A trial of intracranial-pressure monitoring in traumatic brain injury

Intracranial pressure monitoring, cerebral perfusion pressure estimation, and ICP/CPP-guided therapy: a standard of care or optional extra after brain injury?

Measurement of intracranial pressure (ICP) and mean arterial pressure (MAP) is used to derive cerebral perfusion pressure (CPP) and to guide targeted therapy of acute brain injury (ABI) during neurointensive care. Here we provide a narrative review of the evidence for ICP monitoring, CPP estimation, and ICP/CPP-guided therapy after ABI. Despite its widespread use, there is currently no class I evidence that ICP/CPP-guided therapy for any cerebral pathology improves outcomes; indeed some evidence suggests that it makes no difference, and some that it may worsen outcomes. Similarly, no class I evidence can currently advise the ideal CPP for any form of ABI. 'Optimal' CPP is likely patient-, time-, and pathology-specific. Further, CPP estimation requires correct referencing (at the level of the foramen of Monro as opposed to the level of the heart) for MAP measurement to avoid CPP over-estimation and adverse patient outcomes. Evidence is emerging for the role of other monitors of cerebral well-being that enable the clinician to employ an individualized multimodality monitoring approach in patients with ABI, and these are briefly reviewed. While acknowledging difficulties in conducting robust prospective randomized studies in this area, such high-quality evidence for the utility of ICP/CPP-directed therapy in ABI is urgently required. So, too, is the wider adoption of multimodality neuromonitoring to guide optimal management of ICP and CPP, and a greater understanding of the underlying pathophysiology of the different forms of ABI and what exactly the different monitoring tools used actually represent.

Patients with disease of brain, cerebral vasculature, and spine

Several structural abnormalities involving the brain and surrounding structures have perioperative implications. This article reviews the preoperative assessment and preparation of patients with intracranial masses, vascular lesions, cerebrospinal fluid abnormalities, traumatic injuries, and dementia. Until definitive treatment of the underlying condition occurs, prevention of secondary injury to the patient's brain is the goal of medical management and final functional outcome.

Intracranial pressure monitoring in severe head injury: compliance with Brain Trauma Foundation guidelines and effect on outcomes: a prospective study

Object

The Brain Trauma Foundation (BTF) has established guidelines for intracranial pressure (ICP) monitoring in severe traumatic brain injury (TBI). This study assessed compliance with these guidelines and the effect on outcomes.

Methods

This is a prospective, observational study including patients with severe blunt TBI (Glasgow Coma Scale score ≤ 8, head Abbreviated Injury Scale score ≥ 3) between January 2010 and December 2011. Demographics, clinical characteristics, laboratory profile, head CT scans, injury severity indices, and interventions were collected. The study population was stratified into 2 study groups: ICP monitoring and no ICP monitoring. Primary outcomes included compliance with BTF guidelines, overall in-hospital mortality, and mortality due to brain herniation. Secondary outcomes were ICU and hospital lengths of stay. Multiple regression analyses were deployed to determine the effect of ICP monitoring on outcomes.

Results

A total of 216 patients met the BTF guideline criteria for ICP monitoring. Compliance with BTF guidelines was 46.8% (101 patients). Patients with subarachnoid hemorrhage and those who underwent craniectomy/craniotomy were significantly more likely to undergo ICP monitoring. Hypotension, coagulopathy, and increasing age were negatively associated with the placement of ICP monitoring devices. The overall in-hospital mortality was significantly higher in patients who did not undergo ICP monitoring (53.9% vs 32.7%, adjusted p = 0.019). Similarly, mortality due to brain herniation was significantly higher for the group not undergoing ICP monitoring (21.7% vs 12.9%, adjusted p = 0.046). The ICU and hospital lengths of stay were significantly longer in patients subjected to ICP monitoring.

Conclusions

Compliance with BTF ICP monitoring guidelines in our study sample was 46.8%. Patients managed according to the BTF ICP guidelines experienced significantly improved survival.

Viral encephalitis in the ICU

Viral encephalitis causes an altered level of consciousness, which may be associated with fever, seizures, focal deficits, CSF pleocytosis, and abnormal neuroimaging. Potential pathogens include HSV, VZV, enterovirus, and in some regions, arboviruses. Autoimmune (eg, anti-NMDA receptor) and paraneoplastic encephalitis are responsible for some cases where no pathogen is identified. Indications for ICU admission include coma, status epilepticus and respiratory failure. Timely initiation of anti-viral therapy is crucial while relevant molecular and serological test results are being performed. Supportive care should be directed at the prevention and treatment of cerebral edema and other physiological derangements which may contribute to secondary neurological injury.

[Therapeutic hypothermia for severe traumatic brain injury]

Therapeutic hypothermia (TH) is considered a standard of care in the post-resuscitation phase of cardiac arrest. In experimental models of traumatic brain injury (TBI), TH was found to have neuroprotective properties. However, TH failed to demonstrate beneficial effects on neurological outcome in patients with TBI. The absence of benefits of TH uniformly applied in TBI patients should not question the use of TH as a second-tier therapy to treat elevated intracranial pressure. The management of all the practical aspects of TH is a key factor to avoid side effects and to optimize the potential benefit of TH in the treatment of intracranial hypertension. Induction of TH can be achieved with external surface cooling or with intra-vascular devices. The therapeutic target should be set at a 35°C using brain temperature as reference, and should be maintained at least during 48 hours and ideally over the entire period of elevated intracranial pressure. The control of the rewarming phase is crucial to avoid temperature overshooting and should not exceed 1°C/day. Besides its use in the management of intracranial hypertension, therapeutic cooling is also essential to treat hyperthermia in brain-injured patients. In this review, we will discuss the benefit-risk balance and practical aspects of therapeutic temperature management in TBI patients.

Marked reduction in mortality in patients with severe traumatic brain injury

OBJECT

In spite of evidence that use of the Brain Trauma Foundation Guidelines for the Management of Severe Traumatic Brain Injury (Guidelines) would dramatically reduce morbidity and mortality, adherence to these Guidelines remains variable across trauma centers. The authors analyzed 2-week mortality due to severe traumatic brain injury (TBI) from 2001 through 2009 in New York State and examined the trends in adherence to the Guidelines.

METHODS

The authors calculated trends in adherence to the Guidelines and age-adjusted 2-week mortality rates between January 1, 2001, and December 31, 2009. Univariate and multivariate logistic regression analyses were performed to evaluate the effect of time period on case-fatality. Intracranial pressure (ICP) monitor insertion was modeled in a 2-level hierarchical model using generalized linear mixed effects to allow for clustering by different centers.

RESULTS

From 2001 to 2009, the case-fatality rate decreased from 22% to 13% (p < 0.0001), a change that remained significant after adjusting for factors that independently predict mortality (adjusted OR 0.52, 95% CI 0.39-0.70; p < 0.0001). Guidelines adherence increased, with the percentage of patients with ICP monitoring increasing from 56% to 75% (p < 0.0001). Adherence to cerebral perfusion pressure treatment thresholds increased from 15% to 48% (p < 0.0001). The proportion of patients having an ICP elevation greater than 25 mm Hg dropped from 42% to 29% (p = 0.0001).

CONCLUSIONS

There was a significant reduction in TBI mortality between 2001 and 2009 in New York State. Increase in Guidelines adherence occurred at the same time as the pronounced decrease in 2-week mortality and decreased rate of intracranial hypertension, suggesting a causal relationship between Guidelines adherence and improved outcomes. Our findings warrant future investigation to identify methods for increasing and sustaining adherence to evidence-based Guidelines recommendations.

[Increased intracranial pressure and brain edema]

In primary and secondary brain diseases, increasing volumes of the three compartments of brain tissue, cerebrospinal fluid, or blood lead to a critical increase in intracranial pressure (ICP). A rising ICP is associated with typical clinical symptoms; however, during analgosedation it can only be detected by invasive ICP monitoring. Other neuromonitoring procedures are not as effective as ICP monitoring; they reflect the ICP changes and their complications by other metabolic and oxygenation parameters. The most relevant parameter for brain perfusion is cerebral perfusion pressure (CPP), which is calculated as the difference between the middle arterial pressure (MAP) and the ICP. A mixed body of evidence exists for the different ICP-reducing treatment measures, such as hyperventilation, hyperosmolar substances, hypothermia, glucocorticosteroids, CSF drainage, and decompressive surgery.

Towards clinical management of traumatic brain injury: a review of models and mechanisms from a biomechanical perspective

Traumatic brain injury (TBI) is a major worldwide healthcare problem. Despite promising outcomes from many preclinical studies, the failure of several clinical studies to identify effective therapeutic and pharmacological approaches for TBI suggests that methods to improve the translational potential of preclinical studies are highly desirable. Rodent models of TBI are increasingly in demand for preclinical research, particularly for closed head injury (CHI), which mimics the most common type of TBI observed clinically. Although seemingly simple to establish, CHI models are particularly prone to experimental variability. Promisingly, bioengineering-oriented research has advanced our understanding of the nature of the mechanical forces and resulting head and brain motion during TBI. However, many neuroscience-oriented laboratories lack guidance with respect to fundamental biomechanical principles of TBI. Here, we review key historical and current literature that is relevant to the investigation of TBI from clinical, physiological and biomechanical perspectives, and comment on how the current challenges associated with rodent TBI models, particularly those involving CHI, could be improved.

Decreased risk of acute kidney injury with intracranial pressure monitoring in patients with moderate or severe brain injury

OBJECT

The authors undertook this study to evaluate the effects of continuous intracranial pressure (ICP) monitoring-directed mannitol treatment on kidney function in patients with moderate or severe traumatic brain injury (TBI).

METHODS

One hundred sixty-eight patients with TBI were prospectively assigned to an ICP monitoring group or a conventional treatment control group based on the Brain Trauma Foundation guidelines. Clinical data included the dynamic changes of patients' blood concentrations of cystatin C, creatinine (Cr), and blood urea nitrogen (BUN); mannitol use; and 6-month Glasgow Outcome Scale (GOS) scores.

RESULTS

There were no statistically significant differences with respect to hospitalized injury, age, or sex distribution between the 2 groups. The incidence of acute kidney injury (AKI) was higher in the control group than in the ICP monitoring group (p < 0.05). The mean mannitol dosage in the ICP monitoring group (443 ± 133 g) was significantly lower than in the control group (820 ± 412 g) (p < 0.01), and the period of mannitol use in the ICP monitoring group (3 ± 3.8 days) was significantly shorter than in the control group (7 ± 2.3 days) (p < 0.01). The 6-month GOS scores in the ICP monitoring group were significantly better than in the control group (p < 0.05). On the 7th, 14th, and 21st days after injury, the plasma cystatin C and Cr concentrations in the ICP-monitoring group were significantly higher than the control group (p < 0.05).

CONCLUSIONS

In patients with moderate and severe TBI, ICP-directed mannitol treatment demonstrated a beneficial effect on reducing the incidence of AKI compared with treatment directed by neurological signs and physiological indicators.

Declining mortality in neurocritical care patients: a cohort study in Southern Alberta over eleven years

PURPOSE

Few interventions have been proven to improve outcomes in neurocritical care patients. It is unknown whether outcomes in Canada have changed over time. We performed a cohort study in Southern Alberta to determine whether survival and discharge disposition have improved.

METHODS

Using prospectively collected data, we identified patients admitted to regional intensive care units (ICUs) over a more than 11-year period with traumatic brain injury (TBI), subarachnoid hemorrhage (SAH), intracerebral hemorrhage, anoxic encephalopathy, central nervous system infection, or status epilepticus. Four sequential time periods of 2.8 years were compared, as were periods before and after various practice modifications were introduced. Logistic regression was used to adjust for patient age, Glasgow Coma Scale score, and case mix.

RESULTS

A total of 4,097 patients were assessed. The odds of death were lowest in the most recent time quartile (odds ratio [OR] 0.70, 95% confidence interval [CI] 0.56 to 0.88, P < 0.01). The odds of being discharged home without the need for support services increased over time (OR 1.45, 95% CI 1.38 to 1.85, P = 0.003). Improvements were not the same for all diagnostic subgroups. They were statistically significant for patients with TBI and SAH. Neurocritical care consultative services, evidence-based protocols, and clustering of patients within a multidisciplinary ICU were associated with improved outcomes. Length of stay in an ICU increased among hospital survivors (4.6 vs 3.8 days, P < 0.01).

CONCLUSIONS

Mortality and discharge disposition of neurocritical care patients in Southern Alberta have improved over time. Practice modifications in the region were associated with positive outcome trends. Longer ICU length of stay may imply that intensivists are increasingly delaying decisions about withdrawing life-sustaining interventions.

Intracranial pressure monitoring in severe traumatic brain injury: results from the American College of Surgeons Trauma Quality Improvement Program

Although existing guidelines support the utilization of intracranial pressure (ICP) monitoring in patients with traumatic brain injury (TBI), the evidence suggesting benefit is limited. To evaluate the impact on outcome, we determined the relationship between ICP monitoring and mortality in centers participating in the American College of Surgeons Trauma Quality Improvement Program (TQIP). Data on 10,628 adults with severe TBI were derived from 155 TQIP centers over 2009-2011. Random-intercept multilevel modeling was used to evaluate the association between ICP monitoring and mortality after adjusting for important confounders. We evaluated this relationship at the patient level and at the institutional level. Overall mortality (n=3769) was 35%. Only 1874 (17.6%) patients underwent ICP monitoring, with a mortality of 32%. The adjusted odds ratio (OR) for mortality was 0.44 [95% confidence interval (CI), 0.31-0.63], when comparing patients with ICP monitoring to those without. It is plausible that patients receiving ICP monitoring were selected because of an anticipated favorable outcome. To overcome this limitation, we stratified hospitals into quartiles based on ICP monitoring utilization. Hospitals with higher rates of ICP monitoring use were associated with lower mortality: The adjusted OR of death was 0.52 (95% CI, 0.35-0.78) in the quartile of hospitals with highest use, compared to the lowest. ICP monitoring utilization rates explained only 9.9% of variation in mortality across centers. Results were comparable irrespective of the method of case-mix adjustment. In this observational study, ICP monitoring utilization was associated with lower mortality. However, variability in ICP monitoring rates contributed only modestly to variability in institutional mortality rates. Identifying other institutional practices that impact on mortality is an important area for future research.

Beyond intracranial pressure: optimization of cerebral blood flow, oxygen, and substrate delivery after traumatic brain injury

Monitoring and management of intracranial pressure (ICP) and cerebral perfusion pressure (CPP) is a standard of care after traumatic brain injury (TBI). However, the pathophysiology of so-called secondary brain injury, i.e., the cascade of potentially deleterious events that occur in the early phase following initial cerebral insult—after TBI, is complex, involving a subtle interplay between cerebral blood flow (CBF), oxygen delivery and utilization, and supply of main cerebral energy substrates (glucose) to the injured brain. Regulation of this interplay depends on the type of injury and may vary individually and over time. In this setting, patient management can be a challenging task, where standard ICP/CPP monitoring may become insufficient to prevent secondary brain injury. Growing clinical evidence demonstrates that so-called multimodal brain monitoring, including brain tissue oxygen (PbtO₂), cerebral microdialysis and transcranial Doppler among others, might help to optimize CBF and the delivery of oxygen/energy substrate at the bedside, thereby improving the management of secondary brain injury. Looking beyond ICP and CPP, and applying a multimodal therapeutic approach for the optimization of CBF, oxygen delivery, and brain energy supply may eventually improve overall care of patients with head injury. This review summarizes some of the important pathophysiological determinants of secondary cerebral damage after TBI and discusses novel approaches to optimize CBF and provide adequate oxygen and energy supply to the injured brain using multimodal brain monitoring.

Increased risk of pneumonia among ventilated patients with traumatic brain injury: every day counts!

BACKGROUND

Patients with traumatic brain injury (TBI) frequently require mechanical ventilation (MV). The objective of this study was to examine the association between time spent on MV and the development of pneumonia among patients with TBI.

MATERIALS AND METHODS

Patients older than 18 y with head abbreviated injury scale (AIS) scores coded 1-6 requiring MV in the National Trauma Data Bank 2007-2010 data set were included. The study was limited to hospitals reporting pneumonia cases. AIS scores were calculated using ICDMAP-90 software. Patients with injuries in any other region with AIS score >3, significant burns, or a hospital length of stay >30 d were excluded. A generalized linear model was used to determine the approximate relative risk of developing all-cause pneumonia (aspiration pneumonia, ventilator-associated pneumonia [VAP], and infectious pneumonia identified by the International Classification of Disease, Ninth Revision, diagnosis code) for each day of MV, controlling for age, gender, Glasgow coma scale motor score, comorbidity (Charlson comorbidity index) score, insurance status, and injury type and severity.

RESULTS

Among the 24,525 patients with TBI who required MV included in this study, 1593 (6.5%) developed all-cause pneumonia. After controlling for demographic and injury factors, each additional day on the ventilator was associated with a 7% increase in the risk of pneumonia (risk ratio 1.07, 95% confidence interval 1.07-1.08).

CONCLUSIONS

Patients who have sustained TBIs and require MV are at higher risk for VAP than individuals extubated earlier; therefore, shortening MV exposure will likely reduce the risk of VAP. As patients with TBI frequently require MV because of neurologic impairment, it is key to develop aggressive strategies to expedite ventilator independence.

Decompressive craniectomy: past, present and future

Decompressive craniectomy (DC)--a surgical procedure that involves removal of part of the skull to accommodate brain swelling--has been used for many years in the management of patients with brain oedema and/or intracranial hypertension, but its place in contemporary practice remains controversial. Results from a recent trial showed that early (neuroprotective) DC was not superior to medical management in patients with diffuse traumatic brain injury. An ongoing trial is investigating the clinical and cost effectiveness of secondary DC as a last-tier therapy for post-traumatic refractory intracranial hypertension. With regard to ischaemic stroke (malignant middle cerebral artery infarction), a recent Cochrane review concluded that DC improves survival compared with medical management, but that a higher proportion of DC survivors experience moderately severe or severe disability. Although many patients have a good outcome, the issue of DC-related disability raises important ethical issues. As DC and subsequent cranioplasty are associated with a number of complications, indiscriminate use of this surgery is not appropriate. Here, we review the evidence and present considerations regarding surgical technique, ethics and cost-effectiveness of DC. Prospective clinical trials and cohort studies are essential to enable optimization of patient care and outcomes.

Multimodality monitoring in the neurointensive care unit: a special perspective for patients with stroke

Multimodality monitoring (MMM) is a recently developed method that aids in understanding real-time brain physiology. Early detection of physiological disturbances is possible with the help of MMM, which allows identification of underlying causes of deterioration and minimization of secondary brain injury (SBI). MMM is especially helpful in comatose patients with severe brain injury because neurological examinations are not sensitive enough to detect SBI. The variables frequently examined in MMM are hemodynamic parameters such as intracranial pressure, cerebral perfusion pressure, and mean arterial pressure; brainspecific oxygen tension; markers for brain metabolism including glucose, lactate, and pyruvate levels in brain tissue; and cerebral blood flow. Continuous electroencephalography can be performed, if needed. The majority of SBIs stem from brain tissue hypoxia, brain ischemia, and seizures, which lead to a disturbance in brain oxygen levels, cerebral blood flow, and electrical discharges, all of which are easily detected by MMM. In this review, we discuss the clinical importance of physiological variables as well as the practical applicability of MMM in patients with stroke.

Parenchymal brain oxygen monitoring in the neurocritical care unit

Patients admitted to the neurocritical care unit (NCCU) often have serious conditions that can be associated with high morbidity and mortality. Pharmacologic agents or neuroprotectants have disappointed in the clinical environment. Current NCCU management therefore is directed toward identification, prevention, and treatment of secondary cerebral insults that evolve over time and are known to aggravate outcome. This strategy is based on a variety of monitoring techniques including use of intraparenchymal monitors. This article reviews parenchymal brain oxygen monitors, including the available technologies, practical aspects of use, the physiologic rationale behind their use, and patient management based on brain oxygen.

Prognosis in severe brain injury

BACKGROUND

The prediction of neurologic outcome is a fundamental concern in the resuscitation of patients with severe brain injury.

OBJECTIVE

To provide an evidence-based update on neurologic prognosis following traumatic brain injury and hypoxic-ischemic encephalopathy after cardiac arrest.

DATA SOURCE

Search of the PubMed database and manual review of bibliographies from selected articles to identify original data relating to prognostic methods and outcome prediction models in patients with neurologic trauma or hypoxic-ischemic encephalopathy.

DATA SYNTHESIS AND CONCLUSION

Articles were scrutinized regarding study design, population evaluated, interventions, outcomes, and limitations. Outcome prediction in severe brain injury is reliant on features of the neurologic examination, anatomical and physiological changes identified with CT and MRI, abnormalities detected with electroencephalography and evoked potentials, and physiological and biochemical derangements at both the brain and systemic levels. Use of such information in univariable association studies generally lacks specificity in classifying neurologic outcome. Furthermore, the accuracy of established prognostic classifiers may be affected by the introduction of outcome-modifying interventions, such as therapeutic hypothermia following cardiac arrest. Although greater specificity may be achieved with scoring systems derived from multivariable models, they generally fail to predict outcome with sufficient accuracy to be meaningful at the single patient level. Discriminative models which integrate knowledge of genetic determinants and biologic processes governing both injury and repair and account for the effects of resuscitative and rehabilitative care are needed.

Hemodynamic consequences of ketamine vs etomidate for endotracheal intubation in the air medical setting

OBJECTIVE

Recent drug shortages have required the occasional replacement of etomidate for endotracheal intubation (ETI) by helicopter emergency medical services (HEMS), with ketamine. The purpose of this study was to assess whether there was an association between ketamine vs etomidate use as the main ETI drug, with hemodynamic or clinical (airway) end points.

METHODS

This retrospective study used data entered into medical records at the time of HEMS transport. Subjects, 50 ketamine and 50 etomidate, were accrued from 3 US HEMS programs. The study period was from August 2011 through May 2012. Data collection included demographics, diagnostic category, ETI drugs use, ETI success, and complications. Hemodynamic parameters were assessed for up to 2 sets of vital signs before airway management and up to 5 sets of post-ETI vital signs. Significance was defined at the P < .05 level.

RESULTS

Patients on ketamine and etomidate were similar (P > .05) with respect to age, sex, scene/interfacility mission type, trauma vs nontrauma, neuromuscular blocking agent use, and rates of coadministration of fentanyl or midazolam. All patients had successful airway placement. Peri-ETI hypoxemia was seen in 10% of etomidate and 16% of ketamine cases (P = .55). The pre-ETI and post-ETI were similar between the ketamine and etomidate groups with respect to systolic blood pressure and heart rate at every vital signs assessment after ETI.

CONCLUSION

Initial assessment of ETI success and complication rates, as well as peri-ETI hemodynamic changes, suggests no concerning complications associated with large-scale replacement of etomidate with ketamine as the major airway management drug for HEMS.

Advances in the critical care management of ischemic stroke

Given recent advances in diagnostic modalities and revascularization capabilities, clinicians are not only able to rapidly and accurately identify acute ischemic stroke, but may also be able to aggressively intervene to minimize the extent of infarction. In those cases where revascularization cannot occur and/or the extent of infarction is large, there are multiple strategies to prevent secondary decompensation as the stroke evolves, for instance, if malignant cerebral edema should develop. In this paper, we will review the indications for specialized ICU care for an ischemic stroke patient, the treatment principles, and strategies employed by neurointensivists to minimize secondary neuronal injury, the literature in support of such strategies (and the questions to be addressed by future studies), all with the ultimate goal of increasing the likelihood of favorable neurologic outcomes in our ischemic stroke population.

Management of intracerebral pressure in the neurosciences critical care unit

Management of intracranial pressure in neurocritical care remains a potentially valuable target for improvements in therapy and patient outcomes. Surrogate markers of increased intracranial pressure, invasive monitors, and standard therapy, as well as promising new approaches to improve cerebral compliance are discussed, and a current review of the literature addressing this metric in neuroscience critical care is provided.

Surgical treatment of elevated intracranial pressure: decompressive craniectomy and intracranial pressure monitoring

Surgical techniques that address elevated intracranial pressure include (1) intraventricular catheter insertion and cerebrospinal fluid drainage, (2) removal of an intracranial space-occupying lesion, and (3) decompressive craniectomy. This review discusses the role of surgery in the management of elevated intracranial pressure, with special focus on intraventricular catheter placement and decompressive craniectomy. The techniques and potential complications of each procedure are described, and the existing evidence regarding the impact of these procedures on patient outcome is reviewed. Surgical management of mass lesions and ischemic or hemorrhagic stroke occurring in the posterior fossa is not discussed herein.

Estimation of optic nerve sheath diameter on an initial brain computed tomography scan can contribute prognostic information in traumatic brain injury patients

INTRODUCTION

The aim of this study was to evaluate the prognostic value of optic nerve sheath diameter (ONSD) measured on the initial brain computed tomography (CT) scan for intensive care unit (ICU) mortality in severe traumatic brain injury (TBI) patients.

METHODS

A prospective observational study of all severe TBI patients admitted to a neurosurgical ICU (over a 10-month period). Demographic and clinical data and brain CT scan results were recorded. ONSD for each eye was measured on the initial CT scan. The group of ICU survivors was compared to non-survivors. Glasgow Outcome Scale (GOS) was evaluated six months after ICU discharge.

RESULTS

Seventy-seven patients were included (age: 43±18; 81% males; mean Injury Severity Score: 35±15; ICU mortality: 28.5% (n=22)). Mean ONSD on the initial brain CT scan was 7.8±0.1 mm in non-survivors vs. 6.8±0.1 mm in survivors (P<0.001). The operative value of ONSD was a good predictor of mortality (area under the curve: 0.805). An ONSD cutoff≥7.3 had a sensitivity of 86.4% and a specificity of 74.6% and was independently associated with mortality in this population (adjusted odds ratio 95% confidence interval: 22.7 (3.2 to 159.6), P=0.002). There was a relationship between initial ONSD values and six-month GOS (P=0.03).

CONCLUSIONS

ONSD measured on the initial brain CT scan is independently associated with ICU mortality rate (when ≥7.3 mm) in severe TBI patients.See related commentary by Masquère et al.,http://ccforum.com/content/17/3/151.

[Increased intracranial pressure and brain edema]

In primary and secondary brain diseases, increasing volumes of the three compartments of brain tissue, cerebrospinal fluid, or blood lead to a critical increase in intracranial pressure (ICP). A rising ICP is associated with typical clinical symptoms; however, during analgosedation it can only be detected by invasive ICP monitoring. Other neuromonitoring procedures are not as effective as ICP monitoring; they reflect the ICP changes and their complications by other metabolic and oxygenation parameters. The most relevant parameter for brain perfusion is cerebral perfusion pressure (CPP), which is calculated as the difference between the middle arterial pressure (MAP) and the ICP. A mixed body of evidence exists for the different ICP-reducing treatment measures, such as hyperventilation, hyperosmolar substances, hypothermia, glucocorticosteroids, CSF drainage, and decompressive surgery.