Effects of the neurological wake-up test on intracranial pressure and cerebral perfusion pressure in brain-injured patients

Early neurological wake-up test in intubated patients with traumatic brain injury

BACKGROUND

Daily wake-up has been implemented widely in intensive care units (ICU) and could improve the patients' prognosis. However, little is known about the benefit of early neurological wake-up test (ENWT) in patients with acute traumatic brain injury (TBI). We aimed to investigate the role of ENWT as a clinical monitoring tool for TBI and its association with prognosis.

METHODS

This is an observational retrospective study included intubated and continuously sedated TBI in ICU, and all data were extracted from three tertiary hospitals from China. The main exposure of interest was ENWT, defined as cessation of sedation within 24 h after admission. The primary outcome was 28-day mortality. Propensity score matching (PSM) was performed at a 1:1 ratio. Multivariable analyses were further used to adjust for residual confounders.

RESULTS

The pre-matched and propensity score-matched cohorts included 1386 and 704 patients, respectively. In the PSM analysis, 28-day mortality was 24.7% (87/352) in the ENWT group and 37.2% (131/352) in the control group. ENWT was associated with lower 28-day mortality (hazard ratio [HR], 0.57; 95% CI, 0.44-0.76; P < 0.001). ENWT was also associated with lower in-hospital mortality (odds ratio [OR], 0.54; 95% CI, 0.38-0.77; P = 0.001), and higher discharge-home rate (OR, 1.83; 95% CI, 1.19-2.83; P = 0.006). A sensitivity analysis using the entire cohort also demonstrated lower 28-day mortality (HR, 0.58; 95% CI, 0.44-0.75; P < 0.001). However, it should be noted that ENWT was related to a higher rate of delirium during ICU stay (OR, 1.66; 95% CI, 1.21-2.26; P = 0.001). Further analysis demonstrated that tracheostomy during ICU stay led to a significant difference in 28-day mortality.

CONCLUSION

ENWT was associated with a lower risk-adjusted 28-day mortality in acute TBI patients. A higher rate of tracheostomy may partly contribute to this relationship.

Prolonged hourly neurological examinations are associated with increased delirium and no discernible benefit in mild/moderate geriatric traumatic brain injury

BACKGROUND

Serial neurological examinations (NEs) are routinely recommended in the intensive care unit (ICU) within the first 24 hours following a traumatic brain injury (TBI). There are currently no widely accepted guidelines for the frequency of NEs. Disruptions to the sleep-wake cycles increase the delirium rate. We aimed to evaluate whether there is a correlation between prolonged hourly (Q1)-NE and development of delirium and to determine if this practice reduces the likelihood of missing the detection of a process requiring emergent intervention.

METHODS

A retrospective analysis of patients with mild/moderate TBI, admitted to the ICU with serial NEs, was performed. Cohorts were stratified by the duration of exposure to Q1-NE, into prolonged (≥24 hours) and nonprolonged (<24 hours). Our primary outcomes of interest were delirium, evaluated using the Confusion Assessment Method; radiological progression from baseline images; neurological deterioration (focal neurological deficit, abnormal pupillary examination, or Glasgow Coma Scale score decrease >2); and neurosurgical procedures.

RESULTS

A total of 522 patients were included. No significant differences were found in demographics. Patients in the prolonged Q1-NE group (26.1%) had higher Injury Severity Score with similar head Abbreviated Injury Score, significantly higher delirium rate (59% vs. 35%, p < 0.001), and a longer hospital/ICU length of stay when compared with the nonprolonged Q1-NE group. No neurosurgical interventions were found to be performed emergently as a result of findings on NEs. Multivariate analysis demonstrated that prolonged Q1-NE was the only independent risk factor associated with a 2.5-fold increase in delirium rate. The number needed to harm for prolonged Q1-NE was 4.

CONCLUSION

Geriatric patients with mild/moderate TBI exposed to Q1-NE for periods longer than 24 hours had nearly a threefold increase in ICU delirium rate. One of five patients exposed to prolonged Q1-NE is harmed by the development of delirium. No patients were found to directly benefit as a result of more frequent NEs.

LEVEL OF EVIDENCE

Prognostic and Epidemiological; Level IV.

The neurological wake-up test in severe pediatric traumatic brain injury: a long term, single-center experience

Objectives

To describe the use and outcomes of the neurological wake-up test (NWT) in pediatric severe traumatic brain injury (pTBI).

Design

Retrospective single-center observational cohort study.

Setting

Medical-surgical tertiary pediatric intensive care unit (PICU) in a university medical center and Level 1 Trauma Center.

Patients

Children younger than 18 years with severe TBI [i.e., Glasgow Coma Scale (GCS) of ≤8] admitted between January 2010 and December 2020. Subjects with non-traumatic brain injury were excluded.

Measurements and main results

Of 168 TBI patients admitted, 36 (21%) met the inclusion criteria. Median age was 8.5 years [2 months to 16 years], 5 patients were younger than 6 months. Median initial Glasgow Coma Scale (GCS) and Glasgow Motor Scale (GMS) was 6 [3-8] and 3 [1-5]. NWTs were initiated in 14 (39%) patients, with 7 (50%) labelled as successful. Fall from a height was the underlying injury mechanism in those seven. NWT-failure occurred in patients admitted after traffic accidents. Sedation use in both NWT-subgroups (successful vs. failure) was comparable. Cause of NWT-failure was non-arousal (71%) or severe agitation (29%). Subjects with NWT failure subsequently had radiological examination (29%), repeat NWT (43%), continuous interruption of sedation (14%) or intracranial pressure (ICP) monitoring (14%). The primary reason for not doing NWTs was intracranial hypertension in 59%. Compared to the NWT-group, the non-NWT group had a higher PRISM III score (18.9 vs. 10.6), lower GCS/GMS at discharge, more associated trauma, and circulatory support. Nine patients (25%) died during their PICU admission, none of them had an NWT.

Conclusion

We observed limited use of NWTs in pediatric severe TBI. Patients who failed the NWT were indistinguishable from those without NWT. Both groups were more severely affected compared to the NWT successes. Therefore, our results may indicate that only a select group of severe pTBI patients qualify for the NWT.

Neuromonitoring During ECMO Support in Children

Extracorporeal membrane oxygenation is a potentially lifesaving intervention for children with severe cardiac or respiratory failure. It is used with increasing frequency and in increasingly more complex and severe diseases. Neurological injuries are important causes of morbidity and mortality in children treated with extracorporeal membrane oxygenation and include ischemic stroke, intracranial hemorrhage, hypoxic-ischemic injury, and seizures. In this review, we discuss the epidemiology and pathophysiology of neurological injury in patients supported with extracorporeal membrane oxygenation, and we review the current state of knowledge for available modalities of monitoring neurological function in these children. These include structural imaging with computed tomography and ultrasound, cerebral blood flow monitoring with near-infrared spectroscopy and transcranial Doppler ultrasound, and physiological monitoring with electroencephalography and plasma biomarkers. We highlight areas of need and emerging advances that will improve our understanding of neurological injury related to extracorporeal membrane oxygenation and help to reduce the burden of neurological sequelae in these children.

[Postoperative management following decompressive hemicraniectomy for malignant middle cerebral artery infarction-A German nationwide survey study]

BACKGROUND

Malignant middle cerebral artery infarction is a potentially life-threatening disease. Decompressive hemicraniectomy constitutes an evidence-based treatment practice, especially in patients under 60 years of age; however, recommendations with respect to postoperative management and particularly duration of postoperative sedation lack standardization.

OBJECTIVE

This survey study aimed to analyze the current situation of patients with malignant middle cerebral artery infarction following hemicraniectomy in the neurointensive care setting.

MATERIAL AND METHODS

From 20 September 2021 to 31 October 2021, 43 members of the initiative of German neurointensive trial engagement (IGNITE) network were invited to participate in a standardized anonymous online survey. Descriptive data analysis was performed.

RESULTS

Out of 43 centers 29 (67.4%) participated in the survey, including 24 university hospitals. Of the hospitals 21 have their own neurological intensive care unit. While 23.1% favored a standardized approach regarding postoperative sedation, the majority utilized individual criteria (e.g., intracranial pressure increase, weaning parameters, complications) to assess the need and duration. The timing of targeted extubation varied widely between hospitals (≤ 24 h 19.2%, ≤ 3 days in 30.8%, ≤ 5 days in 19.2%, > 5 days in 15.4%). Early tracheotomy (≤ 7 days) is performed in 19.2% and 80.8% of the centers aim for tracheotomy within 14 days. Hyperosmolar treatment is used on a regular basis in 53.9% and 22 centers (84.6%) agreed to participate in a clinical trial addressing the duration of postoperative sedation and ventilation.

CONCLUSION

The results of this nationwide survey among neurointensive care units in Germany reflect a remarkable heterogeneity in the treatment practices of patients with malignant middle cerebral artery infarction undergoing hemicraniectomy, especially with respect to the duration of postoperative sedation and ventilation. A randomized trial in this matter seems warranted.

Decision Support Tool to Judiciously Assign High-Frequency Neurologic Examinations in Traumatic Brain Injury

INTRODUCTION

Traumatic brain injury (TBI) management includes serial neurologic examinations to assess for changes dictating neurosurgical interventions. We hypothesized hourly examinations are overassigned. We conducted a decision tree analysis to determine an algorithm to judiciously assign hourly examinations.

METHODS

A retrospective cohort study of 1022 patients with TBI admitted to a Level 1 trauma center from January 1, 2019, to December 31, 2019, was conducted. Patients with penetrating TBI or immediate or planned interventions and those with nonsurvivable injuries were excluded. Patients were stratified by whether they underwent an unplanned intervention (e.g., craniotomy or invasive intracranial monitoring). Univariate analysis identified factors for inclusion in chi-square automatic interaction detection technique, classifying those at risk for unplanned procedures.

RESULTS

A total of 830 patients were included, 287 (35%) were assigned hourly (Q1) examinations, and 17 (2%) had unplanned procedures, with 16 of 17 (94%) on Q1 examinations. Patients requiring unplanned procedures were more likely to have mixed intracranial hemorrhage pattern (82% versus 39%; P = 0.001), midline shift (35% versus 14%; P = 0.023), an initial poor neurologic examination (Glasgow Comas Scale ≤8, 77% versus 14%; P < 0.001), and be intubated (88% versus 17%; P < 0.001). Using chi-square automatic interaction detection, the decision tree demonstrated low-risk (2% misclassification) and excellent discrimination (area under the curve = 0.915, 95% confidence interval 0.844-0.986; P < 0.001) of patients at risk of an unplanned procedure. By following the algorithm, 167 fewer patients could have been assigned Q1 examinations, resulting in an estimated 6012 fewer examinations.

CONCLUSIONS

Using a 4-factor algorithm can optimize the assignment of neuro examinations and substantially reduce neuro examination burden without sacrificing patient safety.

Focused Management of Patients With Severe Acute Brain Injury and ARDS

Considering the COVID-19 pandemic where concomitant occurrence of ARDS and severe acute brain injury (sABI) has increasingly coemerged, we synthesize existing data regarding the simultaneous management of both conditions. Our aim is to provide readers with fundamental principles and concepts for the management of sABI and ARDS, and highlight challenges and conflicts encountered while managing concurrent disease. Up to 40% of patients with sABI can develop ARDS. Although there are trials and guidelines to support the mainstays of treatment for ARDS and sABI independently, guidance on concomitant management is limited. Treatment strategies aimed at managing severe ARDS may at times conflict with the management of sABI. In this narrative review, we discuss the physiological basis and risks involved during simultaneous management of ARDS and sABI, summarize evidence for treatment decisions, and demonstrate these principles using hypothetical case scenarios. Use of invasive or noninvasive monitoring to assess brain and lung physiology may facilitate goal-directed treatment strategies with the potential to improve outcome. Understanding the pathophysiology and key treatment concepts for comanagement of these conditions is critical to optimizing care in this high-acuity patient population.

Weaning from mechanical ventilation in neurocritical care

In the intensive care unit (ICU), weaning from mechanical ventilation follows a step-by-step process that has been well established in the general ICU population. However, little data is available in brain injury patients, who are often intubated to protect airways and prevent central hypoventilation. In this narrative review, we describe the general principles of weaning and how these principles can be adapted to brain injury patients. We focus on three major issues regarding weaning from mechanic ventilation in brain injury patients: (1) sedation protocol, (2) weaning and extubation protocol and criteria, (3) criteria, timing and technique for tracheostomy.

How do we identify the crashing traumatic brain injury patient - the intensivist's view

PURPOSE OF REVIEW

Over 40% of patients with severe traumatic brain injury (TBI) show clinically significant neurological worsening within the acute admission period. This review addresses the importance of identifying the crashing TBI patient, the difficulties appreciating clinical neurological deterioration in the comatose patient and how neuromonitoring may provide continuous real-time ancillary information to detect physiologic worsening.

RECENT FINDINGS

The latest editions of the Brain Trauma Foundation's Guidelines omitted management algorithms for adult patients with severe TBI. Subsequently, three consensus-based management algorithms were published using a Delphi method approach to provide a bridge between the evidence-based guidelines and integration of the individual treatment modalities at the bedside. These consensus statements highlight the serious situation of critical deterioration requiring emergent evaluation and guidance on sedation holds to obtain a neurological examination while balancing the potential risks of inducing a stress response.

SUMMARY

One of the central tenets of neurocritical care is to detect the brain in trouble. The first and most fundamental neurological monitoring tool is the clinical exam. Ancillary neuromonitoring data may provide early physiologic biomarkers to help anticipate, prevent or halt secondary brain injury processes. Future research should seek to understand how data integration and visualization technologies may reduce the cognitive workload to improve timely detection of neurological deterioration.

Neurologic Assessment of the Neurocritical Care Patient

Sedation is a ubiquitous practice in ICUs and NCCUs. It has the benefit of reducing cerebral energy demands, but also precludes an accurate neurologic assessment. Because of this, sedation is intermittently stopped for the purposes of a neurologic assessment, which is termed a neurologic wake-up test (NWT). NWTs are considered to be the gold-standard in continued assessment of brain-injured patients under sedation. NWTs also produce an acute stress response that is accompanied by elevations in blood pressure, respiratory rate, heart rate, and ICP. Utilization of cerebral microdialysis and brain tissue oxygen monitoring in small cohorts of brain-injured patients suggests that this is not mirrored by alterations in cerebral metabolism, and seldom affects oxygenation. The hard contraindications for the NWT are preexisting intracranial hypertension, barbiturate treatment, status epilepticus, and hyperthermia. However, hemodynamic instability, sedative use for primary ICP control, and sedative use for severe agitation or respiratory distress are considered significant safety concerns. Despite ubiquitous recommendation, it is not clear if additional clinically relevant information is gleaned through its use, especially with the contemporaneous utilization of multimodality monitoring. Various monitoring modalities provide unique and pertinent information about neurologic function, however, their role in improving patient outcomes and guiding treatment plans has not been fully elucidated. There is a paucity of information pertaining to the optimal frequency of NWTs, and if it differs based on type of injury. Only one concrete recommendation was found in the literature, exemplifying the uncertainty surrounding its utility. The most common sedative used and recommended is propofol because of its rapid onset, short duration, and reduction of cerebral energy requirements. Dexmedetomidine may be employed to facilitate serial NWTs, and should always be used in the non-intubated patient or if propofol infusion syndrome (PRIS) develops. Midazolam is not recommended due to tissue accumulation and residual sedation confounding a reliable NWT. Thus, NWTs are well-tolerated in selected patients and remain recommended as the gold-standard for continued neuromonitoring. Predicated upon one expert panel, they should be performed at least one time per day. Propofol or dexmedetomidine are the main sedative choices, both enabling a rapid awakening and consistent NWT.

Consensus Statement on Analgo-sedation in Neurocritical Care and Review of Literature

Aim and objective

Our main objective in developing this consensus is to bring together a set of most agreed-upon statements from a panel of global experts that would act as a guide for clinicians working in neurocritical care units (NCCUs).

Background

Given the physiological benefits of analgo-sedation in the NCCU, there is little information on their tailoring in the NCCU. This lack of evidence and guidelines on the use of sedation and analgesia in patients with neurological injury leads to a variation in clinical care based on patient requirements and institutional protocols.

Review results

Thirty-nine international experts agreed to be a member of this consensus panel. A Delphi method based on a Web-based questionnaire developed with Google Forms on a secure institute server was used to seek opinions of experts. Questions were related to sedation and analgesia in the neurocritical care unit. A predefined threshold of agreement was established as 70% to support any recommendation, strong, moderate, or weak. No recommendations were made below this threshold. Responses were collected from all the experts, summated, and expressed as percentage (%). After three rounds, consensus could be reached for 6 statements related to analgesia and 5 statements related to sedation. Consensus could not be reached for 10 statements related to analgesia and 5 statements related to sedation.

Conclusion

This global consensus statement may help in guiding practitioners in clinical decision-making regarding analgo-sedation in the NCCUs, thereby helping in improving patient recovery profiles.

Clinical significance

In the lack of high-level evidence, the recommendations may be seen as the current best clinical practice.

How to cite this article

Prabhakar H, Tripathy S, Gupta N, Singhal V, Mahajan C, Kapoor I, et al. Consensus Statement on Analgo-sedation in Neurocritical Care and Review of Literature. Indian J Crit Care Med 2021;25(2):126–133.

Sedatives in neurocritical care: an update on pharmacological agents and modes of sedation

PURPOSE OF REVIEW

In this article, the specific and general indications for sedatives in the neurocritical care unit are discussed, together with an overview on current insights in sedative protocols for these patients. In addition, physiological effects of sedative agents on the central nervous system are reviewed.

RECENT FINDINGS

In the general ICU population, a large body of evidence supports light protocolized sedation over indiscriminate deep sedation. Unfortunately, in patients with severe acute brain injury, the evidence from randomized controlled trials is scarce to nonexistent, and practice is supported by expert opinion, physiological studies and observational or small interventional trials. The different sedatives each have different beneficial effects and side-effects.

SUMMARY

Extrapolating the findings from studies in the general ICU population suggests to reserve deep continuous sedation in the neuro-ICU for specific indications. Although an improved understanding of cerebral physiological changes in patients with brain injury may be helpful to guide individualized sedation, we still lack the evidence base to make broad recommendations for specific patient groups.

Effects of propofol on ischemia-reperfusion and traumatic brain injury

Oxidative stress exacerbates brain damage following ischemia-reperfusion and traumatic brain injury (TBI). Management of TBI and critically ill patients commonly involves use of propofol, a sedation medication that acts as a general anesthetic with inherent antioxidant properties. Here we review available evidence from animal model systems and clinical studies that propofol protects against ischemia-reperfusion injury. However, evidence of propofol toxicity in humans exists and manifests as a rare complication, "propofol infusion syndrome" (PRIS). Evidence in animal models suggests that brain injury induces expression of the p75 neurotrophin receptor (p75NTR), which is associated with proapoptotic signaling. p75NTR-mediated apoptosis of neurons is further exacerbated by propofol's superinduction of p75NTR and concomitant inhibition of neurotrophin processing. Propofol is toxic to neurons but not astrocytes, a type of glial cell. Evidence suggests that propofol protects astrocytes from oxidative stress and stimulates astroglial-mediated protection of neurons. One may speculate that in brain injury patients under sedation/anesthesia, propofol provides brain tissue protection or aids in recovery by enhancing astrocyte function. Nevertheless, our understanding of neurologic recovery versus long-term neurological sequelae leading to neurodegeneration is poor, and it is also conceivable that propofol plays a partial as yet unrecognized role in long-term impairment of the injured brain.

The Neurological Wake-up Test-A Role in Neurocritical Care Monitoring of Traumatic Brain Injury Patients?

The most fundamental clinical monitoring tool in traumatic brain injury (TBI) patients is the repeated clinical examination. In the severe TBI patient treated by continuous sedation in a neurocritical care (NCC) unit, sedation interruption is required to enable a clinical evaluation (named the neurological wake-up test; NWT) assessing the level of consciousness, pupillary diameter and reactivity to light, and presence of focal neurological deficits. There is a basic conflict regarding the NWT in the NCC setting; can the clinical information obtained by the NWT justify the risk of inducing a stress response in a severe TBI patient? Furthermore, in the presence of advanced multimodal monitoring and neuroimaging, is the NWT necessary to identify important clinical alterations? In studies of severe TBI patients, the NWT was consistently shown to induce a stress reaction including brief increases in intracranial pressure (ICP) and changes in cerebral perfusion pressure (CPP). However, it has not been established whether these short-lived ICP and CPP changes are detrimental to the injured brain. Daily interruption of sedation is associated with a reduced ventilator time, shorter hospital stay and reduced mortality in many studies of general intensive care unit patients, although such clinical benefits have not been firmly established in TBI. To date, there is no consensus on the use of the NWT among NCC units and systematic studies are scarce. Thus, additional studies evaluating the role of the NWT in clinical decision-making are needed. Multimodal NCC monitoring may be an adjunct in assessing in which TBI patients the NWT can be safely performed. At present, the NWT remains the golden standard for clinical monitoring and detection of neurological changes in NCC and could be considered in TBI patients with stable baseline ICP and CPP readings. The focus of the present review is an overview of the existing literature on the role of the NWT as a clinical monitoring tool for severe TBI patients.

Emergency Neurological Life Support: Airway, Ventilation, and Sedation

Airway management and ventilation are central to the resuscitation of the neurologically ill. These patients often have evolving processes that threaten the airway and adequate ventilation. Furthermore, intubation, ventilation, and sedative choices directly affect brain perfusion. Therefore, Airway, Ventilation, and Sedation was chosen as an Emergency Neurological Life Support protocol. Topics include airway management, when and how to intubate with special attention to hemodynamics and preservation of cerebral blood flow, mechanical ventilation settings and the use of sedative agents based on the patient's neurological status.

Noninvasive Neuromonitoring: Current Utility in Subarachnoid Hemorrhage, Traumatic Brain Injury, and Stroke

Noninvasive neuromonitoring is increasingly being used to monitor the course of primary brain injury and limit secondary brain damage of patients in the neurocritical care unit. Proposed advantages over invasive neuromonitoring methods include a lower risk of infection and bleeding, no need for surgical installation, mobility and portability of some devices, and safety. The question, however, is whether noninvasive neuromonitoring is practical and trustworthy enough already. We searched the recent literature and reviewed English-language studies on noninvasive neuromonitoring in subarachnoid hemorrhage, traumatic brain injury, and ischemic and hemorrhagic stroke between the years 2010 and 2015. We found 88 studies that were eligible for review including the methods transcranial ultrasound, electroencephalography, evoked potentials, near-infrared spectroscopy, bispectral index, and pupillometry. Noninvasive neuromonitoring cannot yet completely replace invasive methods in most situations, but has great potential being complementarily integrated into multimodality monitoring, for guiding management, and for limiting the use of invasive devices and in-hospital transports for imaging.

Early neurological wake-up test in intubated brain-injured patients: A long-term, single-centre experience

BACKGROUND

In prehospital setting, a severe traumatic brain injury (TBI) requires tracheal intubation, sedation and mechanical ventilation pending the initial imagery. An early neurological wake-up test (ENWT), soon after the initial imaging assessment, allows a rapid neurological reassessment. This strategy authorises an initial clinical examination of reference with which will be compared the later examinations. The main objective of this study was to describe the characteristics of the patients who underwent an ENWT, and to determine its causes of failure.

METHODS

We conducted a retrospective, observational, single-centre study including all intubated TBI admitted in the trauma centre. An ENWT was defined as cessation of sedation within 24h after TBI. Data concerning patient characteristics, CT-scan results, and outcomes were extracted from a prospective register of all intubated TBI admitted in the ICU. Characteristic of ENWT and causes of failure were retrieved from patient files. A multivariate logistic regression model was developed to determine the risk factors of ENWT failure.

RESULTS

During 7 years, 242 patients with intubated TBI were included. An ENWT was started in 96 patients, for an overall rate at 40%. The ENWT was stopped in 38 patients (39.5%), mostly due to neurological deterioration in 27 cases (71%) or respiratory distress in 10 cases (26%). Significant predictors of ENWT failure were: the presence of subdural hematoma with a thickness >5mm on first imagery (OR=3.2; 95%CI [1.01-10.28]), and an initial GCS score <5 (OR=7.4; 95%CI [1.92-28.43]). Prevalence of poor outcome at 1year was lesser in patients with successful ENWT compared to those with failure or absence of ENWT: 4% vs. 48% and 49% (p<0.0001).

CONCLUSIONS

The ENWT is achieved in 40% of patients, with a success rate of 60.5%. In presence of a subdural hematoma with a thickness >5mm or an initial GCS score <5, an ENWT failure may be expected.

Postoperative care of the neurosurgical patient

PURPOSE OF REVIEW

Monitoring and therapy of patients in neurocritical care are areas of intensive research and the current evidence needs further confirmation.

RECENT FINDINGS

A consensus statement of the Neurocritical Care Society and the European Society of Intensive Care Medicine provided pragmatic guidance and recommendations for multimodal monitoring in neurocritical care patients. Only a minority of these recommendations have strong evidence. In addition, recent multicenter randomized controlled trials concerning the therapy of subarachnoidal hemorrhage and traumatic brain injury could not show decreased mortality or improved functional neurologic outcome after the interventions. The current evidence for monitoring and medical therapy in patients after traumatic brain injury and aneurysmal subarachnoid hemorrhage is highlighted in this review.

SUMMARY

Although strong evidence is lacking, multimodal monitoring is of great value in neurocritical care patients and may help to provide patients with the optimal therapy based on the individual pathophysiological changes.

Optimizing sedation in patients with acute brain injury

Daily interruption of sedative therapy and limitation of deep sedation have been shown in several randomized trials to reduce the duration of mechanical ventilation and hospital length of stay, and to improve the outcome of critically ill patients. However, patients with severe acute brain injury (ABI; including subjects with coma after traumatic brain injury, ischaemic/haemorrhagic stroke, cardiac arrest, status epilepticus) were excluded from these studies. Therefore, whether the new paradigm of minimal sedation can be translated to the neuro-ICU (NICU) is unclear. In patients with ABI, sedation has ‘general’ indications (control of anxiety, pain, discomfort, agitation, facilitation of mechanical ventilation) and ‘neuro-specific’ indications (reduction of cerebral metabolic demand, improved brain tolerance to ischaemia). Sedation also is an essential therapeutic component of intracranial pressure therapy, targeted temperature management and seizure control. Given the lack of large trials which have evaluated clinically relevant endpoints, sedative selection depends on the effect of each agent on cerebral and systemic haemodynamics. Titration and withdrawal of sedation in the NICU setting has to be balanced between the risk that interrupting sedation might exacerbate brain injury (e.g. intracranial pressure elevation) and the potential benefits of enhanced neurological function and reduced complications. In this review, we provide a concise summary of cerebral physiologic effects of sedatives and analgesics, the advantages/disadvantages of each agent, the comparative effects of standard sedatives (propofol and midazolam) and the emerging role of alternative drugs (ketamine). We suggest a pragmatic approach for the use of sedation-analgesia in the NICU, focusing on some practical aspects, including optimal titration and management of sedation withdrawal according to ABI severity.

Evidence-based guidelines for the management of large hemispheric infarction : a statement for health care professionals from the Neurocritical Care Society and the German Society for Neuro-intensive Care and Emergency Medicine

Large hemispheric infarction (LHI), also known as malignant middle cerebral infarction, is a devastating disease associated with significant disability and mortality. Clinicians and family members are often faced with a paucity of high quality clinical data as they attempt to determine the most appropriate course of treatment for patients with LHI, and current stroke guidelines do not provide a detailed approach regarding the day-to-day management of these complicated patients. To address this need, the Neurocritical Care Society organized an international multidisciplinary consensus conference on the critical care management of LHI. Experts from neurocritical care, neurosurgery, neurology, interventional neuroradiology, and neuroanesthesiology from Europe and North America were recruited based on their publications and expertise. The panel devised a series of clinical questions related to LHI, and assessed the quality of data related to these questions using the Grading of Recommendation Assessment, Development and Evaluation guideline system. They then developed recommendations (denoted as strong or weak) based on the quality of the evidence, as well as the balance of benefits and harms of the studied interventions, the values and preferences of patients, and resource considerations.

Emergency Neurological Life Support: Airway, Ventilation, and Sedation

Airway management and ventilation are central to the resuscitation of the neurologically ill. These patients often have evolving processes that threaten the airway and adequate ventilation. Furthermore, intubation, ventilation, and sedative choices directly affect brain perfusion. Therefore, airway, ventilation, and sedation was chosen as an emergency neurological life support protocol. Topics include airway management, when and how to intubate with special attention to hemodynamics and preservation of cerebral blood flow, mechanical ventilation settings, and the use of sedative agents based on the patient's neurological status.

Clinical monitoring scales in acute brain injury: assessment of coma, pain, agitation, and delirium

Serial clinical examination represents the most fundamental and basic form of neurological monitoring, and is often the first and only form of such monitoring in patients. Even in patients subjected to physiological monitoring using a range of technologies, the clinical examination remains an essential tool to follow neurological progress. Key aspects of the clinical examination have now been systematized into scoring schemes, and address consciousness, pain, agitation, and delirium (PAD). The Glasgow Coma Scale has been the traditional tool to measure consciousness, but the full outline of unresponsiveness (FOUR) score has recently been validated in a variety of settings, and at present, both represent clinically useful tools. Assessment of PAD in neurologically compromised patients present special challenges. For pain, the Numeric Rating Scale is the preferred initial approach, with either the Behavioral Pain Scale or the Critical Care Pain Observation Tool in subjects who are not able to respond. The Nociception Coma Scale-Revised may be useful in patients with severe disorders of consciousness. Conventional sedation scoring tools for critical care, such as the Richmond Area Sedation Scale (RASS) and Sedation-Agitation Scale (SAS) may provide reasonable tools in some neurocritical care patients. The use of sedative drugs and neuromuscular blockers may invalidate the use of some clinical examination tools in others. The use of sedation interruption to assess neurological status can result in physiological derangement in unstable patients (such as those with uncontrolled intracranial hypertension), and is not recommended.

Clinical applications of intracranial pressure monitoring in traumatic brain injury : report of the Milan consensus conference

BACKGROUND

Intracranial pressure (ICP) monitoring has been for decades a cornerstone of traumatic brain injury (TBI) management. Nevertheless, in recent years, its usefulness has been questioned in several reports. A group of neurosurgeons and neurointensivists met to openly discuss, and provide consensus on, practical applications of ICP in severe adult TBI.

METHODS

A consensus conference was held in Milan on October 5, 2013, putting together neurosurgeons and intensivists with recognized expertise in treatment of TBI. Four topics have been selected and addressed in pro-con presentations: 1) ICP indications in diffuse brain injury, 2) cerebral contusions, 3) secondary decompressive craniectomy (DC), and 4) after evacuation of intracranial traumatic hematomas. The participants were asked to elaborate on the existing published evidence (without a systematic review) and their personal clinical experience. Based on the presentations and discussions of the conference, some drafts were circulated among the attendants. After remarks and further contributions were collected, a final document was approved by the participants. The group made the following recommendations: 1) in comatose TBI patients, in case of normal computed tomography (CT) scan, there is no indication for ICP monitoring; 2) ICP monitoring is indicated in comatose TBI patients with cerebral contusions in whom the interruption of sedation to check neurological status is dangerous and when the clinical examination is not completely reliable. The probe should be positioned on the side of the larger contusion; 3) ICP monitoring is generally recommended following a secondary DC in order to assess the effectiveness of DC in terms of ICP control and guide further therapy; 4) ICP monitoring after evacuation of an acute supratentorial intracranial hematoma should be considered for salvageable patients at increased risk of intracranial hypertension with particular perioperative features.

A conceptual approach to managing severe traumatic brain injury in a time of uncertainty

Current controversies in the literature suggest that a reassessment of the current management of severe traumatic brain injury (sTBI) is necessary. This article presents a conceptual framework toward individualizing sTBI treatment with respect to targeting thresholds and strategies on the basis of known physiologic processes and available monitors. Intracranial pressure (ICP) is modeled as an epiphenomenon of cerebral compliance and herniation tendency, as well as cerebral ischemia. By combining serial neurological examinations, imaging studies, and ICP measurements (values, trends, and area-under-the-curve calculations) over time, evidence can be accrued on the necessity of maintaining ICP at a given threshold in the realm of physical changes in the brain. Similarly, by collecting and trending clinical, imaging, and monitoring data on the status of cerebral blood flow, the balance of oxygen consumption and delivery, and the status of cerebral static pressure autoregulation, and analyzing them with respect to measured parameters, such as blood pressure, ICP, and cerebral perfusion pressure, one can attempt to fine-tune these variables as well. Such individualization of management optimizes the possibility of successfully treating demonstrated pathophysiological processes while avoiding unnecessary interventions and treatment toxicity. Monitor values must not be seen as targets but rather as indicators of targetable pathology.

The neurological wake-up test does not alter cerebral energy metabolism and oxygenation in patients with severe traumatic brain injury

BACKGROUND

The neurological wake-up test (NWT) is used to monitor the level of consciousness in patients with traumatic brain injury (TBI). However, it requires interruption of sedation and may elicit a stress response. We evaluated the effects of the NWT using cerebral microdialysis (MD), brain tissue oxygenation (PbtiO2), jugular venous oxygen saturation (SjvO2), and/or arterial-venous difference (AVD) for glucose, lactate, and oxygen in patients with severe TBI.

METHODS

Seventeen intubated TBI patients (age 16-74 years) were sedated using continuous propofol infusion. All patients received intracranial pressure (ICP) and cerebral perfusion pressure (CPP) monitoring in addition to MD, PbtiO2 and/or SjvO2. Up to 10 days post-injury, ICP, CPP, PbtiO2 (51 NWTs), MD (49 NWTs), and/or SjvO2 (18 NWTs) levels during propofol sedation (baseline) and NWT were compared. MD was evaluated at a flow rate of 1.0 μL/min (28 NWTs) or the routine 0.3 μL/min rate (21 NWTs).

RESULTS

The NWT increased ICP and CPP levels (p < 0.05). Compared to baseline, interstitial levels of glucose, lactate, pyruvate, glutamate, glycerol, and the lactate/pyruvate ratio were unaltered by the NWT. Pathological SjvO2 (<50 % or >71 %; n = 2 NWTs) and PbtiO2 (<10 mmHg; n = 3 NWTs) values were rare at baseline and did not change following NWT. Finally, the NWT did not alter the AVD of glucose, lactate, or oxygen.

CONCLUSIONS

The NWT-induced stress response resulted in increased ICP and CPP levels although it did not negatively alter focal neurochemistry or cerebral oxygenation in TBI patients.

Neurological examination of critically ill patients: a pragmatic approach. Report of an ESICM expert panel

OBJECTIVE

Many patients admitted to the intensive care unit (ICU) have pre-existing or acquired neurological disorders which significantly affect their short-term and long-term outcomes. The ESICM Neuro Intensive Care Section convened an expert panel to establish a pragmatic approach to neurological examination (NE) of the critically ill patient.

METHODS

The group conducted a comprehensive review of published studies on the NE of patients with coma, delirium, seizures and neuromuscular weakness in critically ill patients. Quality of data was rated as high, moderate, low, or very low, and final recommendations as strong, weak, or best practice.

SUMMARY AND CONCLUSIONS

The group made the following recommendations: (1) NE should be performed in all patients admitted to ICUs; (2) NE should include an assessment of consciousness and cognition, brainstem function, and motor function; (3) sedation should be managed to maximize the clinical detection of neurological dysfunction, except inpatients with reduced intracranial compliance in whom withdrawal of sedation may be deleterious; (4) the need for additional tests, including neurophysiological and neuroradiological investigations, should be guided by the NE; (5) selected features of the NE have prognostic value which should be considered in well-defined patient populations.

Tracheostomy in stroke patients

OPINION STATEMENT

Patients with severe ischemic and hemorrhagic stroke may require tracheostomy in the course of their disease. This may apply to stroke unit patients whose deficits include a severe dysphagia posing such risk of aspiration as it cannot be sufficiently counteracted by tube feeding and swallowing therapy alone. More often, however, tracheostomy is performed in stroke patients so severely afflicted that they require intensive care unit treatment and mechanical ventilation. In these, long-term ventilation and prolonged insufficient airway protection are the main indications for tracheostomy. Accepted advantages are less pharyngeal and laryngeal lesions than with prolonged orotracheal intubation, better oral hygiene and nursing care, and higher patient comfort. Optimal timing of tracheostomy is unclear, in general, as in stroke intensive care unit patients. Potential benefits of early tracheostomy concerning ventilation duration and length of stay, respirator weaning, airway safety, rate of pneumonia, and other complications, outcome and mortality have been suggested in studies on non-neurologic subgroups of critical care patients. Stroke patients have hardly been investigated with regard to these aspects, and mainly retrospectively. A single randomized pilot trial on early tracheostomy in 60 ventilated patients with severe hemorrhagic and ischemic stroke demonstrated feasibility, safety, and less need of sedation. Regarding the technique, bedside percutaneous dilational tracheostomy should be preferred over surgical tracheostomy because of several reported advantages. As the procedural risk is low and early tracheostomy does not seem to worsen the clinical course of the ventilated stroke patient, it is reasonable to assess the need of further ventilation at the end of the first week of intensive care and proceed to tracheostomy if extubation is not feasible. Reliable prediction of prolonged ventilation need and outcome benefits of early tracheostomy, however, await further clarification. Decannulation of stroke patients after discontinued ventilation has to follow reliable confirmation of swallowing ability, as by endoscopy.

Improved outcome of patients with severe thalamic hemorrhage treated with cerebrospinal fluid drainage and neurocritical care during 1990-1994 and 2005-2009

INTRODUCTION

Patients with thalamic hemorrhage, depressed level of consciousness and/or signs of elevated intracranial pressure may be treated with neurocritical care (NCC) and external ventricular drainage (EVD) for release of cerebrospinal fluid.

METHODS

Forty-three patients with thalamic hemorrhage treated with NCC from 1990 to 1994 (n = 21) and from 2005-2009 (n = 22) were evaluated. Outcome was assessed using the Glasgow Coma Scale (GCS) score at discharge from our unit and the modified Rankin Scale (mRS) for long-term outcome.

RESULTS

Patients' age was 59.5 ± 7 years in 1990-1994, and 58.2 ± 9 years in 2005-2009. The median (25th and 75th percentile) GCS score on admission for the two time periods was 9 (6-12) and 9 (4-14), respectively. Long-term follow-up was assessed at a mean of 37.1 (range 19-65) months after disease onset for the 1990-1994 cohort and at 37.4 (range 14-58) months for the 2005-2009 cohort. Compared to patients from 1990 to 1994, patients from 2005 to 2009 had a significantly better outcome (median mRS [25th and 75th percentile]: 5 [4-6] vs. 4 [2-4.5]; p < 0.01). Most patients (13/21, 62 %) treated from 1990 to 1994 had unchanged or lower GCS scores during their NCC stay in contrast to 7/22 (32 %) from 2005 to 2009. At the last follow-up, 13/21 (62 %) patients from 1990 to 1994 were dead in comparison to 4/21 (19 %) from 2005 to 2009 (p < 0.05). Negative prognostic factors were the 120 h post-admission GCS score in the 1990-1994 patient cohort (p = 0.07) and high age in the recent cohort (p = 0.04).

CONCLUSIONS

Patients with thalamic hemorrhage and depressed level of consciousness on admission had a worse outcome in the early 1990s compared with the late 2000s, which may at least be partially attributed to refined neurocritical care.

[Sedation and weaning in neurocritical care: can concepts from general critical care be applied?]

The translation of modern principles of sedation and weaning from mechanical ventilation from general intensive care to neurocritical care has to take into account specific aspects of brain-injured patients. These include interactions with intracranial hypertension, disturbed autoregulation, a higher frequency of seizures and an increased risk of delirium. The advantages of sedation protocols, scoring tools to steer sedation and analgesia and an individualized choice of drugs with emphasis on analgesia gain more interest and importance in neurocritical care as well, but have not been thoroughly investigated so far. When weaning neurological intensive care unit (ICU) patients from the ventilator and approaching extubation it has to be acknowledged that conventional ICU criteria for weaning and extubation can only have an orienting character and that dysphagia is much more frequent in these patients.

Frequency of non-convulsive seizures and non-convulsive status epilepticus in subarachnoid hemorrhage patients in need of controlled ventilation and sedation

BACKGROUND

Non-convulsive seizures (NCSZ) can be more prevalent than previously recognized among comatose neuro-intensive care patients. The aim of this study was to evaluate the frequency of NCSZ and non-convulsive status epilepticus (NCSE) in sedated and ventilated subarachnoid hemorrhage (SAH) patients.

METHODS

Retrospective study at a university hospital neuro-intensive care unit, from January 2008 until June 2010. Patients were treated according to a local protocol, and were initially sedated with midazolam or propofol or combinations of these sedative agents. Thiopental was added for treatment of intracranial hypertension. No wake-up tests were performed. Using NicoletOne(®) equipment (VIASYS Healthcare Inc., USA), continuous EEG recordings based on four electrodes and a reference electrode was inspected at full length both in a two electrode bipolar and a four-channel referential montage.

RESULTS

Approximately 5,500 h of continuous EEG were registered in 28 SAH patients (33 % of the patients eligible for inclusion). The median Glasgow Coma scale was 8 (range 3-14) and the median Hunt and Hess score was 4 (range 1-4). During EEG registration, no clinical seizures were observed. In none of the patients inter ictal epileptiform activity was seen. EEG seizures were recorded only in 2/28 (7 %) patients. One of the patients experienced 4 min of an NCSZ and one had a 5 h episode of an NCSE.

CONCLUSION

Continuous EEG monitoring is important in detecting NCSZ in sedated patients. Continuous sedation, without wake-up tests, was associated with a low frequency of subclinical seizures in SAH patients in need of controlled ventilation.

Effects of the neurological wake-up test on clinical examination, intracranial pressure, brain metabolism and brain tissue oxygenation in severely brain-injured patients

Introduction

Daily interruption of sedation (IS) has been implemented in 30 to 40% of intensive care units worldwide and may improve outcome in medical intensive care patients. Little is known about the benefit of IS in acutely brain-injured patients.

Methods

This prospective observational study was performed in a neuroscience intensive care unit in a tertiary-care academic center. Twenty consecutive severely brain-injured patients with multimodal neuromonitoring were analyzed for levels of brain lactate, pyruvate and glucose, intracranial pressure (ICP), cerebral perfusion pressure (CPP) and brain tissue oxygen tension (P_btO₂) during IS trials.

Results

Of the 82 trial days, 54 IS-trials were performed as interruption of sedation and analgesics were not considered safe on 28 days (34%). An increase in the FOUR Score (Full Outline of UnResponsiveness score) was observed in 50% of IS-trials by a median of three (two to four) points. Detection of a new neurologic deficit occurred in one trial (2%), and in one-third of IS-trials the trial had to be stopped due to an ICP-crisis (> 20 mmHg), agitation or systemic desaturation. In IS-trials that had to be aborted, a significant increase in ICP and decrease in P_btO₂ (P < 0.05), including 67% with critical values of P_btO₂ < 20 mmHg, a tendency to brain metabolic distress (P < 0.07) was observed.

Conclusions

Interruption of sedation revealed new relevant clinical information in only one trial and a large number of trials could not be performed or had to be stopped due to safety issues. Weighing pros and cons of IS-trials in patients with acute brain injury seems important as related side effects may overcome the clinical benefit.

Emergency neurological life support: airway, ventilation, and sedation

Airway management is central to the resuscitation of the neurologically ill. These patients often have evolving processes that threaten the airway and adequate ventilation. Therefore, airway, ventilation, and sedation were chosen as an Emergency Neurological Life Support (ENLS) protocol. Reviewed topics include airway management; the decision to intubate; when and how to intubate with attention to cardiovascular status; mechanical ventilation settings; and the use of sedation, including how to select sedative agents based on the patient's neurological status.

Prognostic factors and long-term outcome following surgical treatment of 76 patients with spontaneous cerebellar haematoma

BACKGROUND

Although large spontaneous cerebellar haematomas are associated with high mortality, surgical treatment may be life-saving. We evaluated the clinical outcome and identified prognostic factors in 76 patients with cerebellar haematoma, all treated with suboccipital decompression, haematoma evacuation and external ventricular drainage.

METHODS

Patients receiving surgical and neurocritical care treatment within a 10-year period were included. Level of consciousness during hospitalisation was evaluated using the Glasgow Coma Scale (GCS) score. Outcome was assessed with the modified Rankin Scale (mRS). Predictive prognostic factors were analysed using univariate and multivariate regression analysis.

RESULTS

Prior to surgery, the median GCS score was 8.6 (range 3-13). At discharge it had improved to 12.1 (4-15) (p < 0.05). The median long-term follow-up period was 70.5 (22-124) months. At 6 months post-surgery, 19 patients were dead and 28 patients had a good outcome (mRS < 3). In the long term (70.5 months), 31 patients (41.9 %) were dead and the outcome was good in 27 patients (37.8 %). Although approximately 25 % of patients >65 years old had a favourable outcome, age was the strongest negative predictor for a bad outcome at 6 months and long term (p = 0.02 and p = 0.01, respectively). The level of consciousness before surgery did not influence the 6-month or long-term outcome (p = 0.39 and p = 0.65, respectively).

CONCLUSIONS

Although mortality was high, significant complications from the treatment were rare and most survivors had a good outcome, reaching functional independence. High age was the strongest prognostic factor for an unfavourable outcome.

The neurological wake-up test increases stress hormone levels in patients with severe traumatic brain injury

OBJECTIVES

The "neurological wake-up test" is needed to evaluate the level of consciousness in patients with severe traumatic brain injury. However, the neurological wake-up test requires interruption of continuous sedation and may induce a stress response and its use in neurocritical care is controversial. We hypothesized that the neurological wake-up test induces an additional biochemical stress response in patients with severe traumatic brain injury.

PATIENTS

Twenty-four patients who received continuous propofol sedation and mechanical ventilation after moderate to severe traumatic brain injury (Glasgow Coma Scale score ≤ 8; patient age 18-71 yrs old) were analyzed. Exclusion criteria were age <18 yrs old, ongoing pentobarbital infusion, or markedly increased intracranial pressure on interruption of continuous sedation.

DESIGN

Single-center prospective study. During postinjury days 1-8, 65 neurological wake-up tests were evaluated. Adrenocorticotrophic hormone, epinephrine, and norepinephrine levels in plasma and cortisol levels in saliva were analyzed at baseline (during continuous intravenous propofol sedation) and during neurological wake-up test. Data are presented using medians and 25th and 75th percentiles.

SETTING

The study was performed in a university hospital neurocritical care unit.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

At baseline, adrenocorticotrophic hormone and cortisol levels were 10.6 (6.0-19.4) ng/L and 16.0 (10.7-31.8) nmol/L, respectively. Immediately after the neurological wake-up test, adrenocorticotrophic hormone levels increased to 20.5 (11.1-48.4) ng/L (p < .05) and cortisol levels in saliva increased to 24.0 (12.3-42.5) nmol/L (p < .05). The plasma epinephrine and norepinephrine levels increased from a baseline of 0.3 (0.3-0.6) and 1.6 (0.9-2.3) nmol/L, respectively, to 0.75 (0.3-1.4) and 2.8 (1.28-3.58) nmol/L, respectively (both p < .05).

CONCLUSIONS

The neurological wake-up test induces a biochemical stress response in patients with severe traumatic brain injury. The clinical importance of this stress response remains to be established but should be considered when deciding the frequency and use of the neurological wake-up test during neurocritical care.

Brief episodes of intracranial hypertension and cerebral hypoperfusion are associated with poor functional outcome after severe traumatic brain injury

BACKGROUND

Management strategies after severe traumatic brain injury (TBI) target prevention and treatment of intracranial hypertension (ICH) and cerebral hypoperfusion (CH). We have previously established that continuous automated recordings of vital signs (VS) are more highly correlated with outcome than manual end-hour recordings. One potential benefit of automated vital sign data capture is the ability to detect brief episodes of ICH and CH. The purpose of this study was to establish whether a relationship exists between brief episodes of ICH and CH and outcome after severe TBI.

MATERIALS

Patients at the R Adams Cowley Shock Trauma Center were prospectively enrolled over a 2-year period. Inclusion criteria were as follows: age >14 years, admission within the first 6 hours after injury, Glasgow Coma Scale score <9 on admission, and placement of a clinically indicated ICP monitor. From high-resolution automated VS data recording system, we calculated the 5-minute means of intracranial pressure (ICP), cerebral perfusion pressure (CPP), and Brain Trauma Index (BTI = CPP/ICP). Patients were stratified by mortality and 6-month Extended Glasgow Outcome Score (GOSE).

RESULTS

Sixty subjects were enrolled with a mean admission Glasgow Coma Scale score of 6.4 ± 3.1, a mean Head Abbreviated Injury Severity Scale score of 4.2 ± 0.7, and a mean Marshall CT score of 2.5 ± 0.9. Significant differences in the mean number of brief episodes of CPP <50 and BTI <2 in patients with a GOSE 1-4 versus GOSE 5-8 (9.4 vs. 4.7, p = 0.02 and 9.3 vs. 4.9, p = 0.03) were found. There were significantly more mean brief episodes per day of ICP >30 (0.52 vs. 0.29, p = 0.02), CPP <50 (0.65 vs. 0.28, p < 0.001), CPP <60 (1.09 vs. 0.7, p = 0.03), BTI <2 (0.66 vs. 0.31, p = 0.002), and BTI <3 (1.1 vs. 0.64, p = 0.01) in those patients with GOSE 1-4. Number of brief episodes of CPP <50, CPP <60, BTI <2, and BTI <3 all demonstrated high predictive power for unfavorable functional outcome (area under the curve = 0.65-0.75, p < 0.05).

CONCLUSIONS

This study demonstrates that the number of brief 5-minute episodes of ICH and CH is predictive of poor outcome after severe TBI. This finding has important implications for management paradigms which are currently targeted to treatment rather than prevention of ICH and CH. This study demonstrates that these brief episodes may play a significant role in outcome after severe TBI.

Interstitial F(2)-isoprostane 8-iso-PGF(2α) as a biomarker of oxidative stress after severe human traumatic brain injury

Oxidative stress is a major contributor to the secondary injury process after experimental traumatic brain injury (TBI). The importance of oxidative stress in the pathobiology of human TBI is largely unknown. The F(2)-isoprostane 8-iso-prostaglandin F(2α) (8-iso-PGF(2α)), synthesized in vivo through non-enzymatic free radical catalyzed peroxidation of arachidonic acid, is a widely used biomarker of oxidative stress in multiple disease states, including TBI and cerebral ischemia/reperfusion. Our hypothesis is that harvesting of biomarkers directly in the injured brain by cerebral microdialysis (MD) is advantageous because of its high spatial and temporal resolution compared to blood or cerebrospinal fluid sampling. The aim of this study was to test the feasibility of measuring 8-iso-PGF(2α) in MD, ventricular cerebrospinal fluid (vCSF), and plasma samples collected from patients with severe TBI, and to compare the MD signals with MD-glycerol, implicated as a biomarker of oxidative stress, as well as MD-glutamate, a biomarker of excitotoxicity. Six patients (4 men, 2 women) were included in the study, three of whom had a focal/mixed TBI, and three a diffuse axonal injury (DAI). Following the bedside analysis of routine MD biomarkers (glucose, lactate:pyruvate ratio, glycerol, and glutamate), two 12-h MD samples per day were used to analyze 8-iso-PGF(2α) from 24 h up to 8 days post-injury. The interstitial levels of 8-iso-PGF(2α) were markedly higher than the levels obtained from plasma and vCSF (p<0.05), supporting our hypothesis. The MD-8-iso-PGF(2α) levels correlated strongly (p<0.05) with MD-glycerol and MD-glutamate, which are widely used biomarkers of membrane phospholipid degradation/oxidative stress and excitotoxicity, respectively. This study demonstrates the feasibility of analyzing 8-iso-PGF(2α) in MD samples from the human brain. Our results support a close relationship between oxidative stress and excitotoxicity following human TBI. MD-8-iso-PGF(2α) in combination with MD-glycerol may be useful biomarkers of oxidative stress in the neurointensive care setting.