Hypothermia therapy after traumatic brain injury in children

Association of initial assessment variables and mortality in severe pediatric traumatic brain injury

Background

Predictive scales have been used to prognosticate long-term outcomes of traumatic brain injury (TBI), but gaps remain in predicting mortality using initial trauma resuscitation data. We sought to evaluate the association of clinical variables collected during the initial resuscitation of intubated pediatric severe patients with TBI with in-hospital mortality.

Methods

Intubated pediatric trauma patients <18 years with severe TBI (Glasgow coma scale (GCS) score ≤8) from January 2011 to December 2020 were included. Associations between initial trauma resuscitation variables (temperature, pulse, mean arterial blood pressure, GCS score, hemoglobin, international normalized ratio (INR), platelet count, oxygen saturation, end tidal carbon dioxide, blood glucose and pupillary response) and mortality were evaluated with multivariable logistic regression.

Results

Among 314 patients, median age was 5.5 years (interquartile range (IQR): 2.2-12.8), GCS score was 3 (IQR: 3-6), Head Abbreviated Injury Score (hAIS) was 4 (IQR: 3-5), and most had a severe (25-49) Injury Severity Score (ISS) (48.7%, 153/314). Overall mortality was 26.8%. GCS score, hAIS, ISS, INR, platelet count, and blood glucose were associated with in-hospital mortality (all p<0.05). As age and GCS score increased, the odds of mortality decreased. Each 1-point increase in GCS score was associated with a 35% decrease in odds of mortality. As hAIS, INR, and blood glucose increased, the odds of mortality increased. With each 1.0 unit increase in INR, the odds of mortality increased by 1427%.

Conclusions

Pediatric patients with severe TBI are at substantial risk for in-hospital mortality. Studies are needed to examine whether earlier interventions targeting specific parameters of INR and blood glucose impact mortality.

Numerical investigation of LDL nanoparticle collision in coronary artery grafts with porous wall and different implantation angles and two state of inlet velocity

This study aimed to reduce the risk of graft occlusion by evaluating the two-phase flow of blood and LDL nanoparticles in coronary artery grafts. The study considered blood as an incompressible Newtonian fluid, with the addition of LDL nanoparticles, and the artery wall as a porous medium. Two scenarios were compared, with constant inlet velocity (CIV) and other with pulsatile inlet velocity (PIV), with LDL nanoparticles experiencing drag, wall-induced lift, and induced Saffman lift forces, or drag force only. The study also evaluated the concentration polarization of LDLs (CP of LDLs) near the walls, by considering the artery wall with and without permeation. To model LDL nanoparticles, the study randomly injected 100, 500, and 1000 nanoparticles in three release states at each time step, using different geometries. Numerical simulations were performed using COMSOL software, and the results were presented as relative collision of nanoparticles to the walls in tables, diagrams, and shear stress contours. The study found that a graft implantation angle of 15° had the most desirable conditions compared to larger angles, in terms of nanoparticle collision with surfaces and occlusion. The nanoparticle release modes behaved similarly in terms of collision with the surfaces. A difference was observed between CIV and PIV. Saffman lift and wall-induced lift forces having no effect, possibly due to the assumption of a porous artery wall and perpendicular outlet flow. In case of permeable artery walls, relative collision of particles with the graft wall was larger, suggesting the effect of CP of LDLs.

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.

The Australian Traumatic Brain Injury Initiative: Systematic Review of the Effect of Acute Interventions on Outcome for People With Moderate-Severe Traumatic Brain Injury

The Australian Traumatic Brain Injury Initiative (AUS-TBI) is developing a data resource to enable improved outcome prediction for people with moderate-severe TBI (msTBI) across Australia. Fundamental to this resource is the collaboratively designed data dictionary. This systematic review and consultation aimed to identify acute interventions with potential to modify clinical outcomes for people after msTBI, for inclusion in a data dictionary. Standardized searches were implemented across bibliographic databases from inception through April 2022. English-language reports of randomized controlled trials (RCTs) evaluating any association between any acute intervention and clinical outcome in at least 100 patients with msTBI, were included. A predefined algorithm was used to assign a value to each observed association. Consultation with AUS-TBI clinicians and researchers formed the consensus process for interventions to be included in a single data dictionary. Searches retrieved 14,455 records, of which 124 full-length RCTs were screened, with 35 studies included. These studies evaluated 26 unique acute interventions across 21 unique clinical outcomes. Only 4 interventions were considered to have medium modifying value for any outcome from the review, with an additional 8 interventions agreed upon through the consensus process. The interventions with medium value were tranexamic acid and phenytoin, which had a positive effect on an outcome; and decompressive craniectomy surgery and hypothermia, which negatively affected outcomes. From the systematic review and consensus process, 12 interventions were identified as potential modifiers to be included in the AUS-TBI national data resource.

Effectiveness of road safety interventions: An evidence and gap map

Background

Road Traffic injuries (RTI) are among the top ten leading causes of death in the world resulting in 1.35 million deaths every year, about 93% of which occur in low- and middle-income countries (LMICs). Despite several global resolutions to reduce traffic injuries, they have continued to grow in many countries. Many high-income countries have successfully reduced RTI by using a public health approach and implementing evidence-based interventions. As many LMICs develop their highway infrastructure, adopting a similar scientific approach towards road safety is crucial. The evidence also needs to be evaluated to assess external validity because measures that have worked in high-income countries may not translate equally well to other contexts. An evidence gap map for RTI is the first step towards understanding what evidence is available, from where, and the key gaps in knowledge.

Objectives

The objective of this evidence gap map (EGM) is to identify existing evidence from all effectiveness studies and systematic reviews related to road safety interventions. In addition, the EGM identifies gaps in evidence where new primary studies and systematic reviews could add value. This will help direct future research and discussions based on systematic evidence towards the approaches and interventions which are most effective in the road safety sector. This could enable the generation of evidence for informing policy at global, regional or national levels.

Search Methods

The EGM includes systematic reviews and impact evaluations assessing the effect of interventions for RTI reported in academic databases, organization websites, and grey literature sources. The studies were searched up to December 2019.

Selection Criteria

The interventions were divided into five broad categories: (a) human factors (e.g., enforcement or road user education), (b) road design, infrastructure and traffic control, (c) legal and institutional framework, (d) post-crash pre-hospital care, and (e) vehicle factors (except car design for occupant protection) and protective devices. Included studies reported two primary outcomes: fatal crashes and non-fatal injury crashes; and four intermediate outcomes: change in use of seat belts, change in use of helmets, change in speed, and change in alcohol/drug use. Studies were excluded if they did not report injury or fatality as one of the outcomes.

Data Collection and Analysis

The EGM is presented in the form of a matrix with two primary dimensions: interventions (rows) and outcomes (columns). Additional dimensions are country income groups, region, quality level for systematic reviews, type of study design used (e.g., case-control), type of road user studied (e.g., pedestrian, cyclists), age groups, and road type. The EGM is available online where the matrix of interventions and outcomes can be filtered by one or more dimensions. The webpage includes a bibliography of the selected studies and titles and abstracts available for preview. Quality appraisal for systematic reviews was conducted using a critical appraisal tool for systematic reviews, AMSTAR 2.

Main Results

The EGM identified 1859 studies of which 322 were systematic reviews, 7 were protocol studies and 1530 were impact evaluations. Some studies included more than one intervention, outcome, study method, or study region. The studies were distributed among intervention categories as: human factors (n = 771), road design, infrastructure and traffic control (n = 661), legal and institutional framework (n = 424), post-crash pre-hospital care (n = 118) and vehicle factors and protective devices (n = 111). Fatal crashes as outcomes were reported in 1414 records and non-fatal injury crashes in 1252 records. Among the four intermediate outcomes, speed was most commonly reported (n = 298) followed by alcohol (n = 206), use of seatbelts (n = 167), and use of helmets (n = 66). Ninety-six percent of the studies were reported from high-income countries (HIC), 4.5% from upper-middle-income countries, and only 1.4% from lower-middle and low-income countries. There were 25 systematic reviews of high quality, 4 of moderate quality, and 293 of low quality.

Authors' Conclusions

The EGM shows that the distribution of available road safety evidence is skewed across the world. A vast majority of the literature is from HICs. In contrast, only a small fraction of the literature reports on the many LMICs that are fast expanding their road infrastructure, experiencing rapid changes in traffic patterns, and witnessing growth in road injuries. This bias in literature explains why many interventions that are of high importance in the context of LMICs remain poorly studied. Besides, many interventions that have been tested only in HICs may not work equally effectively in LMICs. Another important finding was that a large majority of systematic reviews are of low quality. The scarcity of evidence on many important interventions and lack of good quality evidence-synthesis have significant implications for future road safety research and practice in LMICs. The EGM presented here will help identify priority areas for researchers, while directing practitioners and policy makers towards proven interventions.

Experimental In Vitro Microfluidic Calorimetric Chip Data towards the Early Detection of Infection on Implant Surfaces

Heat flux measurement shows potential for the early detection of infectious growth. Our research is motivated by the possibility of using heat flux sensors for the early detection of infection on aortic vascular grafts by measuring the onset of bacterial growth. Applying heat flux measurement as an infectious marker on implant surfaces is yet to be experimentally explored. We have previously shown the measurement of the exponential growth curve of a bacterial population in a thermally stabilized laboratory environment. In this work, we further explore the limits of the microcalorimetric measurements via heat flux sensors in a microfluidic chip in a thermally fluctuating environment.

Advanced Thermoelectric Textiles for Power Generation: Principles, Design, and Manufacturing

Self-powered wearable thermoelectric (TE) devices significantly reduce the inconvenience caused to users, especially in daily use of portable devices and monitoring personal health. The textile-based TE devices (TETs) exhibit the excellent flexibility, deformability, and light weight, which fulfill demands of long-term wearing for the human body. In comparison to traditional TE devices with their longstanding research history, TETs are still in an initial stage of growth. In recent years, TETs to provide electricity for low-power wearable electronics have attracted increasing attention. This review summarizes the recent progress of TETs from the points of selecting TE materials, scalable fabrication methods of TE fibers/yarns and TETs, structure design of TETs and reported high-performance TETs. The key points to develop TETs with outstanding TE properties and mechanical performance and better than available optimization strategies are discussed. Furthermore, remaining challenges and perspectives of TETs are also proposed to suggest practical applications for heat harvesting from human body.

Nernst-Planck-Gaussian modelling of electrodiffusional recovery from ephaptic excitation between mammalian cardiomyocytes

Introduction: In addition to gap junction conduction, recent reports implicate possible ephaptic coupling contributions to action potential (AP) propagation between successive adjacent cardiomyocytes. Here, AP generation in an active cell, withdraws Na+ from, creating a negative potential within, ephaptic spaces between the participating membranes, activating the initially quiescent neighbouring cardiomyocyte. However, sustainable ephaptic transmission requires subsequent complete recovery of the ephaptic charge difference. We explore physical contributions of passive electrodiffusive ion exchange with the remaining extracellular space to this recovery for the first time. Materials and Methods: Computational, finite element, analysis examined limiting, temporal and spatial, ephaptic [Na+], [Cl-], and the consequent Gaussian charge differences and membrane potential recovery patterns following a ΔV∼130 mV AP upstroke at physiological (37°C) temperatures. This incorporated Nernst-Planck formalisms into equations for the time-dependent spatial concentration gradient profiles. Results: Mammalian atrial, ventricular and purkinje cardiomyocyte ephaptic junctions were modelled by closely apposed circularly symmetric membranes, specific capacitance 1 μF cm-2, experimentally reported radii a = 8,000, 12,000 and 40,000 nm respectively and ephaptic axial distance w = 20 nm. This enclosed an ephaptic space containing principal ions initially at normal extracellular [Na+] = 153.1 mM and [Cl-] = 145.8 mM, respective diffusion coefficients D Na = 1.3 × 109 and D Cl = 2 × 109 nm2s-1. Stable, concordant computational solutions were confirmed exploring ≤1,600 nm mesh sizes and Δt≤0.08 ms stepsize intervals. The corresponding membrane voltage profile changes across the initially quiescent membrane were obtainable from computed, graphically represented a and w-dependent ionic concentration differences adapting Gauss's flux theorem. Further simulations explored biological variations in ephaptic dimensions, membrane anatomy, and diffusion restrictions within the ephaptic space. Atrial, ventricular and Purkinje cardiomyocytes gave 40, 180 and 2000 ms 99.9% recovery times, with 720 or 360 ms high limits from doubling ventricular radius or halving diffusion coefficient. Varying a, and D Na and D Cl markedly affected recovery time-courses with logarithmic and double-logarithmic relationships, Varying w exerted minimal effects. Conclusion: We thereby characterise the properties of, and through comparing atrial, ventricular and purkinje recovery times with interspecies in vivo background cardiac cycle duration data, (blue whale ∼2000, human∼90, Etruscan shrew, ∼40 ms) can determine physical limits to, electrodiffusive contributions to ephaptic recovery.

Development of a Randomized Trial Comparing ICP-Monitor-Based Management of Severe Pediatric Traumatic Brain Injury to Management Based on Imaging and Clinical Examination Without ICP Monitoring-Study Protocol

BACKGROUND AND OBJECTIVES

Traumatic brain injury (TBI) is a major global public health problem. It is a leading cause of death and disability in children and adolescents worldwide. Although increased intracranial pressure (ICP) is common and associated with death and poor outcome after pediatric TBI, the efficacy of current ICP-based management remains controversial. We intend to provide Class I evidence testing the efficacy of a protocol based on current ICP monitor-based management vs care based on imaging and clinical examination without ICP monitoring in pediatric severe TBI.

METHODS

A phase III, multicenter, parallel-group, randomized superiority trial performed in intensive care units in Central and South America to determine the impact on 6-month outcome of children aged 1-12 years with severe TBI (age-appropriate Glasgow Coma Scale score ≤8) randomized to ICP-based or non-ICP-based management.

EXPECTED OUTCOMES

Primary outcome is 6-month Pediatric Quality of Life. Secondary outcomes are 3-month Pediatric Quality of Life, mortality, 3-month and 6-month Pediatric extended Glasgow Outcome Score, intensive care unit length of stay, and number of interventions focused on treating measured or suspected intracranial hypertension.

DISCUSSION

This is not a study of the value of knowing the ICP in sTBI. This research question is protocol-based. We are investigating the added value of protocolized ICP management to treatment based on imaging and clinical examination in the global population of severe pediatric TBI. Demonstrating efficacy should standardize ICP monitoring in severe pediatric TBI. Alternate results should prompt reassessment of how and in which patients ICP data should be applied in neurotrauma care.

Pediatric disorders of consciousness: Considerations, controversies, and caveats

Pediatric disorders of consciousness (PedDOC) encompass conditions that may occur following very severe traumatic or other forms of acquired brain injury sustained during childhood. As in adults, PedDOC is described as a disturbance of awareness and/or responsiveness. PedDOC is a complex condition that requires specialized care, infrastructures, and technologies. PedDOC poses many challenges to healthcare providers and caregivers during recovery and throughout development. In this commentary, we intend to highlight some considerations, controversies, and caveats on the diagnosis, prognosis and treatment of PedDOC.

Ginkgolide B promotes spontaneous recovery and enhances endogenous netrin-1 after neonatal hypoxic-ischemic brain damage

OBJECTIVES

Perinatal hypoxic-ischemic encephalopathy (HIE) is a condition that can lead to long-term cognitive, motor, and behavioral impairments in newborns. Although brain hypothermia therapy is currently the standard treatment for HIE, it does not provide complete neuroprotection. As a result, there is a need to explore additional therapies to enhance treatment outcomes. This study aims to investigate the potential role of Ginkgolide B (GB) in promoting neuroplasticity and facilitating spontaneous recovery after HIE.

METHODS

In this study, we employed a neonatal rat model of HIE to investigate the effects of GB on spontaneous recovery. GB treatment was initiated 24 h after hypoxia and administered continuously for a duration of 14 days. We evaluated several outcome measures after the treatment period, including spontaneous behavioral recovery and brain repair. Additionally, we quantified the levels of netrin-1 in both plasma and the peri-ischemic zone after the occurrence of HIE.

RESULTS

We found that GB treatment significantly facilitated spontaneous behavioral recovery in the HIE pups. Furthermore, cognitive function was restored, and brain tissue repair had a noticeable acceleration. We observed increased cell proliferation in the subventricular, stratum, and subgranular zones. Of particular interest, we observed elevated levels of netrin-1 in both plasma and the ischemic penumbra following GB treatment.

CONCLUSION

Our findings suggest that GB promotes neuroplasticity and enhances spontaneous recovery in newborns affected by HIE. The observed upregulation of netrin-1 may be crucial in mediating these effects. These results highlight the promising potential of GB as a post-HIE therapy, particularly in enhancing spontaneous recovery and improving long-term outcomes.

Overview of Hypothermia, Its Role in Neuroprotection, and the Application of Prophylactic Hypothermia in Traumatic Brain Injury

The current standard of practice is to maintain normothermia in traumatic brain injury (TBI) patients despite the theoretical benefits of hypothermia and numerous animal studies with promising results. While targeted temperature management or induced hypothermia to support neurological function is recommended for a select patient population postcardiac arrest, similar guidelines have not been instituted for TBI. In this review, we will examine the pathophysiology of TBI and discuss the benefits and risks of induced hypothermia in this patient population. In addition, we provide an overview of the largest randomized controlled trials testing-induced hypothermia. Our literature review on hypothermia returned a myriad of studies and trials, many of which have inconclusive results. The aim of this review was to recognize the effects of hypothermia, summarize the latest trials, address the inconsistencies, and discuss future directions for the study of hypothermia in TBI.

Noninvasive and Continuous Monitoring of the Core Body Temperature through the Quantitative Measurement of Blood Perfusion Rate

Core body temperature (CBT) is one of the four vital signs that must be monitored continuously. The continuous recording of CBT is possible through invasive methods by inserting a temperature probe into specific body sites. We report a novel method to monitor CBT through the quantitative measurement of skin blood perfusion rate (ωb,skin). By monitoring the skin temperature, heat flux, and ωb,skin, the arterial blood temperature, equivalent to CBT, can be extracted. ωb,skin is quantitatively evaluated thermally via sinusoidal heating with regulated thermal penetration depth so that the blood perfusion rate is acquired only in the skin. Its quantification is significant because it indicates various physiological events including hyper- or hypothermia, tissue death, and delineation of tumors. A subject showed promising results with steady values of ωb,skin and CBT of 5.2 ± 1.05 × 10-4 s-1 and 36.51 ± 0.23 °C, respectively. For periods where the subject's actual CBT (axillary temperature) did not fall within the estimated range, the average deviation from the actual CBT was only 0.07 °C. This study aims to develop a competent methodology capable of continuously monitoring the CBT and blood perfusion rate at a distant location from the core body region for the diagnosis of a patient's health condition with wearable devices.

Timing of therapeutic interventions against infection-triggered encephalopathy syndrome: a scoping review of the pediatric literature

Our goal was to conduct a scoping review of the literature on the treatment of infection-triggered encephalopathy syndrome/acute encephalopathy in children, focusing on treatment targets and treatment initiation timing. We performed literature searches using PubMed for articles reporting treatments of infection-triggered encephalopathy syndrome/acute encephalopathy. We included articles describing specific treatments for acute encephalopathy with control groups. For the purpose of searching new therapies only experimentally tried in the case series, we also included case series studies without control groups in this review, if the studies contained at least two cases with clear treatment goals. Therapies were classified based on their mechanisms of action into brain protection therapy, immunotherapy, and other therapies. We operationally categorized the timing of treatment initiation as T1 (6-12 h), T2 (12-24 h), T3 (24-48 h), and T4 (>48 h) after the onset of seizures and/or impaired consciousness. Thirty articles were included in this review; no randomized control study was found. Eleven retrospective/historical cohort studies and five case-control studies included control groups with or without specific therapies or outcomes. The targeted conditions and treatment timing varied widely across studies. However, the following three points were suggested to be effective in multiple studies: (1) Careful seizure management and targeted temperature management within 12 h (T1) of onset of febrile seizure/prolonged impaired consciousness without multiple organ failure may reduce the development of acute encephalopathy with biphasic seizures and late reduced diffusion; (2) immunotherapy using corticosteroids, tocilizumab, or plasma exchange within 24 h (T1-T2) of onset of acute necrotizing encephalopathy may reduce sequelae; and (3) anakinra therapy and ketogenic diet demonstrate little evidence of neurologic sequelae reduction, but may reduce seizure frequency and allow for weaning from barbiturates, even when administered weeks (T4) after onset in children with febrile infection-related epilepsy syndrome. Although available studies have no solid evidence in the treatment of infection-triggered encephalopathy syndrome/acute encephalopathy, this scoping review lays the groundwork for future prospective clinical trials.

Performance of a Provider-Assigned Functional Outcome Score in Critically Ill Children

OBJECTIVES

Determine agreement between Pediatric Cerebral Performance Category (PCPC) scores integrated into clinical workflow and traditional investigator-assigned scores.

DESIGN

Longitudinal study.

SETTING

A single-center quaternary-care academic institution.

SUBJECTS

Children admitted to the PICU between November 2019 and April 2020.

INTERVENTIONS

Providers assigned PCPC scores as part of daily workflow. Investigators assigned scores using retrospective chart review.

MEASUREMENTS AND MAIN RESULTS

Of 803 patients admitted to the PICU, 782 survived and were included. Admission and discharge scores were recorded in 95% and 90% of patients, respectively. Agreement between provider- and investigator-assigned scores was excellent, with a weighted kappa of 0.87 (95% CI, 0.84-0.90) and 0.80 (95% CI, 0.76-0.84) for admission and discharge.

CONCLUSIONS

Provider-assigned PCPC scores, documented as standard of care, are largely concordant with retrospective investigator-assigned scores. Measurement of cognitive functional status can be successfully integrated into daily provider workflow for use in the clinical, quality improvement, and research arenas.

Cold temperature extends longevity and prevents disease-related protein aggregation through PA28γ-induced proteasomes

Aging is a primary risk factor for neurodegenerative disorders that involve protein aggregation. Because lowering body temperature is one of the most effective mechanisms to extend longevity in both poikilotherms and homeotherms, a better understanding of cold-induced changes can lead to converging modifiers of pathological protein aggregation. Here, we find that cold temperature (15 °C) selectively induces the trypsin-like activity of the proteasome in Caenorhabditis elegans through PSME-3, the worm orthologue of human PA28γ/PSME3. This proteasome activator is required for cold-induced longevity and ameliorates age-related deficits in protein degradation. Moreover, cold-induced PA28γ/PSME-3 diminishes protein aggregation in C. elegans models of age-related diseases such as Huntington's and amyotrophic lateral sclerosis. Notably, exposure of human cells to moderate cold temperature (36 °C) also activates trypsin-like activity through PA28γ/PSME3, reducing disease-related protein aggregation and neurodegeneration. Together, our findings reveal a beneficial role of cold temperature that crosses evolutionary boundaries with potential implications for multi-disease prevention.

Assent in Pediatric Critical Care Research: A Cross-Sectional Stakeholder Survey of Canadian Research Ethics Boards, Research Coordinators, Pediatric Critical Care Researchers, and Nurses

OBJECTIVES

Survey of four stakeholder groups involved in defining and obtaining assent for research in Canadian PICUs to better understand their perspectives and perceived barriers to assent.

DESIGN

Cross-sectional survey.

SETTING

Fourteen tertiary-care pediatric hospitals in Canada.

PARTICIPANTS

Research Ethics Board Chairs, pediatric critical care nurses, research coordinators, and researchers.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

A total of 193 participants responded. Thirty-seven percent (59/159) thought it was "Never/Almost Never" (59/159, 37%) feasible to obtain assent during the first 48 hours of PICU admission, and 112 of 170 (66%) indicated there are unique barriers to assent at the time of enrollment in PICU studies. Asking children for assent was most frequently rated as Important/Very Important for interviews/focus groups with the child (138/180, 77%), blood sample collection with a needle poke for research (137/178, 77%), and studies involving genetic testing with results communicated to the child/legal guardian (134/180, 74%). In two scenarios where a child and legal guardian disagreed about study participation, most respondents indicated that whether the child should still be enrolled would depend on the patient's age (34-36%), and/or the risk of the study (24-28%). There was a lack of consensus over how the assent process should be operationalized, and when and for how long children should be followed to seek assent for ongoing study participation. Most stakeholders (117/158, 74%) thought that children should have the opportunity to decide if their samples could stay in a biobank once they are old enough to do so.

CONCLUSIONS

There was an overall lack of consensus on the feasibility of, and challenges associated with, obtaining assent at the time of study enrollment and on how key aspects of the assent process should be operationalized in the PICU. This highlights the need for guidelines to clarify the assent process in pediatric critical care research.

Understanding microglial responses in large animal models of traumatic brain injury: an underutilized resource for preclinical and translational research

Traumatic brain injury (TBI) often results in prolonged or permanent brain dysfunction with over 2.8 million affected annually in the U.S., including over 56,000 deaths, with over 5 million total survivors exhibiting chronic deficits. Mild TBI (also known as concussion) accounts for over 75% of all TBIs every year. Mild TBI is a heterogeneous disorder, and long-term outcomes are dependent on the type and severity of the initial physical event and compounded by secondary pathophysiological consequences, such as reactive astrocytosis, edema, hypoxia, excitotoxicity, and neuroinflammation. Neuroinflammation has gained increasing attention for its role in secondary injury as inflammatory pathways can have both detrimental and beneficial roles. For example, microglia-resident immune cells of the central nervous system (CNS)-influence cell death pathways and may contribute to progressive neurodegeneration but also aid in debris clearance and neuroplasticity. In this review, we will discuss the acute and chronic role of microglia after mild TBI, including critical protective responses, deleterious effects, and how these processes vary over time. These descriptions are contextualized based on interspecies variation, sex differences, and prospects for therapy. We also highlight recent work from our lab that was the first to describe microglial responses out to chronic timepoints after diffuse mild TBI in a clinically relevant large animal model. The scaled head rotational acceleration of our large animal model, paired with the gyrencephalic architecture and appropriate white:gray matter ratio, allows us to produce pathology with the same anatomical patterns and distribution of human TBI, and serves as an exemplary model to examine complex neuroimmune response post-TBI. An improved understanding of microglial influences in TBI could aid in the development of targeted therapeutics to accentuate positive effects while attenuating detrimental post-injury responses over time.

Blood proteome of acute intracranial hemorrhage in infant victims of abusive head trauma

Abusive head trauma (AHT) is a leading cause of mortality and morbidity in infants. While the reported incidence is close to 40 cases per 100'000 births/year, misdiagnoses are commonly observed in cases with atypical, subacute, or chronic presentation. Currently, standard clinical evaluation of inflicted intracranial hemorrhagic injury (ICH) in infants urgently requires a screening test able to identify infants who need additional investigations. Blood biomarkers characteristic of AHT may assist in detecting these infants, improving prognosis through early medical care. To date, the application of innovative omics technologies in retrospective studies of AHT in infants is rare, due also to the blood serum and cerebrospinal fluid of AHT cases being scarce and not systematically accessible. Here, we explored the circulating blood proteomes of infants with severe AHT and their atraumatic controls. We discovered 165 circulating serum proteins that display differential changes in AHT cases compared with atraumatic controls. The peripheral blood proteomes of pediatric AHT commonly reflect: (i) potentially secreted proteome from injured brain, and (ii) proteome dysregulated in the system's circulation by successive biological events following acute ICH. This study opens up a novel opportunity for research efforts in clinical screening of AHT cases.

Targeted Temperature Management in Pediatric Traumatic Brain Injury: A Systematic Review and Network Meta-Analysis

BACKGROUND

The efficacy of targeted temperature management, including the appropriate length of time, in pediatric traumatic brain injury is inconclusive. We aimed to compare the efficacy of normothermia and therapeutic hypothermia administered for various durations.

METHODS

We searched four databases without language limitations until December 2021 and included peer-reviewed published randomized controlled trials comparing normothermia (>35.1°C) with therapeutic hypothermia (32°C -35°C) in children aged <18 years with an acute closed severe head injury (Glasgow Coma Scale < 8) requiring hospitalization. A favorable neurological outcome was the primary outcome; secondary outcomes were mortality and arrhythmia. Two reviewers performed screening, extracted data, and assessed the risk of bias. Network meta-analysis was performed using the Grading of Recommendations, Assessment, Development, and Evaluation working group approach.

RESULTS

We included six trials comprising 448 children. No significant difference was observed in favorable neurological outcomes between normothermia and hypothermia at 24, 48, and 72 h (relative risk, 1.05 [95% confidence interval 0.72-1.54]); 1.14 [0.82-1.57]), and 1.19 [0.77-1.85], respectively). Mortality did not differ significantly between normothermia and hypothermia at 24, 48, and 72 hours (0.56 [0.06-5.44]), (0.63 [0.12-3.36]), and 0.90 [0.10-8.18], respectively). Arrhythmias did not differ significantly between normothermia and hypothermia at 24, 48, and 72 h (0.92 [0.01-14.58], 0.36 [0.09-1.45), and 0.95 [0.03-29.92], respectively).

CONCLUSION

No conclusive evidence was found on optimal temperature management for pediatric traumatic brain injury. A large randomized controlled trial that considers the temperature control enforcement duration is required.

3D bioprinting of emulating homeostasis regulation for regenerative medicine applications

Homeostasis is the most fundamental mechanism of physiological processes, occurring simultaneously as the production and outcomes of pathological procedures. Accompanied by manufacture and maturation of intricate and highly hierarchical architecture obtained from 3D bioprinting (three-dimension bioprinting), homeostasis has substantially determined the quality of printed tissues and organs. Instead of only shape imitation that has been the remarkable advances, fabrication for functionality to make artificial tissues and organs that act as real ones in vivo has been accepted as the optimized strategy in 3D bioprinting for the next several years. Herein, this review aims to provide not only an overview of 3D bioprinting, but also the main strategies used for homeostasis bioprinting. This paper briefly introduces the principles of 3D bioprinting system applied in homeostasis regulations firstly, and then summarizes the specific strategies and potential trend of homeostasis regulations using multiple types of stimuli-response biomaterials to maintain auto regulation, specifically displaying a brilliant prospect in hormone regulation of homeostasis with the most recently outbreak of vasculature fabrication. Finally, we discuss challenges and future prospects of homeostasis fabrication based on 3D bioprinting in regenerative medicine, hoping to further inspire the development of functional fabrication in 3D bioprinting.

Recombinant human erythropoietin induces neuroprotection, activates MAPK/CREB pathway, and rescues fear memory after traumatic brain injury with delayed hypoxemia in mice

Therapeutic interventions targeting secondary insults, such as delayed hypoxemia, provide a unique opportunity for treatment in severe traumatic brain injury (TBI). Erythropoietin (EPO) is a hypoxia-responsive cytokine with important roles in neurodevelopment, neuroprotection and neuromodulation. We hypothesized that recombinant human erythropoietin (rhEPO) administration would mitigate injury in a combined injury model of TBI and delayed hypoxemia. Utilizing a clinically relevant murine model of TBI and delayed hypoxemia, we characterized how ongoing rhEPO administration influenced neurogenesis, neuroprotection, synaptic density and, behavioral outcomes early after TBI, and the impact on long-lasting outcomes 6 months after injury. We employed novel object recognition (NOR) and fear conditioning to assess long-term memory. At 1-month post-injury, we observed a significant increase in cued-fear memory response in the rhEPO-injured mice compared with vehicle-injured mice. This was associated with neuroprotection and neurogenesis in the hippocampus and mitogen-activated protein kinase (MAPK)/cAMP response element-binding protein (CREB) signaling activation and increased of excitatory synaptic density in the amygdala. Early rhEPO treatment after injury reduced neurodegeneration and increased excitatory synaptic density in the hippocampus and amygdala at 6 months post-injury. However at 6 months post-injury (4 months after discontinuation of rhEPO), we did not observe changes in behavioral assessments nor MAPK/CREB pathway activation. In summary, these data demonstrate that ongoing rhEPO treatment initiated at a clinically feasible time point improves neurological, cognitive, and histological outcomes after TBI in the setting of secondary hypoxemic insults.

Online closed-loop real-time tES-fMRI for brain modulation: A technical report

Recent studies suggest that transcranial electrical stimulation (tES) can be performed during functional magnetic resonance imaging (fMRI). The novel approach of using concurrent tES-fMRI to modulate and measure targeted brain activity/connectivity may provide unique insights into the causal interactions between the brain neural responses and psychiatric/neurologic signs and symptoms, and importantly, guide the development of new treatments. However, tES stimulation parameters to optimally influence the underlying brain activity may vary with respect to phase difference, frequency, intensity, and electrode's montage among individuals. Here, we propose a protocol for closed-loop tES-fMRI to optimize the frequency and phase difference of alternating current stimulation (tACS) for two nodes (frontal and parietal regions) in individual participants. We carefully considered the challenges in an online optimization of tES parameters with concurrent fMRI, specifically in its safety, artifact in fMRI image quality, online evaluation of the tES effect, and parameter optimization method, and we designed the protocol to run an effective study to enhance frontoparietal connectivity and working memory performance with the optimized tACS using closed-loop tES-fMRI. We provide technical details of the protocol, including electrode types, electrolytes, electrode montages, concurrent tES-fMRI hardware, online fMRI processing pipelines, and the optimization algorithm. We confirmed the implementation of this protocol worked successfully with a pilot experiment.

Mucosa-interfacing electronics

The surface mucosa that lines many of our organs houses myriad biometric signals and, therefore, has great potential as a sensor-tissue interface for high-fidelity and long-term biosensing. However, progress is still nascent for mucosa-interfacing electronics owing to challenges with establishing robust sensor-tissue interfaces; device localization, retention and removal; and power and data transfer. This is in sharp contrast to the rapidly advancing field of skin-interfacing electronics, which are replacing traditional hospital visits with minimally invasive, real-time, continuous and untethered biosensing. This Review aims to bridge the gap between skin-interfacing electronics and mucosa-interfacing electronics systems through a comparison of the properties and functions of the skin and internal mucosal surfaces. The major physiological signals accessible through mucosa-lined organs are surveyed and design considerations for the next generation of mucosa-interfacing electronics are outlined based on state-of-the-art developments in bio-integrated electronics. With this Review, we aim to inspire hardware solutions that can serve as a foundation for developing personalized biosensing from the mucosa, a relatively uncharted field with great scientific and clinical potential.

Effect of Hypothermia Therapy on Children with Traumatic Brain Injury: A Meta-Analysis of Randomized Controlled Trials

Hypothermia therapy is a promising therapeutic strategy for traumatic brain injury (TBI); however, some trials have shown that hypothermia therapy has a negative effect on patients with TBI. The treatment of hypothermia in children with TBI remains controversial. We conducted a search of six online databases to validate the literature on comparing hypothermia with normal therapy for children with TBI. Eight randomized controlled trials (514 patients) were included. The meta-analysis indicated that hypothermia therapy may increase the Glasgow Outcome Scale (GOS) scores. However, in terms of improving the rate of complications, intracranial pressure (ICP), mortality, cerebral perfusion pressure (CPP), and length of stay both in hospital as well as pediatric ICU, the difference was not statistically significant. Hypothermia therapy may have clinical advantages in improving the GOS scores in children with TBI compared with normothermic therapy, but hypothermia therapy may have no benefit in improving the incidence of complications, ICP, mortality, CPP, and length of stay both in pediatric ICU as well as hospital. The decision to implement hypothermia therapy for children with TBI depends on the advantages and disadvantages from many aspects and these must be considered comprehensively.

Magnetic Resonance Imaging Findings in Infants with Severe Traumatic Brain Injury and Associations with Abusive Head Trauma

Young children with severe traumatic brain injury (TBI) have frequently been excluded from studies due to age and/or mechanism of injury. Magnetic resonance imaging (MRI) is now frequently being utilized to detect parenchymal injuries and early cerebral edema. We sought to assess MRI findings in infants with severe TBI, and to determine the association between specific MRI findings and mechanisms of injury, including abusive head trauma (AHT). MRI scans performed within the first 30 days after injury were collected and coded according to NIH/NINDS Common Data Elements (CDEs) for Neuroimaging in subjects age < 2 years old with severe TBI enrolled in the Approaches and Decisions in Acute Pediatric Traumatic Brain Injury Trial. Demographics and injury characteristics were analyzed. A total of 81 children were included from ADAPT sites with MRI scans. Median age was 0.77 years and 57% were male. Most common MRI finding was ischemia, present in 57/81 subjects (70%), in a median of 7 brain regions per subject. Contusion 46/81 (57%) and diffuse axonal injury (DAI) 36/81 (44.4%) subjects followed. Children were dichotomized based on likelihood of AHT with 43/81 subjects classified as AHT. Ischemia was found to be significantly associated with AHT (p = 0.001) and “inflicted” injury mechanism (p = 0.0003). In conclusion, the most common intracerebral injury seen on MRI of infants with severe TBI was ischemia, followed by contusion and DAI. Ischemia was associated with AHT, and ischemia affecting > 4 brain regions was predictive of AHT.

Next-generation time of death estimation: combining surrogate model-based parameter optimization and numerical thermodynamics

The postmortem interval (PMI), i.e. the time since death, plays a key role in forensic investigations, as it aids in the reconstruction of the timeline of events. Currently, the standard method for PMI estimation empirically correlates rectal temperatures and PMIs, frequently necessitating subjective correction factors. To address this shortcoming, numerical thermodynamic algorithms have recently been developed, providing rigorous methods to simulate postmortem body temperatures. Comparing these with measured body temperatures then allows non-subjective PMI determination. This approach, however, hinges on knowledge of two thermodynamic input parameters, which are often irretrievable in forensic practice: the ambient temperature prior to discovery of the body and the body temperature at the time of death (perimortem). Here, we overcome this critical limitation by combining numerical thermodynamic modelling with surrogate model-based parameter optimization. This hybrid computational framework predicts the two unknown parameters directly from the measured postmortem body temperatures. Moreover, by substantially reducing computation times (compared with conventional optimization algorithms), this powerful approach is uniquely suited for use directly at the crime scene. Crucially, we validated this method on deceased human bodies and achieved the lowest PMI estimation errors to date (0.18 h ± 0.77 h). Together, these aspects fundamentally expand the applicability of numerical thermodynamic PMI estimation.

Systematic Endotracheal Aspiration in the Pediatric Intensive Care Unit Reduces Broad-spectrum Antibiotic Use for Ventilator-associated Pneumonia

AIM

To determine the impact of a systematic endotracheal aspiration (ETA) sampling program for mechanically ventilated patients on initial antibiotic therapy for ventilator-acquired pneumonia (VAP).

DESIGN

Retrospective cohort study; before-after study design.

SETTING

Pediatric intensive care unit (PICU) with 16 medical and surgical beds in a tertiary teaching hospital.

SUBJECTS

Patients <16 years of age hospitalized in the PICU who fulfilled VAP criteria.

INTERVENTION

Biweekly systematic ETA sampling was conducted in mechanically ventilated patients.

MEASUREMENTS

We retrospectively studied patients who received antibiotic therapy for suspected VAP 12 months before and after the initiation of systematic ETA (periods 1 and 2, respectively), evaluating the initial antibiotic therapy spectrum in both periods.

RESULTS

During period 1, 56 patients developed VAP and 47 developed VAP during period 2. The incidence was 17 cases of VAP/1000 days of mechanical ventilation in both periods. Ideal antibiotic therapy was prescribed in 19.6% of cases for period 1 and 55.2% for period 2 (P = 0.001). Initial antibiotic therapy for VAP during period 2 had a significantly lower proportion of broad-spectrum antibiotics than therapy during period 1 (P = 0.01).

CONCLUSION

In our PICU, knowledge of bronchial colonization reduced initial broad-spectrum antibiotic use for VAP.

Management of Severe Traumatic Brain Injury in Pediatric Patients

The optimal management of severe traumatic brain injury (TBI) in the pediatric population has not been well studied. There are a limited number of research articles studying the management of TBI in children. Given the prevalence of severe TBI in the pediatric population, it is crucial to develop a reference TBI management plan for this vulnerable population. In this review, we seek to delineate the differences between severe TBI management in adults and children. Additionally, we also discuss the known molecular pathogenesis of TBI. A better understanding of the pathophysiology of TBI will inform clinical management and development of therapeutics. Finally, we propose a clinical algorithm for the management and treatment of severe TBI in children using published data.

Effects of therapeutic hypothermia on the safety of children with severe traumatic brain injury: a systematic review and meta-analysis

BACKGROUND

Therapeutic hypothermia (TH) is effective to treat adult traumatic brain injury (TBI), but there is still controversy about its safety to treat the children with severe TBI.

METHODS

Clinical studies on TH in children with severe TBI from January 2000 to September 2020 were screened in PubMed, Web of Science, Embase, Cochrane Library, Nature, NCKI, and Wanfang online databases. Data were meta-analyzed by Rev Man 5.3. Differences in mortality, adverse outcomes, duration of Pediatric Intensive Care Unit (PICU), incidence of infection, and incidence of arrhythmia were compared between experimental group and control group. The heterogeneity of the results was evaluated by chi-square test and I² test in Rev Man 5.3, and publication bias was evaluated by funnel plot.

RESULTS

Five articles were included, including 421 children. Cochrane evaluation was B grade or above, and Jadad scale score was over three points. The overall mortality between two groups showed great difference [odds ratio (OR) =1.72, 95% CI: 0.98-3.02, Z=1.87, P=0.04]. The incidence of adverse outcomes (OR =1.39, 95% CI: 0.86-2.25, Z=1.34, P=0.18), the duration of PICU [mean difference (MD) =0.51, 95% CI: -0.33 to 1.35, Z=1.19, P=0.24], the incidence of infection (OR =0.79, 95% CI: 0.51-1.23, Z=1.03, P=0.30), and the incidence of arrhythmia (OR =3.10, 95% CI: 0.77-12.50, Z=1.59, P=0.11) were not considerably different.

DISCUSSION

TH significantly reduced overall mortality in children with severe TBI, but did not significantly improve the incidence of adverse outcomes, PICU duration, infection rate, or arrhythmia. These results provided a reference for selecting proper clinical treatment methods for children with severe TBI.

Comparison of Intracranial Pressure Measurements Before and After Hypertonic Saline or Mannitol Treatment in Children With Severe Traumatic Brain Injury

IMPORTANCE

Hyperosmolar agents are cornerstone therapies for pediatric severe traumatic brain injury. Guideline recommendations for 3% hypertonic saline (HTS) are based on limited numbers of patients, and no study to date has supported a recommendation for mannitol.

OBJECTIVES

To characterize current use of hyperosmolar agents in pediatric severe traumatic brain injury and assess whether HTS or mannitol is associated with greater decreases in intracranial pressure (ICP) and/or increases in cerebral perfusion pressure (CPP).

DESIGN, SETTING, AND PARTICIPANTS

In this comparative effectiveness research study, 1018 children were screened and 18 were excluded; 787 children received some form of hyperosmolar therapy during the ICP-directed phase of care, with 521 receiving a bolus. Three of these children were excluded because they had received only bolus administration of both HTS and mannitol in the same hour, leaving 518 children (at 44 clinical sites in 8 countries) for analysis. The study was conducted from February 1, 2014, to September 31, 2017, with follow-up for 1 week after injury. Final analysis was performed July 20, 2021.

INTERVENTIONS

Boluses of HTS and mannitol were administered.

MAIN OUTCOMES AND MEASURES

Data on ICP and CPP were collected before and after medication administration. Statistical methods included linear mixed models and corrections for potential confounding variables to compare the 2 treatments.

RESULTS

A total of 518 children (mean [SD] age, 7.6 [5.4] years; 336 [64.9%] male; 274 [52.9%] White) were included. Participants' mean (SD) Glasgow Coma Scale score was 5.2 (1.8). Bolus HTS was observed to decrease ICP and increase CPP (mean [SD] ICP, 1.03 [6.77] mm Hg; P < .001; mean [SD] CPP, 1.25 [12.47] mm Hg; P < .001), whereas mannitol was observed to increase CPP (mean [SD] CPP, 1.20 [11.43] mm Hg; P = .009). In the primary outcome, HTS was associated with a greater reduction in ICP compared with mannitol (unadjusted β, -0.85; 95% CI, -1.53 to -0.19), but no association was seen after adjustments (adjusted β, -0.53; 95% CI, -1.32 to 0.25; P = .18). No differences in CPP were observed. When ICP was greater than 20 mm Hg, greater than 25 mm Hg, or greater than 30 mm Hg, HTS outperformed mannitol for each threshold in observed ICP reduction (>20 mm Hg: unadjusted β, -2.51; 95% CI, -3.86 to -1.15, P < .001; >25 mm Hg: unadjusted β, -3.88; 95% CI, -5.69 to -2.06, P < .001; >30 mm Hg: unadjusted β, -4.07; 95% CI, -6.35 to -1.79, P < .001), with results remaining significant for ICP greater than 25 mm Hg in adjusted analysis.

CONCLUSIONS AND RELEVANCE

In this comparative effectiveness research study, bolus HTS was associated with lower ICP and higher CPP, whereas mannitol was associated only with higher CPP. After adjustment for confounders, both therapies showed no association with ICP and CPP. During ICP crises, HTS was associated with better performance than mannitol.

Acute minocycline administration reduces brain injury and improves long-term functional outcomes after delayed hypoxemia following traumatic brain injury

Clinical trials of therapeutics for traumatic brain injury (TBI) demonstrating preclinical efficacy for TBI have failed to replicate these results in humans, in part due to the absence of clinically feasible therapeutic windows for administration. Minocycline, an inhibitor of microglial activation, has been shown to be neuroprotective when administered early after experimental TBI but detrimental when administered chronically to human TBI survivors. Rather than focusing on the rescue of primary injury with early administration of therapeutics which may not be clinically feasible, we hypothesized that minocycline administered at a clinically feasible time point (24 h after injury) would be neuroprotective in a model of TBI plus delayed hypoxemia. We first explored several different regimens of minocycline dosing with the initial dose 24 h after injury and 2 h prior to hypoxemia, utilizing short-term neuropathology to select the most promising candidate. We found that a short course of minocycline reduced acute microglial activation, monocyte infiltration and hippocampal neuronal loss at 1 week post injury. We then conducted a preclinical trial to assess the long-term efficacy of a short course of minocycline finding reductions in hippocampal neurodegeneration and synapse loss, preservation of white matter myelination, and improvements in fear memory performance at 6 months after injury. Timing in relation to injury and duration of minocycline treatment and its impact on neuroinflammatory response may be responsible for extensive neuroprotection observed in our studies.

Novel Bacteriophages Show Activity against Selected Australian Clinical Strains of Pseudomonas aeruginosa

Multi-drug resistant (MDR) clinical strains of Pseudomonas aeruginosa are the most prevalent bacteria in the lungs of patients with cystic fibrosis (CF) and burn wounds and among the most common in immunocompromised hospital patients in Australia. There are currently no promising antibiotics in the pipeline being developed against these strains. Phage therapy, which uses viruses known as bacteriophages to infect and kill pathogenic bacteria, could be a possible alternative treatment. To this end, we isolated and characterised four novel phages against Australian clinical strains of P. aeruginosa isolated from patients with cystic fibrosis, from infected blood and joint aspirate in Southeast Queensland, Australia. Activated sludge was enriched for phages using the clinical strains, and four bacteriophages were isolated. The phages were able to cause lysis in a further three identified clinical isolates. Morphology showed that they were all tailed phages (of the order Caudovirales), two belonging to the family Myoviridae and the others assigned to the Podoviridae and Siphoviridae. Their genomes were sequenced to reveal a doubled stranded DNA topology with genome sizes ranging from 42 kb to 65 kb. In isolating and characterising these novel phages, we directed our efforts toward the development and use of these phages as candidates for phage therapy as an alternative strategy for the management or elimination of these pathogenic strains. Here we describe novel phage candidates for potential therapeutic treatment of MDR Australian clinical isolates of P. aeruginosa.

Blood-Brain Barrier Mechanisms in Stroke and Trauma

The brain microenvironment is tightly regulated. The blood-brain barrier (BBB), which is composed of cerebral endothelial cells, astrocytes, and pericytes, plays an important role in maintaining the brain homeostasis by regulating the transport of both beneficial and detrimental substances between circulating blood and brain parenchyma. After brain injury and disease, BBB tightness becomes dysregulated, thus leading to inflammation and secondary brain damage. In this chapter, we overview the fundamental mechanisms of BBB damage and repair after stroke and traumatic brain injury (TBI). Understanding these mechanisms may lead to therapeutic opportunities for brain injury.

Consent models in Canadian critical care randomized controlled trials: a scoping review

PURPOSE

Our primary objective was to describe consent models used in Canadian-led adult and pediatric intensive care unit (ICU/PICU) randomized controlled trials (RCTs). Our secondary objectives were to determine the consent rate of ICU/PICU RCTs that did and did not use an alternate consent model to describe consent procedures.

SOURCE

Using scoping review methodology, we searched MEDLINE, Embase, and CENTRAL databases (from 1998 to June 2019) for trials published in English or French. We included Canadian-led RCTs that reported on the effects of an intervention on ICU/PICU patients or their families. Two independent reviewers assessed eligibility, abstracted data, and achieved consensus.

PRINCIPAL FINDINGS

We identified 48 RCTs of 17,558 patients. Included RCTs had ethics approval to use prior informed consent (43/48; 90%), deferred consent (13/48; 27%), waived consent (5/48; 10%), and verbal consent (1/48; 2%) models. Fifteen RCTs (15/48; 31%) had ethics approval to use more than one consent model. Twice as many trials used alternate consent between 2010 and 2019 (13/19) than between 2000 and 2009 (6/19). The consent rate for RCTs using only prior informed consent ranged from 54 to 91% (ICU) and 43 to 94% (PICU) and from 78 to 100% (ICU) and 74 to 87% (PICU) in trials using an alternate/hybrid consent model.

CONCLUSION

Alternate consent models were used in the minority of Canadian-led ICU/PICU RCTs but have been used more frequently over the last decade. This suggests that Canadian ethics boards and research communities are becoming more accepting of alternate consent models in ICU/PICU trials.

Understanding the cross-talk between mediators of infertility and COVID-19

COVID-19 is the ongoing health emergency affecting individuals of all ages around the globe. Initially, the infection was reported to affect pulmonary structures. However, recent studies have delineated the impacts of COVID-19 on the reproductive system of both men and women. Hence, the present review aims to shed light on the distribution of SARS-CoV-2 entry factors in various reproductive organs. In addition, impacts of COVID-19 mediators like disrupted renin angiotensin system, oxidative stress, cytokine storm, fever, and the mental stress on reproductive physiology have also been discussed. For the present study, various keywords were used to search literature on PubMed, ScienceDirect, and Google Scholar databases. Articles were screened for relevancy and were studied in detail for qualitative synthesis of the review. Through our literature review, we found a multitude of effects of COVID-19 mediators on reproductive systems. Studies reported expression of receptors like ACE-2, TMPRSS2, and CD147 in the testes, epididymis, prostrate, seminal vesicles, and ovarian follicles. These proteins are known to serve as major SARS-CoV-2 entry factors. The expression of lysosomal cathepsins (CTSB/CTSL) and/ neuropilin-1 (NRP-1) are also evident in the testes, epididymis, seminal vesicles, fallopian tube, cervix, and endometrium. The binding of viral spike protein with ACE-2 was found to alter the renin-angiotensin cascade, which could invite additional infertility problems. Furthermore, COVID-19 mediated cytokine storm, oxidative stress, and elevated body temperature could be detrimental to gametogenesis, steroidogenesis, and reproductive cycles in patients. Finally, social isolation, confinement, and job insecurities have fueled mental stress and frustration that might promote glucocorticoid-mediated subnormal sperm quality in men and higher risk of miscarriage in women. Hence, the influence of COVID-19 on the alteration of reproductive health and fertility is quite apparent.

Serum biomarkers in severe paediatric traumatic brain injury-a narrative review

Severe traumatic brain injury continues to present complex management and prediction challenges for the clinician. While there is some evidence that better systems of care can improve outcome, multiple multi-centre randomised controlled trials of specific therapies have consistently failed to show benefit. In addition, clinicians are challenged in attempting to accurately predict which children will recover well and which children will have severe and persisting neurocognitive deficits. Traumatic brain injury is vastly heterogeneous and so it is not surprising that one therapy or approach, when applied to a mixed cohort of children in a clinical trial setting, has yielded disappointing results. Children with severe traumatic brain injury have vastly different brain injury pathologies of widely varying severity, in any number of anatomical locations at what may be disparate stages of brain development. This heterogeneity may also explain why clinicians are unable to accurately predict outcome. Biomarkers are objective molecular signatures of injury that are released following traumatic brain injury and may represent a way of unifying the heterogeneity of traumatic brain injury into a single biosignature. Biomarkers hold promise to diagnose brain injury severity, guide intervention selection for clinical trials, or provide vital prognostic information so that early intervention and rehabilitation can be planned much earlier in the course of a child's recovery. Serum S100B and serum NSE levels show promise as a diagnostic tool with biomarker levels significantly higher in children with severe TBI including children with inflicted and non-inflicted head injury. Serum S100B and serum NSE also show promise as a predictor of neurodevelopmental outcome. The role of biomarkers in traumatic brain injury is an evolving field with the potential for clinical application within the next few years.

Targeted Temperature Management Protocol in a Pediatric Intensive Care Unit: A Quality Improvement Project

BACKGROUND

In patients with acute neurological injury, abrupt temperature change exacerbates increased intracranial pressures and negatively affects perfusion pressure and cerebral blood flow. Critical care nurses must provide coordinated and effective interventions to maintain normothermia without precipitating shivering immediately after acute neurological injury in pediatric patients.

OBJECTIVE

To improve hyperthermia management in a 40-bed pediatric intensive care unit, an interdisciplinary pediatric critical care team developed, implemented, and evaluated a targeted temperature management protocol.

METHODS

The project was guided by the organization's plan-do-study-act quality improvement process. Quality improvement was assessed retrospectively using electronic medical records of patients meeting eligibility criteria. Samples of pediatric patients who received temperature interventions were compared before and after protocol implementation. The protocol included environmental, pharmacological, and body surface cooling device interventions, as well as use of a bedside shivering assessment scale and stepwise interventions to prevent and control shivering.

RESULTS

Before implementation of the targeted temperature management protocol, 64% of patients had documented temperatures higher than 37.5 °C, and body surface cooling devices were used in 10% of patients. After protocol implementation, more than 80% of patients had documented temperatures higher than 37.5 °C, and body surface cooling devices were used in 62% of patients. Four patients (6%) before and 5 patients (31%) after protocol implementation were treated with body surface cooling without requiring use of neuromuscular blockade.

CONCLUSIONS

Creation and implementation of a targeted temperature management protocol increased nurses' documented use of body surface cooling to manage hyperthermia in pediatric intensive care unit patients with acute neurological injury.

Perioperative Hypothermia in Children

Background: First described by paediatric anaesthesiologists, perioperative hypothermia is one of the earliest reported side effects of general anaesthesia. Deviations from normothermia are associated with numerous complications and adverse outcomes, with infants and small children at the highest risk. Nowadays, maintenance of normothermia is an important quality metric in paediatric anaesthesia. Methods: This review is based on our collection of publications regarding perioperative hypothermia and was supplemented with pertinent publications from a MEDLINE literature search. Results: We provide an overview on perioperative hypothermia in the paediatric patient, including definition, history, incidence, development, monitoring, risk factors, and adverse events, and provide management recommendations for its prevention. We also summarize the side effects and complications of perioperative temperature management. Conclusions: Perioperative hypothermia is still common in paediatric patients and may be attributed to their vulnerable physiology, but also may result from insufficient perioperative warming. An effective perioperative warming strategy incorporates the maintenance of normothermia during transportation, active warming before induction of anaesthesia, active warming during anaesthesia and surgery, and accurate measurement of core temperature. Perioperative temperature management must also prevent hyperthermia in children.

Hypothermia as an Outcome Predictor Tool in Pediatric Trauma: A Propensity-Matched Analysis

OBJECTIVE

Hypothermia is an independent risk factor for mortality in adult trauma patients. Two small studies have shown similar results in pediatric trauma patients. Temperature is not included in any pediatric trauma assessment scores. This study sought to compare mortality and various descriptive outcomes between pediatric hypothermic and normothermic trauma patients.

METHODS

Data were obtained from the National Trauma Database from 2009 to 2012. Patients meeting inclusion criteria were stratified by presence of isolated head injury, head injury with multiple trauma, and absence of head injury. These groups were then subdivided into hypothermic (temperature ≤36°C) and normothermic groups. We used propensity score matching to 1:1 match hypothermic and normothermic patients. Mortality, neurosurgical interventions, endotracheal intubation, blood transfusion, length of stay, laparotomy, thoracotomy, conversion of cardiac rhythm, and time receiving mechanical ventilation were evaluated.

RESULTS

Data from 3,011,482 patients were obtained. There were 414,562 patients who met the inclusion criteria. In all patients meeting inclusion criteria, hypothermia was a significant risk factor in all outcomes measured. Following stratification and 1:1 matching, in all groups, hypothermia was associated with increased mortality (P < 0.0001), increased rate of endotracheal intubation (P < 0.0002), increased need for blood transfusion (P < 0.0025), and conversion of cardiac rhythm (P < 0.0027).

CONCLUSION

Hypothermia has been shown to be a significant prognostic indicator in the pediatric trauma patient with further potential application. Future studies are indicated to evaluate the incorporation of hypothermia into the Pediatric Trauma Score not only to help predict injury severity and mortality but also to improve appropriate and expeditious patient transfer to pediatric trauma centers and potentially facilitate earlier intervention.

Nonparametric fuzzy hypothesis testing for quantiles applied to clinical characteristics of COVID-19

The sign test is one of the most popular nonparametric tests for location problems and allows testing for any quantile of a population. However, the common sign test has serious drawbacks such as loss of information by considering solely signs of observations but not their magnitudes, various problems related to handling of ties in the data, and the lack of embedding uncertainty regarding the fraction of underlying quantile. To address these issues, we present an extended sign test based on fuzzy categories and fuzzy formulated hypotheses that improves the generality, versatility, and practicability of the common sign test. This generalized test procedure is neat in theory and practice and avoids disadvantages that are often associated with fuzzy tests (e.g., a considerably higher complexity of the underlying model, a fuzzy test decision, and a possibilistic instead of a probabilistic interpretation of test results). In addition, we perform a comprehensive case study on COVID-19 in HIV-infected individuals with a focus on human body temperature and related measurement problems. The results of the study clearly indicate that fuzzy categories and fuzzy hypotheses improve the performance of the sign test.

Therapeutic Hypothermia in Critically Ill Patients: A Systematic Review and Meta-Analysis of High Quality Randomized Trials

OBJECTIVES

To investigate the effect of the application of therapeutic hypothermia (32-35°C) on survival and major clinical endpoints in critically ill patients.

DATA SOURCES

We searched online database and clinical trial registries dated up to April 30, 2019, and references of relevant studies.

STUDY SELECTION

Low risk of bias randomized trials which compared hypothermia applied for at least 24 hours and conventional therapy in critically ill patients were included. We excluded trials investigating therapeutic hypothermia in indications already supported by international guidelines (adult cardiac arrest and hypoxic-ischemic encephalopathy of newborns) or intraoperative hypothermia.

DATA EXTRACTION

Titles and abstracts were reviewed independently by two authors. If the articles seemed eligible, full-text articles were reviewed, and data were abstracted using a structured template.

DATA SYNTHESIS

Our search retained 14 low risk of bias randomized trials (2,670 patients) performed in three different settings: traumatic brain injury, serious infections, and stroke. Therapeutic hypothermia was associated with an increase in mortality at longest follow-up available (432/1,375 [31%] vs 330/1,295 [25%]; risk ratio, 1.24; 95% CI, 1.10-1.39; p = 0.0004; I = 0%). Pooled results showed no difference of good neurologic outcome among survivors between the two treatment arms (493/1,142 [43%] vs 486/1,067 [46%]; risk ratio, 1.04; 95% CI, 0.97-1.12; p = 0.27; I = 1%). Arrhythmias were significantly increased among patients undergoing therapeutic hypothermia. We found no difference between groups in pneumonia, serious infections, any infection, hemorrhage, renal failure, deep vein thrombosis, and uncontrollable intracranial hypertension.

CONCLUSIONS

High-quality randomized evidence indicates that therapeutic hypothermia is associated with higher mortality and no difference in good neurologic outcome compared with normothermia in critically ill patients. Although there still might be a possibility that therapeutic hypothermia is beneficial in a specific setting, routine application of therapeutic hypothermia would better be avoided outside the settings indicated by international guidelines (adult cardiac arrest and hypoxic-ischemic encephalopathy of newborns).

What Is in a Cat Scratch? Growth of Bartonella henselae in a Biofilm

Bartonella henselae (B. henselae) is a gram-negative bacterium that causes cat scratch disease, bacteremia, and endocarditis, as well as other clinical presentations. B. henselae has been shown to form a biofilm in vitro that likely plays a role in the establishment and persistence of the bacterium in the host. Biofilms are also known to form in the cat flea vector; hence, the ability of this bacterium to form a biofilm has broad biological significance. The release of B. henselae from a biofilm niche appears to be important in disease persistence and relapse in the vertebrate host but also in transmission by the cat flea vector. It has been shown that the BadA adhesin of B. henselae is critical for adherence and biofilm formation. Thus, the upregulation of badA is important in initiating biofilm formation, and down-regulation is important in the release of the bacterium from the biofilm. We summarize the current knowledge of biofilm formation in Bartonella species and the role of BadA in biofilm formation. We discuss the evidence that defines possible mechanisms for the regulation of the genes required for biofilm formation. We further describe the regulation of those genes in the conditions that mimic both the arthropod vector and the mammalian host for B. henselae. The treatment for persistent B. henselae infection remains a challenge; hence, a better understanding of the mechanisms by which this bacterium persists in its host is critical to inform future efforts to develop drugs to treat such infections.

Role of innate inflammation in traumatic brain injury

Traumatic brain injury is one of the leading causes of morbidity and mortality throughout the world. Its increasing incidence, in addition to its fundamental role in the development of neurodegenerative disease, proves especially concerning. Despite extensive preclinical and clinical studies, researchers have yet to identify a safe and effective neuroprotective strategy. Following brain trauma, secondary injury from molecular, metabolic, and cellular changes causes progressive cerebral tissue damage. Chronic neuroinflammation following traumatic brain injuries is a key player in the development of secondary injury. Targeting this phenomenon for development of effective neuroprotective therapies holds promise. This strategy warrants a concrete understanding of complex neuroinflammatory mechanisms. In this review, we discuss pathophysiological mechanisms such as the innate immune response, glial activation, blood-brain barrier disruption, activation of immune mediators, as well as biological markers of traumatic brain injury. We then review existing and emerging pharmacological therapies that target neuroinflammation to improve functional outcome.

Necessity of early and continuous monitoring for possible infectious complications in children undergoing therapeutic hypothermia

AIM

Since therapeutic hypothermia (TH) is known for its inhibitory effects on leucocyte migration and cytokine synthesis, our aim was to underline the necessity of early monitoring for potential immunomodulatory risks.

METHODS

Using a 13-year retrospective case-control study at the paediatric intensive care unit (PICU) of the Medical University in Vienna, all newborn infants and children receiving TH were screened and compared with a diagnosis-matched control group undergoing conventional normothermic treatment (NT). TH was accomplished by using a non-invasive cooling device. Target temperature was 32-34°C. Children with evident infections, a medical history of an immunodeficiency or undergoing immunosuppressive therapy, were excluded.

RESULTS

During the observational period, 108 patients were screened, 27 of which underwent TH. Culture-proven infections occurred in 22% of the TH group compared with 4% of the normothermic controls (P = .1). From the second day following PICU admission, median C-reactive protein (CRP) values were higher in the TH group (day two P = .002, day three P = .0002, day six P = .008).

CONCLUSION

Children undergoing TH showed earlier and higher increases in CRP levels when compared to normothermic controls. These data underline the necessity of early and continuous monitoring for possible infectious complications.

Development of a Mortality Prediction Tool in Pediatric Severe Traumatic Brain Injury

Severe traumatic brain injury (sTBI) is a leading cause of pediatric death, yet outcomes remain difficult to predict. The goal of this study was to develop a predictive mortality tool in pediatric sTBI. We retrospectively analyzed 196 patients with sTBI (pre-sedation Glasgow Coma Scale [GCS] score <8 and head Maximum Abbreviated Injury Scale (MAIS) score >4) admitted to a pediatric intensive care unit (PICU). Overall, 56 patients with sTBI (29%) died during PICU stay. Of the survivors, 88 (63%) were discharged home, and 52 (37%) went to an acute care or rehabilitation facility. Receiver operating characteristic (ROC) curve analyses of admission variables showed that pre-sedation GCS score, Rotterdam computed tomography (CT) score, and partial thromboplastin time (PTT) were fair predictors of PICU mortality (area under the curve [AUC] = 0.79, 0.76, and 0.75, respectively; p < 0.001). Cutoff values best associated with PICU mortality were pre-sedation GCS score <5 (sensitivity = 0.91, specificity = 0.54), Rotterdam CT score >3 (sensitivity = 0.84, specificity = 0.53), and PTT >34.5 sec (sensitivity = 0.69 specificity = 0.67). Combining pre-sedation GCS score, Rotterdam CT score, and PTT in ROC curve analysis yielded an excellent predictor of PICU mortality (AUC = 0.91). In summary, pre-sedation GCS score (<5), Rotterdam CT score (>3), and PTT (>34.5 sec) obtained on hospital admission were fair predictors of PICU mortality, ranked highest to lowest. Combining these three admission variables resulted in an excellent pediatric sTBI mortality prediction tool for further prospective validation.