Aspects on the cerebral perfusion pressure during therapy of a traumatic head injury

Alterations to the gut microbiome after sport-related concussion in a collegiate football players cohort: A pilot study

Concussions, both single and repetitive, cause brain and body alterations in athletes during contact sports. The role of the brain-gut connection and changes in the microbiota have not been well established after sports-related concussions or repetitive subconcussive impacts. We recruited 33 Division I Collegiate football players and collected blood, stool, and saliva samples at three time points throughout the athletic season: mid-season, following the last competitive game (post-season), and after a resting period in the off-season. Additional samples were collected from four athletes that suffered from a concussion. 16S rRNA sequencing of the gut microbiome revealed a decrease in abundance for two bacterial species, Eubacterium rectale, and Anaerostipes hadrus, after a diagnosed concussion. No significant differences were found regarding the salivary microbiome. Serum biomarker analysis shows an increase in GFAP blood levels in athletes during the competitive season. Additionally, S100β and SAA blood levels were positively correlated with the abundance of Eubacterium rectale species among the group of athletes that did not suffer a diagnosed concussion during the sports season. These findings provide initial evidence that detecting changes in the gut microbiome may help to improve concussion diagnosis following head injury.

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A longitudinal study following college football athletes across a sports season.

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Nanopore 16S rRNA sequencing of gut microbiome reveals changes after head injury.

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Serum biomarker GFAP increased during the competitive period of the season.

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S100β and SAA blood levels were positively correlated with Eubacterium rectale.

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Gut microbiota is suggested as a future biomarker for diagnosis following head injury.

Neuroprotective measures in children with traumatic brain injury

Traumatic brain injury (TBI) is a major cause of death and disability in children. Severe TBI is a leading cause of death and often leads to life changing disabilities in survivors. The modern management of severe TBI in children on intensive care unit focuses on preventing secondary brain injury to improve outcome. Standard neuroprotective measures are based on management of intracranial pressure (ICP) and cerebral perfusion pressure (CPP) to optimize the cerebral blood flow and oxygenation, with the intention to avoid and minimise secondary brain injury. In this article, we review the current trends in management of severe TBI in children, detailing the general and specific measures followed to achieve the desired ICP and CPP goals. We discuss the often limited evidence for these therapeutic interventions in children, extrapolation of data from adults, and current recommendation from paediatric guidelines. We also review the recent advances in understanding the intracranial physiology and neuroprotective therapies, the current research focus on advanced and multi-modal neuromonitoring, and potential new therapeutic and prognostic targets.

Adherence to guidelines for management of cerebral perfusion pressure and outcome in patients who have severe traumatic brain injury

PURPOSE

The aims of this study are to assess adherence to the Brain Trauma Foundation (BTF) cerebral perfusion pressure (CPP) guidelines and to determine if adherence is associated with mortality in patients who have a severe traumatic brain injury.

MATERIALS AND METHODS

Retrospective cohort study of 127 patients admitted to one intensive care unit between 2006 and 2012. Adherence to BTF guidelines was measured as the time that the CPP was within 50 to 70 mm Hg divided by the total time of CPP monitoring (CPP time index).

RESULTS

The percentage of time that the CPP was within the recommended range was 31.6% (SD, 22.2); CPP was greater than 70 mm Hg for 63.9% (SD, 26.2) of the time and less than 50 mm Hg for 4.5% of the time (SD, 16.3). After adjustment for covariates, CPP time index (between 50 and 70 mm Hg) was not associated with hospital mortality (odds ratio [OR], 1.2; 95% confidence interval [CI], 0.98-1.6; P= .079). The time indices for CPP ≥70 and <50 mm Hg were associated with decreased (OR, 0.66; 95%CI, 0.52-0.82; P< .0001) and increased (OR, 9.9; 95% CI, 1.4-69.6; P= .021) mortality, respectively.

CONCLUSION

Cerebral perfusion pressure was greater than 70 mm Hg for most of the time. This level of CPP was associated with decreased hospital mortality.

Dynamics of brain tissue changes induced by traumatic brain injury assessed with the Marshall, Morris-Marshall, and the Rotterdam classifications and its impact on outcome in a prostacyclin placebo-controlled study

BACKGROUND

The present study evaluates the types and dynamics of intracranial pathological changes in patients with severe traumatic brain injury (sTBI) who participated in a prospective, randomized, double-blinded study of add-on treatment with prostacyclin. Further, the changes of brain CT scan and their correlation to Glasgow Coma Scale score (GCS), maximal intracranial pressure (ICP(max)), minimal cerebral perfusion pressure (CPP(min)), and Glasgow Outcome Score (GOS) at 3, 6, and 12 months were studied.

METHODS

Forty-eight subjects with severe traumatic brain injury were treated according to an ICP-targeted therapy protocol based on the Lund concept with the addition of prostacyclin or placebo. The first available CT scans (CT(i)) and follow-up scans nearest to 24 h (CT(24)) were evaluated using the Marshall, Rotterdam, and Morris-Marshall classifications.

RESULTS

There was a significant correlation of the initial Marshall, Rotterdam, Morris-Marshall classifications and GOS at 3 and 12 months. The CT(24) Marshall classification did not significantly correlate to GOS while the Rotterdam and the Morris-Marshall classification did. The CT(i) Rotterdam classification predicted outcome evaluated as GOS at 3 and 12 months. Prostacyclin treatment did not influence the dynamic of tissue changes.

CONCLUSIONS

The Rotterdam classification seems to be appropriate for describing the evolution of the injuries on the CT scans and contributes in predicting of outcome in patients treated with an ICP-targeted therapy. The Morris-Marshall classification can also be used for prognostication of outcome but it describes only the impact of traumatic subarachnoid hemorrhage (tSAH).

Absence of electroencephalographic seizure activity in patients treated for head injury with an intracranial pressure-targeted therapy

OBJECT

The authors prospectively studied the occurrence of clinical and nonclinical electroencephalographically verified seizures during treatment with an intracranial pressure (ICP)-targeted protocol in patients with traumatic brain injury (TBI).

METHODS

All patients treated for TBI at the Department of Neurosurgery, University Hospital Umeå, Sweden, were eligible for the study. The inclusion was consecutive and based on the availability of the electroencephalographic (EEG) monitoring equipment. Patients were included irrespective of pupil size, pupil reaction, or level of consciousness as long as their first measured cerebral perfusion pressure was > 10 mm Hg. The patients were treated in a protocol-guided manner with an ICP-targeted treatment based on the Lund concept. The patients were continuously sedated with midazolam, fentanyl, propofol, or thiopental, or combinations thereof. Five-lead continuous EEG monitoring was performed with the electrodes at F3, F4, P3, P4, and a midline reference. Sensitivity was set at 100 muV per cm and filter settings 0.5-70 Hz. Amplitude-integrated EEG recording and relative band power trends were displayed. The trends were analyzed offline by trained clinical neurophysiologists.

RESULTS

Forty-seven patients (mean age 40 years) were studied. Their median Glasgow Coma Scale score at the time of sedation and intubation was 6 (range 3-15). In 8.5% of the patients clinical seizures were observed before sedation and intubation. Continuous EEG monitoring was performed for a total of 7334 hours. During this time neither EEG nor clinical seizures were observed.

CONCLUSIONS

Our protocol-guided ICP targeted treatment seems to protect patients with severe TBI from clinical and subclinical seizures and thus reduces the risk of secondary brain injury.

Apolipoprotein E polymorphism and gender difference in outcome after severe traumatic brain injury

BACKGROUND

Traumatic brain injury (TBI) is one of the most common causes of death and dismal outcome among children and young adults. The morbidity and mortality differ but more aggressive monitoring and more designated neuro intensive care units have improved the results. Studies have demonstrated a connection between apolipoprotein E (APOE) genotype and outcome after TBI, but few are prospective and none is from northern Europe. APOE has three alleles: epsilon2, epsilon3 and epsilon4.

METHODS

A total of 96 patients with Glasgow coma score (GCS) < or =8 were prospectively and consecutively included. APOE genotypes were all analyzed at the same laboratory from blood samples by polymerase chain reaction-restriction fragment length polymorphism.

RESULTS

All patients were assessed at 1 year with Glasgow outcome scale extended (GOSE), National Institute of Health Stroke Scale (NIHSS) and the Barthel daily living index. The genotype was available in all patients. Twenty-six patients expressed APOE epsilon4 while 70 patients did not. Outcome demonstrated that patients with APOE epsilon4 had worse outcome vs. those lacking this allele. When subdividing patients into gender, males with APOE epsilon4 did worse, a difference not detected among female patients.

CONCLUSIONS

APOE epsilon4 correlated to worse outcome in TBI patients. We also found that males with APOE epsilon4 had poor outcome while females did not. Thus, the results indicate that genetic polymorphism may influence outcome after TBI.

Long-term outcomes and prognostic factors in pediatric patients with severe traumatic brain injury and elevated intracranial pressure

OBJECT

The management strategies and outcomes in pediatric patients with elevated intracranial pressure (ICP) following severe traumatic brain injury (TBI) are examined in this study.

METHODS

This study was a retrospective review of a prospectively acquired pediatric trauma database. More than 750 pediatric patients with brain injury were seen over a 10-year period. Records were retrospectively reviewed to determine interventions for correcting ICP, and surviving patients were contacted prospectively to determine functional status and quality of life. Only patients with 2 years of follow-up were included in the study.

RESULTS

Ninety-six pediatric patients (age range 3-18 years) were identified with a Glasgow Coma Scale score<8 and elevated ICP>20 mm Hg on presentation. The mean injury severity score was 65 (range 30-100). All patients were treated using a standardized head injury protocol. The mean time course until peak ICP was 69 hours postinjury (range 2-196 hours). Intracranial pressure control was achieved in 82 patients (85%). Methods employed to achieve ICP control included maximal medical therapy (sedation, hyperosmolar therapy, and paralysis) in 34 patients (35%), ventriculostomy in 23 patients (24%), and surgery in 39 patients (41%). Fourteen patients (15%) had refractory ICP despite all interventions, and all of these patients died. Seventy-two patients (75%) were discharged from the hospital, whereas 24 (25%) died during hospitalization. Univariate and multivariate analysis revealed that the presence of vascular injury, refractory ICP, and cisternal effacement at presentation had the highest correlation with subsequent death (p<0.05). Mean follow-up was 53 months (range 11-126 months). Three patients died during the follow-up period (2 due to infections and 1 committed suicide). The mean 2-year Glasgow Outcome Scale score was 4 (median 4, range 1-5). The mean patient competency rating at follow-up was 4.13 out of 5 (median 4.5, range 1-4.8). Univariate analysis revealed that the extent of intracranial and systemic injuries had the highest correlation with long-term quality of life (p<0.05).

CONCLUSIONS

Controlling elevated ICP is an important factor in patient survival following severe pediatric TBI. The modality used for ICP control appears to be less important. Long-term follow-up is essential to determine neurocognitive sequelae associated with TBI.

Monitoring intracranial pressure in traumatic brain injury

Increased intracranial pressure (ICP) is an important cause of secondary brain injury, and ICP monitoring has become an established component of brain monitoring after traumatic brain injury. ICP cannot be reliably estimated from any specific clinical feature or computed tomography finding and must actually be measured. Different methods of monitoring ICP have been described but intraventricular catheters and microtransducer systems are most widely used in clinical practice. ICP is a complex variable that links ICP and cerebral perfusion pressure and provides additional information from identification and analysis of pathologic ICP wave forms. ICP monitoring can also be augmented by measurement of indices describing cerebrovascular pressure reactivity and pressure-volume compensatory reserve. There is considerable variability in the use of ICP monitoring and treatment modalities among head injury centers. However, there is a large body of clinical evidence supporting the use of ICP monitoring to detect intracranial mass lesions early, guide therapeutic interventions, and assess prognosis, and it is recommended by consensus guidelines for head injury management. There remains a need for a prospective, randomized, controlled trial to identify the value of ICP monitoring and management after head injury.

Traumatic brain injury: intensive care management

Traumatic brain injury (TBI) is a major cause of morbidity and mortality worldwide. The modern management of severe TBI has fallen into the domain of a multidisciplinary team led by neurointensivists, neuroanaesthetists, and neurosurgeons and is based on the avoidance of secondary injury, maintenance of cerebral perfusion pressure (CPP), and optimization of cerebral oxygenation. In this review, we will discuss the intensive care management of severe TBI with emphasis on the specific measures directed at the control of intracranial pressure and CPP.

Beta-Blocker Use is Associated With Improved Outcomes in Adult Trauma Patients

BACKGROUND

Beta-adrenoreceptor blocker (beta-blocker) therapy may improve outcomes in surgical patients by decreasing cardiac oxygen consumption and hypermetabolism. Because beta-blockers can lower the systemic blood pressure and cerebral perfusion pressure, there is concern regarding their use in patients with head injury. However, beta-blockers may protect beta-receptor rich brain cells by attenuating cerebral oxygen consumption and metabolism. We hypothesized that beta-blockers are safe in trauma patients, even if they have suffered a significant head injury.

METHODS

Using pharmacy and trauma registry data of a Level I trauma center, we identified a cohort of trauma patients who received beta-blockers during their hospital stay (beta-cohort). Trauma admissions who did not receive beta-blockers were in the control cohort. beta-blocker status, in combination with other variables associated with mortality, were placed in a stepwise multivariate logistic regression to identify independent predictors of fatal outcome.

RESULTS

In all, 303 (7%) of 4,117 trauma patients received beta-blockers. In the beta-cohort, 45% of patients were on beta-blockers preinjury. The most common reason to initiate beta-blocker therapy was blood pressure (60%) and heart rate (20%) control. The overall mortality rate was 5.6% and head injury was considered to be the major cause of death. After adjusting for age, Injury Severity Scale score, blood pressure, Glasgow Coma Scale score, respiratory status, and mechanism of injury, the odds ratio for fatal outcome was 0.3 (p < 0.001) for beta-cohort as compared with control. Decreased risk of fatal outcome was more pronounced in patients with a significant head injury.

CONCLUSIONS

beta-blocker therapy is safe and may be beneficial in selected trauma patients with or without head injury. Further studies looking at beta-blocker therapy in trauma patients and their effect on cerebral metabolism are warranted.

Cerebral acid—base homeostasis after severe traumatic brain injury

Object. Brain tissue acidosis is known to mediate neuronal death. Therefore the authors measured the main parameters of cerebral acid—base homeostasis, as well as their interrelations, shortly after severe traumatic brain injury (TBI) in humans.

Methods. Brain tissue pH, PCO2, PO2, and/or lactate were measured in 151 patients with severe head injuries, by using a Neurotrend sensor and/or a microdialysis probe. Monitoring was started as soon as possible after the injury and continued for up to 4 days.

During the 1st day following the trauma, the brain tissue pH was significantly lower, compared with later time points, in patients who died or remained in a persistent vegetative state. Six hours after the injury, brain tissue PCO2 was significantly higher in patients with a poor outcome compared with patients with a good outcome. Furthermore, significant elevations in cerebral concentrations of lactate were found during the 1st day after the injury, compared with later time points. These increases in lactate were typically more pronounced in patients with a poor outcome. Similar biochemical changes were observed during later hypoxic events.

Conclusions. Severe human TBI profoundly disturbs cerebral acid—base homeostasis. The observed pH changes persist for the first 24 hours after the trauma. Brain tissue acidosis is associated with increased tissue PCO2 and lactate concentration; these pathobiochemical changes are more severe in patients who remain in a persistent vegetative state or die. Furthermore, increased brain tissue PCO2 (> 60 mm Hg) appears to be a useful clinical indicator of critical cerebral ischemia, especially when accompanied by increased lactate concentrations.

Association between elevated brain tissue glycerol levels and poor outcome following severe traumatic brain injury

Object. Glycerol is considered to be a marker of cell membrane degradation and thus cellular lysis. Recently, it has become feasible to measure via microdialysis cerebral extracellular fluid (ECF) glycerol concentrations at the patient's bedside. Therefore the aim of this study was to investigate the ECF concentration and time course of glycerol after severe traumatic brain injury (TBI) and its relationship to patient outcome and other monitoring parameters.

Methods. As soon as possible after injury for up to 4 days, 76 severely head-injured patients were monitored using a microdialysis probe (cerebral glycerol) and a Neurotrend sensor (brain tissue PO2) in uninjured brain tissue confirmed by computerized tomography scanning. The mean brain tissue glycerol concentration in all monitored patients decreased significantly from 206 ± 31 µmol/L on Day 1 to 9 ± 3 µmol/L on Day 4 after injury (p < 0.0001). Note, however, that there was no significant difference in the time course between patients with a favorable outcome (Glasgow Outcome Scale [GOS] Scores 4 and 5) and those with an unfavorable outcome (GOS Scores 1–3). Significantly increased glycerol concentrations were observed when brain tissue PO2 was less than 10 mm Hg or when cerebral perfusion pressure was less than 70 mm Hg.

Conclusions. Based on results in the present study one can infer that microdialysate glycerol is a marker of severe tissue damage, as seen immediately after brain injury or during profound tissue hypoxia. Given that brain tissue glycerol levels do not yet add new clinically significant information, however, routine monitoring of this parameter following traumatic brain injury needs further validation.

A Mouse Model for Evaluation of Capillary Perfusion, Microvascular Permeability, Cortical Blood Flow, and Cortical Edema in the Traumatized Brain

Genetically engineered mice have successfully been used to investigate molecular and cellular mechanisms associated with cell dysfunction following brain trauma. Such animals may also offer a possibility to investigate mechanisms involved in posttraumatic hemodynamic alterations. The objective of the study was to establish a mouse model in which important hemodynamic alterations following trauma could be analyzed. C57/BL6 male mice were subjected to controlled cortical impact injury (CCI) or sham-injury. Distribution of blood flow was estimated by determining number of perfused capillaries using FITC-dextran as an intravascular marker. Cortical blood flow was measured using [(14)C]-iodoantipyrine, brain water content (BWC) was measured using a wet vs. dry weight method, and permeability surface area product (PS) was estimated by the transfer constant for [(51)Cr]-EDTA. Number of perfused capillaries in the contusion area was progressively reduced during the first 24 h following trauma by at most 60% relative to a value of 329 +/- 61/mm(2) in sham-injured animals. Blood flow in the contusion area decreased simultaneously by at most 50% relative to a control value of 1.8 +/- 0.4 mL.min(-1).g(-1), and was reduced further in subregions within the contusion area. BWC in the injured hemisphere increased from 79.3 +/- 0.5% at control to at most 79.9 +/- 0.6% at 24 h post trauma. PS in the injured hemisphere increased by 71% at 3 h post trauma relative to a control value of 0.45 +/- 0.1 microL.min(-1).g(-1), and was close to control at 24 h. The present study demonstrates that brain trauma in addition to a reduction in cortical blood flow, reduces number of perfused capillaries, which most likely affects exchange of nutrients and fluid. The CCI in mouse is likely to be a useful tool to elucidate mechanisms involved in hemodynamic alterations following brain trauma.

Ventilation and the critically ill parturient

Positive-pressure ventilation is the keystone in the management of pulmonary dysfunction in the critically ill. An increased understanding of both the benefits and hazards has led to a general consensus regarding the optimal techniques to ensure adequate gas exchange. Unfortunately, the same cannot be said for ventilation terminology which, due to a lack of standardization, lends itself to confusion. Pulmonary dysfunction in the parturient may arise from thoracic or extra-thoracic pathologies but both may be defined as acute lung injury. In its most severe form this constitutes acute respiratory distress syndrome. Acute lung injury results in reduced lung compliance and a marked decrease in the volume of functional lung. Ventilation strategies are now designed to recruit as much available lung tissue as possible while simultaneously minimizing the injurious effects of alveolar over-distension. Upon resolution of the underlying pathology mechanical ventilation may be withdrawn. Recent evidence suggests that this final stage need not be protracted, and if certain criteria are fulfilled, rapid weaning is feasible.

A new model for diffuse brain injury by rotational acceleration: II. Effects on extracellular glutamate, intracranial pressure, and neuronal apoptosis

The aim of this study is to monitor excitatory amino acids (EAAs) in the extracellular fluids of the brain and to characterize regional neuronal damage in a new experimental model for brain injury, in which rabbits were exposed to 180-260 krad/s2 rotational head acceleration. This loading causes extensive subarachnoid hemorrhage, focal tissue bleeding, reactive astrocytosis, and axonal damage. Animals were monitored for intracranial pressure (ICP) and for amino acids in the extracellular fluids. Immunohistochemistry was used to study expression of the gene c-Jun and apoptosis with the terminal deoxynucleotidyl transferase nick-end labeling (TUNEL) technique. Extracellular glutamate, glycine, and taurine increased significantly in the hippocampus within a few hours and remained high after 24 h. Neuronal nuclei in the granule layers of the hippocampus and cerebellum were positive for c-Jun after 24 h. Little immunoreactivity was detected in the cerebral cortex. c-Jun-positive neuronal perikarya and processes were found in granule and pyramidal CA4 layers of the hippocampus and among the Purkinje cells of the cerebellum. Also some microglial cells stained positively for c-Jun. TUNEL reactivity was most intense at 10 days after trauma and was extensive in neurons of the cerebral cortex, hippocampus, and cerebellum. The initial response of the brain after rotational head injury involves brain edema after 24 h and an excitotoxic neuronal microenvironment in the first hour, which leads to extensive delayed neuronal cell death by apoptosis necrosis in the cerebral cortex, hippocampus and cerebellum.