Prognostic value of admission laboratory parameters in traumatic brain injury: results from the IMPACT study

Prognostic role of D-dimer level upon admission in patients with traumatic brain injury

BACKGROUND

The aim of this study was to evaluate the prognostic role of D-dimer level upon admission in patients with traumatic brain injury (TBI) through performing a meta-analysis.

METHODS

PubMed, Web of Science, Cochrane Library, and EMBASE were searched for potential eligible literature. The study characteristics and relevant data were extracted. Poor functional outcome was defined according to the Glasgow Outcome Scale (GOS ≤3). Odds ratios (ORs) with 95% confidence intervals (CIs) were pooled to estimate the predictive value of D-dimer for progressive hemorrhagic injury (PHI) and poor functional outcome at 3 months (3M GOS ≤3) in patients with TBI.

RESULTS

Eleven studies with 2761 patients were included. Eight studies examined the predictive role of higher D-dimer level for the risk of PHI, and the pooled OR was 1.72 (95% CI, 1.23-2.42). Three studies examined the predictive role of higher D-dimer level for the risk of 3M GOS ≤3, and the pooled OR was 2.00 (95% CI, 0.87-4.59). Significant between-study heterogeneities were observed, and sensitivity analyses and subgroup analyses were performed. No significant publication bias was found.

CONCLUSIONS

In conclusion, in patients with TBI, higher D-dimer level upon admission was associated with higher risk of PHI, yet no significant relationship was found between D-dimer level and the risk of 3M GOS ≤3. In the future, this readily available marker could help identify patients at risk and tailor management of these patients, thus reducing PHI and improving outcome.

Mortality in Children With Severe Head Trauma: Predictive Factors and Proposal for a New Predictive Scale

BACKGROUND

Traumatic brain injury is a public health problem around the world, and recognition of systemic sources of secondary brain lesions is crucial to improve outcome.

OBJECTIVE

To identify the main predictors of mortality and to propose a grading scale to measure the risk of death.

METHODS

This retrospective study was based on medical records of children with severe traumatic brain injury who were hospitalized at a level I pediatric trauma center between January 2000 and December 2005. Multiple logistic regression analysis was done to identify independent factors related to mortality. A receiver-operating characteristics curve was performed to verify the accuracy of the multiple logistic regression, and associations that increased mortality were verified.

RESULTS

We identified 315 children with severe head injury. Median Glasgow Coma Scale score was 6, and median Pediatric Trauma Score was 4. Global mortality rate was 30%, and deaths occurred despite adequate medical management within the first 48 hours in 79% of the patients. Age < 2 years (P = .02), Glasgow Coma Scale ≤ 5 (P < 10), accidental hypothermia (P = .0002), hyperglycemia (P = .0003), and coagulation disorders (P = .02) were all independent factors predicting mortality. A prognostic scale ranging from 0 to 6 that included these independent factors was then calculated for each patient and resulted in mortality rates ranging from 1% with a score of 6 to 100% with a score of 0.

CONCLUSION

Independent and modifiable mortality predictors could be identified and used for a new grading scale correlated with the risk of mortality in pediatric traumatic brain injury.

Prognostic value of coagulation tests for in-hospital mortality in patients with traumatic brain injury

BACKGROUND

Coagulopathy is commonly observed after traumatic brain injury (TBI). However, it is not known whether using the standard independent predictors in conjunction with coagulation tests would improve their prognostic value. We determined the incidence of TBI-associated coagulopathy in patients with isolated TBI (iTBI), evaluated the prognostic value of coagulation tests for in-hospital mortality, and tested their predictive power for in-hospital mortality in patients with iTBI.

METHODS

We conducted a retrospective, observational database study on 2319 consecutive patients with iTBI who attended the Huashan Hospital Department of the Neurosurgery Neurotrauma Center at Fudan University in China between December 2004 and June 2015. Two models based on the admission characteristics were developed: model A included predictors such as age, Glasgow Coma Scale (GCS) score, pupil reactivity, type of injury, and hemoglobin and glucose levels, while model B included the predictors from model A as well as coagulation test results. A total of 1643 patients enrolled between December 2004 and December 2011 were used to derive the prognostic models, and 676 patients enrolled between January 2012 and June 2015 were used to validate the models.

RESULTS

Overall, 18.6% (n = 432) of the patients developed coagulopathy after iTBI. The prevalence of acute traumatic coagulopathy is associated with the severity of brain injury. The percentage of platelet count <100 × 109/L, international normalized ratio (INR) > 1.25, the prothrombin time (PT) > 14 s, activated partial thromboplastin time (APTT) > 36 s, D-dimer >5 mg/L and fibrinogen (FIB) < 1.5 g/L was also closely related to the severity of brain injury, significance being found among three groups. Age, pupillary reactivity, GCS score, epidural hematoma (EDH), and glucose levels were independent prognostic factors for in-hospital mortality in model A, whereas age, pupillary reactivity, GCS score, EDH, glucose levels, INR >1.25, and APTT >36 s exhibited strong prognostic effects in model B. Discrimination and calibration were good for the development group in both prediction models. However, the external validation test showed that calibration was better in model B than in model A for patients from the validation population (Hosmer-Lemeshow test, p = 0.152 vs. p = 0.046, respectively).

CONCLUSIONS

Coagulation tests can improve the predictive power of the standard model for in-hospital mortality after TBI.

Prognostic value of cortisol and thyroid function tests in poisoned patients admitted to toxicology ICU

BACKGROUND

Prognostic value of cortisol and thyroid function tests (TFTs) has previously been evaluated in medical ICUs. We aimed to evaluate prognostic efficacy of cortisol and TFTs in critically ill poisoned patients admitted to toxicology intensive care unit (ICU).

METHODS

In a prospective study of consecutively enrolled subjects admitted to the toxicology ICU, lab analyses included TFTs (total T3 and T4 as well as TSH) and cortisol levels drawn between 8 am-10 am during period of the first 24 hours post-ingestion/exposure. Simplified Acute Physiology Score II (SAPS II) and Acute Physiology and Chronic Health Evaluation II (APACHE II) were recorded. All scores were compared to detect the best prognostic factor. Type of poisoning was also included.

RESULTS

In 200 patients evaluated, 129 were male and mean age was 31 years. In general, SAPS II, T4, and cortisol could prognosticate death. After regression analysis, only cortisol had such efficacy (P=0.04; OR=1.06; 95%CI=1.05-1.08; cut-off=42 µg/dL; sensitivity=70%; specificity=82%). Between aluminium phosphide (ALP)- and non ALP-poisoned patients, level of consciousness, mean arterial pressure, and cortisol level could prognosticate death in ALP poisoning (all Ps<0.001 in both uni and multivariate analyses). Median (interquartile range; IQR) GCS was 7 (6, 10) and 15 (8, 15) in non-ALP and ALP-poisoned patients (P<0.003). SAPS II and APACHE II could not prognosticate death at all.

CONCLUSION

Cortisol best prognosticated outcomes for subjects admitted to the toxicology ICU. Its level is higher in ALP-poisoned patients probably due to the higher stress while they remain conscious till the final stages of toxicity and are aware of deterioration of their clinical condition or may be due to their significantly lower blood pressures.

Distribution of Laboratory Parameters in Trauma Population

Background:

Biochemical laboratory investigations help plan optimum management and communication in short- as well as long-term outcome to trauma victims.

Objective:

To assess the status of real-time values of biochemical laboratory investigations of different trauma patients and their association with overall mortality.

Materials and Methods:

Data based on prospective, observational registry of “Towards Improved Trauma Care Outcomes” (TITCO) from four Indian city hospitals. Hemoglobin, hematocrit, random blood sugar, blood urea nitrogen (BUN), and serum creatinine of patients on admission were recorded. Logistic regression was applied with all biochemical investigation as independent variable and overall mortality as dependent variable.

Results:

Among 17047 trauma patients, 3456 with available laboratory result details were considered for this study. Overall mortality was 20% (range 14%–21%). For the higher laboratory results, value mortality was 21%–70%, with highest death (70%) for higher hemoglobin patients, followed by hematocrit (44%) and then creatinine (43%). Odds of high hemoglobin compared to normal were 15.20; odds of higher and lower of normal creatinine were 3.80 and 1.65 and for BUN were 2.17 and 1.92, respectively. Gender-wise significant difference was in overall female mortality (29%)% compared males (18%). Similar differences were replicated with results of each laboratory tests.

Conclusion:

The study ascertained the composite additional explanatory values of laboratory parameters in predicting outcome among injured patients in our population from Indian settings.

Correlation of arterial blood gas markers and lactate levels with outcomes in pediatric traumatic brain injury

Background:

Various physical markers have been used to predict outcome of traumatic brain injury in children. However, the utility of metabolic alterations for prognostication has been poorly described. Thus, we aim to correlate arterial blood gas markers and lactate levels with outcomes in children with moderate to severe traumatic brain injury.

Methods:

This is a retrospective cohort study that included all patients <16 years old who presented to the Emergency Department with moderate to severe traumatic brain injury (Glasgow Coma Scale ⩽13). Serial arterial blood gas results and lactate levels in the first five days of admission to a pediatric intensive care unit (PICU) were reviewed. Primary outcome was in-hospital mortality. Secondary outcomes were 28-day ventilator-free and PICU-free days. A stepwise logistic regression analysis in conjunction with receiver operating characteristic analysis were used to identify variables that were associated with in-hospital mortality. Secondary outcomes were analyzed using multiple linear regression.

Results:

Among the 43 patients analyzed, more than half of the patients (60%) had severe traumatic brain injury (Glasgow Coma Scale 8). Twenty-seven of the 43 (65%) patients underwent neurosurgical intervention and overall mortality was 9/43 (20.9%). The worst base excess and lactate levels of Day 2 of PICU stay were found to be most predictive for mortality with maximal area-under-curve (95% confidence interval) of 0.967 (0.906, 1.000). Worst lactate level on day 2 of PICU stay was also found to be associated with ventilator-free days and PICU-free days.

Conclusion:

In children with moderate to severe traumatic brain injury, base excess and lactate on Day 2 of PICU stay were predictors of mortality, duration of mechanical ventilation and length of PICU stay.

Impact of tranexamic acid on coagulation and inflammation in murine models of traumatic brain injury and hemorrhage

BACKGROUND

Posttraumatic coagulopathy and inflammation can exacerbate secondary cerebral damage after traumatic brain injury (TBI). Tranexamic acid (TXA) has been shown clinically to reduce mortality in hemorrhaging and head-injured trauma patients and has the potential to mitigate secondary brain injury with its reported antifibrinolytic and antiinflammatory properties. We hypothesized that TXA would improve posttraumatic coagulation and inflammation in a murine model of TBI alone and in a combined injury model of TBI and hemorrhage (TBI/H).

METHODS

An established murine weight drop model was used to induce a moderate TBI. Mice were administered intraperitoneal injections of 10 mg/kg TXA or equivalent volume of saline 10 min after injury. An additional group of mice was subjected to TBI followed by hemorrhagic shock using a pressure-controlled model. TBI/H mice were given intraperitoneal injections of TXA or saline during resuscitation. Blood was collected at intervals after injury to assess coagulation by rotational thromboelastometry (ROTEM) and inflammation by Multiplex cytokine analysis. Soluble P-selectin, a biomarker of platelet activation, and serum neuron-specific enolase, a biomarker of cerebral injury, were measured at intervals. Brain homogenates were analyzed for inflammatory changes by Multiplex enzyme-linked immunosorbent assay, and splenic tissue was collected for splenic cell population assessment by flow cytometry.

RESULTS

There were no coagulation, serum or cerebral cytokine, P-selectin, or neuron-specific enolase differences between mice treated with TXA or saline after TBI. After the addition of hemorrhagic shock and resuscitation to TBI, TXA administration still did not affect coagulation parameters, systemic or cerebral inflammation, or platelet activation, as compared with saline alone. At 24 hours after TBI, mice given TXA demonstrated lower splenic total cell counts central memory CD8, effector CD8, B cell, and increased naive CD4 cell populations. By contrast, TXA did not affect splenic leukocyte populations after combined TBI/H.

CONCLUSIONS

Despite clinical data suggesting a mortality benefit, TXA did not modulate coagulation, inflammation, or biomarker generation in either the TBI or TBI/H murine models. Administration of TXA after TBI altered splenic leukocyte populations, which may contribute to a change in posttraumatic immune status. Future studies should be done to investigate the role of TXA in the development of posttraumatic immunosuppression and risk of nosocomial infections.

Early Brain Edema is a Predictor of In-Hospital Mortality in Traumatic Brain Injury

BACKGROUND

Identifying patients who may progress to a poor clinical outcome will encourage earlier appropriate therapeutic interventions. Brain edema may contribute to secondary injury in traumatic brain injury (TBI) and thus, may be a useful prognostic indicator.

OBJECTIVE

We determined whether the presence of brain edema on the initial computed tomography (CT) scan of TBI patients would predict poor in-hospital outcome.

METHODS

We performed a retrospective review of all trauma patients with nonpenetrating head trauma at a Level I Trauma Center. International Classification of Diseases, Ninth Revision codes indicated the presence of brain edema and we evaluated the validity of this pragmatic assessment quantitatively in a random subset of patients. In-hospital mortality was the primary outcome variable. Univariate analysis and logistic regression identified predictors of mortality in all TBI patients and those with mild TBI.

RESULTS

Over 7200 patients were included in the study, including 6225 with mild TBI. Measurements of gray and white matter CT density verified radiological assessments of brain edema. Patients with documented brain edema had a mortality rate over 10 times that of the entire study population. With logistic regression accounting for Injury Severity Score, Glasgow Coma Scale score, other CT findings, and clinical variables, brain edema predicted an eightfold greater mortality rate in all patients (odds ratio 8.0, 95% confidence interval 4.6-14.0) and fivefold greater mortality rate for mild TBI patients (odds ratio 4.9, 95% confidence interval 2.0-11.7).

CONCLUSIONS

Brain edema is an independent prognostic variable across all categories of TBI severity. By alerting emergency physicians to patients with poor predicted clinical outcomes, this finding will drive better resource allocation, earlier intervention, and reduced patient mortality.

Blood transfusion indications in neurosurgical patients: A systematic review

Neurosurgical procedures can be complicated by significant blood losses that have the potential to decrease tissue perfusion to critical brain tissue. Red blood cell transfusion is used in a variety of capacities both inside, and outside, of the operating room to prevent untoward neurologic damage. However, evidence-based guidelines concerning thresholds and indications for transfusion in neurosurgery remain limited. Consequently, transfusion practices in neurosurgical patients are highly variable and based on institutional experiences. Recently, a paradigm shift has occurred in neurocritical intensive care units, whereby restrictive transfusion is increasingly favored over liberal transfusion but the ideal strategy remains in clinical equipoise. The authors of this study perform a systematic review of the literature with the objective of capturing the changing landscape of blood transfusion indications in neurosurgical patients.

Management of neurologic complications of coagulopathies

Coagulopathy is common in intensive care units (ICUs). Many physiologic derangements lead to dysfunctional hemostasis; these may be either congenital or acquired. The most devastating outcome of coagulopathy in the critically ill is major bleeding, defined by transfusion requirement, hemodynamic instability, or intracranial hemorrhage. ICU coagulopathy often poses complex management dilemmas, as bleeding risk must be tempered with thrombotic potential. Coagulopathy associated with intracranial hemorrhage bears directly on prognosis and outcome. There is a paucity of high-quality evidence for the management of coagulopathies in neurocritical care; however, data derived from studies of patients with intraparenchymal hemorrhage may inform treatment decisions. Coagulopathy is often broadly defined as any derangement of hemostasis resulting in either excessive bleeding or clotting, although most typically it is defined as impaired clot formation. Abnormalities in coagulation testing without overt clinical bleeding may also be considered evidence of coagulopathy. This chapter will focus on acquired conditions, such as organ failure, pharmacologic therapies, and platelet dysfunction that are associated with defective clot formation and result in, or exacerbate, intracranial hemorrhage, specifically spontaneous intraparenchymal hemorrhage and traumatic brain injury.

Improving on Laboratory Traumatic Brain Injury Models to Achieve Better Results

Experimental modeling of traumatic brain injury (TBI) in animals has identified several potential means and interventions that might have beneficial applications for treating traumatic brain injury clinically. Several of these interventions have been applied and tried with humans that are at different phases of testing (completed, prematurely terminated and others in progress). The promising results achieved in the laboratory with animal models have not been replicated with human trails as expected. This review will highlight some insights and significance attained via laboratory animal modeling of TBI as well as factors that require incorporation into the experimental studies that could help in translating results from laboratory to the bedside. Major progress has been made due to laboratory studies; in explaining the mechanisms as well as pathophysiological features of brain damage after TBI. Attempts to intervene in the cascade of events occurring after TBI all rely heavily on the knowledge from basic laboratory investigations. In looking to discover treatment, this review will endeavor to sight and state some central discrepancies between laboratory models and clinical scenarios.

Mechanism of death after early decompressive craniectomy in traumatic brain injury

Background

Decompressive craniectomy in devastating traumatic brain injury is controversial. The impact of decompressive craniectomy on mechanism of death is unclear in the literature to date. Our goal was to determine the mechanism of death between those receiving early decompressive craniectomy and those managed medically.

Methods

We performed an institutional retrospective review, from June 2003 to June 2013, of adult patients with devastating blunt traumatic brain injury undergoing early decompressive craniectomy who subsequently died. We compared this group to a retrospectively matched group based on: age, pre-hospital KPS, Marshall diffuse computed tomography grades, Injury Severity Scores, and admission laboratory values.

Results

Forty patients were analyzed; 20 with decompressive craniectomy and 20 without. The two groups were similar based on admission demographics, with the only statistically significant difference being platelet levels. Upon analysis, through both univariate and multivariate regression analysis, the mechanism of death was significantly different (p = 0.003; OR: 0.07 (0.01–0.41) and p = 0.04; OR: 0.08 (0.01–0.87)) with the decompressive craniectomy and non-decompressive craniectomy groups displaying neurological death rates of 10.0% versus 60.0%, respectively, with all other patients in both groups dying secondary to circulatory arrest after withdrawal of life-sustaining therapy. Time to death was significantly longer in the decompressive craniectomy group (2.83 vs. 9.21 days, respectively) (p = 0.01; OR: 0.65 (0.46–0.91).

Conclusions

Progression to neurological death appears to be more common in those devastating blunt traumatic brain injury patients treated medically compared to those undergoing early decompressive craniectomy. Given the implications of end-of-life care and societal implications, the mechanism of death determination and organ donation should be reported as relevant outcomes in devastating traumatic brain injury studies.

Prediction of in-hospital mortality and morbidity using high-sensitivity C-reactive protein after burr hole craniostomy

BACKGROUND

The purpose of this study was to assess whether preanesthetic laboratory values can predict in-hospital mortality and morbidity in patients who have undergone burr hole craniostomy due to chronic subdural hematoma.

METHODS

From January 2007 to February 2016, the records of 502 consecutive patients who underwent burr hole craniotomy were analyzed. All cases of burr hole craniostomy were fitted with a drain, as required by our institutional protocol.

RESULTS

Patients' demographic data and preoperative laboratory values were subjected to logistic regression analysis to predict in-hospital mortality and morbidity after burr hole craniostomy. Hemoglobin, prothrombin time, activated partial thromboplastin time, serum glucose, and high-sensitivity C-reactive protein (hsCRP) were found to be significantly associated with in-hospital mortality and morbidity by univariate regression analysis, but of these, only hsCRP (hazard ratio 1.210, 95 % confidence interval 1.089-1.345, P < 0.001) was found to significantly predict in-hospital mortality and morbidity by multivariate regression analysis. Areas under the curve for predicting in-hospital mortality and morbidity were 0.765 (95 % confidence interval 0.624-0.906, P = 0.002) and 0.646 (0.559-0.733, P = 0.001), respectively.

CONCLUSIONS

Preoperative hsCRP was found to be an independent predictor of in-hospital mortality and morbidity after burr hole craniostomy due to chronic subdural hematoma.

Predictors for outcome after surgery for traumatic acute subdural hematoma

Introduction: Acute traumatic subdural hematoma (ASDH) is one of the most frequent conditions in neurosurgery demanding emergency surgery. The aim of the study was to identify factors influencing outcome in patients who had surgery for evacuation of ASDH. Methods: From 2005 to 2012 eighty-five patients at age above 18 years had surgery for evacuation of ASDH. Outcome was measured according GOS at discharge and was dichotomized as “favorable outcome” (GOS 4 to 5) and “unfavorable outcome” (GOS 1 to 3). These factors were evaluated with univariate and logistic regression analysis for significance with outcome. Results: The mean age of the 85 patients was 62.7 years (SD±18.5). 45.9% patients were with favorable outcome and 54.1% had unfavorable outcome. Patients with GCS score 3-8 (54.1%) had 80.4% unfavorable outcome whereas 78.6% of patients with GCS score 13-15 (32.9%) had favorable outcome. All patients with nonreactive pupils (bilaterally or unilaterally - 31.8%) had unfavorable outcome whereas patients (36.5%) with both reactive pupils (36.5%) had in 80.6% favorable outcome. All patients (40%) with Rotterdam CT scores 5 and 6 had unfavorable outcome. The factors determining outcome were admission GSC score, Rotterdam CT scores, and prothrombin time. Conclusion: Patients who have GSC score of 3, unresponsive pupil(s) or have Rotterdam CT scores 5 and 6 have little chance of survival. Patients with coagulopathy have two times more unfavorable outcome. The patients with ASDH should have surgery as soon as possible after correction of vital parameters in order to avoid deterioration which can be very rapid and irreversible.

Anemia management after acute brain injury

Anemia is frequent among brain-injured patients, where it has been associated with an increased risk of poor outcome. The pathophysiology of anemia in this patient population remains multifactorial; moreover, whether anemia merely reflects a higher severity of the underlying disease or is a significant determinant of the neurological recovery of such patients remains unclear. Interestingly, the effects of red blood cell transfusions (RBCT) in moderately anemic patients remain controversial; although hemoglobin levels are increased, different studies observed only a modest and inconsistent improvement in cerebral oxygenation after RBCT and raised serious concerns about the risk of increased complications. Thus, considering this "blood transfusion anemia paradox", the optimal hemoglobin level to trigger RBCT in brain-injured patients has not been defined yet; also, there is insufficient evidence to provide strong recommendations regarding which hemoglobin level to target and which associated transfusion strategy (restrictive versus liberal) to select in this patient population. We summarize in this review article the more relevant studies evaluating the effects of anemia and RBCT in patients with an acute neurological condition; also, we propose some potential strategies to optimize transfusion management in such patients.

Relationship between trauma-induced coagulopathy and progressive hemorrhagic injury in patients with traumatic brain injury

Progressive hemorrhagic injury (PHI) can be divided into coagulopathy-related PHI and normal coagu- lation PHI. Coagulation disorders after traumatic brain injuries can be included in trauma-induced coagulopathy (TIC). Some studies showed that TIC is associated with PHI and increases the rates of disability and mortality. In this review, we discussed some mechanisms in TIC, which is of great importance in the development of PHI, including tissue factor (TF) hypothesis, protein C pathway and thrombocytopenia. The main mechanism in the relation of TIC to PHI is hypocoagulability. We also reviewed some coagulopathy parameters and proposed some possible risk factors, predictors and therapies.

Moderate traumatic brain injury, acute phase course and deviations in physiological variables: an observational study

BACKGROUND

Patients with moderate traumatic brain injury (TBI) are a heterogeneous group with great variability in clinical course. Guidelines for monitoring and level of care in the acute phase are lacking. The main aim of this observational study was to describe injury severity and the acute phase course during the first three days post-injury in a cohort of patients with moderate TBI. Deviations from defined parameters in selected physiological variables were also studied, based on guidelines for severe TBI during the same period.

METHODS

During a 5-year period (2004-2009), 119 patients ≥16 years (median age 47 years, range 16-92) with moderate TBI according to the Head Injury Severity Scale were admitted to a Norwegian level 1 trauma centre. Injury-related and acute phase data were collected prospectively. Deviations in six physiological variables were collected retrospectively.

RESULTS

Eighty-six percent of the patients had intracranial pathology on CT scan and 61 % had extracranial injuries. Eighty-four percent of all patients were admitted to intensive care units (ICUs) the first day, and 51 % stayed in ICUs ≥3 days. Patients staying in ICUs ≥3 days had lower median Glasgow Coma Scale score; 12 (range 9-15) versus 13 (range 9-15, P = 0.003) and more often extracranial injuries (77 % versus 42 %, P = 0.001) than patients staying in ICU 0-2 days. Most patients staying in ICUs ≥3 days had at least one episode of hypotension (53 %), hypoxia (57 %), hyperthermia (59 %), anaemia (56 %) and hyperglycaemia (65 %), and the proportion of anaemia related to number of measurements was high (33 %).

CONCLUSION

Most of the moderate TBI patients stayed in an ICU the first day, and half of them stayed in ICUs ≥3 days due to not only intracranial, but also extracranial injuries. Deviations in physiological variables were often seen in this latter group of patients. Lack of guidelines for patients with moderate TBI may leave these deviations uncorrected. We propose that in future research of moderate TBI, patients might be differentiated with regard to their need for monitoring and level of care the first few days post-injury. This could contribute to improvement of acute phase management.

The European guideline on management of major bleeding and coagulopathy following trauma: fourth edition

BACKGROUND

Severe trauma continues to represent a global public health issue and mortality and morbidity in trauma patients remains substantial. A number of initiatives have aimed to provide guidance on the management of trauma patients. This document focuses on the management of major bleeding and coagulopathy following trauma and encourages adaptation of the guiding principles to each local situation and implementation within each institution.

METHODS

The pan-European, multidisciplinary Task Force for Advanced Bleeding Care in Trauma was founded in 2004 and included representatives of six relevant European professional societies. The group used a structured, evidence-based consensus approach to address scientific queries that served as the basis for each recommendation and supporting rationale. Expert opinion and current clinical practice were also considered, particularly in areas in which randomised clinical trials have not or cannot be performed. Existing recommendations were reconsidered and revised based on new scientific evidence and observed shifts in clinical practice; new recommendations were formulated to reflect current clinical concerns and areas in which new research data have been generated. This guideline represents the fourth edition of a document first published in 2007 and updated in 2010 and 2013.

RESULTS

The guideline now recommends that patients be transferred directly to an appropriate trauma treatment centre and encourages use of a restricted volume replacement strategy during initial resuscitation. Best-practice use of blood products during further resuscitation continues to evolve and should be guided by a goal-directed strategy. The identification and management of patients pre-treated with anticoagulant agents continues to pose a real challenge, despite accumulating experience and awareness. The present guideline should be viewed as an educational aid to improve and standardise the care of the bleeding trauma patients across Europe and beyond. This document may also serve as a basis for local implementation. Furthermore, local quality and safety management systems need to be established to specifically assess key measures of bleeding control and outcome.

CONCLUSIONS

A multidisciplinary approach and adherence to evidence-based guidance are key to improving patient outcomes. The implementation of locally adapted treatment algorithms should strive to achieve measureable improvements in patient outcome.

Increased blood glucose is related to disturbed cerebrovascular pressure reactivity after traumatic brain injury

BACKGROUND

Increased blood glucose and impaired pressure reactivity (PRx) after traumatic brain injury (TBI) are both known to correlate with unfavorable patient outcome. However, the relationship between these two variables is unknown.

METHODS

To test the hypothesis that increased blood glucose leads to increased PRx, we retrospectively analyzed data from 86 traumatic brain injured patients admitted to the Neurocritical Care Unit. Data analyzed included arterial glucose concentration, intracranial pressure (ICP), cerebral perfusion pressure (CPP) and end-tidal CO2. PRx was calculated as the moving correlation coefficient between averaged (10 seconds) arterial blood pressure and ICP. One arterial glucose concentration and one time-aligned PRx value were obtained for each patient, during each day until the fifth day after ictus.

RESULTS

Mean arterial glucose concentrations during the first 5 days since ictus were positively correlated with mean PRx (Pearson correlation coefficient = 0.25, p = 0.02). The correlation was strongest on the first day after injury (Pearson correlation coefficient = 0.47, p = 0.008).

CONCLUSION

Our preliminary findings indicate that increased blood glucose may impair cerebrovascular reactivity, potentially contributing to a mechanistic link between increased blood glucose and poorer outcome after TBI.

Time Course of Coagulation and Fibrinolytic Parameters in Patients with Traumatic Brain Injury

Traumatic brain injury (TBI) has long been associated with coagulopathy; however, the time course of coagulation/fibrinolytic parameters in the acute phase of TBI remains unclear. The purpose of the study was to analyze the time course of coagulation/fibrinolytic parameters in the acute phase of TBI and to elucidate parameter relationships to prognosis. We retrospectively evaluated 234 patients with severe isolated TBI with initial blood samples obtained no more than 1 h after injury. Platelet count, prothrombin time, activated partial thromboplastin time (aPTT), plasma levels of fibrinogen, and D-dimer were measured on arrival in the emergency department and 3, 6, and 12 h after injury. Multivariate logistic regression analysis was performed to identify risk factors for poor prognosis at each time point. From hospital admission to 12 h after injury, an elevated D-dimer level was a significant negative prognostic indicator (admission: p < 0.0001; 3 h after injury: p = 0.0005; 6 h after injury: p = 0.005; 12 h after injury: p = 0.0009). An upward trend of aPTT on admission and 3 h after injury was also a significant negative prognostic indicator (admission: p = 0.0011; 3 h after injury: p = 0.013). On multivariate logistic regression analysis, which included all initial variables, independent risk factors for poor prognosis included older age (p = 0.0005), low Glasgow Coma Scale score (p < 0.0001), high Abbreviated Injury Score (p = 0.015), aPTT >30.2 sec (p = 0.019), and elevated D-dimer level (p = 0.0005). We concluded that D-dimer is the best coagulation/fibrinolytic parameter to monitor for prediction of outcome.

Monitoring of hematological and hemostatic parameters in neurocritical care patients

Anemia and bleeding are paramount concerns in neurocritical care and often relate to the severity of intracranial hemorrhage. Anemia is generally associated with worse outcomes, and efforts to minimize anemia through reduced volume of blood sampled are encouraged. Point-of-care-testing reliably detects the use of non-steroidal anti-inflammatory drugs that may worsen bleeding and reduce platelet activity, particularly in patients with intracerebral hemorrhage. How best to monitor the effect of platelet transfusion or platelet-activating therapy is not well studied. For patients known to take novel oral anticoagulants, drug-specific coagulation tests before neurosurgical intervention are prudent.

Neuroglobin and Nogo-a as biomarkers for the severity and prognosis of traumatic brain injury

OBJECTIVE

To identify the early changes of serum neuroglobin and Nogo-A concentrations and the relations to traumatic brain injury (TBI) severity and prognosis.

METHODS

Serum samples were obtained and analyzed from 34 patients with TBI within the first 96 h after injury. Comparative analysis combined with Glasgow Coma Scale (GCS) scores and the 6-month prognosis of these patients was performed.

RESULTS

Significant correlations were found between peak serum neuroglobin and Nogo-A concentrations and a patient's GCS score on admission (p < 0.001). The mean peak serum neuroglobin and Nogo-A concentrations were both significantly higher in patients with an unfavorable outcome at 6 months after injury (p < 0.05).

CONCLUSIONS

Serum neuroglobin and Nogo-A levels could be suggested as biomarkers for predicting TBI severity and prognosis.

Subarachnoid hemorrhage prevalence and its association with short-term outcome in pediatric severe traumatic brain injury

BACKGROUND

Subarachnoid hemorrhage (SAH) is an independent prognostic indicator of outcome in adult severe traumatic brain injury (sTBI). There is a paucity of investigations on SAH in pediatric sTBI. The goal of this study was to determine in pediatric sTBI patients SAH prevalence, associated factors, and its relationship to short-term outcome.

METHODS

We retrospectively analyzed 171 sTBI patients (pre-sedation GCS ≤8 and head MAIS ≥4) who underwent CT head imaging within the first 24 h of hospital admission. Data were analyzed with both univariate and multivariate techniques.

RESULTS

SAH was found in 42 % of sTBI patients (n = 71/171), and it was more frequently associated with skull fractures, cerebral edema, diffuse axonal injury, contusion, and intraventricular hemorrhage (p < 0.05). Patients with SAH had higher Injury Severity Scores (p = 0.032) and a greater frequency of fixed pupil(s) on admission (p = 0.001). There were no significant differences in etiologies between sTBI patients with and without SAH. Worse disposition occurred in sTBI patients with SAH, including increased mortality (p = 0.009), increased episodes of central diabetes insipidus (p = 0.002), greater infection rates (p = 0.002), and fewer ventilator-free days (p = 0.001). In sTBI survivors, SAH was associated with increased lengths of stay (p < 0.001) and a higher level of care required on discharge (p = 0.004). Despite evidence that SAH is linked to poorer outcomes on univariate analyses, multivariate analysis failed to demonstrate an independent association between SAH and mortality (p = 0.969).

CONCLUSION

SAH was present in almost half of pediatric sTBI patients, and it was indicative of TBI severity and a higher level of care on discharge. SAH in pediatric patients was not independently associated with increased risk of mortality.

Glucose administration after traumatic brain injury exerts some benefits and no adverse effects on behavioral and histological outcomes

The impact of hyperglycemia after traumatic brain injury (TBI), and even the administration of glucose-containing solutions to head injured patients, remains controversial. In the current study adult male Sprague-Dawley rats were tested on behavioral tasks and then underwent surgery to induce sham injury or unilateral controlled cortical impact (CCI) injury followed by injections (i.p.) with either a 50% glucose solution (Glc; 2g/kg) or an equivalent volume of either 0.9% or 8% saline (Sal) at 0, 1, 3 and 6h post-injury. The type of saline treatment did not significantly affect any outcome measures, so these data were combined. Rats with CCI had significant deficits in beam-walking traversal time and rating scores (p's < 0.001 versus sham) that recovered over test sessions from 1 to 13 days post-injury (p's < 0.001), but these beam-walking deficits were not affected by Glc versus Sal treatments. Persistent post-CCI deficits in forelimb contraflexion scores and forelimb tactile placing ability were also not differentially affected by Glc or Sal treatments. However, deficits in latency to retract the right hind limb after limb extension were significantly attenuated in the CCI-Glc group (p < 0.05 versus CCI-Sal). Both CCI groups were significantly impaired in a plus maze test of spatial working memory on days 4, 9 and 14 post-surgery (p < 0.001 versus sham), and there was no effect of Glc versus Sal on this cognitive outcome measure. At 15 days post-surgery the loss of cortical tissue volume (p < 0.001 versus sham) was significantly less in the CCI-Glc group (30.0%; p < 0.05) compared to the CCI-Sal group (35.7%). Counts of surviving hippocampal hilar neurons revealed a significant (~40%) loss ipsilateral to CCI (p < 0.001 versus sham), but neuronal loss in the hippocampus was not different in the CCI-Sal and CCI-Glc groups. Taken together, these results indicate that an early elevation of blood glucose may improve some neurological outcomes and, importantly, the induction of hyperglycemia after isolated TBI did not adversely affect any sensorimotor, cognitive or histological outcomes.

Traumatic Intracerebral Hemorrhage: Risk Factors Associated with Progression

The increase in the volume of a traumatic intracerebral hemorrhage (TICH) is a widely studied phenomenon that has a direct impact on the prognosis of patients. The objective of this study was to identify the risk factors associated with the progression of TICH. We retrospectively analyzed the records of 1970 adult patients >15 years of age who were consecutively admitted after sustaining a closed severe traumatic brain injury (TBI) between January 1987 and November 2013 at a single center. Beginning in 2007, patients with moderate TBIs were also included. A total of 782 patients exhibited one or more TICH on the initial CT scan, and met the selection criteria. The main outcome variable was the presence or absence of progression of the TICH. Univariate and multivariate statistical analyses were performed. Factors independently associated with the growth of TICH obtained through logistic regression included the following: an initial volume <5 cc (odds ratio [OR] 2.42, p<0.001), cisternal compression (OR 1.95, p<0.001), decompressive craniectomy (OR 2.18, p<0.001), age (mean 37.67 vs. 42.95 years; OR 1.01, p<0.001), falls as mechanism of trauma (OR 1.72, p=0.001), multiple TICHs (OR 1.56, p=0.007), and hypoxia (OR 1.56, p=0.02). TICH progression occurred with a frequency of 63% in our study. We showed that there was a correlation between TICH growth and some variables, such as multiple TICHs, a lower initial volume, acute subdural hematoma, cisternal compression, older patient age, hypoxia, falls, and decompressive craniectomy.

Microparticles impact coagulation after traumatic brain injury

BACKGROUND

The pathophysiology that drives the subacute hypercoagulable state commonly seen after traumatic brain injury (TBI) is not well understood. Alterations caused by TBI in platelet and microparticle (MP) numbers and function have been suggested as possible causes; however, the contributions of platelets and MPs are currently unknown.

MATERIALS AND METHODS

A weight-drop technique of TBI using a murine model of moderate head injury was used. Blood was collected at intervals after injury. MP enumeration and characterization were performed using Nanoparticle Tracking Analysis, and platelet counts and coagulation parameters were determined using thromboelastometry. A MP procoagulant assay was used to compare activity between injured and sham mice.

RESULTS

At 24 h after injury, there were no changes in circulating platelet numbers. However, there was a decrease in platelet contribution to clot formation. In contrast, there was a decline in circulating total MP numbers. When MPs from sham mice were added to the blood from head-injured animals, there was a normalization of platelet contribution to clot formation. Conversely, when MPs from TBI mice were added to sham blood, there was a significant decrease in platelet contribution to clot formation. Notably, there was an increase in MP procoagulant activity in head-injured mice.

CONCLUSIONS

MPs generated after TBI likely contribute to altered coagulation after head injury and may play a key role in the development of a posttraumatic hypercoagulable state in TBI patients.

Desmopressin acetate in intracranial haemorrhage

Introduction. The secondary increase in the size of intracranial haematomas as a result of spontaneous haemorrhage or trauma is of particular relevance in the event of prior intake of platelet aggregation inhibitors. We describe the effect of desmopressin acetate as a means of temporarily stabilising the platelet function. Patients and Methods. The platelet function was analysed in 10 patients who had received single (N = 4) or multiple (N = 6) doses of acetylsalicylic acid and 3 patients (control group) who had not taken acetylsalicylic acid. All subjects had suffered intracranial haemorrhage. Analysis was performed before, half an hour and three hours after administration of desmopressin acetate. Statistical analysis was performed by applying a level of significance of P ≤ 0.05. Results. (1) Platelet function returned to normal 30 minutes after administration of desmopressin acetate. (2) The platelet function worsened again after three hours. (3) There were no complications related to electrolytes or fluid balance. Conclusion. Desmopressin acetate can stabilise the platelet function in neurosurgical patients who have received acetylsalicylic acid prior to surgery without causing transfusion-related side effects or a loss of time. The effect is, however, limited and influenced by the frequency of drug intake. Further controls are needed in neurosurgical patients.

Coagulopathy associated with traumatic brain injury

Coagulopathy is often observed after traumatic brain injury (TBI), but the pathogenic mechanisms of this phenomenon remain elusive. Brain injury is the leading cause of trauma deaths, and the development of coagulopathy after TBI is associated with increased morbidity and mortality in these patients. The coagulopathy after TBI comprises a hypocoagulable and a hypercoagulable state with hemorrhagic and thrombotic phenotypes that are both associated with worse outcome. Some theories of its pathogenesis include massive release of tissue factor, altered protein C homeostasis, microparticle upregulation, and platelet hyperactivity. This article aims to examine the coagulopathy associated with blunt head injury, to review its effect on progression of hemorrhagic injury, and to discuss the possible relevant pathophysiological mechanisms.

Transfusion of red blood cells in patients with a prehospital Glasgow Coma Scale score of 8 or less and no evidence of shock is associated with worse outcomes

BACKGROUND

Red blood cell transfusion practices vary, and the optimal hemoglobin for patients with traumatic brain injury has not been established.

METHODS

A retrospective review of data collected prospectively as part of a randomized, controlled trial involving emergency medical service agencies within the Resuscitation Outcomes Consortium was conducted. In patients with a Glasgow Coma Scale (GCS) score of 8 or less without evidence of shock (defined by a systolic blood pressure [SBP] < 70 or SBP of 70 to 90 with a heart rate ≥108), the association of red blood cell transfusion with 28-day survival, adult respiratory distress syndrome-free survival, Multiple Organ Dysfunction Score (MODs), and 6-month Extended Glasgow Outcome Scale (GOSE) score was modeled using multivariable logistic regression with robust SEs adjusting for age, sex, injury severity (Injury Severity Score [ISS]), initial GCS score, initial SBP, highest field heart rate, penetrating injury, fluid use, study site, and hemoglobin (Hgb) level.

RESULTS

A total of 1,158 patients had a mean age of 40, 76% were male, and 98% experienced blunt trauma. The initial mean GCS score was 5, and the initial mean SBP was 134. The mean head Abbreviated Injury Scale (AIS) score was 3.5. A categorical interaction of red blood cell transfusion stratified by initial Hgb showed that when the first Hgb was greater than 10 g/dL, volume of packed red blood cell was associated with a decreased 28-day survival (odds ratio, 0.83; 95% confidence interval [CI], 0.74-0.93; p < 0.01) and decreased adult respiratory distress syndrome-free survival (odds ratio, 0.82; 95% CI, 0.74-0.92; p < 0.01). When the initial Hgb was greater than 10, each unit of blood transfused increased the MODs by 0.45 (coefficient 95% CI, 0.19-0.70; p < 0.01).

CONCLUSION

In patients with a suspected traumatic brain injury and no evidence of shock, transfusion of red blood cells was associated with worse outcomes when the initial Hgb was greater than 10.

LEVEL OF EVIDENCE

Therapeutic study, level III.

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.

External Validation of the International Mission for Prognosis and Analysis of Clinical Trials Model and the Role of Markers of Coagulation

BACKGROUND:

Markers of coagulation have shown to have important value in predicting traumatic brain injury outcome.

OBJECTIVE:

To externally validate and investigate the role of markers of coagulation for outcome prediction by using the International Mission for Prognosis and Analysis of Clinical Trials (IMPACT) model while adjusting for overall injury severity.

METHODS:

A retrospective chart analysis of traumatic brain injury patients admitted to Helsinki University Central Hospital between 2009 and 2010 was performed. Outcome was estimated by using the criteria of the IMPACT model. Admission international normalized ratio (INR) and platelet count were used as markers of coagulation. Overall injury severity was categorized with the injury severity score (ISS). Variables were added to the calculated IMPACT risk, generating new models. Model performance was assessed by analyzing and comparing the area under the curve (AUC) of the models.

RESULTS:

For 342 included patients, 6-month mortality was 32% and unfavorable neurological outcome was 36%. Patients with a poor outcome had lower platelets and higher INR and ISS than those with good outcome (P &lt; .001). The IMPACT model had an AUC of 0.85 for predicting mortality and 0.81 for neurological outcome. Addition of INR but not ISS or platelets to the IMPACT predicted risk improved the predictive validity for mortality ([INCREMENT]AUC 0.02, P = .034) but not neurological outcome ([INCREMENT]AUC 0.00, P = .401). In multivariate analysis, INR remained significant for mortality but not for neurological outcome when adjusting for IMPACT risk and ISS (P = .012).

CONCLUSION:

The IMPACT model showed excellent performance, and INR was an independent predictor for mortality, independent of overall injury severity.

S100B is an important outcome predictor in traumatic brain injury

The objective of the study was to examine how S100B, a biomarker of traumatic brain injury (TBI), contributes to outcome prediction after adjusting for known parameters, including age, Glasgow Coma Scale (GCS), pupil reaction, and computed tomography (CT) variables; to examine which parameters have the best correlation to elevated serum levels of S100B; and to investigate when to sample S100B to achieve the strongest association to outcome. This retrospective study included 265 patients with TBI admitted to the neurointensive care unit, Karolinska University Hospital Solna, Stockholm, Sweden. Univariate and multivariate proportional odds regressions were performed to determine parameters most closely related to outcome, and how S100B adds to prediction accuracy. Age (p<0.0001), pupil reaction (p<0.0001), and levels of S100B (p<0.0001) had the strongest statistical correlation to outcome. The area under curve of S100B, the first 48 h after trauma, yielded an additional explained variance of 6.6% in excess of known outcome parameters, including age, GCS, pupil reaction, and CT variables, themselves exhibiting an explained variance of 29.3%. S100B adds substantial information regarding patient outcome, in excess of that provided by known parameters. Only CT variables were found to be significant predictors of increased levels of S100B in uni- and multivariate analysis. Early samples of S100B, within 12 h after trauma, appear to have little prognostic value, and S100B should likely be sampled 12-36 h following trauma to best enhance TBI outcome prediction.

Prognosis Research Strategy (PROGRESS) 2: prognostic factor research

Prognostic factor research aims to identify factors associated with subsequent clinical outcome in people with a particular disease or health condition. In this article, the second in the PROGRESS series, the authors discuss the role of prognostic factors in current clinical practice, randomised trials, and developing new interventions, and explain why and how prognostic factor research should be improved.

Physiopathology of anemia and transfusion thresholds in isolated head injury

BACKGROUND

Blood transfusion strategies among patients with critical illness use a restrictive hemoglobin threshold. However, among patients with head injury, no outcome differences have been shown between either liberal or restrictive strategies. Several studies and literature reviews suggest that anemia is associated with markers of tissue ischemia. The paucity of prospective data confuses the association between surrogates of tissue ischemia and neurological outcome.

METHODS

A narrative review of transfusion practices among patients in the acute phase of head injury was performed using PubMed, MEDLINE, EMBASE, Cochrane, and WEB of Science databases. A total of 104 articles were reviewed.

RESULTS

There are few data to guide clinical practice. Clinicians use blood hemoglobin concentrations to trigger transfusion. Markers of potential cerebral injury are not in regular use despite experimental and observational data rising from histologic examination, microdialysis, oximetry, and flow-based multimonitoring systems recommending their use to titrate blood transfusion in neurotrauma.

CONCLUSION

The generalization of transfusion triggers is common practice. Evidence-based approaches to transfusions strategies in head injury are lacking and not based on an understanding of cerebral physiopathology.

Hemoglobin levels and transfusions in neurocritically ill patients: a systematic review of comparative studies

Introduction

Accumulating evidence suggests that, in critically ill patients, a lower hemoglobin transfusion threshold is safe. However, the optimal hemoglobin level and associated transfusion threshold remain unknown in neurocritically ill patients.

Methods

We conducted a systematic review of comparative studies (randomized and nonrandomized) to evaluate the effect of hemoglobin levels on mortality, neurologic function, intensive care unit (ICU) and hospital length of stay, duration of mechanical ventilation, and multiple organ failure in adult and pediatric neurocritically ill patients. We searched MEDLINE, The Cochrane Central Register of Controlled Trials, Embase, Web of Knowledge, and Google Scholar. Studies focusing on any neurocritical care conditions were included. Data are presented by using odds ratios for dichotomous outcomes and mean differences for continuous outcomes.

Results

Among 4,310 retrieved records, six studies met inclusion criteria (n = 537). Four studies were conducted in traumatic brain injury (TBI), one in subarachnoid hemorrhage (SAH), and one in a mixed population of neurocritically ill patients. The minimal hemoglobin levels or transfusion thresholds ranged from 7 to 10 g/dl in the lower-Hb groups and from 9.3 to 11.5 g/dl in the higher-Hb groups. Three studies had a low risk of bias, and three had a high risk of bias. No effect was observed on mortality, duration of mechanical ventilation, or multiple organ failure. In studies reporting on length of stay (n = 4), one reported a significant shorter ICU stay (mean, -11.4 days (95% confidence interval, -16.1 to -6.7)), and one, a shorter hospital stay (mean, -5.7 days (-10.3 to -1.1)) in the lower-Hb groups, whereas the other two found no significant association.

Conclusions

We found insufficient evidence to confirm or refute a difference in effect between lower- and higher-Hb groups in neurocritically ill patients. Considering the lack of evidence regarding long-term neurologic functional outcomes and the high risk of bias of half the studies, no recommendation can be made regarding which hemoglobin level to target and which associated transfusion strategy (restrictive or liberal) to favor in neurocritically ill patients.

Multivariate outcome prediction in traumatic brain injury with focus on laboratory values

Traumatic brain injury (TBI) is a major cause of morbidity and mortality. Identifying factors relevant to outcome can provide a better understanding of TBI pathophysiology, in addition to aiding prognostication. Many common laboratory variables have been related to outcome but may not be independent predictors in a multivariate setting. In this study, 757 patients were identified in the Karolinska TBI database who had retrievable early laboratory variables. These were analyzed towards a dichotomized Glasgow Outcome Scale (GOS) with logistic regression and relevance vector machines, a non-linear machine learning method, univariately and controlled for the known important predictors in TBI outcome: age, Glasgow Coma Score (GCS), pupil response, and computed tomography (CT) score. Accuracy was assessed with Nagelkerke's pseudo R². Of the 18 investigated laboratory variables, 15 were found significant (p<0.05) towards outcome in univariate analyses. In contrast, when adjusting for other predictors, few remained significant. Creatinine was found an independent predictor of TBI outcome. Glucose, albumin, and osmolarity levels were also identified as predictors, depending on analysis method. A worse outcome related to increasing osmolarity may warrant further study. Importantly, hemoglobin was not found significant when adjusted for post-resuscitation GCS as opposed to an admission GCS, and timing of GCS can thus have a major impact on conclusions. In total, laboratory variables added an additional 1.3-4.4% to pseudo R².