A systematic review of therapeutic hypothermia for adult patients following traumatic brain injury

Clinical Insights and Future Directions in Hypothermia for Severe Traumatic Brain Injury: A Narrative Review

Fever control is essential in patients with severe traumatic brain injury (TBI). The efficacy of therapeutic hypothermia (TH) in severe TBI has been investigated over the last few decades; however, in contrast to experimental studies showing benefits, no evidence of efficacy has been demonstrated in clinical practice. In this review, the mechanisms and history of hypothermia were briefly outlined, while the results of major randomized controlled trials (RCTs) and meta-analyses investigating TH for adult TBI were introduced and discussed. The retrieved meta-analyses showed conflicting results, with a limited number of studies indicating the benefits of TH. Some studies have shown the benefits of long-term TH compared with short-term TH. Although TH is effective at lowering elevated intracranial pressure (ICP), reduced ICP does not lead to favorable outcomes. Low-quality RCTs overestimated the benefits of TH, while high-quality RCTs showed no difference or worse outcomes with TH. RCTs assessing standardized TH quality demonstrated the benefits of TH. As TBI has heterogeneous and complicated pathologies, applying a uniform treatment may not be ideal. A meta-analysis of young patients who underwent early cooling and hematoma removal showed better TH results. TH should not be abandoned, and its optimal usage should be advocated on an individual basis.

Temperature Control in Acute Brain Injury: An Update

Temperature control in severe acute brain injury (SABI) is a key component of acute management. This manuscript delves into the complex role of temperature management in SABI, encompassing conditions like traumatic brain injury (TBI), acute ischemic stroke (AIS), intracerebral hemorrhage (ICH), aneurysmal subarachnoid hemorrhage (aSAH), and hypoxemic/ischemic brain injury following cardiac arrest. Fever is a common complication in SABI and is linked to worse neurological outcomes due to increased inflammatory responses and intracranial pressure (ICP). Temperature management, particularly hypothermic temperature control (HTC), appears to mitigate these adverse effects primarily by reducing cerebral metabolic demand and dampening inflammatory pathways. However, the effectiveness of HTC varies across different SABI conditions. In the context of post-cardiac arrest, the impact of HTC on neurological outcomes has shown inconsistent results. In cases of TBI, HTC seems promising for reducing ICP, but its influence on long-term outcomes remains uncertain. For AIS, clinical trials have yet to conclusively demonstrate the benefits of HTC, despite encouraging preclinical evidence. This variability in efficacy is also observed in ICH, aSAH, bacterial meningitis, and status epilepticus. In pediatric and neonatal populations, while HTC shows significant benefits in hypoxic-ischemic encephalopathy, its effectiveness in other brain injuries is mixed. Although the theoretical basis for employing temperature control, especially HTC, is strong, the clinical outcomes differ among various SABI subtypes. The current consensus indicates that fever prevention is beneficial across the board, but the application and effectiveness of HTC are more nuanced, underscoring the need for further research to establish optimal temperature management strategies. Here we provide an overview of the clinical evidence surrounding the use of temperature control in various types of SABI.

Therapeutic Hypothermia Compared with Normothermia in Adults with Traumatic Brain Injury; Functional Outcome, Mortality, and Adverse Effects: A Systematic Review and Meta-Analysis

BACKGROUND

The main focus of traumatic brain injury (TBI) management is prevention of secondary injury. Therapeutic hypothermia (TH), the induction of a targeted low core body temperature, has been explored as a potential neuroprotectant in TBI. The aim of this article is to synthesize the available clinical data comparing the use of TH with the use of normothermia in TBI.

METHODS

A systematic search was conducted through MEDLINE, EMBASE, and Cochrane Central Register of Controlled Trials for randomized clinical trials including one or more outcome of interest associated with TH use in TBI. Independent reviewers evaluated quality of the studies and extracted data on patients with TBI undergoing TH treatment compared with those undergoing normothermia treatment. Pooled estimates, confidence intervals (CIs), and risk ratios (RRs) or odds ratios were calculated for all outcomes.

RESULTS

A total of 3,909 patients from 32 studies were eligible for analysis. Pooled analysis revealed a significant benefit of TH on mortality and functional outcome (RR 0.81, 95% CI 0.68-0.96, I2 = 41%; and RR 0.77; 95% CI 0.67-0.88, I2 = 68%, respectively). However, subgroup analysis based on risk of bias showed that only studies with a high risk of bias maintained this benefit. When divided by cooling method, reduced poor functional outcome was seen in the systemic surface cooling and cranial cooling groups (RR 0.68, 95% CI 0.59-0.79, I2 = 35%; and RR 0.44, 95% CI 0.29-0.67, I2 = 0%), and no difference was seen for the systemic intravenous or gastric cooling group. Reduced mortality was only seen in the systemic surface cooling group (RR 0.63, 95% CI 0.53-0.75, I2 = 0%,); however, this group had mostly high risk of bias studies. TH had an increased rate of pneumonia (RR 1.24, 95% CI 1.10-1.40, I2 = 32%), coagulation abnormalities (RR 1.63, 95% CI 1.09-2.44, I2 = 55%), and cardiac arrhythmias (RR 1.78, 95% CI 1.05-3.01, I2 = 21%). Once separated by low and high risk of bias, we saw no difference in these complications in the groups with low risk of bias. Overall quality of the evidence was moderate for mortality, functional outcome, and pneumonia and was low for coagulation abnormalities and cardiac arrhythmias.

CONCLUSIONS

With the addition of several recent randomized clinical trials and a thorough quality assessment, we have provided an updated systematic review and meta-analysis that concludes that TH does not show any benefit over normothermia in terms of mortality and functional outcome.

Trauma Anesthesiology Perioperative Management Update

Anesthesia for patients with life-threatening injuries is an essential part of post-accident care. Unfortunately, there is variability in trauma anesthesia care and numerous nonstandardized methods of working with patients remain. Uncertainty exists as to when and how best to intubate trauma patients, the use of vasopressors, and the appropriate management of severe traumatic brain injury. Some physicians recommend prehospital rapid sequence intubation, whereas others use bag-mask ventilation at lower pressures with no cricoid pressure and early transport to a trauma center. Overall, the absence of uniformity in trauma anesthesia care underlines the need for continued study and dialogue to define best practices and optimize patient outcomes.

Selective head cooling in the acute phase of concussive injury: a neuroimaging study

Introduction

Neurovascular decoupling is a common consequence after brain injuries like sports-related concussion. Failure to appropriately match cerebral blood flow (CBF) with increases in metabolic demands of the brain can lead to alterations in neurological function and symptom presentation. Therapeutic hypothermia has been used in medicine for neuroprotection and has been shown to improve outcome. This study aimed to examine the real time effect of selective head cooling on healthy controls and concussed athletes via magnetic resonance spectroscopy (MRS) and arterial spin labeling (ASL) measures.

Methods

24 participants (12 controls; 12 concussed) underwent study procedures including the Post-Concussion Symptom Severity (PCSS) Rating Form and an MRI cooling protocol (pre-cooling (T1 MPRAGE, ASL, single volume spectroscopy (SVS)); during cooling (ASL, SVS)).

Results

Results showed general decreases in brain temperature as a function of time for both groups. Repeated measures ANOVA showed a significant main effect of time (F = 7.94, p < 0.001) and group (F = 22.21, p < 0.001) on temperature, but no significant interaction of group and time (F = 1.36, p = 0.237). CBF assessed via ASL was non-significantly lower in concussed individuals at pre-cooling and generalized linear mixed model analyses demonstrated a significant main effect of time for the occipital left ROI (F = 11.29, p = 0.002) and occipital right ROI (F = 13.39, p = 0.001). There was no relationship between any MRI metric and PCSS symptom burden.

Discussion

These findings suggest the feasibility of MRS thermometry to monitor alterations of brain temperature in concussed athletes and that metabolic responses in response to cooling after concussion may differ from controls.

Regulation of Dihydropyrimidinase-like 3 Gene Expression by MicroRNAs in PC12 Cells with Induced Ischaemia and Hypothermia

Although hypothermic treatment has been reported to have some beneficial effects on ischaemia at the clinical level, the mechanism of ischaemia suppression by hypothermia remains unclear due to a lack of mechanism understanding and insufficient data. The aim of this study was to isolate and characterize microRNAs specifically expressed in ischaemia-hypothermia for the dihydropyrimidinase-like 3 (Dpysl3) gene. PC12 cells were induced with CoCl2 for chemical ischaemia and incubated at 32 ℃ for hypothermia. In ischaemia-hypothermia, four types of microRNAs (miR-106b-5p, miR-194-5p, miR-326-5p, and miR-497-5p) were highly related to the Dpysl3 gene based on exosomal microRNA analysis. Dpysl3 gene expression was up-regulated by miR-497-5p but down-regulated by miR-106b-5p, miR-194-5p and miR-326-5p. Our results suggest that these four microRNAs are involved in the regulation of Dpysl3 gene expression. These findings provide valuable clues that exosomal microRNAs could be used as therapeutic targets for effective treatment of ischaemia.

Target Temperature Management Versus Normal Temperature Management for Cardiac Arrest After Traumatic Brain Injury Patient: A Meta-Analysis and Systemic Review

This study compares the treatment outcomes between target temperature management (TTM) and normal temperature management (NTM) for cardiac arrest after traumatic brain injury (TBI). Two reviewers searched PubMed/MEDLINE, China National Infrastructure database for studies reporting on the use of TTM and NTM. All publications from inception to October 2021 were considered. Randomized control trials (RCTs) with cardiac arrest after TBI diagnoses were made based on the 2019 American Stroke Association (ASA) guidelines,1 wherein the included cardiac arrest patients underwent TTM or NTM treatment were included in this study. A Preferred Reporting Items for Systematic Reviews and Meta-Analyses recommended tool was used for assessing the risk of bias of the included RCTs. In all, 1920 publications were identified. However, after applying the inclusion and exclusion criteria, 6 RCTs, including 1617 patients who received TTMs (n = 826) and NTMs (n = 791), were considered eligible. The meta-analysis indicated that compared with NTM, TTM did not show a decrease in the mortality, however, for those mild patients in the early stage, TTM still can decrease the mortality and better the prognosis. Compared with NTM, TTM is an effective measure to treat mild and severe patients in the early stage and improve the prognosis.

Therapeutic hypothermia alleviates myocardial ischaemia-reperfusion injury by inhibiting inflammation and fibrosis via the mediation of the SIRT3/NLRP3 signalling pathway

Therapeutic hypothermia (TH) may attenuate myocardial ischaemia–reperfusion injury, thereby improving outcomes in acute myocardial infarction. However, the specific mechanism by which TH alleviates MIRI has not been elucidated so far. In this study, 120 healthy male Sprague‐Dawley rats were randomly divided into five groups. Haemodynamic parameters, myocardial infarction area, histological changes and the levels of cardiac enzymes, caspase‐1 and inflammatory cytokines were determined. In addition, the extent of myocardial fibrosis, the degree of cardiomyocyte apoptosis and the expression levels of SIRT3, GSDMD‐N, fibrosis‐related proteins and inflammation‐related proteins were estimated.TH reduced myocardial infarct area and cardiac enzyme levels, improved cardiomyopathic damage and haemodynamic indexes, and attenuated myocardial fibrosis, the protein expression levels of collagen I and III, myocardial apoptosis, the levels of inflammatory cytokines and inflammation‐related proteins. Notably, the immunofluorescence and protein expression levels of SIRT3 were upregulated in the 34H+DMSO group compared to the I/R group, but this protective effect was abolished by the SIRT3 inhibitor 3‐TYP. After administration of Mcc950, the reversal effects of 3‐TYP were significantly abolished, and TH could protect against MIRI in a rat isolated heart model by inhibiting inflammation and fibrosis. The SIRT3/NLRP3 signalling pathway is one of the most important signalling pathways in this regard.

Hypothermia Induced Impairment of Platelets: Assessment With Multiplate vs. ROTEM—An In Vitro Study

Introduction: This experimental in vitro study aimed to identify and characterize hypothermia-associated coagulopathy and to compare changes in mild to severe hypothermia with the quantitative measurement of rotational thromboelastometry (ROTEM) and multiple-electrode aggregometry (MULTIPLATE).

Methods: Whole blood samples from 18 healthy volunteers were analyzed at the target temperatures of 37, 32, 24, 18, and 13.7°C with ROTEM (ExTEM, InTEM and FibTEM) and MULTIPLATE using the arachidonic acid 0.5 mM (ASPI), thrombin receptor-activating peptide-6 32 µM (TRAP) and adenosine diphosphate 6.4 µM (ADP) tests at the corresponding incubating temperatures for coagulation assessment.

Results: Compared to baseline (37°C) values ROTEM measurements of clotting time (CT) was prolonged by 98% (at 18°C), clot formation time (CFT) was prolonged by 205% and the alpha angle dropped to 76% at 13.7°C (p < 0.001). At 24.0°C CT was prolonged by 56% and CFT by 53%. Maximum clot firmness was only slightly reduced by ≤2% at 13.7°C. Platelet function measured by MULTIPLATE was reduced with decreasing temperature (p < 0.001): AUC at 13.7°C −96% (ADP), −92% (ASPI) and −91% (TRAP).

Conclusion: Hypothermia impairs coagulation by prolonging coagulation clotting time and by decreasing the velocity of clot formation in ROTEM measurements. MULTIPLATE testing confirms a linear decrease in platelet function with decreasing temperatures, but ROTEM fails to adequately detect hypothermia induced impairment of platelets.

Prevention and management of perioperative hypothermia in adult elective surgical patients: A systematic review

BACKGROUND

Body temperature is tightly regulated with hormonal and cellular metabolism for normal functioning; however perioperative hypothermia is common secondary to anesthesia and surgical exposure.Prevention and maintaining body temperature should be started 1-2hrs before induction of anesthesia, to do this both active and passive warming system are effective to prevent complications associated with perioperative hypothermia.

METHODS

The aim of this systematic review is to develop a clear clinical practice protocol in prevention and management of perioperative hypothermia for elective adult surgical patients.The study is conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guideline 2020. After formulating clear criteria for the evidences to be included an appropriate method of searching was conducted by using the Pub Med, Google scholar and Cochrane library using the following MeSH terms: (inadvertent hypothermia AND anesthesia, hypothermia AND perioperative management and thermoregulation AND anesthesia) were used to draw evidences.After a reasonable amount of evidences were collected, appraisal and evaluation of study quality was based on WHO 2011 level of evidence and degree of recommendation. Final conclusions and recommendations are done by balancing the benefits and downsides of alternative management strategies for perioperative management of hypothermia.This systematic review registered with research registry unique identifying number (UIN) of "reviewregistry1253" in addition the overall AMSTAR 2 quality of this systematic review is moderate level.

DISCUSSION

Preserving a patient's body temperature during anesthesia and surgery is to minimize heat loss by reducing radiation and convection from the skin, evaporation from exposed surgical areas, and cooling caused by the introduction of cold intravenous fluids.

CONCLUSION

Hypothermia is least monitored complication during anesthesia and surgery results cardiac abnormalities, impaired wound healing, increased surgical site infections, shivering and delayed postoperative recovery, and coagulopathies.

Topical Neck Cooling Prolongs Survival of Rats with Intra-Abdominal Feculent Sepsis by Activation of the Vagus Nerve

Global hypothermia prolongs survival in rats with intraabdominal feculent sepsis by inhibiting inflammatory responses. We hypothesized that topical neck cooling (TNC) has similar benefits. Septic shock was induced by cecal ligation and incision (CLI) in Sprague Dawley rats. Rats were randomized to sham laparotomy, control with CLI, CLI with TNC, or vagotomy at the gastroesophageal junction before CLI and TNC. Two more groups underwent peritoneal washout with and without TNC two hours after CLI. TNC significantly lowered neck skin temperature (16.7 ± 1.4 vs. 30.5 ± 0.6 °C, p < 0.05) while maintaining core body normothermia. TNC rats recovered from anesthesia 70 min earlier than the control (p < 0.05). Three hours following CLI, the control and vagotomy with TNC groups had significantly more splenic contraction, fewer circulating leukocytes and higher plasma IL-1β, IL-10 and TNF-α levels than TNC rats (p < 0.05). TNC prolonged survival duration after CLI by a median of four hours vs. control (p < 0.05), but no benefit was seen if vagotomy preceded TNC. Peritoneal washout alone increased survival by 3 h (9.2 (7.8–10.5) h). Survival duration increased dramatically with TNC preceding washout, to a 56% survival rate (>10 days). TNC significantly prolonged the survival of rats with severe intraabdominal sepsis by inhibiting systemic proinflammatory responses by activating vagal anti-inflammatory pathways.

Selective head-neck cooling after concussion shortens return-to-play in ice hockey players

We aimed to investigate whether selective head–neck cooling could shorten recovery after sports-related concussions (SRCs). In a nonrandomized study of 15 Swedish professional ice hockey teams, 29 concussed players received immediate head and neck cooling for ≥30 min (initiated at 12.3 ± 9.2 min post-SRC by a portable cooling system), and 52 SRC controls received standard management. Players receiving head–neck cooling had shorter time to return-to-play than controls (7 vs 12.5 days, p < 0.0001), and 7% in the intervention group versus 25% in the control group were out of play for ≥3 weeks (p = 0.07). Immediate selective head–neck cooling is a promising option in the acute management of SRC that should be addressed in larger cohorts.

Efficacy and Safety of a Nasopharyngeal Catheter for Selective Brain Cooling in Patients with Traumatic Brain Injury: A Prospective, Non-randomized Pilot Study

BACKGROUND

The efficacy objective was to determine whether a novel nasopharyngeal catheter could be used to cool the human brain after traumatic brain injury, and the safety objective was to assess the local and systemic effects of this therapeutic strategy.

METHODS

This was a prospective, non-randomized, interventional clinical trial that involved five patients with severe traumatic brain injury. The intervention consisted of inducing and maintaining selective brain cooling for 24 h by positioning a catheter in the nasopharynx and circulating cold water inside the catheter in a closed-loop arrangement. Core temperature was maintained at ≥ 35 °C using counter-warming.

RESULTS

In all study participants, a brain temperature reduction of ≥ 2 °C was achieved. The mean brain temperature reduction from baseline was 2.5 ± 0.9 °C (P = .04, 95% confidence interval). The mean systemic temperature was 37.3 ± 1.1 °C at baseline and 36.0 ± 0.8 °C during the intervention. The mean difference between the brain temperature and the systemic temperature during intervention was - 1.2 ± 0.8 °C (P = .04). The intervention was well tolerated with no significant changes observed in the hemodynamic parameters. No relevant variations in intracranial pressure and transcranial Doppler were observed. The laboratory results underwent no major changes, aside from the K+ levels and blood counts. The K+ levels significantly varied (P = .04); however, the variation was within the normal range. Only one patient experienced an event of mild localized and superficial nasal discoloration, which was re-evaluated on the seventh day and indicated complete recovery.

CONCLUSION

The results suggest that our noninvasive method for selective brain cooling, using a novel nasopharyngeal catheter, was effective and safe for use in humans.

Brain Herniation and Intracranial Hypertension

This article introduces the basic concepts of intracranial physiology and pressure dynamics. It also includes discussion of signs and symptoms and examination and radiographic findings of patients with acute cerebral herniation as a result of increased as well as decreased intracranial pressure. Current best practices regarding medical and surgical treatments and approaches to management of intracranial hypertension as well as future directions are reviewed. Lastly, there is discussion of some of the implications of critical medical illness (sepsis, liver failure, and renal failure) and treatments thereof on causation or worsening of cerebral edema, intracranial hypertension, and cerebral herniation.

Low-Value Clinical Practices in Adult Traumatic Brain Injury: An Umbrella Review

Despite numerous interventions and treatment options, the outcomes of traumatic brain injury (TBI) have improved little over the last 3 decades, which raises concern about the value of care in this patient population. We aimed to synthesize the evidence on 14 potentially low-value clinical practices in TBI care. Using umbrella review methodology, we identified systematic reviews evaluating the effectiveness of 14 potentially low-value practices in adults with acute TBI. We present data on methodological quality (Assessing the Methodological Quality of Systematic Reviews), reported effect sizes, and credibility of evidence (I to IV). The only clinical practice with evidence of benefit was therapeutic hypothermia (credibility of evidence II to IV). However, the most recent meta-analysis on hypothermia based on high-quality trials suggested harm (credibility of evidence IV). Meta-analyses on platelet transfusion for patients on antiplatelet therapy were all consistent with harm but were statistically non-significant. For the following practices, effect estimates were consistently close to the null: computed tomography (CT) in adults with mild TBI who are low-risk on a validated clinical decision rule; repeat CT in adults with mild TBI on anticoagulant therapy with no clinical deterioration; antibiotic prophylaxis for external ventricular drain placement; and decompressive craniectomy for refractory intracranial hypertension. We identified five clinical practices with evidence of lack of benefit or harm. However, evidence could not be considered to be strong for any clinical practice as effect measures were imprecise and heterogeneous, systematic reviews were often of low quality, and most included studies had a high risk of bias.

The effectiveness of early prophylactic hypothermia in adult patients with traumatic brain injury: A systematic review and meta-analysis

OBJECTIVES

Previously published systematic reviews have explored the effects of therapeutic hypothermia on adult patients with traumatic brain injury (TBI). However, none explored the effect of early prophylactic hypothermia (within 6 h from injury to hypothermia induction). Animal studies indicated that early prophylactic hypothermia may reduce secondary injury and improve neurological outcomes. This systematic review aimed to investigate the effects of early prophylactic hypothermia on adult TBI regarding mortality, favourable outcomes, and complications.

DATA SOURCE

We searched electronic databases including Cochrane CENTRAL, PubMed, MEDLINE, CINAHL, EMBASE, Web of Science, OpenGrey, and ClinicalTrials.gov from inception to June 12, 2019. Manual search was conducted for additional information.

REVIEW METHODS

Only randomised controlled trials were included. The Cochrane Collaboration Risk of Bias Tool was used to assess the quality of included studies. We extracted general demographic characteristics, the initiation timing, methods of cooling, duration, target temperature, rewarming rate, mortality, neurological outcomes, and complications.

RESULTS

Six studies with a total of 1207 participants were included. Meta-analyses showed no significant difference in mortality and favourable outcomes (risk ratio = 1.11, 95% confidence interval = 0.90-1.37, P = 0.32; risk ratio = 1.03, 95% confidence interval = 0.91-1.16, P = 0.65, respectively). Similar results were found regarding different durations of hypothermia and different rewarming rates. Various complications were reported in the included studies. No statistical difference was found in three studies, while complications were reported to be significantly higher in the hypothermia group in the other three studies.

CONCLUSIONS

This review does not support the use of early prophylactic hypothermia (within 6 h after injury) as a neurological protection strategy in adult patients with TBI, irrespective of the short term or long term. No significant benefits were found regarding hypothermia with different rewarming rates. Owing to the limited number of studies, more randomised controlled trials with higher quality are required to establish true effects of early hypothermia in adult TBI.

Therapeutic hypothermia for pediatric refractory status epilepticus May Ameliorate post-status epilepticus epilepsy

BACKGROUND

To compare the clinical characteristics and outcomes of pediatric patients with refractory status epilepticus (RSE) and super-refractory status epilepticus (SRSE) who received therapeutic hypothermia (TH) plus anticonvulsants or anticonvulsants alone.

METHODS

Two-medical referral centers, retrospective cohort study. Pediatric Intensive Care Unit (PICU) at Taoyuan Chang Gung Children's hospital and Kaohsiung Chang Gung Memorial Hospital. We reviewed the medical records of 23 patients with RSE/SRSE who were admitted to PICU from January 2014 to December 2017. Of these, 11 patients received TH (TH group) and 12 patients did not (control group).

RESULTS

The selective endpoints were RSE/SRSE duration, length of PICU stay, and Glasgow Outcome Scale (GOS) score. We applied TH using the Artic Sun® temperature management system (target temperature, 34-35 °C; duration, 48-72 h). Of the 11 patients who received TH, 7 had febrile infection-related epilepsy syndrome (FIRSE), one had Dravet syndrome, and three had traumatic brain injury. The TH group had significantly shortern seizure durations than did the control group (hrs; median (IQR) 24(40) vs. 96(90), p < 0.05). Two patients in the TH group died of pulmonary embolism and extreme brain edema. The length of PICU stay was similar between the groups (days; median (IQR) 30(42) v.s 30.5(30.25)). The TH group had significantly better long-term outcomes than did the control group (GOS score, median (IQR) 4(2) v.s 3 (0.75), p = 0.01∗). The TH group had a significantly lower incidence of later chronic refractory epilepsy than did the control group (TH v.s non-TH, 5/11 (45%) v.s. 12/12(100%), p < 0.01).

CONCLUSIONS

TH effectively reduced the seizure burden in patients with RSE/SRSE. Our findings support that for patients with RSE/SRSE, TH shortens the seizure duration, ultimately reducing the occurrence of post-status epilepticus epilepsy and improving patients' long-term survival.

An overview of management of intracranial hypertension in the intensive care unit

Intracranial hypertension (IH) is a clinical condition commonly encountered in the intensive care unit, which requires immediate treatment. The maintenance of normal intracranial pressure (ICP) and cerebral perfusion pressure in order to prevent secondary brain injury (SBI) is the central focus of management. SBI can be detected through clinical examination and invasive and non-invasive ICP monitoring. Progress in monitoring and understanding the pathophysiological mechanisms of IH allows the implementation of targeted interventions in order to improve the outcome of these patients. Initially, general prophylactic measures such as patient's head elevation, fever control, adequate analgesia and sedation depth should be applied immediately to all patients with suspected IH. Based on specific indications and conditions, surgical resection of mass lesions and cerebrospinal fluid drainage should be considered as an initial treatment for lowering ICP. Hyperosmolar therapy (mannitol or hypertonic saline) represents the cornerstone of medical treatment of acute IH while hyperventilation should be limited to emergency management of life-threatening raised ICP. Therapeutic hypothermia could have a possible benefit on outcome. To control elevated ICP refractory to maximum standard medical and surgical treatment, at first, high-dose barbiturate administration and then decompressive craniectomy as a last step are recommended with unclear and probable benefit on outcomes, respectively. The therapeutic strategy should be based on a staircase approach and be individualized for each patient. Since most therapeutic interventions have an uncertain effect on neurological outcome and mortality, future research should focus on both studying the long-term benefits of current strategies and developing new ones.

Additive Protective Effects of Delayed Mild Therapeutic Hypothermia and Antioxidants on PC12 Cells Exposed to Oxidative Stress

Mild therapeutic hypothermia is protective against several cellular stresses, but the mechanisms underlying this protection are not completely resolved. In the present study, we used an in vitro model to investigate whether therapeutic hypothermia at 33°C applied following a peroxide-induced oxidative stress would protect PC12 cells. A 1-hour exposure to tert-butyl peroxide increased cell death measured 24 hours later. This cell death was dose-dependent in the range of 100-1000 μM tert-butyl peroxide with ∼50% cell death observed at 24 hours from 500 μM peroxide exposure. Cell survival/death was measured with an alamarBlue viability assay, and propidium iodide/Hoechst imaging for counts of living and dead cells. Therapeutic hypothermia at 33°C applied for 2 hours postperoxide exposure significantly increased cell survival measured 24 hours postperoxide-induced stress. This protection was present even when delayed hypothermia, 15 minutes after the peroxide washout, was applied. Addition of any of the three FDA-approved antioxidants (Tempol, EUK134, Edaravone at 100 μM) in combination with hypothermia improved cell survival. With the therapeutic hypothermia treatment, a significant downregulation of caspases-3 and -8 and tumor necrosis factor-α was observed at 3 and 24 hours poststress. Consistent with this, a cell-permeable pan-caspase inhibitor Z-VAD-FMK applied in combination with hypothermia significantly increased cell survival. Overall, these results suggest that the antioxidants quenching of reactive oxygen species likely works with hypothermia to reduce mitochondrial damage and/or apoptotic mechanisms. Further studies are required to confirm and extend these results to other cell types, including neuronal cells, and other forms of oxidative stress as well as to optimize the critical parameters of hypothermia treatment such as target temperature and duration.

A meta-analysis of the effects of therapeutic hypothermia in adult patients with traumatic brain injury

Purpose

Therapeutic hypothermia management remains controversial in patients with traumatic brain injury. We conducted a meta-analysis to evaluate the risks and benefits of therapeutic hypothermia management in patients with traumatic brain injury.

Methods

We searched the Web of Science, PubMed, Embase, Cochrane (Central) and Clinical Trials databases from inception to January 17, 2019. Eligible studies were randomised controlled trials that investigated therapeutic hypothermia management versus normothermia management in patients with traumatic brain injury. We collected the individual data of the patients from each included study. Meta-analyses were performed for 6-month mortality, unfavourable functional outcome and pneumonia morbidity. The risk of bias was evaluated using the Cochrane Risk of Bias tool.

Results

Twenty-three trials involving a total of 2796 patients were included. The randomised controlled trials with a high quality show significantly more mortality in the therapeutic hypothermia group [risk ratio (RR) 1.26, 95% confidence interval (CI) 1.04 to 1.53, p = 0.02]. Lower mortality in the therapeutic hypothermia group occurred when therapeutic hypothermia was received within 24 h (RR 0.83, 95% CI 0.71 to 0.96, p = 0.01), when hypothermia was received for treatment (RR 0.66, 95% CI 0.49 to 0.88, p = 0.006) or when hypothermia was combined with post-craniectomy measures (RR 0.69, 95% CI 0.48 to 1.00, p = 0.05). The risk of unfavourable functional outcome following therapeutic hypothermia management appeared to be significantly reduced (RR 0.78, 95% CI 0.67 to 0.91, p = 0.001). The meta-analysis suggested that there was a significant increase in the risk of pneumonia with therapeutic hypothermia management (RR 1.48, 95% CI 1.11 to 1.97, p = 0.007).

Conclusions

Our meta-analysis demonstrated that therapeutic hypothermia did not reduce but might increase the mortality rate of patients with traumatic brain injury in some high-quality studies. However, traumatic brain injury patients with elevated intracranial hypertension could benefit from hypothermia in therapeutic management instead of prophylaxis when initiated within 24 h.

Effect of mild hypothermia on prognosis of patients with severe traumatic brain injury: A meta-analysis with trial sequential analysis

BACKGROUND

Severe traumatic brain injury (sTBI) is a leading cause of death and neurologic disability worldwide. Although numerous previous studies have reported a positive effect of mild hypothermia treatment on sTBI, recent randomised controlled trials have not shown consistent benefits.

OBJECTIVE

The objective of this study was to explore the effects of mild hypothermia on prognosis in patients with sTBI and provide the best evidence to clinical practice.

METHODS

The databases PubMed, Embase, the Cochrane Library, ClinicalTrials.gov, and China National Knowledge Infrastructure (CNKI) were systematically searched from their inception to December 31, 2018, to identify relevant randomised controlled trials. Two authors independently reviewed and extracted data from included studies. The outcomes of interest were mortality and favourable neurological outcome. Review Manager, version 5.3, and trial sequential analysis (TSA) (beta = 0.9) were used to evaluate the collected data.

RESULTS

A total of 15 trials involving 2523 patients with sTBI were included. The pooled results showed that there was no significant statistical difference of mortality between two groups (risk ratio [RR] = 0.94, 95% confidence interval [CI] = 0.77-1.14, P = 0.53), and TSA indicated that the current available evidence was conclusive. However, patients receiving mild hypothermia therapy had better neurological outcome than those receiving normothermia therapy (RR = 1.20, 95% CI = 1.01-1.42, P = 0.04), and TSA indicated that more studies should be conducted to clarify this issue.

CONCLUSION

Our findings suggest that mild hypothermia can improve long-term neurological recovery for patients with sTBI, but which is not helpful to decrease the mortality. More well-designed rigorous clinical trials are needed to verify these results.

P value-driven methods were underpowered to detect publication bias: analysis of Cochrane review meta-analyses

OBJECTIVES

The aim of the study was to investigate the effect of number of studies in a meta-analysis on the detection of publication bias using P value-driven methods.

METHODS

The proportion of meta-analyses detected by Egger's, Harbord's, Peters', and Begg's tests to have asymmetry suggestive of publication bias were examined in 5,014 meta-analyses from Cochrane reviews. P values were also assessed in meta-analyses with varying number of studies, whereas symmetry was held constant. A simulation study was conducted to investigate if the above tests underestimate or overestimate the presence of publication bias.

RESULTS

The proportion of meta-analyses detected as asymmetrical via Egger's, Harbord's, Peters', and Begg's tests decreased by 42.6%, 41.1%, 29.3%, and 28.3%, respectively, when the median number of studies in the meta-analysis decreased from 87 to 14. P values decreased as the number of studies increased in the meta-analysis, despite the level of symmetry remaining constant. The simulation study confirmed that when publication bias is present, P value tests underestimate the presence of publication bias, particularly when study numbers are small.

CONCLUSION

P value-based tests used for the detection of publication bias-related asymmetry in meta-analysis require careful examination, as they underestimate asymmetry. Alternative methods not dependent on the number of studies are preferable.

Revisited: A Systematic Review of Therapeutic Hypothermia for Adult Patients Following Traumatic Brain Injury

OBJECTIVES

Therapeutic hypothermia has been of topical interest for many years and with the publication of two international, multicenter randomized controlled trials, the evidence base now needs updating. The aim of this systematic review of randomized controlled trials is to assess the efficacy of therapeutic hypothermia in adult traumatic brain injury focusing on mortality, poor outcomes, and new pneumonia.

DATA SOURCES

The following databases were searched from January 1, 2011, to January 26, 2018: Cochrane Central Register of Controlled Trial, MEDLINE, PubMed, and EMBASE.

STUDY SELECTION

Only foreign articles published in the English language were included. Only articles that were randomized controlled trials investigating adult traumatic brain injury sustained following an acute, closed head injury were included. Two authors independently assessed at each stage.

DATA EXTRACTION

Quality was assessed using the Cochrane Collaboration's tool for assessing the risk of bias. All extracted data were combined using the Mantel-Haenszel estimator for pooled risk ratio with 95% CIs. p value of less than 0.05 was considered statistically significant. All statistical analyses were conducted using RevMan 5 (Cochrane Collaboration, Version 5.3, Copenhagen: The Nordic Cochrane Centre, The Cochrane Collaboration, 2014).

DATA SYNTHESIS

Twenty-two studies with 2,346 patients are included. Randomized controlled trials with a low risk of bias show significantly more mortality in the therapeutic hypothermia group (risk ratio, 1.37; 95% CI, 1.04-1.79; p = 0.02), whereas randomized controlled trials with a high risk of bias show the opposite with a higher mortality in the control group (risk ratio, 0.70; 95% CI, 0.60-0.82; p < 0.00001).

CONCLUSIONS

Overall, this review is in-keeping with the conclusions published by the most recent randomized controlled trials. High-quality studies show no significant difference in mortality, poor outcomes, or new pneumonia. In addition, this review shows a place for fever control in the management of traumatic brain injury.

Intracarotid cold saline infusion contributes to neuroprotection in MCAO‑induced ischemic stroke in rats via serum and glucocorticoid‑regulated kinase 1

Intracarotid cold saline infusion (ICSI) brings about neuroprotective effects in ischemic stroke. However, the involvement of serum and glucocorticoid‑regulated kinase 1 (SGK1) in the underlying mechanism of ICSI is not fully understood; therefore, we used the rat middle cerebral artery occlusion (MCAO) model to investigate the neuroprotective effects of ICSI on ischemic stroke in rats, as well as the involvement of SGK1 in these effects. ICSI decreased infarct size and brain swelling, as determined by 2,3,5‑triphenyltetrazolium chloride staining and the dry‑wet weight method, respectively. The results of terminal deoxynucleotidyl transferase mediated nick end labeling (TUNEL) and Nissl staining showed that ICSI also suppressed apoptosis and increased the relative integral optical density (IOD) values of Nissl bodies in the rat MCAO model. Regarding the mechanism, the results of immunohistochemistry and western blotting revealed that ICSI upregulated SGK1 expression and downregulated beclin‑1 and LC‑3 expression in the rat MCAO model. In addition, SGK1 knockdown increased ICSI‑mediated infarct size and brain swelling, promoted apoptosis, and reduced the IOD values of Nissl bodies in the rat MCAO model. In addition, we found that SGK1 knockdown upregulated beclin‑1 and LC‑3 expression mediated by ICSI. Overall, ICSI had a neuroprotective effect on ischemic stroke after reperfusion by upregulating SGK1 and inhibiting autophagy.

Temperature Variability in a Modern Targeted Temperature Management Trial

OBJECTIVES

The Eurotherm3235 trial showed that therapeutic hypothermia was deleterious in patients with raised intracranial pressure following traumatic brain injury. We sought to ascertain if increased temperature variability within the first 48 hours, or for 7 days post randomization, were modifiable risk factors associated with poorer outcome.

DESIGN

Eurotherm3235 was a multicenter randomized controlled trial. Patients were randomized to receive either therapeutic hypothermia in addition to standard care or the later only. Mean moving range (mr) was used to stratify subjects into tertiles by the variability present in their core temperature within the first 48 hours post randomization and within 7 days post randomization. The primary outcome measure was a collapsed Glasgow Outcome Scale-Extended at 6 months post randomization. The temperature variability effect was estimated with ordinal logistic regression adjusted for baseline covariates and treatment effect.

SETTING

Forty-seven critical care units in 18 countries.

PATIENTS

Patients enrolled in the Eurotherm3235 trial to either therapeutic hypothermia or control treatments only.

MEASUREMENTS AND MAIN RESULTS

Three hundred eighty-six patients were included in our study. High level of temperature variability during the first 48 hours was associated with poorer collapsed Glasgow Outcome Scale-Extended. This effect remained statistically significant when only the control arm of the study was analyzed. No statistically significant effect was seen within the first 48 hours in the hypothermia group or within 7 days in either group.

CONCLUSIONS

When targeting normothermia, temperature variability may be a statistically significant variable in an ordinal analysis adjusted for baseline covariates.

Therapeutic hypothermia to reduce intracranial pressure after traumatic brain injury: the Eurotherm3235 RCT

BACKGROUND

Traumatic brain injury (TBI) is a major cause of disability and death in young adults worldwide. It results in around 1 million hospital admissions annually in the European Union (EU), causes a majority of the 50,000 deaths from road traffic accidents and leaves a further ≈10,000 people severely disabled.

OBJECTIVE

The Eurotherm3235 Trial was a pragmatic trial examining the effectiveness of hypothermia (32-35 °C) to reduce raised intracranial pressure (ICP) following severe TBI and reduce morbidity and mortality 6 months after TBI.

DESIGN

An international, multicentre, randomised controlled trial.

SETTING

Specialist neurological critical care units.

PARTICIPANTS

We included adult participants following TBI. Eligible patients had ICP monitoring in place with an ICP of > 20 mmHg despite first-line treatments. Participants were randomised to receive standard care with the addition of hypothermia (32-35 °C) or standard care alone. Online randomisation and the use of an electronic case report form (CRF) ensured concealment of random treatment allocation. It was not possible to blind local investigators to allocation as it was obvious which participants were receiving hypothermia. We collected information on how well the participant had recovered 6 months after injury. This information was provided either by the participant themself (if they were able) and/or a person close to them by completing the Glasgow Outcome Scale - Extended (GOSE) questionnaire. Telephone follow-up was carried out by a blinded independent clinician.

INTERVENTIONS

The primary intervention to reduce ICP in the hypothermia group after randomisation was induction of hypothermia. Core temperature was initially reduced to 35 °C and decreased incrementally to a lower limit of 32 °C if necessary to maintain ICP at < 20 mmHg. Rewarming began after 48 hours if ICP remained controlled. Participants in the standard-care group received usual care at that centre, but without hypothermia.

MAIN OUTCOME MEASURES

The primary outcome measure was the GOSE [range 1 (dead) to 8 (upper good recovery)] at 6 months after the injury as assessed by an independent collaborator, blind to the intervention. A priori subgroup analysis tested the relationship between minimisation factors including being aged < 45 years, having a post-resuscitation Glasgow Coma Scale (GCS) motor score of < 2 on admission, having a time from injury of < 12 hours and patient outcome.

RESULTS

We enrolled 387 patients from 47 centres in 18 countries. The trial was closed to recruitment following concerns raised by the Data and Safety Monitoring Committee in October 2014. On an intention-to-treat basis, 195 participants were randomised to hypothermia treatment and 192 to standard care. Regarding participant outcome, there was a higher mortality rate and poorer functional recovery at 6 months in the hypothermia group. The adjusted common odds ratio (OR) for the primary statistical analysis of the GOSE was 1.54 [95% confidence interval (CI) 1.03 to 2.31]; when the GOSE was dichotomised the OR was 1.74 (95% CI 1.09 to 2.77). Both results favoured standard care alone. In this pragmatic study, we did not collect data on adverse events. Data on serious adverse events (SAEs) were collected but were subject to reporting bias, with most SAEs being reported in the hypothermia group.

CONCLUSIONS

In participants following TBI and with an ICP of > 20 mmHg, titrated therapeutic hypothermia successfully reduced ICP but led to a higher mortality rate and worse functional outcome.

LIMITATIONS

Inability to blind treatment allocation as it was obvious which participants were randomised to the hypothermia group; there was biased recording of SAEs in the hypothermia group. We now believe that more adequately powered clinical trials of common therapies used to reduce ICP, such as hypertonic therapy, barbiturates and hyperventilation, are required to assess their potential benefits and risks to patients.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN34555414.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 22, No. 45. See the NIHR Journals Library website for further project information. The European Society of Intensive Care Medicine supported the pilot phase of this trial.

A new improved graphical and quantitative method for detecting bias in meta-analysis

Detection of publication and related biases remains suboptimal and threatens the validity and interpretation of meta-analytical findings. When bias is present, it usually differentially affects small and large studies manifesting as an association between precision and effect size and therefore visual asymmetry of conventional funnel plots. This asymmetry can be quantified and Egger's regression is, by far, the most widely used statistical measure for quantifying funnel plot asymmetry. However, concerns have been raised about both the visual appearance of funnel plots and the sensitivity of Egger's regression to detect such asymmetry, particularly when the number of studies is small. In this article, we propose a new graphical method, the Doi plot, to visualize asymmetry and also a new measure, the LFK index, to detect and quantify asymmetry of study effects in Doi plots. We demonstrate that the visual representation of asymmetry was better for the Doi plot when compared with the funnel plot. We also show that the diagnostic accuracy of the LFK index in discriminating between asymmetry due to simulated publication bias versus chance or no asymmetry was also better with the LFK index which had areas under the receiver operating characteristic curve of 0.74-0.88 with simulations of meta-analyses with five, 10, 15, and 20 studies. The Egger's regression result had lower areas under the receiver operating characteristic curve values of 0.58-0.75 across the same simulations. The LFK index also had a higher sensitivity (71.3-72.1%) than the Egger's regression result (18.5-43.0%). We conclude that the methods proposed in this article can markedly improve the ability of researchers to detect bias in meta-analysis.

Evidence-Based Review of Clinical Trials in Neurocritical Care

Neurocritical care is a rapidly growing specialty of complex care for the critically ill patient with neurological injury. This rapid growth has led to an increase in the number of important clinical trials to guide clinical practice and evidence-based care of the critically ill patient with neurological injury. Specialty-trained critical care nurses and advanced practice providers are integral members of neurocritical care teams and must remain informed about pivotal trials shaping practice recommendations. This article presents a summary of recent trials that have affected current practice and influenced care recommendations in the neurocritical care setting.

Esophageal Temperature Management in Patients Suffering from Traumatic Brain Injury

Traumatic brain injury (TBI) is a leading cause of death in the United States, and represents 2.5 million Emergency Department attendances, admissions into hospital, and deaths. A range of temperature modulating devices have been used to proactively cool TBI patients; however, there are currently no uniform targeted temperature management (TTM) guidelines in this patient population. Esophageal temperature management (ETM) is a relatively new TTM modality and the purpose of this study is to determine whether ETM is effective in controlling core temperature in TBI cases. This prospective interventional trial was a single-site study that enrolled 12 patients who received a TTM protocol using ETM. Eleven out of 12 patients reached target temperature during the first 10 hours of treatment. A total of 480 temperature measurements were recorded; 85% of the total measurements were within ±1°C of target temperature (408 measurements) and 75% were within ±0.5°C of target temperature (360 measurements). The average time to target was 5.83 ± 5.01 hours (range 1–20), with an average cooling rate of 0.58°C/h (range 0.15–1.5°C/h). This prospective interventional trial supports that ETM is a feasible TTM modality for severe TBI cases. The esophageal heat transfer device used in this study demonstrated comparable or superior performance to other commercially available TTM modalities, and the low adverse event rate may offer advantages over more invasive methods with reported higher complication rates.

Slow as Compared to Rapid Rewarming After Mild Hypothermia Improves Survival in Experimental Shock

BACKGROUND

Accidental hypothermia following trauma is an independent risk factor for mortality. However, in most experimental studies, hypothermia clearly improves outcome. We hypothesized that slow rewarming is beneficial over rapid rewarming following mild hypothermia in a rodent model of hemorrhagic shock.

MATERIALS AND METHODS

We subjected 32 male Wistar rats to severe hemorrhagic shock (25-30 mmHg for 30 min). Rats were assigned to four experimental groups (normothermia, hypothermia, rapid rewarming [RW], and slow RW). During induction of severe shock, all but the normothermia group were cooled to 34°C. After 60 min of shock, rats were resuscitated with Ringer's solution. The two RW groups were rewarmed at differing rates (6°C/h versus 2°C/h).

RESULTS

Slow RW animals exhibit a significantly prolonged survival compared with the rapid RW animals (P < 0.05). Nevertheless, hypothermic animals show a significant survival benefit as compared to all other experimental groups. Whereas seven animals of the hypothermia group survived to the end of the experiment, none of the other animals did (P < 0.001). No significant differences were found regarding acid base status, metabolism, parameters of organ injury, and coagulation.

CONCLUSIONS

The results indicate that even slow RW with 2°C/h may be still too fast in the setting of experimental hemorrhage. Too rapid rewarming may result in a loss of the protective effects of hypothermia. As rewarming is ultimately inevitable in patients with trauma, potential effects of rewarming on patient outcome should be further investigated in clinical studies.

Characterization of the Effect of Prolonged Therapeutic Hypothermia on Serum Magnesium and Potassium Following Neurological Injury

Current American Heart Association/American Stroke Association guidelines for the management of spontaneous intracerebral hemorrhage suggest therapeutic hypothermia (TH) as a salvage therapy in patients with elevated intracranial pressure. Electrolyte disorders may develop at any stage of the cooling process. Such deregulation can place patients at an increased risk for arrhythmias and worsened neurologic outcomes. The impact of TH on serum electrolyte concentration has been described, but electrolyte changes and repletions are yet to be quantified. The primary objective of this study was to quantify the trends in serum potassium and magnesium concentrations during TH and determine the median amount of electrolyte repletions administered. This study was a single-center retrospective cohort conducted at Virginia Commonwealth University Health. Data were collected from neurosurgical patients with intracranial hypertension who underwent TH (<36°C) for ≥48 hours. Patients with a primary neurological insult cooled with the Arctic Sun^® 5000 Temperature Management System, who were ≥13 years of age at the time of therapy with a core body temperature of ≥36°C before therapeutic hypothermia, were eligible for inclusion. Forty-three patients meeting the inclusion criteria were analyzed. A total of 42 patients (98%) experienced hypokalemia (<3.5 mEq/L) during TH. A median of 45 mEq per day of potassium repletion was administered during the maintenance phase of cooling. Despite those repletions, patients remained hypokalemic 30% of the time. Median serum magnesium concentrations during the maintenance phase of TH remained consistently within goal range of 1.8-2.5 mg/dL. Five patients (12%) experienced at least one episode of cardiac dysrhythmia during the cooling period. Standard potassium electrolyte repletion protocols did not adequately maintain serum potassium concentrations above our target of 3.5 mEq/L in neurosurgical patients undergoing TH. Standard magnesium repletion protocols were sufficient to maintain a normal serum concentration in this patient population when magnesium sulfate was not used for other indications.

Increasing Adherence to Brain Trauma Foundation Guidelines for Hospital Care of Patients With Traumatic Brain Injury

BACKGROUND

The Brain Trauma Foundation has developed treatment guidelines for the care of patients with acute traumatic brain injury. The Adam Williams Initiative is a program established to provide education and resources to encourage hospitals across the United States to incorporate the guidelines into practice.

OBJECTIVE

To explore the relationship in hospitals between participation in the Adam Williams Initiative and adherence to the Brain Trauma Foundation guidelines for patients with acute traumatic brain injury.

METHOD

Hospitals that participated in the Adam Williams Initiative entered data into an online tracking system of patients with traumatic brain injury for at least 2 years after the initial site training. Data included baseline hospital records and daily records on hospital care of patients with traumatic brain injury, including blood pressure, intracranial pressure, cerebral perfusion pressure, oxygenation, and other data relevant to the 15 key metrics in the Brain Trauma Foundation guidelines.

RESULTS

The 16 hospitals funded by the Adam Williams Initiative had good overall adherence to the 15 key metrics of the recommendations detailed in the Brain Trauma Foundation guidelines. Variability in results was primarily due to data collection methods and analysis.

CONCLUSIONS

The Adam Williams Initiative helps promote adherence to the Brain Trauma Foundation guidelines for hospital care of patients with traumatic brain injury by providing a platform for developing and standardizing best practices. Participation in the initiative is associated with high adherence to clinical guidelines, a situation that may subsequently improve care and outcomes for patients with traumatic brain injury.

The currency, completeness and quality of systematic reviews of acute management of moderate to severe traumatic brain injury: A comprehensive evidence map

OBJECTIVE

To appraise the currency, completeness and quality of evidence from systematic reviews (SRs) of acute management of moderate to severe traumatic brain injury (TBI).

METHODS

We conducted comprehensive searches to March 2016 for published, English-language SRs and RCTs of acute management of moderate to severe TBI. Systematic reviews and RCTs were grouped under 12 broad intervention categories. For each review, we mapped the included and non-included RCTs, noting the reasons why RCTs were omitted. An SR was judged as 'current' when it included the most recently published RCT we found on their topic, and 'complete' when it included every RCT we found that met its inclusion criteria, taking account of when the review was conducted. Quality was assessed using the AMSTAR checklist (trichotomised into low, moderate and high quality).

FINDINGS

We included 85 SRs and 213 RCTs examining the effectiveness of treatments for acute management of moderate to severe TBI. The most frequently reviewed interventions were hypothermia (n = 17, 14.2%), hypertonic saline and/or mannitol (n = 9, 7.5%) and surgery (n = 8, 6.7%). Of the 80 single-intervention SRs, approximately half (n = 44, 55%) were judged as current and two-thirds (n = 52, 65.0%) as complete. When considering only the most recently published review on each intervention (n = 25), currency increased to 72.0% (n = 18). Less than half of the 85 SRs were judged as high quality (n = 38, 44.7%), and nearly 20% were low quality (n = 16, 18.8%). Only 16 (20.0%) of the single-intervention reviews (and none of the five multi-intervention reviews) were judged as current, complete and high-quality. These included reviews of red blood cell transfusion, hypothermia, management guided by intracranial pressure, pharmacological agents (various) and prehospital intubation. Over three-quarters (n = 167, 78.4%) of the 213 RCTs were included in one or more SR. Of the remainder, 17 (8.0%) RCTs post-dated or were out of scope of existing SRs, and 29 (13.6%) were on interventions that have not been assessed in SRs.

CONCLUSION

A substantial number of SRs in acute management of moderate to severe TBI lack currency, completeness and quality. We have identified both potential evidence gaps and also substantial research waste. Novel review methods, such as Living Systematic Reviews, may ameliorate these shortcomings and enhance utility and reliability of the evidence underpinning clinical care.

How does blood regulate cerebral temperatures during hypothermia?

Macro-modeling of cerebral blood flow can help determine the impact of thermal intervention during instances of head trauma to mitigate tissue damage. This work presents a bioheat model using a 3D fluid-porous domain coupled with intersecting 1D arterial and venous vessel trees. This combined vascular porous (VaPor) model resolves both cerebral blood flow and energy equations, including heat generated by metabolism, using vasculature extracted from MRI data and is extended using a tree generation algorithm. Counter-current flows are expected to increase thermal transfer within the brain and are enforced using either the vascular structure or flow reversal, represented by a flow reversal constant, C_R. These methods exhibit larger average brain cooling (from 0.56 °C ± <0.01 °C to 0.58 °C ± <0.01 °C) compared with previous models (0.39 °C) when scalp temperature is reduced. An greater reduction in core brain temperature is observed (from 0.29 °C ± <0.01 °C to 0.45 °C ± <0.01 °C) compared to previous models (0.11 °C) due to the inclusion of counter-current cooling effects. The VaPor model also predicts that a hypothermic average temperature (<36 °C) can be reached in core regions of neonatal models using scalp cooling alone.

Therapeutic hypothermia and targeted temperature management for traumatic brain injury: Experimental and clinical experience

Traumatic brain injury (TBI) is a worldwide medical problem, and currently, there are few therapeutic interventions that can protect the brain and improve functional outcomes in patients. Over the last several decades, experimental studies have investigated the pathophysiology of TBI and tested various pharmacological treatment interventions targeting specific mechanisms of secondary damage. Although many preclinical treatment studies have been encouraging, there remains a lack of successful translation to the clinic and no therapeutic treatments have shown benefit in phase 3 multicenter trials. Therapeutic hypothermia and targeted temperature management protocols over the last several decades have demonstrated successful reduction of secondary injury mechanisms and, in some selective cases, improved outcomes in specific TBI patient populations. However, the benefits of therapeutic hypothermia have not been demonstrated in multicenter randomized trials to significantly improve neurological outcomes. Although the exact reasons underlying the inability to translate therapeutic hypothermia into a larger clinical population are unknown, this failure may reflect the suboptimal use of this potentially powerful therapeutic in potentially treatable severe trauma patients. It is known that multiple factors including patient recruitment, clinical treatment variables, and cooling methodologies are all important in yielding beneficial effects. High-quality multicenter randomized controlled trials that incorporate these factors are required to maximize the benefits of this experimental therapy. This article therefore summarizes several factors that are important in enhancing the beneficial effects of therapeutic hypothermia in TBI. The current failures of hypothermic TBI clinical trials in terms of clinical protocol design, patient section, and other considerations are discussed and future directions are emphasized.

Hypothermia for traumatic brain injury

BACKGROUND

Hypothermia has been used in the treatment of brain injury for many years. Encouraging results from small trials and laboratory studies led to renewed interest in the area and some larger trials.

OBJECTIVES

To determine the effect of mild hypothermia for traumatic brain injury (TBI) on mortality, long-term functional outcomes and complications.

SEARCH METHODS

We ran and incorporated studies from database searches to 21 March 2016. We searched the Cochrane Injuries Group's Specialised Register, Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library), MEDLINE (OvidSP), Embase Classic+Embase (OvidSP), PubMed, ISI Web of science (SCI-EXPANDED, SSCI, CPCI-S & CPSI-SSH), clinical trials registers, and screened reference lists. We also re-ran these searches pre-publication in June 2017; the result from this search is presented in 'Studies awaiting classification'.

SELECTION CRITERIA

We included randomised controlled trials of participants with closed TBI requiring hospitalisation who were treated with hypothermia to a maximum of 35 ºC for at least 12 consecutive hours. Treatment with hypothermia was compared to maintenance with normothermia (36.5 to 38 ºC).

DATA COLLECTION AND ANALYSIS

Two review authors assessed data on mortality, unfavourable outcomes according to the Glasgow Outcome Scale, and pneumonia.

MAIN RESULTS

We included 37 eligible trials with a total of 3110 randomised participants; nine of these were new studies since the last update (2009) and five studies had been previously excluded but were re-assessed and included during the 2017 update. We identified two ongoing studies from searches of clinical trials registers and database searches and two studies await classification.Studies included both adults and children with TBI. Most studies commenced treatment immediately on admission to hospital or after craniotomies and all treatment was maintained for at least 24 hours. Thirty-three studies reported data for mortality, 31 studies reported data for unfavourable outcomes (death, vegetative state or severe disability), and 14 studies reported pneumonia. Visual inspection of the results for these outcomes showed inconsistencies among studies, with differences in the direction of effect, and we did not pool these data for meta-analysis. We considered duration of hypothermia therapy and the length of follow-up in collected data for these subgroups; differences in study data remained such that we did not perform meta-analysis.Studies were generally poorly reported and we were unable to assess risk of bias adequately. Heterogeneity was evident both in the trial designs and participant inclusion. Inconsistencies in results may be explained by heterogeneity among study participants or bias introduced by individual study methodology but we did not explore this in detail in subgroup or sensitivity analyses. We used the GRADE approach to judge the quality of the evidence for each outcome and downgraded the evidence for mortality and unfavourable outcome to very low. We downgraded the evidence for the pneumonia outcome to low.

AUTHORS' CONCLUSIONS

Despite a large number studies, there remains no high-quality evidence that hypothermia is beneficial in the treatment of people with TBI. Further research, which is methodologically robust, is required in this field to establish the effect of hypothermia for people with TBI.

Optimization of brain metabolism using metabolic-targeted therapeutic hypothermia can reduce mortality from traumatic brain injury

BACKGROUND

Therapeutic hypothermia is widely used to treat traumatic brain injuries (TBIs). However, determining the best hypothermia therapy strategy remains a challenge. We hypothesized that reducing the metabolic rate, rather than reaching a fixed body temperature, would be an appropriate target because optimizing metabolic conditions especially the brain metabolic environment may enhance neurologic protection. A pilot single-blind randomized controlled trial was designed to test this hypothesis, and a nested metabolomics study was conducted to explore the mechanics thereof.

METHODS

Severe TBI patients (Glasgow Coma Scale score, 3-8) were randomly divided into the metabolic-targeted hypothermia treatment (MTHT) group, 50% to 60% rest metabolic ratio as the hypothermia therapy target, and the body temperature-targeted hypothermia treatment (BTHT) control group, hypothermia therapy target of 32°C to 35°C body temperature. Brain and circulatory metabolic pool blood samples were collected at baseline and on days 1, 3, and 7 during the hypothermia treatment, which were selected randomly from a subgroup of MTHT and BTHT groups. The primary outcome was mortality. Using H nuclear magnetic resonance technology, we tracked and located the disturbances of metabolic networks.

RESULTS

Eighty-eight severe TBI patients were recruited and analyzed from December 2013 to December 2014, 44 each were assigned in the MTHT and BTHT groups (median age, 42 years; 69.32% men; mean Glasgow Coma Scale score, 6.17 ± 1.02). The mortality was significantly lower in the MTHT than the BTHT group (15.91% vs. 34.09%; p = 0.049). From these, eight cases of MTHT and six cases from BTHT group were enrolled for metabolomics analysis, which showed a significant difference between the brain and circulatory metabolic patterns in MTHT group on day 7 based on the model parameters and scores plots. Finally, metabolites representing potential neuroprotective monitoring parameters for hypothermia treatment were identified through H nuclear magnetic resonance metabolomics.

CONCLUSION

MTHT can significantly reduce the mortality of severe TBI patients. Metabolomics research showed that this strategy could effectively improve brain metabolism, suggesting that reducing the metabolic rate to 50% to 60% should be set as the hypothermia therapy target.

LEVEL OF EVIDENCE

Therapeutic study, Level I.

Targeted temperature management in the ICU: Guidelines from a French expert panel

Over the recent period, the use of induced hypothermia has gained an increasing interest for critically ill patients, in particular in brain-injured patients. The term "targeted temperature management" (TTM) has now emerged as the most appropriate when referring to interventions used to reach and maintain a specific level temperature for each individual. TTM may be used to prevent fever, to maintain normothermia, or to lower core temperature. This treatment is widely used in intensive care units, mostly as a primary neuroprotective method. Indications are, however, associated with variable levels of evidence based on inhomogeneous or even contradictory literature. Our aim was to conduct a systematic analysis of the published data in order to provide guidelines. We present herein recommendations for the use of TTM in adult and paediatric critically ill patients developed using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) method. These guidelines were conducted by a group of experts from the French Intensive Care Society (Société de réanimation de langue française [SRLF]) and the French Society of Anesthesia and Intensive Care Medicine (Société francaise d'anesthésie réanimation [SFAR]) with the participation of the French Emergency Medicine Association (Société française de médecine d'urgence [SFMU]), the French Group for Pediatric Intensive Care and Emergencies (Groupe francophone de réanimation et urgences pédiatriques [GFRUP]), the French National Association of Neuro-Anesthesiology and Critical Care (Association nationale de neuro-anesthésie réanimation française [ANARLF]), and the French Neurovascular Society (Société française neurovasculaire [SFNV]). Fifteen experts and two coordinators agreed to consider questions concerning TTM and its practical implementation in five clinical situations: cardiac arrest, traumatic brain injury, stroke, other brain injuries, and shock. This resulted in 30 recommendations: 3 recommendations were strong (Grade 1), 13 were weak (Grade 2), and 14 were experts' opinions. After two rounds of rating and various amendments, a strong agreement from voting participants was obtained for all 30 (100%) recommendations, which are exposed in the present article.

Targeted temperature management in the ICU: guidelines from a French expert panel

Over the recent period, the use of induced hypothermia has gained an increasing interest for critically ill patients, in particular in brain-injured patients. The term “targeted temperature management” (TTM) has now emerged as the most appropriate when referring to interventions used to reach and maintain a specific level temperature for each individual. TTM may be used to prevent fever, to maintain normothermia, or to lower core temperature. This treatment is widely used in intensive care units, mostly as a primary neuroprotective method. Indications are, however, associated with variable levels of evidence based on inhomogeneous or even contradictory literature. Our aim was to conduct a systematic analysis of the published data in order to provide guidelines. We present herein recommendations for the use of TTM in adult and paediatric critically ill patients developed using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) method. These guidelines were conducted by a group of experts from the French Intensive Care Society (Société de Réanimation de Langue Française [SRLF]) and the French Society of Anesthesia and Intensive Care Medicine (Société Francaise d’Anesthésie Réanimation [SFAR]) with the participation of the French Emergency Medicine Association (Société Française de Médecine d’Urgence [SFMU]), the French Group for Pediatric Intensive Care and Emergencies (Groupe Francophone de Réanimation et Urgences Pédiatriques [GFRUP]), the French National Association of Neuro-Anesthesiology and Critical Care (Association Nationale de Neuro-Anesthésie Réanimation Française [ANARLF]), and the French Neurovascular Society (Société Française Neurovasculaire [SFNV]). Fifteen experts and two coordinators agreed to consider questions concerning TTM and its practical implementation in five clinical situations: cardiac arrest, traumatic brain injury, stroke, other brain injuries, and shock. This resulted in 30 recommendations: 3 recommendations were strong (Grade 1), 13 were weak (Grade 2), and 14 were experts’ opinions. After two rounds of rating and various amendments, a strong agreement from voting participants was obtained for all 30 (100%) recommendations, which are exposed in the present article.

Mortality Risk Stratification After Traumatic Brain Injury and Hazard of Death With Titrated Hypothermia in the Eurotherm3235Trial

Supplemental Digital Content is available in the text.

Objectives:

Hypothermia reduces intracranial hypertension in patients with traumatic brain injury but was associated with harm in the Eurotherm3235Trial. We stratified trial patients by International Mission for Prognosis and Analysis of Clinical Trials in [Traumatic Brain Injury] (IMPACT) extended model sum scores to determine where the balance of risks lay with the intervention.

Design:

The Eurotherm3235Trial was a randomized controlled trial, with standardized and blinded outcome assessment. Patients in the trial were split into risk tertiles by IMPACT extended model sum scores. A proportional hazard analysis for death between randomization and 6 months was performed by intervention and IMPACT extended model sum scores tertiles in both the intention-to-treat and the per-protocol populations of the Eurotherm3235Trial.

Setting:

Forty-seven neurologic critical care units in 18 countries.

Patients:

Adult traumatic brain injury patients admitted to intensive care who had suffered a primary, closed traumatic brain injury; increased intracranial pressure; an initial head injury less than 10 days earlier; a core temperature at least 36°C; and an abnormal brain CT.

Intervention:

Titrated Hypothermia in the range 32-35°C as the primary intervention to reduce raised intracranial pressure.

Measurements and Main Results:

Three hundred eighty-six patients were available for analysis in the intention-to-treat and 257 in the per-protocol population. The proportional hazard analysis (intention-to-treat and per-protocol populations) showed that the treatment effect behaves similarly across all risk stratums. However, there is a trend that indicates that patients in the low-risk group could be at greater risk of suffering harm due to hypothermia.

Conclusions:

Hypothermia as a first line measure to reduce intracranial pressure to less than 20 mm Hg is harmful in patients with a lower severity of injury and no clear benefit exists in patients with more severe injuries.

Acute brain trauma, lung injury, and pneumonia: more than just altered mental status and decreased airway protection

Traumatic brain injury (TBI) is a major cause of mortality and morbidity worldwide. Even when patients survive the initial insult, there is significant morbidity and mortality secondary to subsequent pulmonary edema, acute lung injury (ALI), and nosocomial pneumonia. Whereas the relationship between TBI and secondary pulmonary complications is recognized, little is known about the mechanistic interplay of the two phenomena. Changes in mental status secondary to acute brain injury certainly impair airway- and lung-protective mechanisms. However, clinical and translational evidence suggests that more specific neuronal and cellular mechanisms contribute to impaired systemic and lung immunity that increases the risk of TBI-mediated lung injury and infection. To better understand the cellular mechanisms of that immune impairment, we review here the current clinical data that support TBI-induced impairment of systemic and lung immunity. Furthermore, we also review the animal models that attempt to reproduce human TBI. Additionally, we examine the possible role of damage-associated molecular patterns, the chlolinergic anti-inflammatory pathway, and sex dimorphism in post-TBI ALI. In the last part of the review, we discuss current treatments and future pharmacological therapies, including fever control, tracheostomy, and corticosteroids, aimed to prevent and treat pulmonary edema, ALI, and nosocomial pneumonia after TBI.

Traumatic Brain Injury Advances

There have been many recent advances in the management of traumatic brain injury (TBI). Research regarding established and novel therapies is ongoing. Future research must not only focus on development of new strategies but determine the long-term benefits or disadvantages of current strategies. In addition, the impact of these advances on varying severities of brain injury must not be ignored. It is hoped that future research strategies in TBI will prioritize large-scale trials using common data elements to develop large registries and databases, and leverage international collaborations.