responses to 118 CQs. We also incorporated visual information for each CQ according to the time course of treatment, and we will also distribute this as an app. The J-SSCG 2020 is expected to be widely used as a useful bedside guideline in the field of sepsis treatment both in Japan and overseas involving multiple disciplines.

Characterising the dynamics of cerebral metabolic dysfunction following traumatic brain injury: A microdialysis study in 619 patients

Traumatic brain injury (TBI) is a major cause of death and disability, particularly amongst young people. Current intensive care management of TBI patients is targeted at maintaining normal brain physiology and preventing secondary injury. Microdialysis is an invasive monitor that permits real-time assessment of derangements in cerebral metabolism and responses to treatment. We examined the prognostic value of microdialysis parameters, and the inter-relationships with other neuromonitoring modalities to identify interventions that improve metabolism. This was an analysis of prospective data in 619 adult TBI patients requiring intensive care treatment and invasive neuromonitoring at a tertiary UK neurosciences unit. Patients had continuous measurement of intracranial pressure (ICP), arterial blood pressure (ABP), brain tissue oxygenation (PbtO2), and cerebral metabolism and were managed according to a standardized therapeutic protocol. Microdialysate was assayed hourly for metabolites including glucose, pyruvate, and lactate. Cerebral perfusion pressure (CPP) and cerebral autoregulation (PRx) were derived from the ICP and ABP. Outcome was assessed with the Glasgow Outcome Score (GOS) at 6 months. Relationships between monitoring variables was examined with generalized additive mixed models (GAMM). Lactate/Pyruvate Ratio (LPR) over the first 3 to 7 days following injury was elevated amongst patients with poor outcome and was an independent predictor of ordinal GOS (p<0.05). Significant non-linear associations were observed between LPR and cerebral glucose, CPP, and PRx (p<0.001 to p<0.05). GAMM models suggested improved cerebral metabolism (i.e. reduced LPR with CPP >70mmHg, PRx <0.1, PbtO2 >18mmHg, and brain glucose >1mM. Deranged cerebral metabolism is an important determinant of patient outcome following TBI. Variations in cerebral perfusion, oxygenation and glucose supply are associated with changes in cerebral LPR and suggest therapeutic interventions to improve cerebral metabolism. Future prospective studies are required to determine the efficacy of these strategies.

Nutrition Therapy, Glucose Control, and Brain Metabolism in Traumatic Brain Injury: A Multimodal Monitoring Approach

The goal of neurocritical care in patients with traumatic brain injury (TBI) is to prevent secondary brain damage. Pathophysiological mechanisms lead to loss of body mass, negative nitrogen balance, dysglycemia, and cerebral metabolic dysfunction. All of these complications have been shown to impact outcomes. Therapeutic options are available that prevent or mitigate their negative impact. Nutrition therapy, glucose control, and multimodality monitoring with cerebral microdialysis (CMD) can be applied as an integrated approach to optimize systemic immune and organ function as well as adequate substrate delivery to the brain. CMD allows real-time bedside monitoring of aspects of brain energy metabolism, by measuring specific metabolites in the extracellular fluid of brain tissue. Sequential monitoring of brain glucose and lactate/pyruvate ratio may reveal pathologic processes that lead to imbalances in supply and demand. Early recognition of these patterns may help individualize cerebral perfusion targets and systemic glucose control following TBI. In this direction, recent consensus statements have provided guidelines and recommendations for CMD applications in neurocritical care. In this review, we summarize data from clinical research on patients with severe TBI focused on a multimodal approach to evaluate aspects of nutrition therapy, such as timing and route; aspects of systemic glucose management, such as intensive vs. moderate control; and finally, aspects of cerebral metabolism. Research and clinical applications of CMD to better understand the interplay between substrate supply, glycemic variations, insulin therapy, and their effects on the brain metabolic profile were also reviewed. Novel mechanistic hypotheses in the interpretation of brain biomarkers were also discussed. Finally, we offer an integrated approach that includes nutritional and brain metabolic monitoring to manage severe TBI patients.

Metabolism and inflammation: implications for traumatic brain injury therapeutics

INTRODUCTION

Traumatic Brain Injury (TBI) is a leading cause of death and disability in young people, affecting 69 million people annually, worldwide. The initial trauma disrupts brain homeostasis resulting in metabolic dysfunction and an inflammatory cascade, which can then promote further neurodegenerative effects for months or years, as a 'secondary' injury. Effective targeting of the cerebral inflammatory system is challenging due to its complex, pleiotropic nature. Cell metabolism plays a key role in many diseases, and increased disturbance in the TBI metabolic state is associated with poorer patient outcomes. Investigating critical metabolic pathways, and their links to inflammation, can potentially identify supplements which alter the brain's long-term response to TBI and improve recovery. Areas covered: The authors provide an overview of literature on metabolism and inflammation following TBI, and from relevant pre-clinical and clinical studies, propose therapeutic strategies. Expert opinion: There is still no specific active drug treatment for TBI. Changes in metabolic and inflammatory states have been reported after TBI and appear linked. Understanding more about abnormal cerebral metabolism following TBI, and its relationship with cerebral inflammation, will provide essential information for designing therapies, with implications for neurocritical care and for alleviating long-term disability and neurodegeneration in post-TBI patients.

Electrical stimulation for limb spasticity in children with traumatic brain injury: Study protocol for a systematic review of randomized controlled trial

BACKGROUND

Previous clinical studies have reported that electrical stimulation (ES) can be utilized to treat children with limbs spasticity (LS) after traumatic brain injury (TBI). Currently, no systematic review has addressed the effect of ES in children with LS following TBI. Thus, this systematic review will assess the effect and safety of ES for the children with LS after TBI.

METHODS

We will conduct the present systematic review of randomized controlled trials that will be retrieved from searches of PubMed, PsycINFO, WOS, Scopus, OpenGrey, Google Scholar, Cochrane Central Register of Controlled Trials, Embase, Cumulative Index to Nursing and Allied Health Literature, Allied and Complementary Medicine Database, and Chinese Biomedical Literature Database from the inception to the date of the literature searched. In addition, the clinical register websites, and reference lists of relevant studies will also be searched. Two independent reviewers will evaluate the eligibility criteria for all papers, extract the data and determine the methodology quality by using Cochrane risk of bias tool.

RESULTS

The results of this systematic review will pool the latest available data, and are expected to provide the summary of present evidence of ES for children with LS following TBI.

TIMELINE

This systematic review will start on January 10, 2019 and expected to complete by June 1, 2019.

ETHICS AND DISSEMINATION

No research ethic approval is needed in this study, because the data of this systematic review will not base on the individual data level. The results will be disseminated to publish at peer-reviewed journals or will present at relevant conferences.

PROSPERO REGISTRATION NUMBER

CRD42019120037.