The relation between acute physiological variables and outcome on the Glasgow Outcome Scale and Disability Rating Scale following severe traumatic brain injury

Long-Term Outcomes in Severe Traumatic Brain Injury and Associated Factors: A Prospective Cohort Study

OBJECTIVE

The presence of focal lesion (FL) after a severe traumatic brain injury is an important factor in determining morbidity and mortality. Despite this relevance, few studies show the pattern of recovery of patients with severe traumatic brain injury (TBI) with FL within one year. The objective of this study was to identify the pattern of recovery, independence to perform activities of daily living (ADL), and factors associated with mortality and unfavorable outcome at six and twelve months after severe TBI with FL.

METHODOLOGY

This is a prospective cohort, with data collected at admission, hospital discharge, three, six, and twelve months after TBI.

RESULTS

The study included 131 adults with a mean age of 34.08 years. At twelve months, 39% of the participants died, 80% were functionally independent by the Glasgow Outcome Scale Extended, 79% by the Disability Rating Scale, 79% were independent for performing ADLs by the Katz Index, and 53.9% by the Lawton Scale. Report of alcohol intake, sedation time, length of stay in intensive care (ICU LOS), Glasgow Coma Scale, trauma severity indices, hyperglycemia, blood glucose, and infection were associated with death. At six and twelve months, tachypnea, age, ICU LOS, trauma severity indices, respiratory rate, multiple radiographic injuries, and cardiac rate were associated with dependence.

CONCLUSIONS

Patients have satisfactory functional recovery up to twelve months after trauma, with an accentuated improvement in the first three months. Clinical and sociodemographic variables were associated with post-trauma outcomes. Almost all victims of severe TBI with focal lesions evolved to death or independence.

Downstream TRPM4 Polymorphisms Are Associated with Intracranial Hypertension and Statistically Interact with ABCC8 Polymorphisms in a Prospective Cohort of Severe Traumatic Brain Injury

Sulfonylurea-receptor-1(SUR1) and its associated transient-receptor-potential cation channel subfamily-M (TRPM4) channel are key contributors to cerebral edema and intracranial hypertension in traumatic brain injury (TBI) and other neurological disorders. Channel inhibition by glyburide is clinically promising. ABCC8 (encoding SUR1) single-nucleotide polymorphisms (SNPs) are reported as predictors of raised intracranial pressure (ICP). This project evaluated whether TRPM4 SNPs predicted ICP and TBI outcome. DNA was extracted from 435 consecutively enrolled severe TBI patients. Without a priori selection, all 11 TRPM4 SNPs available on the multiplex platform (Illumina:Human-Core-Exome v1.0) were genotyped spanning the 25 exon gene. A total of 385 patients were analyzed after quality control. Outcomes included ICP and 6 month Glasgow Outcome Scale (GOS) score. Proxy SNPs, spatial modeling, and functional predictions were determined using established software programs. rs8104571 (intron-20) and rs150391806 (exon-24) were predictors of ICP. rs8104571 heterozygotes predicted higher average ICP (β = 10.3 mm Hg, p = 0.00000029), peak ICP (β = 19.6 mm Hg, p = 0.0007), and proportion ICP >25 mm Hg (β = 0.16 p = 0.004). rs150391806 heterozygotes had higher mean (β = 7.2 mm Hg, p = 0.042) and peak (β = 28.9 mm Hg, p = 0.0015) ICPs. rs8104571, rs150391806, and 34 associated proxy SNPs in linkage-disequilibrium clustered downstream. This region encodes TRPM4's channel pore and a region postulated to juxtapose SUR1 sequences encoded by an ABCC8 DNA segment containing previously identified relevant SNPs. There was an interaction effect on ICP between rs8104571 and a cluster of predictive ABCC8 SNPs (rs2237982, rs2283261, rs11024286). Although not significant in univariable or a basic multivariable model, in an expanded model additionally accounting for injury pattern, computed tomographic (CT) appearance, and intracranial hypertension, heterozygous rs8104571 was associated with favorable 6 month GOS (odds ratio [OR] = 16.7, p = 0.007951). This trend persisted in a survivor-only subcohort (OR = 20.67, p = 0.0168). In this cohort, two TRPM4 SNPs predicted increased ICP with large effect sizes. Both clustered downstream, spanning a region encoding the channel pore and interacting with SUR1. If validated, this may guide risk stratification and eventually inform treatment-responder classification for SUR1-TRPM4 inhibition in TBI. Larger studies are warranted.

Prognosis of Six-Month Glasgow Outcome Scale in Severe Traumatic Brain Injury Using Hospital Admission Characteristics, Injury Severity Characteristics, and Physiological Monitoring during the First Day Post-Injury

Gold standard prognostic models for long-term outcome in patients with severe traumatic brain injury (TBI) use admission characteristics and are considered useful in some areas but not for clinical practice. In this study, we aimed to build prognostic models for 6-month Glasgow Outcome Score (GOS) in patients with severe TBI, combining baseline characteristics with physiological, treatment, and injury severity data collected during the first 24 h after injury. We used a training dataset of 472 TBI subjects and several data mining algorithms to predict the long-term neurological outcome. Performance of these algorithms was assessed in an independent (test) sample of 158 subjects. The least absolute shrinkage and selection operator (LASSO) led to the highest prediction accuracy (area under the receiving operating characteristic curve = 0.86) in the test set. The most important post-baseline predictor of GOS was the best motor Glasgow Coma Scale (GCS) recorded in the first day post-injury. The LASSO model containing the best motor GCS and baseline variables as predictors outperformed a model with baseline data only. TBI patient physiology of the first day-post-injury did not have a major contribution to patient prognosis six months after injury. In conclusion, 6-month GOS in patients with TBI can be predicted with good accuracy by the end of the first day post-injury, using hospital admission data and information on the best motor GCS achieved during those first 24 h post-injury. Passed the first day after injury, important physiological predictors could emerge from landmark analyses, leading to prediction models of higher accuracy than the one proposed in the current research.

Longitudinal Changes in Disability Rating Scale Scores: A Secondary Analysis Among Patients With Severe TBI Enrolled in the Epo Clinical Trial

OBJECTIVES

Long-term neurological response to treatment after a severe traumatic brain injury (sTBI) is a dynamic process. Failure to capture individual heterogeneity in recovery may impact findings from single endpoint sTBI randomized controlled trials (RCT). The present study re-examined the efficacy of erythropoietin (Epo) and transfusion thresholds through longitudinal modeling of sTBI recovery as measured by the Disability Rating Scale (DRS). This study complements the report of primary outcomes in the Epo sTBI RCT, which failed to detect significant effects of acute treatment at 6 months post-injury.

METHODS

We implemented mixed effects models to characterize the recovery time-course and to examine treatment efficacy as a function of time post-injury and injury severity.

RESULTS

The inter-quartile range (25th-75th percentile) of DRS scores was 20-28 at week1; 8-24 at week 4; and 3-17 at 6 months. TBI severity group was found to significantly interact with Epo randomization group on mean DRS recovery curves. No significant differences in DRS recovery were found in transfusion threshold groups.

CONCLUSIONS

This study demonstrated the value of taking a comprehensive view of recovery from sTBI in the Epo RCT as a temporally dynamic process that is shaped by both treatment and injury severity, and highlights the importance of the timing of primary outcome measurement. Effects of Epo treatment varied as a function of injury severity and time. Future studies are warranted to understand the possible moderating influence of injury severity on treatment effects pertaining to sTBI recovery. (JINS, 2019, 25, 293-301).

Effect of hypoxia on mortality and disability in traumatic brain injury according to shock status: A cross-sectional analysis

OBJECTIVES

This study aimed to test the association between hypoxia level and outcomes according to shock status in traumatic brain injury (TBI) patients.

METHODS

Adult TBI patients transported by emergency medical services in 10 provinces were enrolled. Hypoxia was a main exposure; three groups by oxygen saturation (SaO2, non-hypoxia (≥94%), mild hypoxia (90 ≤ SaO2 < 94%)), and severe hypoxia (<90%). Shock status (<systolic blood pressure 90 mmHg) was an interactive exposure. The outcomes were hospital mortality and worsened disability (a 2-point increase of Glasgow Outcome Scale). Multivariable logistic regression was used to calculate the adjusted odds (AORs) with 95% Confidence intervals (CIs).

RESULTS

Of the 6125 patients, the mortality/disability rates were 49.4%/69.0% in severe hypoxia, 30.7%/46.9% in mild hypoxia, and 18.5%/27.5% in normoxia (p < 0.0001). Mortality/disability rates were 47.1%/57.1% in shock status and 20.5%/31.4% in non-shock status (p < 0.0001). AORs (95% CIs) for worsened disability/mortality compared with normoxia (reference) were 3.23 (2.47-4.21)/2.24 (1.70-2.96) in patients with severe hypoxia and 2.11 (1.63-2.74)/1.84 (1.39-2.45) in those with mild hypoxia. AORs (95% CIs) for worsened disability/mortality was 1.58 (1.20-2.09)/1.33 (1.01-1.76) by severe hypoxia than normoxia in patient with only non-shock status in the interaction analysis.

CONCLUSIONS

There was a trend toward worsened outcomes with mild and severe hypoxia in patient with and without shock, however, the only met statistical significance for patients with both severe hypoxia and non-shock status.

A Precision Medicine Approach to Cerebral Edema and Intracranial Hypertension after Severe Traumatic Brain Injury: Quo Vadis?

PURPOSE OF REVIEW

Standard clinical protocols for treating cerebral edema and intracranial hypertension after severe TBI have remained remarkably similar over decades. Cerebral edema and intracranial hypertension are treated interchangeably when in fact intracranial pressure (ICP) is a proxy for cerebral edema but also other processes such as extent of mass lesions, hydrocephalus, or cerebral blood volume. A complex interplay of multiple molecular mechanisms results in cerebral edema after severe TBI, and these are not measured or targeted by current clinically available tools. Addressing these underpinnings may be key to preventing or treating cerebral edema and improving outcome after severe TBI.

RECENT FINDINGS

This review begins by outlining basic principles underlying the relationship between edema and ICP including the Monro-Kellie doctrine and concepts of intracranial compliance/elastance. There is a subsequent brief discussion of current guidelines for ICP monitoring/management. We then focus most of the review on an evolving precision medicine approach towards cerebral edema and intracranial hypertension after TBI. Personalization of invasive neuromonitoring parameters including ICP waveform analysis, pulse amplitude, pressure reactivity, and longitudinal trajectories are presented. This is followed by a discussion of cerebral edema subtypes (continuum of ionic/cytotoxic/vasogenic edema and progressive secondary hemorrhage). Mechanisms of potential molecular contributors to cerebral edema after TBI are reviewed. For each target, we present findings from preclinical models, and evaluate their clinical utility as biomarkers and therapeutic targets for cerebral edema reduction. This selection represents promising candidates with evidence from different research groups, overlap/inter-relatedness with other pathways, and clinical/translational potential. We outline an evolving precision medicine and translational approach towards cerebral edema and intracranial hypertension after severe TBI.

Modified Revised Trauma-Marshall score as a proposed tool in predicting the outcome of moderate and severe traumatic brain injury

Background

Traumatic brain injury (TBI) is a common healthcare problem related to disability. An easy-to-use trauma scoring system informs physicians about the severity of trauma and helps to decide the course of management. The purpose of this study is to use the combination of both physiological and anatomical assessment tools that predict the outcome and develop a new modified prognostic scoring system in TBIs.

Patients and methods

A total of 181 subjects admitted to the emergency department (ED) of Sanglah General Hospital were documented for both Marshall CT scan classification score (MCTC) and Revised Trauma Score (RTS) upon admission. Glasgow Outcome Scale (GOS) was then documented at six months after brain injury. A new Modified Revised Trauma–Marshall score (m-RTS) was developed using statistical analytic methods.

Results

The total sample enrolled for this study was 181 patients. The mean RTS upon admission was 10.2±1.2. Of the 181 subjects, 110 (60.8%) were found to have favorable GOS (GOS score >3). Best Youden’s index results were obtained with any of the RTS of ≤10 with area under receiver operating characteristic (ROC) curve of 0.2542 and with risk ratio of 2.9 (95% CI=1.98−4.28; P=0.001); and Marshall score ≤2 with area under ROC curve of 0.2249 with risk ratio of 3.9 (95% CI=2.52−5.89; P=0.001). The RTS–Marshall combination has higher sensitivity with risk ratio of 4.5 (CI 95%=2.55−8.0; P=0.001) for screening tools of unfavorable outcome. The Pearson’s correlation between RTS and Marshall classification is 0.464 (P<0.001).

Conclusion

Combination of physiological and anatomical score improves the prognostic of outcome in moderate and severe TBI patients, formulated in this accurate, simple, applicable and reliable m-RTS prognostic score model.

COBI (COntinuous hyperosmolar therapy for traumatic Brain-Injured patients) trial protocol: a multicentre randomised open-label trial with blinded adjudication of primary outcome

INTRODUCTION

Traumatic brain injury (TBI) is a major cause of death and severe prolonged disability. Intracranial hypertension (ICH) is a critical risk factor of bad outcomes after TBI. Continuous infusion of hyperosmolar therapy has been proposed for the prevention and the treatment of ICH. Whether an early administration of continuous hyperosmolar therapy improves long-term outcomes of patients with TBI is uncertain. The aim of the COBI study (number clinicaltrial.gov 03143751, pre-results stage) is to assess the efficiency and the safety of continuous hyperosmolar therapy in patients with TBI.

METHODS AND ANALYSIS

The COBI (COntinuous hyperosmolar therapy in traumatic Brain-Injured patients) trial is a multicentre, randomised, controlled, open-label, two-arms study with blinded adjudication of primary outcome. Three hundred and seventy patients hospitalised in intensive care unit with a TBI (Glasgow Coma Scale ≤12 and abnormal brain CT scan) are randomised in the first 24 hours following trauma to standard care or continuous hyperosmolar therapy (20% NaCl) plus standard care. Continuous hyperosmolar therapy is maintained for at least 48 hours in the treatment group and continued for as long as is necessary to prevent ICH. The primary outcome is the score on the Extended Glasgow Outcome Scale at 6 months. The treatment effect is estimated with ordinal logistic regression adjusted for prespecified prognostic factors and expressed as a common OR.

ETHICS AND DISSEMINATION

The COBI trial protocol has been approved by the ethics committee of Paris Ile de France VIII and will be carried out according to the principles of the Declaration of Helsinki and the Good Clinical Practice guidelines. The results of this study will be disseminated through presentation at scientific conferences and publication in peer-reviewed journals. The COBI trial is the first randomised controlled trial powered to investigate whether continuous hyperosmolar therapy in patients with TBI improve long-term recovery.

TRIAL REGISTRATION NUMBER

Trial registration number is NCT03143751.

International Classification of Diseases 10th edition-based disability adjusted life years for measuring of burden of specific injury

Objective

We aimed to develop an International Classification of Diseases (ICD) 10th edition injury code-based disability-adjusted life year (DALY) to measure the burden of specific injuries.

Methods

Three independent panels used novel methods to score disability weights (DWs) of 130 indicator codes sampled from 1,284 ICD injury codes. The DWs were interpolated into the remaining injury codes (n=1,154) to estimate DWs for all ICD injury codes. The reliability of the estimated DWs was evaluated using the test-retest method. We calculated ICD-DALYs for individual injury episodes using the DWs from the Korean National Hospital Discharge Injury Survey (HDIS, n=23,160 of 2004) database and compared them with DALY based on a global burden of disease study (GBD-DALY) regarding validation, correlation, and agreement for 32 injury categories.

Results

Using 130 ICD 10th edition injury indicator codes, three panels determined the DWs using the highest reliability (person trade-off 1, Spearman r=0.724, 0.788, and 0.875 for the three panel groups). The test-retest results for the reliability were excellent (Spearman r=0.932) (P<0.001). The HDIS database revealed injury burden (years) as follows: GBD-DALY (138,548), GBD-years of life disabled (130,481), and GBD-years of life lost (8,117) versus ICD-DALY (262,246), ICD-years of life disabled (255,710), and ICD-years of life lost (6,537), respectively. Spearman’s correlation coefficient of the DALYs between the two methods was 0.759 (P<0.001), and the Bland-Altman test displayed an acceptable agreement, with exception of two categories among 32 injury groups.

Conclusion

The ICD-DALY was developed to calculate the burden of injury for all injury codes and was validated with the GBD-DALY. The ICD-DALY was higher than the GBD-DALY but showed acceptable agreement.

Past, Present, and Future of Traumatic Brain Injury Research

Traumatic brain injury (TBI) is the greatest cause of death and severe disability in young adults; its incidence is increasing in the elderly and in the developing world. Outcome from severe TBI has improved dramatically as a result of advancements in trauma systems and supportive critical care, however we remain without a therapeutic which acts directly to attenuate brain injury. Recognition of secondary injury and its molecular mediators has raised hopes for such targeted treatments. Unfortunately, over 30 late-phase clinical trials investigating promising agents have failed to translate a therapeutic for clinical use. Numerous explanations for this failure have been postulated and are reviewed here. With this historical context we review ongoing research and anticipated future trends which are armed with lessons from past trials, new scientific advances, as well as improved research infrastructure and funding. There is great hope that these new efforts will finally lead to an effective therapeutic for TBI as well as better clinical management strategies.

Intracranial pressure monitoring: fundamental considerations and rationale for monitoring

Traumatic brain injury (TBI) is a major cause of death and disability worldwide. In large part critical care for TBI is focused on the identification and management of secondary brain injury. This requires effective neuromonitoring that traditionally has centered on intracranial pressure (ICP). The purpose of this paper is to review the fundamental literature relative to the clinical application of ICP monitoring in TBI critical care and to provide recommendations on how the technique maybe applied to help patient management and enhance outcome. A PubMed search between 1980 and September 2013 identified 2,253 articles; 244 of which were reviewed in detail to prepare this report and the evidentiary tables. Several important concepts emerge from this review. ICP monitoring is safe and is best performed using a parenchymal monitor or ventricular catheter. While the indications for ICP monitoring are well established, there remains great variability in its use. Increased ICP, particularly the pattern of the increase and ICP refractory to treatment is associated with increased mortality. Class I evidence is lacking on how monitoring and management of ICP influences outcome. However, a large body of observational data suggests that ICP management has the potential to influence outcome, particularly when care is targeted and individualized and supplemented with data from other monitors including the clinical examination and imaging.

[Fluid resuscitation in hemorrhage]

How fluid resuscitation has to be performed for acute hemorrhage situations is still controversially discussed. Although the forced administration of crystalloids and colloids has been and still is practiced, nowadays there are good arguments that a cautious infusion of crystalloids may be initially sufficient. Saline should no longer be used for fluid resuscitation. The main argument for cautious fluid resuscitation is that no large prospective randomized clinical trials exist which have provided evidence of improved survival when fluid resuscitation is applied in an aggressive manner. The explanation that no positive effect has so far been observed is that fluid resuscitation is thought to boost bleeding by increasing blood pressure and dilutional coagulopathy. Nevertheless, national and international guidelines recommend that fluid resuscitation should be applied at the latest when hemorrhage causes hemodynamic instability. Consideration should be given to the fact that damage control resuscitation per se will neither improve already reduced tissue perfusion nor hemostasis. In acute and possibly rapidly progressing hypovolemic shock, colloids can be used. The third and fourth generations of hydroxyethyl starch (HES) are safe and effective if used correctly and within prescribed limits. If fluid resuscitation is applied with ongoing re-evaluation of the parameters which determine oxygen supply, it should be possible to keep fluid resuscitation restricted without causing undesirable side effects and also to administer a sufficient quantity so that survival of patients is ensured.

Design of acute neuroprotection studies

Traumatic brain injury (TBI) is a substantial public health problem. The discovery of progressive, ongoing damage to the brain by means of complex molecular mechanisms which follow the initial injury has raised the possibility of targeted therapeutic intervention. Despite a substantial investment in trials testing dozens of therapeutics in humans, however, to date none has demonstrated robust efficacy. Deficiencies in the design of human clinical trials is likely to explain many translational failures, at least in part. Here we review secondary injury mediators and key trials which have targeted them. We provide a thorough discussion of putative reasons why trials thus far have failed and suggestions for the design of future clinical studies. Important insights from the IMPACT study are also presented in detail; in addition to providing critical insights for future trial design and analysis it suggests that reanalysis of completed studies may reveal inappropriately discarded treatments. Unfortunately limited resources are available for translational research and it is difficult to procure funds needed for well-resourced, large and definitive studies. History suggests, however, that investing in studies that are unlikely to provide a definitive answer only serves to increase required investment as they tend to mandate further study.

Addressing the challenges of obtaining functional outcomes in traumatic brain injury research: missing data patterns, timing of follow-up, and three prognostic models

Traumatic brain injury (TBI) is common and debilitating. Randomized trials of interventions for TBI ideally assess effectiveness by using long-term functional neurological outcomes, but such outcomes are difficult to obtain and costly. If there is little change between functional status at hospital discharge versus 6 months, then shorter-term outcomes may be adequate for use in future clinical trials. Using data from a previously published multi-center, randomized, placebo-controlled TBI clinical trial, we evaluated patterns of missing outcome data, changes in functional status between hospital discharge and 6 months, and three prognostic models to predict long-term functional outcome from covariates available at hospital discharge (functional measures, demographics, and injury characteristics). The Resuscitation Outcomes Consortium Hypertonic Saline trial enrolled 1282 TBI patients, obtaining the primary outcome of 6-month Glasgow Outcome Score Extended (GOSE) for 85% of patients, but missing the primary outcome for the remaining 15%. Patients with missing outcomes had less-severe injuries, higher neurological function at discharge (GOSE), and shorter hospital stays than patients whose GOSE was obtained. Of 1066 (83%) patients whose GOSE was obtained both at hospital discharge and at 6-months, 71% of patients had the same dichotomized functional status (severe disability/death vs. moderate/no disability) after 6 months as at discharge, 28% had an improved functional status, and 1% had worsened. Performance was excellent (C-statistic between 0.88 and 0.91) for all three prognostic models and calibration adequate for two models (p values, 0.22 and 0.85). Our results suggest that multiple imputation of the standard 6-month GOSE may be reasonable in TBI research when the primary outcome cannot be obtained through other means.

Intracranial pressure versus cerebral perfusion pressure as a marker of outcomes in severe head injury: a prospective evaluation

BACKGROUND

Intracranial pressure (ICP) monitoring is a standard of care in severe traumatic brain injury when clinical features are unreliable. It remains unclear, however, whether elevated ICP or decreased cerebral perfusion pressure (CPP) predicts outcome.

METHODS

This is a prospective observational study of patients sustaining severe blunt head injury, admitted to the surgical intensive care unit at the Los Angeles County and University of Southern California Medical Center between January 2010 and December 2011. The study population was stratified according to the findings of ICP and CPP. Primary outcomes were overall in-hospital mortality and mortality because of cerebral herniation. Secondary outcomes were development of complications during the hospitalization.

RESULTS

A total of 216 patients met Brain Trauma Foundation guidelines for ICP monitoring. Of those, 46.8% (n = 101) were subjected to the intervention. Sustained elevated ICP significantly increased all in-hospital mortality (adjusted odds ratio [95% confidence interval]: 3.15 [1.11, 8.91], P = .031) and death because of cerebral herniation (adjusted odds ratio [95% confidence interval]: 9.25 [1.19, 10.48], P = .035). Decreased CPP had no impact on mortality.

CONCLUSIONS

A single episode of sustained increased ICP is an accurate predictor of poor outcomes. Decreased CPP did not affect survival.

Persistent extreme regressive behavior in severe traumatic brain injury patients: a rare neurological phenomenon

Regressive behavior is a known sequela after severe traumatic brain injury (TBI). However, prolonged "infantile-like" behavior has received little attention in the literature, suggesting that this is a rare phenomenon. It is typically characterized by long-lasting childish, extremely dependent, and sometimes aggressive behavior, which is distinguished from the expected recovery process. The relevant theoretical framework lies in the field of disorders called "Neuropathologies of the self" (NPS). We report three cases of young adults who, following a severe TBI, developed continual regressive behavior. The Disability Rating Scale (DRS) was used to assess possible change in their condition. First, while admitted, which was performed in retrospect, and again 6 years later at the time stated. Inter-rater reliability for the scale items showed adequate correlation. Results showed no significant difference in patients' scores, indicating persistent functional difficulties. We conclude that this "regressive syndrome" presents an unusual form of behavior that is stable over time. It seems to be in line with other NPS disorders, and may stem from an interaction of organic factors and primary mental complexity. Nevertheless, further research is required to examine the factors affecting the emergence and recovery from this phenomenon.

The emerging use of ketamine for anesthesia and sedation in traumatic brain injuries

Traditionally, the use of ketamine for patients with traumatic brain injuries is contraindicated due to the concern of increasing intracranial pressure (ICP). These concerns, however, originated from early studies and case reports that were inadequately controlled and designed. Recently, the concern of using ketamine in these patients has been challenged by a number of published studies demonstrating that the use of ketamine was safe in these patients. This article reviews the current literature in regards to using ketamine in patients with traumatic brain injuries in different clinical settings associated with anesthesia, as well as reviews the potential mechanisms underlying the neuroprotective effects of ketamine. Studies examining the use of ketamine for induction, maintenance, and sedation in patients with TBI have had promising results. The use of ketamine in a controlled ventilation setting and in combination with other sedative agents has demonstrated no increase in ICP. The role of ketamine as a neuroprotective agent in humans remains inconclusive and adequately powered; randomized controlled trials performed in patients undergoing surgery for traumatic brain injury are necessary.

The role of endothelin and endothelin antagonists in traumatic brain injury: a review of the literature

OBJECTIVES

To date, there is increasing evidence for the role of endothelins in the pathophysiological development of cerebral vasospasms associated with a variety of neurological diseases, e.g., stroke and subarachnoid hemorrhage. In contrast, only little is known regarding the role of endothelins in impaired cerebral hemodynamics after traumatic brain injury. Therapeutic work in blocking the endothelin system has led to the discovery of a number of antagonists potentially useful in restoring cerebral blood flow after traumatic brain injury, potentially reducing the detrimental effects of secondary brain injury. Therefore, the present work provides an overview of background topics such as structures and biosynthesis of endothelins, different types as well as potential mechanisms and sites of action. In addition, the role of age for the effects of endothelins on cerebral hemodynamics after traumatic brain injury is discussed.

RESULTS

Description of data supporting the role of the endothelins play in a host of neurological deficits.

CONCLUSIONS

Endothelin antagonists may be effective as novel treatments for various neuropathologies.

Dispositional optimism and outcome following traumatic brain injury

OBJECTIVE

Despite vast literature examining the predictors of patient outcome following traumatic brain injury (TBI), the complicated relationship between personality and psychological, cognitive and functional outcomes remains poorly understood. The present study examined the relationship between the personality trait of dispositional optimism (DO) and outcome after moderate and severe TBI in the context of a proposed theoretical model.

METHODS

Forty-five individuals who had sustained moderate-to-severe TBI were recruited through mailings and completed the Symptom Checklist Questionnaire-90 Revised (SCL-90-R), the Telephone Interview for Cognitive Status (TICS), the Craig Handicap Assessment Reporting Technique (CHART) and the Life Orientation Test-Revised (LOT-R). Analyses were conducted to test a model predicting the relationship between personality and patient outcome after TBI.

RESULTS

DO was significantly correlated with psychological distress, but did not predict functional outcome. In addition, two significant mediating relationships were demonstrated: (1) psychological distress was shown to mediate the relationship between dispositional optimism and cognitive ability and (2) cognitive ability mediated the relationship between psychological distress and functional outcome.

CONCLUSION

These findings illustrate that higher levels of DO in individuals sustaining moderate-to-severe TBI are related to better psychological functioning which in turn predicts improved cognitive and functional outcomes.

Prediction of depression and anxiety 1 year after moderate-severe traumatic brain injury

This study examined three scales of the Personality Assessment Inventory (PAI; Anxiety, Anxiety-Related Disorders, and Depression) in 88 participants 1 year after they suffered a moderate-severe traumatic brain injury (TBI). Participants were all enrolled in the federally funded Traumatic Brain Injury Model System project at Carolinas Rehabilitation. The following variables were assessed at the time of injury: age, sex, employment and marital status, and length of loss of consciousness. Disability status, using the Disability Rating Scale (DRS), was assessed at the time of discharge from the rehabilitation hospital. A series of three linear regression analyses found that these variables significantly predicted scores on the Anxiety and Anxiety-Related Disorders scales, which accounted for 14% and 17.7% of the variance, respectively. The variables did not significantly predict scores on the Depression scale. Within each regression analysis, DRS was consistently and negatively related to each PAI scale, such that greater disability was associated with better psychological functioning. Such seemingly paradoxical findings are discussed in terms of anosognosia or poor awareness of psychological functioning among those with greater disability 1 year after TBI.

Relationship of aggressive monitoring and treatment to improved outcomes in severe traumatic brain injury

OBJECT

Despite being common practice for decades and being recommended by national guidelines, aggressive monitoring and treatment of patients with severe traumatic brain injury (TBI) have not been supported by convincing evidence.

METHODS

The authors reviewed trials and case series reported after 1970 in which patients were treated for severe closed TBI, and mortality rates and favorable outcomes at 6 months after injury were analyzed. The patient groups were divided into those with and without intracranial pressure (ICP) monitoring and intensive therapy, and the authors performed a meta-analysis to assess the effects of treatment intensity on outcome.

RESULTS

Although the mortality rate fell during the years reviewed, it was consistently approximately 12% lower among patients in the intense treatment group (p < 0.001). Favorable outcomes did not change significantly over time, and were 6% higher among the aggressively treated patients (p = 0.0105).

CONCLUSIONS

Aggressive ICP monitoring and treatment of patients with severe TBI is associated with a statistically significant improvement in outcome. This improvement occurs independently of temporal effects.

Early prognosis in traumatic brain injury: from prophecies to predictions

Traumatic brain injury (TBI) is a heterogeneous condition that encompasses a broad spectrum of disorders. Outcome can be highly variable, particularly in more severely injured patients. Despite the association of many variables with outcome, prognostic predictions are notoriously difficult to make. Multivariable analysis has identified age, clinical severity, CT abnormalities, systemic insults (hypoxia and hypotension), and laboratory variables as relevant factors to include in models to predict outcome in individual patients. Advances in statistical modelling and the availability of large datasets have facilitated the development of prognostic models that have greater performance and generalisability. Two prediction models are currently available, both of which have been developed on large datasets with state-of-the-art methods, and offer new opportunities. We see great potential for their use in clinical practice, research, and policy making, as well as for assessment of the quality of health-care delivery. Continued development, refinement, and validation is advocated, together with assessment of the clinical impact of prediction models, including treatment response.

Effect of urbanicity of residence on TBI outcome at one year post-injury

OBJECTIVE

To determine the impact of urbanicity of residence and occurrence of medical complications on outcome after traumatic brain injury (TBI).

STUDY DESIGN

A consecutive series of persons admitted for inpatient TBI rehabilitation followed for 1 year post-injury.

SETTING

Inpatient brain injury rehabilitation programme in the southeastern US.

PARTICIPANTS

One hundred and eleven persons with severe (67%), moderate (18%) or mild (15%) TBI.

OUTCOME MEASURE

Functional status at 2 year post-injury as measured by the Disability Rating Scale (DRS).

RESULTS

Functional status at follow-up was predicted by age, DRS at admission for rehabilitation, injury severity, alcohol use, continued need for medications and medical complications (validated R2 = 0.57; p < 0.0001). Urbanicity of residence was not predictive of functional status.

CONCLUSIONS

As expected, participants who experienced more medical complications and required continued use of medications had poorer functional outcomes. Contrary to expectation, more rural residents did not have poorer outcomes than persons residing in more urban areas.

Physiologic and functional outcome correlates of brain tissue hypoxia in traumatic brain injury

OBJECTIVE

Assess the prevalence of brain tissue hypoxia in patients with severe traumatic brain injuries (TBI), and to characterize the relationship between brain tissue hypoxia and functional outcome.

DESIGN

Retrospective review of severe TBI patients.

SETTING

Intensive care unit of a level I trauma center.

PATIENTS

Twenty-seven patients with severe TBI requiring intracranial pressure (ICP) monitoring. Median age was 22 yrs, and a majority (63%) had traumatic subarachnoid hemorrhage.

INTERVENTIONS

Hourly assessments of ICP, brain tissue oxygen, mean arterial pressure, fraction of inspired oxygen (FiO2), partial pressure of arterial carbon dioxide (PaCO2), and hemoglobin concentration (hemoglobin) were recorded. Outcome was assessed 6-9 months postinjury.

MEASUREMENTS AND MAIN RESULTS

Mean (SD) ICP and BTpO2 were 13.7 (6.6) cm H2O and 30.8 (13.6) mm Hg. A total of 13.5% (379) of the BTpO2 values recorded were < 20 mm Hg, only 86 of which were associated with ICP > or = 20 cm H2O. This prevalence was comparable with episodes of ICP elevations above 20 cm H2O (14.1%, 397). Hypoxic episodes were more common when cerebral perfusion pressure was below 60 mm Hg (relative risk = 3.0, p < 0.0001). We did not find an association in hypoxic risk and hemoglobin in the range of 7-12 g/dL or PaCO2 in the range of 25-40 mm Hg. Subjects with hourly episodes (epochs) of hypoxia > 20% of the time had poorer scores on outcome measures compared with those with fewer hypoxic epochs.

CONCLUSIONS

Hypoxic episodes are common after severe TBI, and most are independent of ICP elevations. Most episodes of hypoxia occur while cerebral perfusion pressure and mean arterial pressure are within the accepted target range. There is no clear association between PaCO2 and hemoglobin with BTpO2. The young age and high prevalence of traumatic subarachnoid hemorrhage in this cohort may limit its generalizability. Increased frequency of hypoxic episodes is associated with poor functional outcome.

Blood Pressure Management in Acute Head Injury

Head injury remains a major cause of preventable death and serious morbidity in young adults. Based on the available evidence, it appears that a cerebral perfusion pressure of 50 to 70 mm Hg is generally adequate to ensure cerebral oxygen delivery and prevent ischemia. However, evidence suggests that perfusion requirements may not only vary across the injured brain but also differ depending on the time since injury. Such heterogeneity, both within and between subjects, suggests that individualized therapy may be an appropriate treatment strategy. Future studies should aim to assess which groups of patients, and what regional pathophysiological derangements, may benefit with improvements in functional outcome from therapeutic increases or decreases in cerebral perfusion pressure beyond these proposed limits. Such functional improvements may be of immense importance to patients and require formal neurocognitive assessments to discriminate improvements.

Cushing's ulcer in traumatic brain injury

Traumatic brain injury (TBI) remains a complicated and urgent disease in our modernized cities. It becomes now a public health disease. We have got more and more patients in Neurosurgery Intensive Care Unit following motor vehicle accidents and others causes. TBI brings multiple disorders, from the primary injury to secondary injury. The body received the disturbances in the brain, in the hypothalamo-pituitary-adrenocortical (HPA) axis, in the gastric mucosa, in the immune and neuroendocrine systems. The mortality of TBI is more than 50 000 deaths / year, the third of the mortality of all injuries. Cushing ulcer is one of the severe complications of TBI and its mortality rate is more than 50%. Many studies have improved the management of TBI and the associated complications to give patients a better outcome. Furthers studies need to be done based on the similar methodology to clarify the different steps of the HPA axis and the neuroendocrine change associated. The aim of the present review is to assess the clinical and endocrinal features of hypopituitarism and stress ulcer following TBI.

Intensive care unit variables and outcome after pediatric traumatic brain injury: a retrospective study of survivors

OBJECTIVE

Traumatic brain injury is a leading cause of death and disability in children. Hypotension has been associated with poor survival and outcome in children after traumatic brain injury, but the effect of acute hypertension is less certain. The objective was to obtain acute physiologic variables during the early hospitalization period in a cohort of children prospectively enrolled in another study.

DESIGN

Retrospective chart reviews.

SETTING

University-affiliated pediatric rehabilitation center.

PATIENTS

Fifty-seven survivors, 5-17 yrs of age, admitted for rehabilitation between 1992 and 1995 after sustaining a traumatic brain injury.

INTERVENTIONS

Standard of care.

MEASUREMENTS AND MAIN RESULTS

Outcomes were assessed at 1 yr postinjury through cognitive testing of the child and parent interview of the child's global functional skills. Cognitive outcome was measured using the Performance IQ from the Wechsler Intelligence Scale for Children, Third Edition. Overall functional outcome was assessed using the Disability Rating Scale.

CONCLUSIONS

This study suggests that early markers of secondary injury after moderate to severe traumatic brain injury in children may be predictive of long-term outcome. This study reinforces the need for longer term, systematic, and more precise measurements of outcomes in children with traumatic brain injury and prospective studies to examine the predictive value of acute management variables on multiple types of outcomes after traumatic brain injury in children.

New approaches to physiological informatics in neurocritical care

INTRODUCTION

A fundamental purpose of neurocritical care is the management of secondary brain injury. This is often accomplished by monitoring and managing individual patient parameters including physiological vital signs. Yet, the ability to record physiological data exceeds our ability to fully integrate it into patient care. We propose that advances in monitoring must be accompanied by advances in methods of high-frequency, multivariate data analysis that integrate the multiple processes occurring in critically ill patients.

METHODS

We describe initial work in the emerging field of physiological informatics in critical care medicine. We analyzed data on 23 patients with brain injury from our Neurotrauma and Critical Care Database, which contains more than 20 physiological parameters recorded automatically at one-minute intervals via bedside monitors connected to standard personal computers. We performed exploratory data analysis, studied two patient cases in detail, and implemented a data-driven classification approach using hierarchical clustering.

RESULTS

In this study, we present challenges and opportunities for high-frequency multimodal monitoring to quantitatively detect secondary brain insults, and develop clustering methodology to construct multivariate physiological data "profiles" to classify patients for diagnosis and treatment.

CONCLUSIONS

Recording of many physiological variables across multiple patients is feasible and can lead to new clinical insights. Computational and analytical methods previously used primarily for basic science may have clinical relevance and can potentially be adapted to provide physicians with improved ability to integrate complex information for decision making in neurocritical care.

Hemodynamic manipulation in the neuro-intensive care unit: cerebral perfusion pressure therapy in head injury and hemodynamic augmentation for cerebral vasospasm

PURPOSE OF REVIEW

The intent of this manuscript is to summarize the pathophysiologic basis for hemodynamic manipulation in subarachnoid hemorrhage and traumatic brain injury, highlight the most recent literature and present expert opinion on indications and use.

RECENT FINDINGS

Hemodynamic augmentation with vasopressors and inotropes along with hypervolemia are the mainstay of treatment of vasospasm due to subarachnoid hemorrhage. Considerable variation continues to exist regarding fluid management and the use of vasopressors and inotropes. Blood pressure augmentation, volume expansion and cardiac contractility enhancement improve cerebral blood flow in ischemic areas, ameliorate vasospasm and improve clinical condition. In patients suffering from severe traumatic brain injury, while every attempt is made to control intracranial hypertension, cerebral perfusion-directed therapy with fluids and vasopressors is also used to keep cerebral perfusion pressure above 60-70 mmHg. Yet, recent observations suggest that posttraumatic mitochondrial dysfunction has been proposed as an alternative explanation for lower cerebral blood flow after acute trauma.

SUMMARY

Hemodynamic manipulation is routinely used in the management of patients with acute vasospasm following subarachnoid hemorrhage and severe head injury. The rationale is to improve blood flow to the injured brain and prevent secondary ischemia.

Effect of Continuous Display of Cerebral Perfusion Pressure on Outcomes in Patients With Traumatic Brain Injury

• Background Clinical bedside monitoring systems do not provide prominent displays of data on cerebral perfusion pressure (CPP). Immediate visual feedback would allow more rapid intervention to prevent or minimize suboptimal pressures.

• Objective To evaluate the effect of a highly visible CPP display on immediate and long-term functional outcome in patients with traumatic brain injury.

• Methods A total of 157 patients with traumatic brain injury at a level 1 trauma center who had invasive arterial blood pressure and intracranial pressure monitoring were randomized to beds with or without an additional, prominent continuous CPP display. Primary end points were scores on the Extended Glasgow Outcome Scale (GOSE) and Functional Status Examination (FSE) 6 months after injury. Secondary end points were GOSE scores at discharge and 3 months after injury and FSE score 3 months after injury.

• Results Although GOSE and FSE scores at 6 months were better in the group with the highly visible CPP display, the differences were not significant. Slope of recovery for GOSE and FSE over all follow-up time points did not differ significantly between groups. However, the intervention’s positive effect on odds of survival at hospital discharge was strong and significant. Within a subgroup of more severely injured patients, the intervention group was much less likely than the control group to have CPP deviations.

• Conclusions The presence of a highly visible display of CPP was associated with significantly better odds of survival and overall condition at discharge.

The vegetative state: a report of two cases with a long-term follow-up

OBJECTIVES

To demonstrate that patients with Prolonged Vegetative State (PVS) can show signs of improvements and important changes and, consequently, to strengthen the necessity to evaluate them with long-term serial follow-ups.

SETTING

Rehabilitation of patients with severe traumatic brain injury (TBI).

PARTICIPANTS

Two people with severe TBI discharged after a long period of inpatient rehabilitation in a condition of PVS.

RESULTS

After 5 years some important changes happened and the initial prognosis was proved to be wrong.

CONCLUSION

Sometimes patients declared to be in PVS have the possibility to recover, especially when initial clinical conditions are particularly severe and do not allow the emergence of the state of consciousness. It is important to conduct regular follow-ups to better evaluate changes and, if it is necessary, to re-adjust the rehabilitation accordingly.

Early Versus Later Admission to Postacute Rehabilitation: Impact on Functional Outcome After Traumatic Brain Injury

OBJECTIVE

To examine the impact of participation in a postacute community reentry program on functional outcome after traumatic brain injury (TBI).

DESIGN

Cohort, nonrandomized, intervention study. Pretest-posttest, follow-up design.

SETTING

Nonprofit outpatient community reentry program affiliated with an inpatient rehabilitation hospital.

PARTICIPANTS

Three groups of persons with moderate to severe TBI differing in length of time between injury and admission. The first group entered postacute rehabilitation within 6 months of injury (n=115); the second group, between 6 and 12 months (n=23); and the third group, greater than 12 months (n=29).

INTERVENTIONS

Persons with TBI participated in a postacute community reentry program (average, 4.3mo) that emphasized (1) teaching compensatory strategies to address residual cognitive deficits; (2) arranging environmental supports to maximize functioning; (3) counseling and education to address personal and family adjustment and to improve accurate self-awareness; and (4) transition from simulated activities in the clinic to productive activities in the community.

MAIN OUTCOME MEASURES

Disability Rating Scale, Supervision Rating Scale, and the Community Integration Questionnaire.

RESULTS

All groups showed improvements between admission and discharge on measures of overall disability, independence, home competency, and productivity, and these gains were maintained at follow-up. For the group beginning postacute rehabilitation the earliest (<6mo postinjury) independence continued to improve after discharge. Community integration total score and home competency also continued to improve even after discharge.

CONCLUSIONS

The results point toward the effectiveness of postacute rehabilitation in improving functional outcome after TBI even for persons who have reached stable neurologic recovery at 12 or more months postinjury.

Brain tissue oxygen monitoring in intracerebral hemorrhage

INTRODUCTION

Brain tissue oxygen (PbrO2) monitoring is an emerging technique for detection of secondary brain injury in neurocritical care. Although it has been extensively reported in traumatic brain injury and aneurysmal subarachnoid hemorrhage, its use in nontraumatic intracerebral hemorrhage (ICH) has not been well described. We report complementary preliminary studies in a large animal model and in patients that demonstrate the feasibility of PbrO2 monitoring after ICH.

METHODS

To assess early events after ICH, Licox Clark-type oxygen probes were inserted in the bilateral frontal white matter of four anesthetized swine that subsequently underwent right parietal hematoma formation in an experimental model of ICH. Intracranial pressure (ICP) was monitored as well. Seven patients with acute ICH, who were undergoing ICP monitoring as part of standard neurocritical care, had placement of a frontal oxygen probe, with subsequent monitoring for up to 7 days.

RESULTS

In the swine ICH model, a rise in ICP early after hematoma formation was accompanied by a decrease in ipsilateral and contralateral PbrO2. Secondary increases in hematoma volume resulted in further decreases in PbrO2 over the first hour after ICH. In patients undergoing oxygen monitoring, low PbrO2 (<15 mmHg) was common. In these patients, changes in FiO2, mean arterial pressure, and cerebral perfusion pressure (but not ICP) predicted subsequent change in PbrO2.

CONCLUSION

Brain tissue oxygen monitoring is feasible in ICH patients, as well as in a swine model of ICH. Translational research that emphasizes complementary information derived from human and animal studies may yield additional insights not available from either alone.

Mitochondrial damage and dysfunction in traumatic brain injury

The enduring cognitive deficits and histopathology associated with traumatic brain injury (TBI) may arise from damage to mitochondrial populations, which initiates the metabolic dysfunction observed in clinical and experimental TBI. The anecdotal evidence for in vivo structural damage to mitochondria corroborates metabolic and physiologic dysfunction, which depletes substrates and promotes free radical generation. Excessive calcium pathology differentially disrupts the heterogeneous mitochondrial population, such that calcium sensitivity increases after TBI. The ongoing pathology may escalate to include protein and DNA oxidation that impacts mitochondrial function and promotes cell death. Thus, in vivo TBI damages, if not eliminates, mitochondrial populations depending on injury severity, with the remaining population left to provide metabolic support for survival or repair in the wake of cellular pathology. With a considerable understanding of post-injury mitochondrial populations, therapeutic interventions targeted to the mitochondria may delay or prevent secondary cascades that lead to long-term cell death and neurobehavioral disability.

Lateral fluid percussion brain injury: a 15-year review and evaluation

This article comprehensively reviews the lateral fluid percussion (LFP) model of traumatic brain injury (TBI) in small animal species with particular emphasis on its validity, clinical relevance and reliability. The LFP model, initially described in 1989, has become the most extensively utilized animal model of TBI (to date, 232 PubMed citations), producing both focal and diffuse (mixed) brain injury. Despite subtle variations in injury parameters between laboratories, universal findings are evident across studies, including histological, physiological, metabolic, and behavioral changes that serve to increase the reliability of the model. Moreover, demonstrable histological damage and severity-dependent behavioral deficits, which partially recover over time, validate LFP as a clinically-relevant model of human TBI. The LFP model, also has been used extensively to evaluate potential therapeutic interventions, including resuscitation, pharmacologic therapies, transplantation, and other neuroprotective and neuroregenerative strategies. Although a number of positive studies have identified promising therapies for moderate TBI, the predictive validity of the model may be compromised when findings are translated to severely injured patients. Recently, the clinical relevance of LFP has been enhanced by combining the injury with secondary insults, as well as broadening studies to incorporate issues of gender and age to better approximate the range of human TBI within study design. We conclude that the LFP brain injury model is an appropriate tool to study the cellular and mechanistic aspects of human TBI that cannot be addressed in the clinical setting, as well as for the development and characterization of novel therapeutic interventions. Continued translation of pre-clinical findings to human TBI will enhance the predictive validity of the LFP model, and allow novel neuroprotective and neuroregenerative treatment strategies developed in the laboratory to reach the appropriate TBI patients.

Réunion de neuroanesthésie-réanimation. Prise en charge anesthésique du patient en hypertension intracrânienne aiguë

Transcranial Doppler and, if possible, measurement of intracranial pressure (ICP) allow preoperative diagnosis of acute intracranial hypertension (ICH) after brain trauma. The main goal of the anaesthesiologist is to prevent the occurrence of secondary brain injuries and to avoid cerebral ischaemia. Treatment of high ICP is mainly achieved with osmotherapy. High-dose mannitol administration (1.4 to 2 g/kg given in bolus doses) may be considered a better option than conventional doses, especially before emergency evacuation of a cerebral mass lesion. Hypertonic saline seems as effective as mannitol without rebound effect and without diuresis increase. Haemostasis should be normalized before neurosurgery and invasive blood pressure monitoring is mandatory. For anaesthesia induction, thiopental or etomidate may be used. In case of ICH, halogenated and nitrous oxide should be avoided. Until the dura is open, mean arterial pressure should be maintained around 90 mmHg (or cerebral perfusion pressure around 70 mmHg). If a long-lasting (several hours) extracranial surgery is necessary, ICP should be monitored and treatment of ICH should have been instituted before.

Influence of data resolution and interpolation method on assessment of secondary brain insults in neurocritical care

Continuous monitoring of physiologic vital signs is routine in neurocritical care. However, this patient information is usually only recorded intermittently (most often hourly) in the medical record. It is unclear whether this is sufficient to represent the occurrence of secondary brain insults (SBIs) or whether more frequent data collection will provide more comprehensive information for patient care. In 16 patients, physiologic data were acquired concurrently via two methods: per clinical routine, usually hourly, in the medical record (MR) and every minute via a custom data acquisition system (DA). SBIs were defined as a mean arterial pressure<90 mmHg, an intracranial pressure>20 mmHg or a temperature>37.5 degrees C. Number of events, cumulative duration of events and area under the curve (AUC) were compared between the two methods and 95% limits of agreement were assessed for various methods of MR data interpolation. For all three parameters, analysis of the DA and MR data frequently differed with regard to number of events, total duration of events and AUC. MR data tended to underestimate the number of total events. 95% limits of agreement were most narrow for trapezoidal interpolation of MR data, but even these limits were fairly broad. Assessment of secondary brain insults is highly dependent on (1) the temporal resolution of the method used to acquire patient data and on (2) the interpolation method if data are acquired intermittently. High frequency data acquisition may be necessary for more precise evaluation of secondary brain injury in neurocritical care.

Age, intracranial pressure, autoregulation, and outcome after brain trauma

Object. The object of this study was to investigate whether a failure of cerebrovascular autoregulation contributes to the relationship between age and outcome in patients following head injury.

Methods. Data obtained from continuous bedside monitoring of intracranial pressure (ICP), arterial blood pressure (ABP), and cerebral perfusion pressure (CPP = ABP — ICP) in 358 patients with head injuries and intermittent monitoring of transcranial Doppler blood flow velocity (FV) in the middle cerebral artery in 237 patients were analyzed retrospectively. Indices used to describe cerebral autoregulation and pressure reactivity were calculated as correlation coefficients between slow waves of systolic FV and CPP (autoregulation index [ARI]) and between ABP and ICP (pressure reactivity index [PRI]).

Older patients had worse outcomes after brain trauma than younger patients (p = 0.00001), despite the fact that the older patients had higher initial Glasgow Coma Scale scores (p = 0.006). When age was considered as an independent variable, it appeared that ICP decreased with age (p = 0.005), resulting in an increasing mean CPP (p = 0.0005). Blood FV was not dependent on age (p = 0.58). Indices of autoregulation and pressure reactivity demonstrated a deterioration in cerebrovascular control with advancing age (PRI: p = 0.003; ARI: p = 0.007).

Conclusions. An age-related decline in cerebrovascular autoregulation was associated with a relative deterioration in outcome in elderly patients following head trauma.