Inflicted Childhood Neurotrauma: New Insight into The Detection, Pathobiology, Prevention, and Treatment of Our Youngest Patients with Traumatic Brain Injury

Intracranial pressure monitoring in severe traumatic brain injury in latin america: process and methods for a multi-center randomized controlled trial

In patients with severe traumatic brain injury (TBI), the influence on important outcomes of the use of information from intracranial pressure (ICP) monitoring to direct treatment has never been tested in a randomized controlled trial (RCT). We are conducting an RCT in six trauma centers in Latin America to test this question. We hypothesize that patients randomized to ICP monitoring will have lower mortality and better outcomes at 6-months post-trauma than patients treated without ICP monitoring. We selected three centers in Bolivia to participate in the trial, based on (1) the absence of ICP monitoring, (2) adequate patient accession and data collection during the pilot phase, (3) preliminary institutional review board approval, and (4) the presence of equipoise about the value of ICP monitoring. We conducted extensive training of site personnel, and initiated the trial on September 1, 2008. Subsequently, we included three additional centers. A total of 176 patients were entered into the trial as of August 31, 2010. Current enrollment is 81% of that expected. The trial is expected to reach its enrollment goal of 324 patients by September of 2011. We are conducting a high-quality RCT to answer a question that is important globally. In addition, we are establishing the capacity to conduct strong research in Latin America, where TBI is a serious epidemic. Finally, we are demonstrating the feasibility and utility of international collaborations that share resources and unique patient populations to conduct strong research about global public health concerns.

Predicting 14-day mortality after severe traumatic brain injury: application of the IMPACT models in the brain trauma foundation TBI-trac® New York State database

Prognostic models for outcome prediction in patients with traumatic brain injury (TBI) are important instruments in both clinical practice and research. To remain current a continuous process of model validation is necessary. We aimed to investigate the performance of the International Mission on Prognosis and Analysis of Clinical Trials in TBI (IMPACT) prognostic models in predicting mortality in a contemporary New York State TBI registry developed and maintained by the Brain Trauma Foundation. The Brain Trauma Foundation (BTF) TBI-trac® database contains data on 3125 patients who sustained severe TBI (Glasgow Coma Scale [GCS] score ≤ 8) in New York State between 2000 and 2009. The outcome measure was 14-day mortality. To predict 14-day mortality with admission data, we adapted the IMPACT Core and Extended models. Performance of the models was assessed by determining calibration (agreement between observed and predicted outcomes), and discrimination (separation of those patients who die from those who survive). Calibration was explored graphically with calibration plots. Discrimination was expressed by the area under the receiver operating characteristic (ROC) curve (AUC). A total of 2513 out of 3125 patients in the BTF database met the inclusion criteria. The 14-day mortality rate was 23%. The models showed excellent calibration. Mean predicted probabilities were 20% for the Core model and 24% for the Extended model. Both models showed good discrimination with AUCs of 0.79 (Core) and 0.83 (Extended). We conclude that the IMPACT models validly predict 14-day mortality in the BTF database, confirming generalizability of these models for outcome prediction in TBI patients.

Modafinil: Underarousal, Somnolence, and Fatigue Related to Brain Injury

This Hospital Pharmacy feature is extracted from Off-Label Drug Pacts, a quarterly publication available from Wolters Kluwer Health. Off-Label Drug Pacts is a practitioner-oriented resource for information about specific drug uses that are unapproved by the US Food and Drug Administration. This new guide to the literature enables the health care professional or clinician to quickly identify published studies on off-label uses and determine if a specific use is rational in a patient care scenario. References direct the reader to the full literature for more comprehensive information before patient care decisions are made. Direct questions or comments regarding Off-Label Drug Uses to jgeneral@kumc.edu .

Is aggressive treatment of traumatic brain injury cost-effective?

OBJECT

The object of this study was to determine whether aggressive treatment of severe traumatic brain injury (TBI), including invasive intracranial monitoring and decompressive craniectomy, is cost-effective.

METHODS

A decision-analytical model was created to compare costs, outcomes, and cost-effectiveness of 3 strategies for treating a patient with severe TBI. The aggressive-care approach is compared with "routine care," in which Brain Trauma Foundation guidelines are not followed. A "comfort care" category, in which a single day in the ICU is followed by routine floor care, is included for comparison only. Probabilities of each treatment resulting in various Glasgow Outcome Scale (GOS) scores were obtained from the literature. The GOS scores were converted to quality-adjusted life years (QALYs), based on expected longevity and calculated quality of life associated with each GOS category. Estimated direct (acute and long-term medical care) and indirect (loss of productivity) costs were calculated from the perspective of society. Sensitivity analyses employed a 2D Monte Carlo simulation of 1000 trials, each with 1000 patients. The model was also used to estimate these values for patients 40, 60, and 80 years of age.

RESULTS

For the average 20-year-old, aggressive care yields 11.7 (± 1.6 [SD]) QALYs, compared with routine care (10.0 ± 1.5 QALYs). This difference is highly significant (p < 0.0001). Although the differences in effectiveness between the 2 strategies diminish with advancing age, aggressive care remains significantly better at all ages. When all costs are considered, aggressive care is also significantly less costly than routine care ($1,264,000 ± $118,000 vs $1,361,000 ± $107,000) for the average 20-year-old. Aggressive care remains significantly less costly until age 80, at which age it costs more than routine care. However, even in the 80-year-old, aggressive care is likely the more cost-effective approach. Comfort care is associated with poorer outcomes at all ages and with higher costs for all groups except 80-year-olds.

CONCLUSIONS

When all the costs of severe TBI are considered, aggressive treatment is a cost-effective option, even for older patients. Comfort care for severe TBI is associated with poor outcomes and high costs, and should be reserved for situations in which aggressive approaches have failed or testing suggests such treatment is futile.

Pathophysiology of hypopituitarism in the setting of brain injury

The complex pathophysiology of traumatic brain injury (TBI) involves not only the primary mechanical event but also secondary insults such as hypotension, hypoxia, raised intracranial pressure and changes in cerebral blood flow and metabolism. It is increasingly evident that these initial insults as well as transient events and treatments during the early injury phase can impact hypothalamic-pituitary function both acutely and chronically after injury. In turn, untreated pituitary hormonal dysfunction itself can further hinder recovery from brain injury. Secondary adrenal insufficiency, although typically reversible, occurs in up to 50% of intubated TBI victims and is associated with lower systemic blood pressure. Chronic anterior hypopituitarism, although reversible in some patients, persists in 25-40% of moderate and severe TBI survivors and likely contributes to long-term neurobehavioral and quality of life impairment. While the rates and risk factors of acute and chronic pituitary dysfunction have been documented for moderate and severe TBI victims in numerous recent studies, the pathophysiology remains ill-defined. Herein we discuss the hypotheses and available data concerning hypothalamic-pituitary vulnerability in the setting of head injury. Four possible pathophysiological mechanisms are considered: (1) the primary brain injury event, (2) secondary brain insults, (3) the stress of critical illness and (4) medication effects. Although each of these factors appears to be important in determining which hormonal axes are affected, the severity of dysfunction, their time course and possible reversibility, this process remains incompletely understood.

Molecular biomarkers of epileptogenesis

The heterogeneity of epilepsy syndromes and pathologies creates a great challenge for the search for biomarkers. Not surprisingly, identification of a marker that is specific and sensitive for a given epileptogenic pathology remains an unmet need. There have, however, been several studies of major epileptogenic etiologies like traumatic brain injury that aimed to identify molecular markers in blood and cerebrospinal fluid that predict outcome, by using proteomics and metabolomics. Unfortunately, epileptogenesis has not been analyzed as an outcome measure. Another question to be explored is whether a palette of molecular markers is needed, rather than a single molecule, with each marker probing a different component of epileptogenic pathology. Further, perhaps multiple biomarker platforms (e.g., imaging, proteomics, electrophysiology) should be used in combination and/or in a defined temporal sequence.

Perioperative glucose control in neurosurgical patients

Many neurosurgery patients may have unrecognized diabetes or may develop stress-related hyperglycemia in the perioperative period. Diabetes patients have a higher perioperative risk of complications and have longer hospital stays than individuals without diabetes. Maintenance of euglycemia using intensive insulin therapy (IIT) continues to be investigated as a therapeutic tool to decrease morbidity and mortality associated with derangements in glucose metabolism due to surgery. Suboptimal perioperative glucose control may contribute to increased morbidity, mortality, and aggravate concomitant illnesses. The challenge is to minimize the effects of metabolic derangements on surgical outcomes, reduce blood glucose excursions, and prevent hypoglycemia. Differences in cerebral versus systemic glucose metabolism, time course of cerebral response to injury, and heterogeneity of pathophysiology in the neurosurgical patient populations are important to consider in evaluating the risks and benefits of IIT. While extremes of glucose levels are to be avoided, there are little data to support an optimal blood glucose level or recommend a specific use of IIT for euglycemia maintenance in the perioperative management of neurosurgical patients. Individualized treatment should be based on the local level of blood glucose control, outpatient treatment regimen, presence of complications, nature of the surgical procedure, and type of anesthesia administered.

[Severe traumatic brain injury]

Traumatic brain injury is a leading cause of morbidity and mortality, especially under 45 years of age. The primary brain injury occurs at the moment of trauma and is defined by the direct damage to tissue. In contrast, secondary brain injury develops over time and is accessible to therapeutic interventions. Patients with severe traumatic brain injury have to be transferred to a specialized trauma centre in order to perform appropriate diagnostic and therapeutic procedures. These include surgical management of lesions (e.g. haematoma evacuation) as well as specific neurointensive care. Neurointensive care medicine principles such as treatment of increased intracranial pressure and advanced invasive neuromonitoring of brain tissue have to be followed.

Hypertonic saline for treating raised intracranial pressure: literature review with meta-analysis

Object

Currently, mannitol is the recommended first choice for a hyperosmolar agent for use in patients with elevated intracranial pressure (ICP). Some authors have argued that hypertonic saline (HTS) might be a more effective agent; however, there is no consensus as to appropriate indications for use, the best concentration, and the best method of delivery. To answer these questions better, the authors performed a review of the literature regarding the use of HTS for ICP reduction.

Methods

A PubMed search was performed to locate all papers pertaining to HTS use. This search was then narrowed to locate only those clinical studies relating to the use of HTS for ICP reduction.

Results

A total of 36 articles were selected for review. Ten were prospective randomized controlled trials (RCTs), 1 was prospective and nonrandomized, 15 were prospective observational trials, and 10 were retrospective trials. The authors did not distinguish between retrospective observational studies and retrospective comparison trials. Prospective studies were considered observational if the effects of a treatment were evaluated over time but not compared with another treatment.

Conclusions

The available data are limited by low patient numbers, limited RCTs, and inconsistent methods between studies. However, a greater part of the data suggest that HTS given as either a bolus or continuous infusion can be more effective than mannitol in reducing episodes of elevated ICP. A meta-analysis of 8 prospective RCTs showed a higher rate of treatment failure or insufficiency with mannitol or normal saline versus HTS.

Re-orientation of clinical research in traumatic brain injury: report of an international workshop on comparative effectiveness research

During the National Neurotrauma Symposium 2010, the DG Research of the European Commission and the National Institutes of Health/National Institute of Neurological Disorders and Stroke (NIH/NINDS) organized a workshop on comparative effectiveness research (CER) in traumatic brain injury (TBI). This workshop reviewed existing approaches to improve outcomes of TBI patients. It had two main outcomes: First, it initiated a process of re-orientation of clinical research in TBI. Second, it provided ideas for a potential collaboration between the European Commission and the NIH/NINDS to stimulate research in TBI. Advances in provision of care for TBI patients have resulted from observational studies, guideline development, and meta-analyses of individual patient data. In contrast, randomized controlled trials have not led to any identifiable major advances. Rigorous protocols and tightly selected populations constrain generalizability. The workshop addressed additional research approaches, summarized the greatest unmet needs, and highlighted priorities for future research. The collection of high-quality clinical databases, associated with systems biology and CER, offers substantial opportunities. Systems biology aims to identify multiple factors contributing to a disease and addresses complex interactions. Effectiveness research aims to measure benefits and risks of systems of care and interventions in ordinary settings and broader populations. These approaches have great potential for TBI research. Although not new, they still need to be introduced to and accepted by TBI researchers as instruments for clinical research. As with therapeutic targets in individual patient management, so it is with research tools: one size does not fit all.

Prospective independent validation of IMPACT modeling as a prognostic tool in severe traumatic brain injury

Clinical trials in traumatic brain injury (TBI) have been fraught with failure due in part to heterogeneity in pathology and insensitive outcome measurements. The International Mission for Prognosis and Analysis of Clinical Trials in TBI (IMPACT) prognostic model has been purposed as a means of risk adjustment and outcome prediction for use in trial design and analysis. The purpose of this study was to evaluate the performance of the IMPACT model in predicting 6-month functional outcome and mortality using prospectively collected data at a large, Level 1 neurotrauma center. This population-based cohort study included all TBI patients ≥14 years of age admitted with a Glasgow Coma Scale (GCS) score of ≤8 (severe TBI) to the University of Pittsburgh Medical Center between July 1994 and May 2009. Clinical data were prospectively collected and linked to 6-month functional outcome (Glasgow Outcome Scale [GOS]) and mortality. The discriminatory power and calibration of the three iterations of the IMPACT model (core, extended, and lab) were assessed using multiple regression analyses and indicated by the area under the receiver operating characteristic curve (AUC). A sample of 587 patients was available for analysis; the mean age was 37.8±17 years. The median 6-month GOS was 3 (IQR 3); 6-month mortality was 41%. The prognostic models were composed of age, motor score, and pupillary reactivity (core model), Marshall grade on head CT and secondary insults (extended), and laboratory values (lab); all of these displayed good prediction ability for unfavorable outcome and mortality (unfavorable outcome AUC=0.76, 0.79, 0.76; mortality AUC=0.78, 0.83, 0.83, respectively). All model iterations displayed adequate calibration for predicting unfavorable outcome and mortality. Prospective, independent validation supports the IMPACT prognostic model's prediction of patient 6-month functional status and mortality after severe TBI. The IMPACT prognostic model is an effective instrument to assist TBI study design and analysis.

Epidemiology, severity classification, and outcome of moderate and severe traumatic brain injury: a prospective multicenter study

Changes in the demographics, approach, and treatment of traumatic brain injury (TBI) patients require regular evaluation of epidemiological profiles, injury severity classification, and outcomes. This prospective multicenter study provides detailed information on TBI-related variables of 508 moderate-to-severe TBI patients. Variability in epidemiology and outcome is examined by comparing our cohort with previous multicenter studies. Additionally, the relation between outcome and injury severity classification assessed at different time points is studied. Based on the emergency department Glasgow Coma Scale (GCS), 339 patients were classified as having severe and 129 as having moderate TBI. In 15%, the diagnosis differed when the accident scene GCS was used for classification. In-hospital mortality was higher if severe TBI was diagnosed at both time points (44%) compared to moderate TBI at one or both time points (7-15%, p<0.001). Furthermore, 14% changed diagnosis when a threshold (≥6 h) for impaired consciousness was used as a criterion for severe TBI: In-hospital mortality was<5% when impaired consciousness lasted for<6 h. This suggests that combining multiple clinical assessments and using a threshold for impaired consciousness may improve the classification of injury severity and prediction of outcome. Compared to earlier multicenter studies, our cohort demonstrates a different case mix that includes a higher age (mean=47.3 years), more diffuse (Traumatic Coma Databank [TCDB] I-II) injuries (58%), and more major extracranial injuries (40%), with relatively high 6 month mortality rates for both severe (46%) and moderate (21%) TBI. Our results confirm that TBI epidemiology and injury patterns have changed in recent years whereas case fatality rates remain high.

Risk factors for posttraumatic vasospasm

OBJECT

Posttraumatic vasospasm (PTV) is an underrecognized cause of ischemic damage after severe traumatic brain injury (TBI) that independently predicts poor outcome. There are, however, no guidelines for PTV screening and management, partly due to limited understanding of its pathogenesis and risk factors.

METHODS

A database review of 46 consecutive cases of severe TBI in pediatric and adult patients was conducted to identify risk factors for the development of PTV. Univariate analysis was performed to identify potential risk factors for PTV, which were subsequently analyzed using a multivariate logistic regression model to calculate odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

Fever on admission was an independent risk factor for development of PTV (OR 22.2, 95% CI 1.9-256.8), and patients with hypothermia on admission did not develop clinically significant vasospasm during their hospital stay. The presence of small parenchymal contusions was also an independent risk factor for PTV (OR 7.8, 95% CI 0.9-69.5), whereas the presence of subarachnoid hemorrhage or other patterns of intracranial injury were not. Other variables, such as age, sex, ethnicity, degree of TBI severity, or admission laboratory values, were not independent predictors for the development of clinically significant PTV.

CONCLUSIONS

Independent risk factors for PTV include parenchymal contusions and fever. These results suggest that diffuse mechanical injury and activation of inflammatory pathways may be underlying mechanisms for the development of PTV, and that a subset of patients with these risk factors may be an appropriate population for aggressive screening. Further studies are needed to determine if treatments targeting fever and inflammation may be effective in reducing the incidence of vasospasm following severe TBI.

Decrease in proven ventriculitis by reducing the frequency of cerebrospinal fluid sampling from extraventricular drains

OBJECT

Ventriculitis associated with extraventricular drains (EVD) increases rates of morbidity and mortality as well as costs. Surveillance samples of CSF are taken routinely from EVD, but there is no consensus on the optimum frequency of sampling. The goal of this study was to assess whether the incidence of ventriculitis changed when CSF sampling frequency was reduced once every 3 days.

METHODS

After receiving institutional ethics committee approval for their project, the authors compared a prospective sample of EVD-treated patients (admitted 2008-2009) and a historical comparison group (admitted 2005-2007) at two tertiary hospital ICUs. A broad definition of ventriculitis included suspected ventriculitis (that is, treated with antibiotics for ventriculitis) and proven ventriculitis (positive CSF culture). Adult ICU patients with no preexisting neurological infection were enrolled in the study. After staff was provided with an education package, sampling of CSF was changed from daily to once every 3 days. All other management of the EVD remained unchanged. More frequent sampling was permitted if clinically indicated during the third daily sampling phase.

RESULTS

Two hundred seven patients were recruited during the daily sampling phase and 176 patients when sampling was reduced to once every 3 days. The Acute Physiology and Chronic Health Evaluation (APACHE) II score was lower for the daily sampling group than for the every-3rd-day group (18.6 vs 20.3, respectively; p < 0.01), but there was no difference in mean age (47 and 45 years, respectively; p = 0.14), male or female sex (61% and 59%, respectively; p = 0.68), or median EVD duration in the ICU (4.9 and 5.8 days, respectively; p = 0.14). Most patients were admitted with subarachnoid hemorrhage (42% in the daily group and 33% in the every-3rd-day group) or traumatic head injuries (29% and 36%, respectively). The incidence of ventriculitis decreased from 17% to 11% overall and for proven ventriculitis from 10% to 3% once sampling frequency was reduced. Sampling of CSF once every 3 days was independently associated with ventriculitis (OR 0.44, 95% CI 0.22-0.88, p = 0.02).

CONCLUSIONS

Reducing the frequency of CSF sampling to once every 3 days was associated with a significant decrease in the incidence of ventriculitis. The authors suggest that CSF sampling should therefore be performed once every 3 days in the absence of clinical indicators of ventriculitis. Reducing frequency of CSF sampling from EVDs decreased proven ventriculitis.

Dyskalaemia associated with thiopentone barbiturate coma for refractory intracranial hypertension: a case series

PURPOSE

There have been case reports of hypokalaemia and hyperkalaemia on induction and cessation of thiopentone barbiturate coma for refractory intracranial hypertension, respectively. However, the incidence and characteristics are not well described.

METHODS

We performed a retrospective review of all patients who received thiopentone barbiturate therapy for refractory intracranial hypertension during an 18-month period from January 2004 to June 2005 in our neurosurgical intensive care unit (ICU).

RESULTS

During this time period, 47 patients received thiopentone barbiturate therapy for refractory intracranial hypertension. Forty-two (89.4%) patients developed hypokalaemia after induction of barbiturate therapy. The median time to onset of hypokalaemia was 11 (6-23) h and time to nadir of serum potassium levels was 25 (15-41) h. Sixteen (34%) patients developed hyperkalaemia on weaning of barbiturate therapy. The peak serum potassium levels developed 31 (28-56) h after cessation. All patients who developed hyperkalaemia had been hypokalaemic previously. The mean potassium replaced during hypokalaemia was higher in patients who developed hyperkalaemia compared to those who did not (230 ± 135 vs. 66 ± 70, p < 0.001).

CONCLUSIONS

Hypokalaemia and hyperkalaemia are frequently associated with induction and cessation of thiopentone barbiturate coma. Serum potassium levels must be monitored vigilantly. Patients who develop hypokalaemia and receive large potassium replacement may be at greater risk of hyperkalaemia on cessation.

Cyclosporin A preserves mitochondrial function after traumatic brain injury in the immature rat and piglet

Cyclosporin A (CsA) has been shown to be neuroprotective in mature animal models of traumatic brain injury (TBI), but its effects on immature animal models of TBI are unknown. In mature animal models, CsA inhibits the opening of the mitochondrial permeability transition pore (MPTP), thereby maintaining mitochondrial homeostasis following injury by inhibiting calcium influx and preserving mitochondrial membrane potential. The aim of the present study was to evaluate CsA's ability to preserve mitochondrial bioenergetic function following TBI (as measured by mitochondrial respiration and cerebral microdialysis), in two immature models (focal and diffuse), and in two different species (rat and piglet). Three groups were studied: injured+CsA, injured+saline vehicle, and uninjured shams. In addition, we evaluated CsA's effects on cerebral hemodynamics as measured by a novel thermal diffusion probe. The results demonstrate that post-injury administration of CsA ameliorates mitochondrial dysfunction, preserves cerebral blood flow (CBF), and limits neuropathology in immature animals 24 h post-TBI. Mitochondria were isolated 24 h after controlled cortical impact (CCI) in rats and rapid non-impact rotational injury (RNR) in piglets, and CsA ameliorated cerebral bioenergetic crisis with preservation of the respiratory control ratio (RCR) to sham levels. Results were more dramatic in RNR piglets than in CCI rats. In piglets, CsA also preserved lactate pyruvate ratios (LPR), as measured by cerebral microdialysis and CBF at sham levels 24 h after injury, in contrast to the significant alterations seen in injured piglets compared to shams (p<0.01). The administration of CsA to piglets following RNR promoted a 42% decrease in injured brain volume (p<0.01). We conclude that CsA exhibits significant neuroprotective activity in immature models of focal and diffuse TBI, and has exciting translational potential as a therapeutic agent for neuroprotection in children.

Hypertonic saline and mannitol therapy in critical care neurology

Osmotic agents play a vital role in the reduction of elevated intracranial pressure and treatment of cerebral edema in Neurologic critical care. Both mannitol and hypertonic saline reduce cerebral edema in many clinical syndromes, yet there is controversy over agent selection, timing, and dosing regimens. Despite the lack of randomized, controlled trials, our knowledge base on the appropriate clinical use of osmotic agents continues to expand. This review will summarize the evidence for the use of mannitol and hypertonic saline in a variety of disease states causing cerebral edema, as well as outlining monitoring and safety considerations.

Advanced neuroimaging in children with nonaccidental trauma

Physical abuse associated with nonaccidental trauma (NAT) affects approximately 144,000 children per year in the USA and, frequently, these injuries affect the developing brain. Most infants with suspected NAT are initially evaluated by skull X-rays and computed tomography to determine whether fractures are present, the severity of the acute injury and the need for urgent neurosurgical intervention. Increasingly, magnetic resonance imaging (MRI) is conducted as it provides additional diagnostic and prognostic information about the extent and nature of the injury. In this review, we examine 4 MRI techniques as they apply to children who present acutely after NAT. Susceptibility-weighted imaging is a 3-D high-resolution MRI technique that is more sensitive than conventional imaging in detecting hemorrhagic lesions that are often associated with diffuse axonal injury (DAI). Magnetic resonance spectroscopy acquires metabolite information reflecting neuronal integrity and function from multiple brain regions and provides a sensitive, noninvasive assessment of neurochemical alterations that offers early prognostic information regarding outcome. Diffusion-weighted imaging (DWI) is based on differences in the diffusion of water molecules within the brain and has been shown to be very sensitive in the early detection of ischemic injury. It is now being used to study the direct effects of traumatic injury as well as those due to secondary ischemia. Diffusion tensor imaging is a form of DWI and allows better evaluation of white matter fiber tracts by taking advantage of the intrinsic directionality (anisotropy) of water diffusion in the human brain. It has been shown to be useful in identifying white matter abnormalities after DAI when conventional imaging appears normal. Although these imaging methods have been studied primarily in adults and children with accidental traumatic brain injury, it is clear that they have the potential to provide additional value in the imaging and clinical evaluation of children with NAT.

Aminoglycoside pharmacokinetic parameters in neurocritical care patients undergoing induced hypothermia

STUDY OBJECTIVE

To determine the effects of mild-to-moderate induced hypothermia-a neuroprotectant and/or therapeutic strategy for the management of intracranial hypertension in neurologically injured patients-on the pharmacokinetics of aminoglycoside therapy.

DESIGN

Pharmacokinetic analysis.

SETTING

Critical care unit at a university-affiliated hospital.

PATIENTS

Three patients, aged 22, 24, and 47 years, who received tobramycin and had documented tobramycin levels while undergoing induced hypothermia for more than 24 hours for intracranial hypertension.

MEASUREMENTS AND MAIN RESULTS

For each of the three patients, predicted pharmacokinetic parameters (volume of distribution, first-order elimination rate constant, half-life, and renal drug clearance) based on population data were compared with their actual pharmacokinetic parameters that were calculated based on observed tobramycin serum levels. All three patients had a normal creatinine clearance, estimated according to established methods. When pharmacokinetic parameters were calculated after the first tobramycin dose using a one-compartment method, all patients had a slower first-order elimination rate and a larger volume of distribution compared with predicted population estimates.

CONCLUSION

These findings suggest that induced hypothermia may result in impaired elimination of aminoglycosides. Caution should be exercised when attempting to use predicted pharmacokinetic parameters to dose aminoglycosides in this patient population, and first-dose pharmacokinetics should be considered to optimize the dose and dosing interval early in the course of therapy. Further investigation of this phenomenon with greater numbers of patients are needed to confirm these findings and to determine optimal dosing strategies of aminoglycosides in patients undergoing induced hypothermia.

Prediction of outcome utilizing both physiological and biochemical parameters in severe head injury

Traumatic brain injury is a major socioeconomic burden, and the use of statistical models to predict outcomes after head injury can help to allocate limited health resources. Earlier prediction models analyzing admission data have been used to achieve prediction accuracies of up to 80%. Our aim was to design statistical models utilizing a combination of both physiological and biochemical variables obtained from multimodal monitoring in the neurocritical care setting as a complement to earlier models. We used decision tree and logistic regression analysis on variables including intracranial pressure (ICP), mean arterial pressure (MAP), cerebral perfusion pressure (CPP), and pressure reactivity index (PRx), as well as multimodal monitoring parameters to assess brain tissue oxygenation (PbtO(2)), and microdialysis parameters to predict outcomes based on a dichotomized Glasgow Outcome Score. Further analysis was carried out on various subgroup combinations of physiological and biochemical parameters. The reliability of the head injury models was assessed using a 10-fold cross-validation technique. In addition, the confusion matrix was also used to assess the sensitivity, specificity, and the F-ratio. In all, 2,413 time series records were extracted from 26 patients treated at our neurocritical care unit over a 1-year period. Decision tree analysis was found to be superior to logistic regression analysis in predictive accuracy of outcome. The combined use of microdialysis variables and PbtO(2), in addition to ICP, MAP, and CPP was found have the best predictive accuracy. The use of physiological and biochemical variables based on a decision tree analysis model has shown to provide an improvement in predictive accuracy compared with other previous models. The potential application is for outcome prediction in the multivariate setting of advanced multimodality monitoring, and validates the use of multimodal monitoring in the neurocritical care setting to have a potential benefit in predicting outcomes of patients with severe head injury.

Effect of short periods of normobaric hyperoxia on local brain tissue oxygenation and cerebrospinal fluid oxidative stress markers in severe traumatic brain injury

Preliminary evidence suggests local brain tissue oxygenation (PbtO(2)) values of <or=15 mm Hg following severe traumatic brain injury (TBI) represent brain tissue hypoxia. Accordingly, many neurotrauma units attempt to maintain PbtO(2) >or=20 mm Hg to avoid hypoxia. This study tested the impact of a short (2 h) trial of normobaric hyperoxia on measures of oxidative stress. We hypothesized this treatment would positively affect cerebral oxygenation but negatively affect the cellular environment via oxidative stress mechanisms. Cerebrospinal fluid (CSF) was serially assessed in 11 adults (9 male, 2 female), aged 26 +/- 1.8 years with severe TBI (Glasgow Coma Scale score, 6 +/- 1.4) before, during, and after a FiO(2) = 1.0 challenge for markers of oxidative stress, including lipid peroxidation (F(2)-isoprostane [ELISA]), protein oxidation (protein sulfhydryl [fluorescence]), and antioxidant defenses (total antioxidant reserve (AOR) [chemiluminescence] and glutathione [fluorescence]). Physiological parameters [PbtO(2), arterial oxygen content (PaO(2)), intracranial pressure (ICP), mean arterial pressure (MAP), and cerebral perfusion pressure (CPP)] were assessed at the same time points. Mean (+/-SD) PbtO(2) and PaO(2) levels significantly changed for each time point. Oxidative stress markers, antioxidant reserve defenses, and ICP, MAP, and CPP did not significantly change for any time period. These preliminary findings suggest that brief periods of normobaric hyperoxia do not produce oxidative stress and/or change antioxidant reserves in CSF. Additional studies are required to examine extended periods of normobaric hyperoxia in a larger sample.

Shaken baby syndrome in Switzerland: results of a prospective follow-up study, 2002-2007

Since the incidence of shaken baby syndrome in Switzerland was not known, we conducted a nationwide prospective follow-up study for a 5-year period (from 2002 to 2007). The data were collected through the Swiss Pediatric Surveillance Unit. Inclusion criteria were the presence, in a child <or=6 years of age, of 1) more than or equal to two clinical symptoms (altered consciousness, convulsions, respiratory irregularities, and bulging fontanel), 2) one eye finding (retinal hemorrhages, vitreous hemorrhages), 3) one MRI/CT finding (subdural hematoma, subarachnoid hematoma, and parenchymatous lesions), or 4) history of shaking. Exclusion criteria were age >6 years or documented accident/disease explaining symptoms/findings. To describe outcome, we used the King's Outcome Scale for Childhood Head Injury (KOSCHI). 56 cases were reported from 13 of 26 Swiss cantons, representing 80% of the Swiss population; 49 cases met the inclusion criteria. Preponderance of male infants was high (31 male and 18 female); median age at admission was 4 months (1-58). Clinical symptoms were present in 42 infants, retinal/vitreous hemorrhages in 39 infants, and pathological brain/head imaging in 46 infants. In 13 cases, the caregivers admitted shaking the child. Outcomes (KOSCHI 1-5; n = 47 patients) were death (KOSCHI 1) 8 (17.7%), vegetative state (KOSCHI 2) 0, severe disability (KOSCHI 3) 11 (22.2%), moderate disability (KOSCHI 4) 14 (31.1%), and good recovery (KOSCHI 5) 14 (28.8%). Based on these data, the incidence of shaken baby syndrome in Switzerland is 14 per 100 000 live births, which corresponds to the incidence in other Western countries. Demographic characteristics and outcomes of Swiss patients were comparable to published studies.

Contemporary pharmacologic issues in the management of traumatic brain injury

Traumatic brain injury (TBI) is a major cause of death and disability in the United States. While there are no pharmacotherapeutic options currently available for attenuating the neurologic injury cascade after TBI, numerous pharmacologic issues are encountered in these critically ill patients. Adequate fluid resuscitation, reversal of coagulopathy, maintenance of cerebral perfusion, and treatment of intracranial hypertension are common interventions early in the treatment of TBI. Other deleterious complications such as venous thromboembolism, extremes in glucose concentrations, and stress-related mucosal disease should be anticipated and avoided. Early provision of nutrition and prevention of drug or alcohol withdrawal are also cornerstones of routine care in TBI patients. Prevention of infections and seizures may also be helpful. Clinicians caring for TBI patients should be familiar with the pharmacologic issues typical of this vulnerable population in order to develop optimal strategies of care to anticipate and prevent common complications.

Surgical innovations arising from the Iraq and Afghanistan wars

The delivery of combat casualty care poses numerous challenges including austere conditions, limited supplies and medical personnel, and multiple simultaneous patients. However, the exigent circumstances of the battlefield compel the development of research and the advancement of adaptive, practical medical technologies to support and sustain military health. In Operation Enduring Freedom (OEF) and Operation Iraqi Freedom (OIF), modern changes in medical management, coupled with improved protective gear and evacuation capabilities, have facilitated the highest survival rate in combat history.

A prospective, randomized clinical trial to compare the effect of hyperbaric to normobaric hyperoxia on cerebral metabolism, intracranial pressure, and oxygen toxicity in severe traumatic brain injury

Object

Oxygen delivered in supraphysiological amounts is currently under investigation as a therapy for severe traumatic brain injury (TBI). Hyperoxia can be delivered to the brain under normobaric as well as hyperbaric conditions. In this study the authors directly compare hyperbaric oxygen (HBO2) and normobaric hyperoxia (NBH) treatment effects.

Methods

Sixty-nine patients who had sustained severe TBIs (mean Glasgow Coma Scale Score 5.8) were prospectively randomized to 1 of 3 groups within 24 hours of injury: 1) HBO2, 60 minutes of HBO2 at 1.5 ATA; 2) NBH, 3 hours of 100% fraction of inspired oxygen at 1 ATA; and 3) control, standard care. Treatments occurred once every 24 hours for 3 consecutive days. Brain tissue PO2, microdialysis, and intracranial pressure were continuously monitored. Cerebral blood flow (CBF), arteriovenous differences in oxygen, cerebral metabolic rate of oxygen (CMRO2), CSF lactate and F2-isoprostane concentrations, and bronchial alveolar lavage (BAL) fluid interleukin (IL)–8 and IL-6 assays were obtained pretreatment and 1 and 6 hours posttreatment. Mixed-effects linear modeling was used to statistically test differences among the treatment arms as well as changes from pretreatment to posttreatment.

Results

In comparison with values in the control group, the brain tissue PO2 levels were significantly increased during treatment in both the HBO2 (mean ± SEM, 223 ± 29 mm Hg) and NBH (86 ± 12 mm Hg) groups (p < 0.0001) and following HBO2 until the next treatment session (p = 0.003). Hyperbaric O2 significantly increased CBF and CMRO2 for 6 hours (p ≤ 0.01). Cerebrospinal fluid lactate concentrations decreased posttreatment in both the HBO2 and NBH groups (p < 0.05). The dialysate lactate levels in patients who had received HBO2 decreased for 5 hours posttreatment (p = 0.017). Microdialysis lactate/pyruvate (L/P) ratios were significantly decreased posttreatment in both HBO2 and NBH groups (p < 0.05). Cerebral blood flow, CMRO2, microdialysate lactate, and the L/P ratio had significantly greater improvement when a brain tissue PO2 ≥ 200 mm Hg was achieved during treatment (p < 0.01). Intracranial pressure was significantly lower after HBO2 until the next treatment session (p < 0.001) in comparison with levels in the control group. The treatment effect persisted over all 3 days. No increase was seen in the CSF F2-isoprostane levels, microdialysate glycerol, and BAL inflammatory markers, which were used to monitor potential O2 toxicity.

Conclusions

Hyperbaric O2 has a more robust posttreatment effect than NBH on oxidative cerebral metabolism related to its ability to produce a brain tissue PO2 ≥ 200 mm Hg. However, it appears that O2 treatment for severe TBI is not an all or nothing phenomenon but represents a graduated effect. No signs of pulmonary or cerebral O2 toxicity were present.

Ventilatory strategies for patients with acute brain injury

PURPOSE OF REVIEW

The ventilation of patients with acute brain injuries can present significant challenges. Frequently, guidelines recommending management strategies for patients with traumatic brain injuries come into conflict with what is now considered best ventilatory practice. In this review, we will explore many of these areas of conflict.

RECENT FINDINGS

The use of ventilatory strategies to control partial pressure of carbon dioxide in patients with traumatic brain injury is associated with the development of acute lung injury. Analysis of the International Mission for Prognosis And Clinical Trial (IMPACT) database has confirmed the association between hypoxia and poor neurological outcome. Although a recent meta-analysis has suggested a survival benefit for steroids in acute lung injury, the use of steroids has been associated with a worsening of outcome in patients with traumatic brain injuries and their effects on the brain have not been fully elucidated.

SUMMARY

There are unlikely to be randomized controlled trials advising how best to ventilate patients with acute brain injuries because of the heterogeneous nature of such injuries. Hypoxia should be avoided. The more widespread use of multimodal brain monitoring, including brain tissue oxygen and cerebral blood flow monitoring, may allow clinicians to tolerate a higher arterial partial pressure of carbon dioxide than has been traditional, allowing a less injurious ventilatory strategy. Modest positive end-expiratory pressure can be used. In severe respiratory failure, most 'rescue' strategies have been attempted in patients with acute brain injuries. Choice of rescue therapy at present is best decided on a case-by-case basis in conjunction with local expertise.

Explosive blast neurotrauma

Explosive blast traumatic brain injury (TBI) is one of the more serious wounds suffered by United States service members injured in the current conflicts in Iraq and Afghanistan. Some military medical treatments for blast TBI that have been introduced successfully in the war theater include decompressive craniectomy, cerebral angiography, transcranial Doppler, hypertonic resuscitation fluids, among others. Stateside neurosurgery, neuro-critical care, and rehabilitation for these patients have similarly progressed. With experience, military physicians have been able to clinically describe blast TBI across the entire severity spectrum. One important clinical finding is that a significant number of severe blast TBI victims develop pseudoaneurysms and vasospasm, which can lead to delayed decompensation. Another is that mild blast TBI shares clinical features with post-traumatic stress disorder (PTSD). Observations suggest that the mechanism by which explosive blast injures the central nervous system may be more complex than initially assumed. Rigorous study at the basic science and clinical levels, including detailed biomechanical analysis, is needed to improve understanding of this disease. A comprehensive epidemiological study is also warranted to determine the prevalence of this disease and the factors that contribute most to the risk of developing it. Sadly, this military-specific disease has significant potential to become a civilian one as well.

Brain tissue oxygen and outcome after severe traumatic brain injury: a systematic review

OBJECTIVE

In this study, available medical literature were reviewed to determine whether brain hypoxia as measured by brain tissue oxygen (Bto2) levels is associated with increased risk of poor outcome after traumatic brain injury (TBI). A secondary objective was to examine the safety profile of a direct BtO2 probe. DATA SOURCE AND EXTRACTION: Clinical studies published between 1993 and 2008 were identified from electronic databases, Index Medicus, bibliographies of pertinent articles, and expert consultation. The following inclusion criteria were applied for outcome analysis: 1) more than 10 patients described, 2) use of a direct Bto2 monitor, 3) brain hypoxia defined as Bto2 <10 mm Hg for >15 or 30 minutes, 4) 6-month outcome data, and 5) clear reporting of patient outcome associated with Bto2. For the analysis, each selected article had to have adequate data to determine odds ratios (ORs) and confidence intervals (CIs). Thirteen studies met the initial inclusion criteria and three were included in the final outcome analysis. Safety data were abstracted from any report where it was mentioned.

DATA SYNTHESIS

The three studies included 150 evaluable patients with severe TBI (Glasgow Coma Scale <or=8). Brain hypoxia was identified in 71 (47%) of these patients. Among the patients with brain hypoxia, 52 (73%) had unfavorable outcome including 39 (55%) who died. In the absence of brain hypoxia, 34 (43%) patients had an unfavorable outcome, including 17 (22%) who died. Overall brain hypoxia (Bto2 <10 mm Hg >15 minutes) was associated with worse outcome (OR 4.0; 95% CI 1.9-8.2) and increased mortality (OR 4.6; 95% CI 2.2-9.6). We reviewed published safety data; in 292 patients monitored with a Bto2 probe, only two adverse events were reported.

CONCLUSION

Summary results indicate that brain hypoxia (<10 mm Hg) is associated with worse outcome after severe TBI and that Bto2 probes are safe. These results imply that treating patients to increase Bto2 may improve outcome after severe TBI. This question will require further study.

Combination therapies for traumatic brain injury: prospective considerations

Traumatic brain injury (TBI) initiates a cascade of numerous pathophysiological events that evolve over time.Despite the complexity of TBI, research aimed at therapy development has almost exclusively focused on single therapies, all of which have failed in multicenter clinical trials. Therefore, in February 2008 the National Institute of Neurological Disorders and Stroke, with support from the National Institute of Child Health and Development, the National Heart, Lung, and Blood Institute, and the Department of Veterans Affairs, convened a workshop to discuss the opportunities and challenges of testing combination therapies for TBI. Workshop participants included clinicians and scientists from a variety of disciplines, institutions, and agencies. The objectives of the workshop were to: (1) identify the most promising combinations of therapies for TBI; (2) identify challenges of testing combination therapies in clinical and pre-clinical studies; and (3) propose research methodologies and study designs to overcome these challenges. Several promising combination therapies were discussed, but no one combination was identified as being the most promising. Rather, the general recommendation was to combine agents with complementary targets and effects (e.g., mechanisms and time-points), rather than focusing on a single target with multiple agents. In addition, it was recommended that clinical management guidelines be carefully considered when designing pre-clinical studies for therapeutic development.To overcome the challenges of testing combination therapies it was recommended that statisticians and the U.S. Food and Drug Administration be included in early discussions of experimental design. Furthermore, it was agreed that an efficient and validated screening platform for candidate therapeutics, sensitive and clinically relevant biomarkers and outcome measures, and standardization and data sharing across centers would greatly facilitate the development of successful combination therapies for TBI. Overall there was great enthusiasm for working collaboratively to act on these recommendations.

Transorbital penetrating head injury by a toilet brush handle

BACKGROUND

Transorbital penetrating brain injuries are rare lesions without defined therapy standards.

CLINICAL PRESENTATION AND INTERVENTION

A male patient presented at our institution with a toilet brush handle in the right cerebral hemisphere. CT imaging identified the object entering the right orbit and having crossed the right hemisphere in the ventricular plane. After performing a medium-sized craniotomy, the object was removed step-by-step under monitoring with an intraoperative CT scan to ensure no involving major hemorrhage.

CONCLUSION

Transorbital penetrating brain injuries are treated best by utilizing all up-to-date technical developments such as intraoperative CT-scanning to increase the safety in the management of such exceptional lesions with increased risk of immediate life-threatening intracranial bleeding.

Clinical impact of early hyperglycemia during acute phase of traumatic brain injury

INTRODUCTION

While tight glucose control has been widely adopted in the critical care setting, the optimal target glucose level following acute traumatic brain injury (TBI) remains debatable. This observational study was conducted to delineate the relationship between glucose levels and clinical outcomes during acute phase (first 5 days) of TBI.

METHODS

We retrospectively identified 429 TBI patients admitted to the intensive care unit (ICU) from January 2005 to December 2006. Of those, 380 patients were retained for final analysis. Collected data included demographics, admission Glasgow Coma Scale (GCS), and APACHE II, glucose on admission and during the first 5 days of admission, and insulin use. Clinical outcomes included mortality, ICU, and hospital length of stay.

RESULTS

The overall hospital mortality was 13.2% (n = 50). Demographics were similar between survivor and nonsurvivor groups; however, nonsurvivors were older and had worse disease severity on admission. Nonsurvivors also had significantly higher glucose levels at admission and during the first 24 h of admission (P < 0.001). Based on the receiver operating characteristic (ROC) curve, admission and day-1 peak glucose were better predictors for mortality compared to hospital days 2-5 glucose levels, with day-1 peak glucose being the best predictor of mortality (AUC = 0.820). A Kaplan-Meier survival analysis also showed that patients with glucose <160 mg/dl during the first day of ICU admission had a significantly better survival rate compared to those with glucose > or =160 mg/dl (P < 0.001). Two glucose bands, <60 and > or =160 mg/dl, were identified to be associated with increased mortality irrespective of injury severity (OR = 1.130; 95% CI 1.034-1.235; P = 0.007; OR = 1.034; 95% CI 1.021-1.047, P < 0.001; respectively).

CONCLUSIONS

Findings from our study suggest a glucose level > or =160 mg/dl within the first 24 h of admission following TBI is associated with poor outcomes irrespective of severity of injury, and this presents a timeframe for which active therapeutic interventions may improve clinical outcomes. Prospective efficacy trials are needed to corroborate these findings.

Emerging treatments for traumatic brain injury

BACKGROUND

This review summarizes promising approaches for the treatment of traumatic brain injury (TBI) that are in either preclinical or clinical trials.

OBJECTIVE

The pathophysiology underlying neurological deficits after TBI is described. An overview of select therapies for TBI with neuroprotective and neurorestorative effects is presented.

METHODS

A literature review of preclinical TBI studies and clinical TBI trials related to neuroprotective and neurorestorative therapeutic approaches is provided.

RESULTS/CONCLUSION

Nearly all Phase II/III clinical trials in neuroprotection have failed to show any consistent improvement in outcome for TBI patients. The next decade will witness an increasing number of clinical trials that seek to translate preclinical research discoveries to the clinic. Promising drug- or cell-based therapeutic approaches include erythropoietin and its carbamylated form, statins, bone marrow stromal cells, stem cells singularly or in combination or with biomaterials to reduce brain injury via neuroprotection and promote brain remodeling via angiogenesis, neurogenesis, and synaptogenesis with a final goal to improve functional outcome of TBI patients. In addition, enriched environment and voluntary physical exercise show promise in promoting functional outcome after TBI, and should be evaluated alone or in combination with other treatments as therapeutic approaches for TBI.

Cerebral pressure autoregulation in traumatic brain injury

An understanding of normal cerebral autoregulation and its response to pathological derangements is helpful in the diagnosis, monitoring, management, and prognosis of severe traumatic brain injury (TBI). Pressure autoregulation is the most common approach in testing the effects of mean arterial blood pressure on cerebral blood flow. A gold standard for measuring cerebral pressure autoregulation is not available, and the literature shows considerable disparity in methods. This fact is not surprising given that cerebral autoregulation is more a concept than a physically measurable entity. Alterations in cerebral autoregulation can vary from patient to patient and over time and are critical during the first 4-5 days after injury. An assessment of cerebral autoregulation as part of bedside neuromonitoring in the neurointensive care unit can allow the individualized treatment of secondary injury in a patient with severe TBI. The assessment of cerebral autoregulation is best achieved with dynamic autoregulation methods. Hyperventilation, hyperoxia, nitric oxide and its derivates, and erythropoietin are some of the therapies that can be helpful in managing cerebral autoregulation. In this review the authors summarize the most important points related to cerebral pressure autoregulation in TBI as applied in clinical practice, based on the literature as well as their own experience.

Induced normothermia attenuates intracranial hypertension and reduces fever burden after severe traumatic brain injury

INTRODUCTION

Hyperthermia following a severe traumatic brain injury (TBI) is common, potentiates secondary injury, and worsens neurological outcome. Conventional fever treatment is often ineffective. An induced normothermia protocol, utilizing intravascular cooling, was used to assess the impact on fever incidence and intracranial pressure (ICP) in patients with severe TBI.

METHODS

A comparative cohort study of 21 adult patients with severe TBI (GCS <or= 8) treated with induced normothermia [36-36.5 degrees C rectal probe setting; intravascular cooling catheter (CoolLine, Alsius Corporation, Irvine, CA)] were matched by age, gender, and severity of injury to 21 historical control severe TBI patients treated with conventional fever control methods. ICP was measured via an external ventricular catheter and time duration for ICP > 25 mmHg was calculated for the initial 72-h monitoring period. Non-parametric rank tests were performed.

RESULTS

Mean (+/-SD) or median [range] demographics did not differ between groups [total N = 42 (6 female, 36 male, age 36.4 +/- 14.8 years and initial GCS 7 [3-8], median and range]. Fever burden in the first 3 days (time >38 degrees C) in the induced normothermia versus control group was significantly less at 1.6% versus 10.6%, respectively (P = 0.03). Mean ICP for patients with induced normothermia versus control was 12.74 +/- 4.0 and 16.37 +/- 6.9 mmHg, respectively. Furthermore, percentage of time with ICP > 25 mmHg was significantly less in the induced normothermia group (P = 0.03).

CONCLUSION

Induced normothermia (fever prophylaxis via intravascular cooling catheter) is effective in reducing fever burden and may offer a means to attenuate secondary injury, as evidenced by a reduction in the intracranial hypertension burden.