Hospital-acquired pneumonia is an independent predictor of poor global outcome in severe traumatic brain injury up to 5 years after discharge

Modelling lung infection with Klebsiella pneumoniae after murine traumatic brain injury

Pneumonia is a common comorbidity in patients with severe traumatic brain injury (TBI), and is associated with increased morbidity and mortality. In this study, we established a model of intratracheal Klebsiella pneumoniae administration in young adult male and female mice, at 4 days following an experimental TBI, to investigate how K. pneumoniae infection influences acute post-TBI outcomes. A dose-response curve determined the optimal dose of K. pneumoniae for inoculation (1 x 10^6 colony forming units), and administration at 4 days post-TBI resulted in transient body weight loss and sickness behaviors (hypoactivity and acute dyspnea). K. pneumoniae infection led to an increase in pro-inflammatory cytokines in serum and bronchoalveolar lavage fluid at 24 h post-infection, in both TBI and sham (uninjured) mice. By 7 days, when myeloperoxidase + neutrophil numbers had returned to baseline in all groups, lung histopathology was observed with an increase in airspace size in TBI + K. pneumoniae mice compared to TBI + vehicle mice. In the brain, increased neuroinflammatory gene expression was observed acutely in response to TBI, with an exacerbated increase in Ccl2 and Hmox1 in TBI + K. pneumoniae mice compared to either TBI or K. pneumoniae alone. However, the presence of neuroinflammatory immune cells in the injured brain, and the extent of damage to cortical and hippocampal brain tissue, was comparable between K. pneumoniae and vehicle-treated mice by 7 days. Examination of the fecal microbiome across a time course did not reveal any pronounced effects of either injury or K. pneumoniae on bacterial diversity or abundance. Together, these findings demonstrate that K. pneumoniae lung infection after TBI induces an acute and transient inflammatory response, primarily localized to the lungs with some systemic effects. However, this infection had minimal impact on secondary injury processes in the brain following TBI. Future studies are needed to evaluate the potential longer-term consequences of this dual-hit insult.

Association of antimicrobial use and incidence of hospital-acquired pneumonia in critically ill trauma patients with pulmonary contusion: an observational study

BACKGROUND

Pneumonia occurs in about 20% of trauma patients with pulmonary contusions. This study aims to evaluate the association between empirical antibiotic therapy and nosocomial pneumonia in this population.

METHODS

Retrospective cohort of adult patients admitted to a trauma-surgical ICU. The Antibiotic Therapy Group (ATG) was defined by intravenous antibiotic use for more than 48 h starting on hospital admission, while the Conservative Group (CG) was determined by antibiotic use no longer than 48 h. Primary outcome was microbiologically documented nosocomial pneumonia within 14 days after hospital admission. Logistic regression was used to estimate the association between group allocation and primary outcome. Exploratory analyses evaluating the association between resistant strains in pneumonia and antibiotic use were performed.

RESULTS

The study included 177 patients with chest trauma and pulmonary contusion on CT scan. ATG were more severely ill than CG, as shown by higher Injury Severity Score, SAPS3, SOFA score, higher rates, and longer duration of mechanical ventilation. In the multivariate analysis, ATG was associated with a lower incidence of primary outcome (OR = 0.25, 95% CI 0.09-0.64; p < 0.01). Similar results were found in the sensitivity analysis with another set of variables. However, each day of antibiotic use was associated with an increased risk of pneumonia by resistant bacteria (OR = 1.18 per day, 95% CI 1.05-1.36; p < 0.01).

CONCLUSIONS

Empiric antibiotic therapy was independently associated with lower incidence of nosocomial pneumonia in critically ill patients with pulmonary contusion. However, each day of antibiotic use was associated with increased resistant strains in infected patients.

Factors Associated With Time to Decannulation in Patients With Tracheostomy Following Severe Traumatic Brain Injury

BACKGROUND

Prolonged tracheal tube placement following severe traumatic brain injury (TBI) can cause serious complications. Safe removal requires sufficient ability for independent breathing and airway protection. Thus, identifying important factors for time to removal of the tracheal tube (decannulation) is essential for safe and efficient weaning. This study aimed to identify significant factors for time to decannulation in a Danish population of subjects with tracheostomy after TBI.

METHODS

This was a retrospective register-based cohort study. Subjects with moderate and severe TBI and a tracheal tube were selected from the Danish Head Trauma Database between 2011-2021. Time to decannulation was calculated as time from injury to decannulation. Associations between selected explanatory variables representing demographic and clinical characteristics and time to decannulation were analyzed using linear regression models.

RESULTS

A total 324 subjects were included with a median of 44 d to decannulation. Primary analysis found that an improvement in swallowing ability during the initial 4 weeks of rehabilitation was associated with an 8.2 d reduction in time to decannulation (95% CI -12.3 to -4.2, P < .001). Change in overall sensorimotor ability reduced time to decannulation by 0.94 (95% CI -0.78 to -0.10, P = .03) d. Change in cognitive abilities from rehab admission to 4-week follow-up did not significantly affect the number of days to decannulation (P = .66). Secondary analysis showed pneumonia was associated with the largest estimated increase of 24.4 (95% CI 15.9-32.9, P < .001) d and that increased cognitive functioning at rehabilitation admission was associated with a significant reduction in time to decannulation.

CONCLUSIONS

This study found that a change in swallowing ability is a potentially significant factor for reducing time to decannulation. Identifying factors that could explain differences in time to decannulation is essential for patient outcomes, especially if these factors are modifiable and could be targeted in rehabilitation and treatment.

Effect of early mobilization on the development of pneumonia in patients with traumatic brain injury in the neurosurgical intensive care unit: A historical controls study

BACKGROUND

Pneumonia has a high incidence in traumatic brain injury (TBI) patients and lacks effective treatments. Early mobilization (EM) may be a potentially effective treatment.

AIM

To explore the impact of EM on TBI-related pneumonia in the neurosurgical intensive care unit (NICU).

METHOD

This study was a historical control study. 100 TBI patients who received EM intervention were prospectively included as the experimental group (EM cohort), and 250 TBI patients were retrospectively included as the control group. The propensity score matching (PSM) method was employed to balance baseline and minimize potential bias. The relationship between EM and TBI-related pneumonia was investigated by univariate and multivariate logistic regression, then further determined by subgroup analysis. The influence of other variables was excluded by interaction analyses. Finally, the effect of EM on the prognosis of TBI patients was analysed by comparing the Glasgow Coma Scale (GCS) and the hospital stay.

RESULTS

After screening, 86 patients were included in the EM cohort and 199 patients were included in the control cohort. There were obvious differences between the two cohorts at baseline, and these differences were eliminated after PSM, when the incidence of pneumonia was significantly lower in the EM cohort than in the control cohort (35.0% vs. 61.9%, p < .001). Multivariate logistic regression showed that EM was an independent risk factor for TBI-related pneumonia and was significantly associated with a decreased incidence of pneumonia. This correlation was present in most subgroups and was not affected by other variables (p for interaction >.05). Patients in the EM cohort had shorter length of ICU stay (6 vs. 7 days, p = .017) and higher GCS at discharge (12 vs. 11, p = .010).

CONCLUSION

EM is a safe and effective treatment for TBI patients in NICU, which can reduce the incidence of pneumonia, help to improve prognosis and shorten the length of ICU stay.

RELEVANCE TO CLINICAL PRACTICE

Although the utilization rate of EM is low in TBI patients for various reasons, EM is still an effective method to prevent complications. Our study confirms that a scientific and detailed EM strategy can effectively reduce the incidence of pneumonia while ensuring the safety of TBI patients, which is worthy of further research and clinical application.

Experimental Models of Hospital-Acquired Infections After Traumatic Brain Injury: Challenges and Opportunities

Patients hospitalized after a moderate or severe traumatic brain injury (TBI) are at increased risk of nosocomial infections, including bacterial pneumonia and other upper respiratory tract infections. Infections represent a secondary immune challenge for vulnerable TBI patients that can lead to increased morbidity and poorer long-term prognosis. This review first describes the clinical significance of infections after TBI, delving into the known mechanisms by which a TBI can alter systemic immunological responses towards an immunosuppressive state, leading to promotion of increased vulnerability to infections. Pulmonary dysfunction resulting from respiratory tract infections is considered in the context of neurotrauma, including the bidirectional relationship between the brain and lungs. Turning to pre-clinical modeling, current laboratory approaches to study experimental TBI and lung infections are reviewed, to highlight findings from the limited key studies to date that have incorporated both insults. Then, practical decisions for the experimental design of animal studies of post-injury infections are discussed. Variables associated with the host animal, the infectious agent (e.g., species, strain, dose, and administration route), as well as the timing of the infection relative to the injury model are important considerations for model development. Together, the purpose of this review is to highlight the significant clinical need for increased pre-clinical research into the two-hit insult of a hospital-acquired infection after TBI to encourage further scientific enquiry in the field.

Current state of neuroprotective therapy using antibiotics in human traumatic brain injury and animal models

TBI is a leading cause of death and disability in young people and older adults worldwide. There is no gold standard treatment for TBI besides surgical interventions and symptomatic relief. Post-injury infections, such as lower respiratory tract and surgical site infections or meningitis are frequent complications following TBI. Whether the use of preventive and/or symptomatic antibiotic therapy improves patient mortality and outcome is an ongoing matter of debate. In contrast, results from animal models of TBI suggest translational perspectives and support the hypothesis that antibiotics, independent of their anti-microbial activity, alleviate secondary injury and improve neurological outcomes. These beneficial effects were largely attributed to the inhibition of neuroinflammation and neuronal cell death. In this review, we briefly outline current treatment options, including antibiotic therapy, for patients with TBI. We then summarize the therapeutic effects of the most commonly tested antibiotics in TBI animal models, highlight studies identifying molecular targets of antibiotics, and discuss similarities and differences in their mechanistic modes of action.

A pre-existing Toxoplasma gondii infection exacerbates the pathophysiological response and extent of brain damage after traumatic brain injury in mice

Traumatic brain injury (TBI) is a key contributor to global morbidity that lacks effective treatments. Microbial infections are common in TBI patients, and their presence could modify the physiological response to TBI. It is estimated that one-third of the human population is incurably infected with the feline-borne parasite, Toxoplasma gondii, which can invade the central nervous system and result in chronic low-grade neuroinflammation, oxidative stress, and excitotoxicity-all of which are also important pathophysiological processes in TBI. Considering the large number of TBI patients that have a pre-existing T. gondii infection prior to injury, and the potential mechanistic synergies between the conditions, this study investigated how a pre-existing T. gondii infection modified TBI outcomes across acute, sub-acute and chronic recovery in male and female mice. Gene expression analysis of brain tissue found that neuroinflammation and immune cell markers were amplified in the combined T. gondii + TBI setting in both males and females as early as 2-h post-injury. Glutamatergic, neurotoxic, and oxidative stress markers were altered in a sex-specific manner in T. gondii + TBI mice. Structural MRI found that male, but not female, T. gondii + TBI mice had a significantly larger lesion size compared to their uninfected counterparts at 18-weeks post-injury. Similarly, diffusion MRI revealed that T. gondii + TBI mice had exacerbated white matter tract abnormalities, particularly in male mice. These novel findings indicate that a pre-existing T. gondii infection affects the pathophysiological aftermath of TBI in a sex-dependent manner, and may be an important modifier to consider in the care and prognostication of TBI patients.

Clinical characteristics and functional outcome of surgically treated adult head trauma patients with acute subdural hematoma: Ethiopian tertiary hospitals experience

Background

Acute subdural hematoma (ASDH) is one of the most common and devastating lesions in traumatic brain injury with a mortality rate upto 60 % especially in low-income countries. The present study aimed to determine the clinical characteristics and functional outcomes and the associated factors of surgically treated head trauma patients with ASDH.

Methods

Between January 2018 and January 2021 we identified 140 head trauma patients with ASDH who underwent surgical evacuation in three tertiary hospitals. Epidemiological data were collected; the six-month functional outcome was studied using an extended Glasgow outcome score (EGOS) and associated factors were also studied. Univariate analysis was performed at first, and variables with a P-value of <0.05 were entered into the multivariable logistic regression model.

Results

Male predominance was seen accounting for 87 % and assault was the most common mechanism of injury (35.7 %). Sixty-five (56.5 %) of patients achieved favorable functional recovery (EGOS of 5-8) and 50 (43.5 %) of patients had unfavorable recovery (EGOS of 1-4) after 6 months of follow-up. In multivariate logistic regression models, GCS <5, Pupillary abnormality, hypotension, oxygen saturation <90 at presentation, and hospital-acquired pneumonia were the independent factors associated with unfavorable functional outcomes.

Conclusion

In our setup, most of the patients are male from assault injuries. There is still a high rate of unfavorable outcomes in patients with acute subdural hematoma. GCS <5, pupillary abnormality, hypotension and desaturation at presentation, and postoperative hospital-acquired infection are predictors for unfavorable functional outcomes.

Construction and validation of a predictive model of pneumonia for ICU patients with traumatic brain injury (TBI)

The incidence of pneumonia in ICU patients with TBI is very high, seriously affecting the prognosis. This study aims to construct a predictive model for pneumonia in ICU patients with TBI and provide help for the prevention of TBI-related pneumonia.Clinical data of ICU patients with TBI were collected from the Medical Information Mart for Intensive Care (MIMIC)-IV database and hospital data. Variables were screened by lasso and multivariate logistic regression to construct a predictive nomogram model, verified in internal validation cohort and external validation cohort by receiver operator characteristic (ROC) curve, calibration curve and decision curve analysis (DCA).A total of 1850 ICU patients with TBI were enrolled in the study from the MIMIC-IV database, including 1298 in the training cohort and 552 in internal validation cohort. The external validation cohort included 240 ICU patients with TBI from hospital data. Nine variables were selected from the training cohort by lasso regression and multivariate logistic regression, and a pneumonia prediction nomogram was constructed. This nomogram has a high discrimination in training, internal validation and external validation cohorts (AUC = 0.857, 0.877, 0.836). The calibration curve and DCA showed that this nomogram had a high calibration and better clinical decision-making efficiency.The nomogram showed excellent discrimination and clinical utility to predict pneumonia, and could identify pneumonia high-risk patients early, thus providing personalised treatment strategies for ICU patients with TBI.

Machine learning algorithms for prediction of ventilator associated pneumonia in traumatic brain injury patients from the MIMIC-III database

BACKGROUND

Ventilator associated pneumonia (VAP) is a common complication and associated with poor prognosis of traumatic brain injury (TBI) patients.

OBJECTIVES

This study was conducted to explore the predictive performance of different machine-learning algorithms for VAP in TBI patients.

METHODS

TBI patients receiving mechanical ventilation more than 48 hours from the Medical Information Mart for Intensive Care-III (MIMIC-III) database were eligible for the study. The VAP was confirmed based on the ICD-9 code. Included patients were separated to the training cohort and the validation cohort with a ratio of 7:3. Predictive models based on different machine learning algorithms were developed using 5-fold cross validation in the training cohort and then verified in the validation cohort by evaluating the area under the receiver operating characteristic curve (AUC), sensitivity, specificity, accuracy and F score.

RESULTS

786 TBI patients from the MIMIC-III were finally included with the VAP incidence of 44.0%. The random forest performed the best on predicting VAP in the training cohort with a AUC of 1.000. The XGBoost and AdaBoost were ranked the second and the third with a AUC of 0.915 and 0.789 in the training cohort. While the AdaBoost performed the best on predicting VAP in the validation cohort with a AUC of 0.706. The XGBoost and random forest were ranked the second and the third with the AUC of 0.685 and 0.683 in the validation cohort. Generally, the random forest and XGBoost were likely to be over-fitting while the AdaBoost was relatively stable in predicting the VAP.

CONCLUSIONS

The AdaBoost performed well and stably on predicting the VAP in TBI patients. Developing programs using AdaBoost in portable electronic devices may effectively assist physicians in assessing the risk of VAP in TBI.

The immune suppressive properties of damage associated molecular patterns in the setting of sterile traumatic injury

Associated with the development of hospital-acquired infections, major traumatic injury results in an immediate and persistent state of systemic immunosuppression, yet the underlying mechanisms are poorly understood. Detected in the circulation in the minutes, days and weeks following injury, damage associated molecular patterns (DAMPs) are a heterogeneous collection of proteins, lipids and DNA renowned for initiating the systemic inflammatory response syndrome. Suggesting additional immunomodulatory roles in the post-trauma immune response, data are emerging implicating DAMPs as potential mediators of post-trauma immune suppression. Discussing the results of in vitro, in vivo and ex vivo studies, the purpose of this review is to summarise the emerging immune tolerising properties of cytosolic, nuclear and mitochondrial-derived DAMPs. Direct inhibition of neutrophil antimicrobial activities, the induction of endotoxin tolerance in monocytes and macrophages, and the recruitment, activation and expansion of myeloid derived suppressor cells and regulatory T cells are examples of some of the immune suppressive properties assigned to DAMPs so far. Crucially, with studies identifying the molecular mechanisms by which DAMPs promote immune suppression, therapeutic strategies that prevent and/or reverse DAMP-induced immunosuppression have been proposed. Approaches currently under consideration include the use of synthetic polymers, or the delivery of plasma proteins, to scavenge circulating DAMPs, or to treat critically-injured patients with antagonists of DAMP receptors. However, as DAMPs share signalling pathways with pathogen associated molecular patterns, and pro-inflammatory responses are essential for tissue regeneration, these approaches need to be carefully considered in order to ensure that modulating DAMP levels and/or their interaction with immune cells does not negatively impact upon anti-microbial defence and the physiological responses of tissue repair and wound healing.

Effect of Different Early Oxygenation Levels on Clinical Outcomes of Patients Presenting in the Emergency Department With Severe Traumatic Brain Injury

STUDY OBJECTIVE

Despite the almost universal administration of supplemental oxygen in patients presenting in the emergency department (ED) with severe traumatic brain injury, optimal early oxygenation levels are unknown. Therefore, we aimed to examine the effect of different early oxygenation levels on the clinical outcomes of patients presenting in the emergency department with severe traumatic brain injury.

METHODS

We performed a secondary analysis of the Resuscitation Outcomes Consortium Traumatic Brain Injury Hypertonic Saline randomized controlled trial by including patients with Glasgow Coma Scale ≤8. Early oxygenation levels were assessed by the worst value of arterial partial pressure of oxygen (PaO₂) during the first 4 hours of presentation in the emergency department. The primary outcome was 6-month neurologic status, as assessed by the Extended Glasgow Outcome Scale. A binary logistic regression was utilized, and an odds ratio (OR) with 95% (95% confidence intervals) was calculated.

RESULTS

A total of 910 patients were included. In unadjusted (crude) analysis, a PaO₂ of 101 to 250 mmHg (OR, 0.59 [0.38 to 0.91]), or 251 to 400 mmHg (OR, 0.53 [0.34 to 0.83]) or ≥401 mmHg (OR, 0.31 [0.20 to 0.49]) was less likely to be associated with poor neurologic status when compared with a PaO₂ of ≤100 mmHg. This was also the case for adjusted analyses (including age, pupillary reactivity, and Revised Trauma Score).

CONCLUSION

High oxygenation levels as early as the first 4 hours of presentation in the emergency department may not be adversely associated with the long-term neurologic status of patients with severe traumatic brain injury. Therefore, during the early phase of trauma, clinicians may focus on stabilizing patients while giving low priority to the titration of oxygenation levels.

Breaking down the cellular responses to type I interferon neurotoxicity in the brain

Since their original discovery, type I interferons (IFN-Is) have been closely associated with antiviral immune responses. However, their biological functions go far beyond this role, with balanced IFN-I activity being critical to maintain cellular and tissue homeostasis. Recent findings have uncovered a darker side of IFN-Is whereby chronically elevated levels induce devastating neuroinflammatory and neurodegenerative pathologies. The underlying causes of these 'interferonopathies' are diverse and include monogenetic syndromes, autoimmune disorders, as well as chronic infections. The prominent involvement of the CNS in these disorders indicates a particular susceptibility of brain cells to IFN-I toxicity. Here we will discuss the current knowledge of how IFN-Is mediate neurotoxicity in the brain by analyzing the cell-type specific responses to IFN-Is in the CNS, and secondly, by exploring the spectrum of neurological disorders arising from increased IFN-Is. Understanding the nature of IFN-I neurotoxicity is a crucial and fundamental step towards development of new therapeutic strategies for interferonopathies.

Effect of Folic Acid Treatment for Patients with Traumatic Brain Injury (TBI)-Related Hospital Acquired Pneumonia (HAP): A Retrospective Cohort Study

Hospital Acquired Pneumonia (HAP) is one of the most common complications and late causes of death in TBI patients. Targeted prevention and treatment of HAP are of great significance for improving the prognosis of TBI patients. In the previous clinical observation, we found that folic acid treatment for TBI patients has a good effect on preventing and treating HAP. We conducted this retrospective cohort study to demonstrate what we observed by selecting 293 TBI patients from two medical centers and analyzing their hospitalization data. The result showed that the incidence of HAP was significantly lower in TBI patients who received folic acid treatment (44.1% vs. 63.0%, p = 0.012). Multivariate logistic regression analysis showed that folic acid treatment was an independent protective factor for the occurrence of HAP in TBI patients (OR = 0.418, p = 0.031), especially in high-risk groups of HAP, such as the old (OR: 1.356 vs. 2.889), ICU (OR: 1.775 vs. 5.996) and severe TBI (OR: 0.975 vs. 5.424) patients. At the same time, cohort studies of HAP patients showed that folic acid also had a good effect on delaying the progression of HAP, such as reducing the chance of tracheotomy (26.1% vs. 50.8%, p = 0.041), and reduced the length of hospital stay (15 d vs. 19 d, p = 0.029) and ICU stay (5 d vs. 8 d, p = 0.046). Therefore, we believe that folic acid treatment in TBI patients has the potential for preventing and treating HAP, and it is worthy of further clinical research.

How the immune system shapes neurodegenerative diseases

Neurodegenerative diseases are a major cause of death and disability worldwide and are influenced by many factors including age, genetics, and injuries. While these diseases are often thought to result from the accumulation and spread of aberrant proteins, recent studies have demonstrated that they can be shaped by the innate and adaptive immune system. Resident myeloid cells typically mount a sustained response to the degenerating CNS, but peripheral leukocytes such as T and B cells can also alter disease trajectories. Here, we review the sometimes-dichotomous roles played by immune cells during neurodegenerative diseases and explore how brain trauma can serve as a disease initiator or accelerant. We also offer insights into how failure to properly resolve a CNS injury might promote the development of a neurodegenerative disease.

Traumatic brain injury alters dendritic cell differentiation and distribution in lymphoid and non-lymphoid organs

Background

Pathophysiological consequences of traumatic brain injury (TBI) mediated secondary injury remain incompletely understood. In particular, the impact of TBI on the differentiation and maintenance of dendritic cells (DCs), which are regarded as the most professional antigen presenting cells of the immune system, remains completely unknown. Here, we report that DC-differentiation, maintenance and functions are altered on day 3 and day 7 after TBI.

Methods

Long bones, spleen, peripheral lymph nodes (pLNs), mesenteric lymph nodes (mLNs), liver, lungs, skin and blood were collected from mice with either moderate-level cortical impact (CCI) or sham on day 1, day 3 or day 7 after TBI. Bone marrow cells were isolated from the tibias and femurs of hind limb through flushing. Tissues were digested with Collagenase-D and DNase I. Skin biopsies were digested in the presence of liberase + DNase I. Single cell suspensions were made, red blood cells were lysed with Ammonium chloride (Stem Cell Technology) and subsequently filtered using a 70 μM nylon mesh. DC subsets of the tissues and DC progenitors of the BM were identified through 10-color flow cytometry-based immunophenotyping studies. Intracellular reactive oxygen species (ROS) were identified through H2DCFDA staining.

Results

Our studies identify that; (1) frequencies and absolute numbers of DCs in the spleen and BM are altered on day 3 and day 7 after TBI; (2) surface expression of key molecules involved in antigen presentation of DCs were affected on day 3 and day 7 after TBI; (3) distribution and functions of tissue-specific DC subsets of both circulatory and lymphatic systems were imbalanced following TBI; (4) early differentiation program of DCs, especially the commitment of hematopoietic stem cells to common DC progenitors (CDPs), were deregulated after TBI; and (5) intracellular ROS levels were reduced in DC progenitors and differentiated DCs on day 3 and day 7 after TBI.

Conclusions

Our data demonstrate, for the first time, that TBI affects the distribution pattern of DCs and induces an imbalance among DC subsets in both lymphoid and non-lymphoid organs. In addition, the current study demonstrates that TBI results in reduced levels of ROS in DCs on day 3 and day 7 after TBI, which may explain altered DC differentiation paradigm following TBI. A deeper understanding on the molecular mechanisms that contribute to DC defects following TBI would be essential and beneficial in treating infections in patients with acute central nervous system (CNS) injuries, such as TBI, stroke and spinal cord injury.

Prognostic Value of Serum Procalcitonin Based Model in Moderate to Severe Traumatic Brain Injury Patients

Objective

Procalcitonin (PCT) is an acknowledged marker of systemic inflammatory response. Previous studies have not reached agreement on the association between serum PCT and outcome of traumatic brain injury (TBI) patients. We designed this study to confirm the prognostic value of PCT in isolated TBI and those with extracranial injury, respectively.

Methods

Patients hospitalized in our hospital for moderate-to-severe TBI between March 2015 and December 2019 were included. Logistic regression analysis was performed to validate the association between PCT and in-hospital mortality in these patients. AUC (area under the receiver operating characteristics curve) of PCT and constructed model were calculated and compared.

Results

Among the included 211 patients, 81 patients suffered a poor outcome, with a mortality rate of 38.4%. Non-survivors had a higher level of serum PCT (2.73 vs 0.72, p<0.001) and lower GCS (5 vs 7, p<0.001) on admission than survivors. AUC of single PCT for predicting mortality in isolated TBI and those with extracranial injury were 0.767 and 0.553, respectively. Multivariate logistic regression showed that GCS (OR=0.744, p=0.008), glucose (OR=1.236, p<0.001), cholesterol (OR=0.526, p=0.002), and PCT (OR=1.107, p=0.022) were independently associated with mortality of isolated TBI. The AUC of the prognostic model composed of GCS, glucose, cholesterol, and PCT was 0.868 in isolated TBI.

Conclusion

PCT is an efficient marker of outcome in isolated moderate-to-severe TBI but not those with extracranial injury. A prognostic model incorporating PCT is useful for clinicians to make early risk stratification for isolated TBI.

Pneumonia in Nervous System Injuries: An Analytic Review of Literature and Recommendations

Pneumonia is one of the most common complications in intensive care units and is the most common nosocomial infection in this setting. Patients with neurocritical conditions who are admitted to ICUs are no exception, and in fact, are more prone to infections such as pneumonia because of factors such as swallow dysfunction, need for mechanical ventilation, longer length of stay in hospitals, etc. Common central nervous system pathologies such as ischemic stroke, traumatic brain injury, subarachnoid hemorrhage, intracerebral hemorrhage, neuromuscular disorders, status epilepticus, and demyelinating diseases can cause long in-hospital admissions and increase the risk of pneumonia each with a mechanism of its own. Brain injury-induced immunosuppression syndrome is usually considered the common mechanism through which patients with critical central nervous system conditions become susceptible to different kinds of infection including pneumonia. Evaluating the patients and assessment of the risk factors can lead our attention toward better infection control in this population and therefore decrease the risk of infections in central nervous system injuries.

Inflammation and the role of infection: Complications and treatment options following neurotrauma

Traumatic brain injury can have devastating consequences for patients and extended hospital stays and recovery course. Recent data indicate that the initial insult causes profound changes to the immune system and leads to a pro-inflammatory state. This alteration in homeostasis predisposes patients to an increased risk of infection and underlying autoimmune conditions. Increased emphasis has been placed on understanding this process both in the clinical and preclinical literature. This review highlights the intrinsic inflammatory conditions that can occur within the initial hospital stay, discusses long-term immune consequences, highlights emerging treatment options, and delves into important pathways currently being investigated with preclinical models.

Immune dynamics in the CNS and its barriers during homeostasis and disease

The central nervous system (CNS) has historically been viewed as an immunologically privileged site, but recent studies have uncovered a vast landscape of immune cells that reside primarily along its borders. While microglia are largely responsible for surveying the parenchyma, CNS barrier sites are inhabited by a plethora of different innate and adaptive immune cells that participate in everything from the defense against microbes to the maintenance of neural function. Static and dynamic imaging studies have revolutionized the field of neuroimmunology by providing detailed maps of CNS immune cells as well as information about how these cells move, organize, and interact during steady-state and inflammatory conditions. These studies have also redefined our understanding of neural-immune interactions at a cellular level and reshaped our conceptual view of immune privilege in this specialized compartment. This review will focus on insights gained using imaging techniques in the field of neuroimmunology, with an emphasis on anatomy and CNS immune dynamics during homeostasis, infectious diseases, injuries, and aging.

Pediatric traumatic brain injury and a subsequent transient immune challenge independently influenced chronic outcomes in male mice

Traumatic brain injury (TBI) is a major contributor to death and disability worldwide. Children are at particularly high risk of both sustaining a TBI and experiencing serious long-term consequences, such as cognitive deficits, mental health problems and post-traumatic epilepsy. Severe TBI patients are highly susceptible to nosocomial infections, which are mostly acquired within the first week of hospitalization post-TBI. Yet the potential chronic impact of such acute infections following pediatric TBI remains unclear. In this study, we hypothesized that a peripheral immune challenge, such as lipopolysaccharide (LPS)-mimicking a hospital-acquired infection-would worsen inflammatory, neurobehavioral, and seizure outcomes after experimental pediatric TBI. To test this, three-week old male C57Bl/6J mice received a moderate controlled cortical impact or sham surgery, followed by 1 mg/kg i.p. LPS (or 0.9% saline vehicle) at 4 days TBI. Mice were randomized to four groups; sham-saline, sham-LPS, TBI-saline or TBI-LPS (n = 15/group). Reduced general activity and increased anxiety-like behavior were observed within 24 h in LPS-treated mice, indicating a transient sickness response. LPS-treated mice also exhibited a reduction in body weights, which persisted chronically. From 2 months post-injury, mice underwent a battery of tests for sensorimotor, cognitive, and psychosocial behaviors. TBI resulted in hyperactivity and spatial memory deficits, independent of LPS; whereas LPS resulted in subtle deficits in spatial memory retention. At 5 months post-injury, video-electroencephalographic recordings were obtained to evaluate both spontaneous seizure activity as well as the evoked seizure response to pentylenetetrazol (PTZ). TBI increased susceptibility to PTZ-evoked seizures; whereas LPS appeared to increase the incidence of spontaneous seizures. Post-mortem analyses found that TBI, but not LPS, resulted in robust glial reactivity and loss of cortical volume. A TBI × LPS interaction in hippocampal volume suggested that TBI-LPS mice had a subtle increase in ipsilateral hippocampus tissue loss; however, this was not reflected in neuronal cell counts. Both TBI and LPS independently had modest effects on chronic hippocampal gene expression. Together, contrary to our hypothesis, we observed minimal synergy between TBI and LPS. Instead, pediatric TBI and a subsequent transient immune challenge independently influenced chronic outcomes. These findings have implications for future preclinical modeling as well as acute post-injury patient management.

Central nervous system injury-induced immune suppression

Central nervous system trauma is a common cause of morbidity and mortality. Additionally, these injuries frequently occur in younger individuals, leading to lifetime expenses for patients and caregivers and the loss of opportunity for society. Despite this prevalence and multiple attempts to design a neuroprotectant, clinical trials for a pharmacological agent for the treatment of traumatic brain injury (TBI) or spinal cord injury (SCI) have provided disappointing results. Improvements in outcome from these disease processes in the past decades have been largely due to improvements in supportive care. Among the many challenges facing patients and caregivers following neurotrauma, posttraumatic nosocomial infection is a significant and potentially reversible risk factor. Multiple animal and clinical studies have provided evidence of posttraumatic systemic immune suppression, and injuries involving the CNS may be even more prone, leading to a higher risk for in-hospital infections following neurotrauma. Patients who have experienced neurotrauma with nosocomial infection have poorer recovery and higher risks of long-term morbidity and in-hospital mortality than patients without infection. As such, the etiology and reversal of postneurotrauma immune suppression is an important topic. There are multiple possible etiologies for these posttraumatic changes including the release of damage-associated molecular patterns, the activation of immunosuppressive myeloid-derived suppressor cells, and sympathetic nervous system activation. Postinjury systemic immunosuppression, particularly following neurotrauma, provides a challenge for clinicians but also an opportunity for improvement in outcome. In this review, the authors sought to outline the evidence of postinjury systemic immune suppression in both animal models and clinical research of TBI, TBI polytrauma, and SCI.

Traumatic brain injury and hemorrhage in a juvenile rat model of polytrauma leads to immunosuppression and splenic alterations

BACKGROUND

Traumatic brain injury (TBI) is a common cause of morbidity and mortality. We have previously shown that TBI with a concurrent extra-cranial injury reliably leads to post-injury suppression of the innate immune system, but the impact of this injury on the adaptive immune system is unknown. We present data showing that combined injury reduced immune response as assayed in both blood and spleen samples and that these changes parallel apoptosis in the spleen. To assess the clinical relevance of these changes, we examined lungs for spontaneous bacterial colonization.

METHODS

For these studies, prepubescent (28 day old) rats were injured using a controlled cortical impact model and then 25% blood volume removal by arteriotomy, and injured animals were compared with sham injured animals. Blood and spleen samples at post-injury day 1 were incubated with or without immunostimulant and examined for IFN-γ production using an Eli-Spot assay. Spleen samples were also examined for apoptosis using Annexin V staining, and lungs were harvested and plated on blood agar to examine for spontaneous bacterial colonization.

RESULTS

Stimulations of whole blood and spleen samples with phorbol 12-myristate 13-acetate/ionomycin (PMA/I) at post-injury day 1 were associated with significant decreases in IFN-γ-positive cells/million in injured animals. Stimulation of whole blood with either PMA/I or pokeweed mitogen led to reduced tumor necrosis factor alpha production. Spleen from injured animals showed a marked increase in apoptosis. Lung samples showed a 300% increase in colonies per plate in injured animals.

CONCLUSIONS

These data suggest that the combined injury can lead to adaptive immunosuppression, and our findings further suggest a potential role for the spleen in altering leukocyte function following injury.

Long-term follow-up of neurodegenerative phenomenon in severe traumatic brain injury using MRI

BACKGROUND

Traumatic brain injury (TBI) lesions are known to evolve over time, but the duration and consequences of cerebral remodeling are unclear. Degenerative mechanisms occurring in the chronic phase after TBI could constitute "tertiary" lesions related to the neurological outcome.

OBJECTIVE

The objective of this prospective study of severe TBI was to longitudinally evaluate the volume of white and grey matter structures and white matter integrity with 2 time-point multimodal MRI.

METHODS

Longitudinal MRI follow-up was obtained for 11 healthy controls (HCs) and 22 individuals with TBI (mean [SD] 60 [15] months after injury) along with neuropsychological assessments. TBI individuals were classified in the "favourable" recovery group (Glasgow Outcome Scale Extended [GOSE] 6-8) and "unfavourable" recovery group (GOSE 3-5) at 5 years. Variation in brain volumes (3D T1-weighted image) and white matter integrity (diffusion tensor imaging [DTI]) were quantitatively assessed over time and used to predict neurological outcome.

RESULTS

TBI individuals showed a marked decrease in volumes of whole white matter (median -11.4% [interquartile range -5.8; -14.6]; p <0.001) and deep grey nuclear structures (-17.1% [-10.6; -20.5]; p <0.001). HCs did not show any significant change over the same time period. Median volumetric loss in several brain regions was higher with GOSE 3-5 than 6-8. These lesions were associated with lower fractional anisotropy and higher mean diffusivity at baseline. Volumetric variations were positively correlated with normalized fractional anisotropy and negatively with normalized mean diffusivity at baseline and follow-up. A computed predictive model with baseline DTI showed good accuracy to predict neurological outcome (area under the receiver operating characteristic curve 0.82 [95% confidence interval 0.81-0.83]) Conclusions. We characterised the striking atrophy of deep brain structures after severe TBI. DTI imaging in the subacute phase can predict the occurrence and localization of these tertiary lesions as well as long-term neurological outcome.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT00577954. Registered on October 2006.

Factors Influencing Functional Recovery during Rehabilitation after Severe Acquired Brain Injuries: A Retrospective Analysis

Severe acquired brain injuries (sABI) represent one of the main causes of disability and limitation in social life participation that need an intensive rehabilitation approach. The purpose of this study was to identify a possible correlation between different supposed conditioning factors and the efficiency of rehabilitation interventions. In this retrospective study, data were processed regarding 44 patients admitted to a neurorehabilitation department after sABI. A significant correlation with the efficiency of the rehabilitation intervention (expressed as the variation of the Barthel score between discharge and admittance in relation to the duration of the rehabilitative hospitalization) was found for both the etiology of the brain injury (p = 0.023), the precocity of the rehabilitation treatment (p = 0.0475), the presence of a tracheal cannula (p = 0.0084) and forms of nutrition other than oral (p < 0.0001). The results of this study suggest that improving the management of the respiratory system, swallowing and nutritional aspects, and favoring an early and personalized rehabilitation treatment, can help to optimize the overall care of patients suffering from sABI, thus allowing a reduction in complications, improvement in functional recovery and ensuring a better management of economic, social and health resources.

Antimicrobial immunity impedes CNS vascular repair following brain injury

Traumatic brain injury (TBI) and cerebrovascular injury are leading causes of disability and mortality worldwide. Systemic infections often accompany these disorders and can worsen outcomes. Recovery after brain injury depends on innate immunity, but the effect of infections on this process is not well understood. Here, we demonstrate that systemically introduced microorganisms and microbial products interfered with meningeal vascular repair after TBI in a type I interferon (IFN-I)-dependent manner, with sequential infections promoting chronic disrepair. Mechanistically, we discovered that MDA5-dependent detection of an arenavirus encountered after TBI disrupted pro-angiogenic myeloid cell programming via induction of IFN-I signaling. Systemic viral infection similarly blocked restorative angiogenesis in the brain parenchyma after intracranial hemorrhage, leading to chronic IFN-I signaling, blood-brain barrier leakage and a failure to restore cognitive-motor function. Our findings reveal a common immunological mechanism by which systemic infections deviate reparative programming after central nervous system injury and offer a new therapeutic target to improve recovery.

Neutrophil-to-Lymphocyte Ratios and Infections after Traumatic Brain Injury: Associations with Hospital Resource Utilization and Long-Term Outcome

Traumatic brain injury (TBI) induces immune dysfunction that can be captured clinically by an increase in the neutrophil-to-lymphocyte ratio (NLR). However, few studies have characterized the temporal dynamics of NLR post-TBI and its relationship with hospital-acquired infections (HAI), resource utilization, or outcome. We assessed NLR and HAI over the first 21 days post-injury in adults with moderate-to-severe TBI (n = 196) using group-based trajectory (TRAJ), changepoint, and mixed-effects multivariable regression analysis to characterize temporal dynamics. We identified two groups with unique NLR profiles: a high (n = 67) versus a low (n = 129) TRAJ group. High NLR TRAJ had higher rates (76.12% vs. 55.04%, p = 0.004) and earlier time to infection (p = 0.003). In changepoint-derived day 0–5 and 6–20 epochs, low lymphocyte TRAJ, early in recovery, resulted in more frequent HAIs (p = 0.042), subsequently increasing later NLR levels (p ≤ 0.0001). Both high NLR TRAJ and HAIs increased hospital length of stay (LOS) and days on ventilation (p ≤ 0.05 all), while only high NLR TRAJ significantly increased odds of unfavorable six-month outcome as measured by the Glasgow Outcome Scale (GOS) (p = 0.046) in multivariable regression. These findings provide insight into the temporal dynamics and interrelatedness of immune factors which collectively impact susceptibility to infection and greater hospital resource utilization, as well as influence recovery.

A Population-Based Study of Pre-Existing Health Conditions in Traumatic Brain Injury

Health factors impacting both the occurrence of, and recovery from traumatic brain injury (TBI) vary in complexity, and present genuine challenges to researchers and healthcare professionals seeking to characterize injury consequences and determine prognosis. However, attempts to clarify causal links between injury characteristics and clinical outcomes (including mortality) often compel researchers to exclude pre-existing health conditions (PECs) in their samples, including psychiatric history, medication usage, and other comorbid conditions. In this pre-registered population-based study (total starting n = 939,123 patients), we examined trends in PEC incidence over 22 years in the state of Pennsylvania (1997-2019) in individuals sustaining TBI (n = 169,452) and individuals with orthopedic injury (n = 87,637). The goal was to determine how PECs interact with age and injury severity to influence short-term outcomes. A further goal was to determine whether number of PECs, or specific PEC clusters contributed to worse outcomes within the TBI cohort, compared with orthopedic injury alone. Primary findings indicate that PECs significantly influenced mortality within the TBI cohort; patients having four or more PECs were associated with approximately a two times greater likelihood of dying in acute care (odds ratio [OR] 1.9). Additionally, cluster analyses revealed four distinct PEC clusters that are age and TBI severity dependent. Overall, the likelihood of zero PECs hovers at ∼25%, which is critical to consider in TBI outcomes work and could potentially contribute to the challenges facing intervention science with regard to reproducibility of findings.

Inflammation in Traumatic Brain Injury

There is an increasing evidence that inflammation contributes to clinical and functional outcomes in traumatic brain injury (TBI). Many successful target-engaging, lesion-reducing, symptom-alleviating, and function-improving interventions in animal models of TBI have failed to show efficacy in clinical trials. Timing and immunological context are paramount for the direction, quality, and intensity of immune responses to TBI and the resulting neuroanatomical, clinical, and functional course. We present components of the immune system implicated in TBI, potential immune targets, and target-engaging interventions. The main objective of our article is to point toward modifiable molecular and cellular mechanisms that may modify the outcomes in TBI, and contribute to increasing the translational value of interventions that have been identified in animal models of TBI.

The Traumatic Brain Injury Model Systems National Database: A Review of Published Research

The Traumatic Brain Injury Model Systems (TBIMS) is the largest longitudinal TBI data set in the world. Our study reviews the works using TBIMS data for analysis in the last 5 years. A search (2015–2020) was conducted across PubMed, EMBASE, and Google Scholar for studies that used the National Institute on Disability, Independent Living and Rehabilitation Research NIDILRR/VA-TBIMS data. Search terms were as follows: [“TBIMS” national database] within PubMed and Google Scholar, and [“TBIMS” AND national AND database] on EMBASE. Data sources, study foci (in terms of data processing and outcomes), study outcomes, and follow-up information usage were collected to categorize the studies included in this review. Variable usage in terms of TBIMS' form-based variable groups and limitations from each study were also noted. Assessment was made on how TBIMS' objectives were met by the studies. Of the 74 articles reviewed, 23 used TBIMS along with other data sets. Fifty-four studies focused on specific outcome measures only, 6 assessed data aspects as a major focus, and 13 explored both. Sample sizes of the included studies ranged from 11 to 15,835. Forty-two of the 60 longitudinal studies assessed follow-up from 1 to 5 years, and 15 studies used 10 to 25 years of the same. Prominent variable groups as outcome measures were “Employment,” “FIM,” “DRS,” “PART-O,” “Satisfaction with Life,” “PHQ-9,” and “GOS-E.” Limited numbers of studies were published regarding tobacco consumption, the Brief Test of Adult Cognition by Telephone (BTACT), the Supervision Rating Scale (SRS), general health, and comorbidities as variables of interest. Generalizability was the most significant limitation mentioned by the studies. The TBIMS is a rich resource for large-sample longitudinal analyses of various TBI outcomes. Future efforts should focus on under-utilized variables and improving generalizability by validation of results across large-scale TBI data sets to better understand the heterogeneity of TBI.

Early chronic systemic inflammation and associations with cognitive performance after moderate to severe TBI

BACKGROUND

Cognitive dysfunction adversely effects multiple functional outcomes and social roles after TBI. We hypothesize that chronic systemic inflammation exacerbates cognitive deficits post-injury and diminishes functional cognition and quality of life (QOL). Yet few studies have examined relationships between inflammation and cognition after TBI. Associations between early chronic serum inflammatory biomarker levels, cognitive outcomes, and QOL 6-months and 12-months after moderate-to-severe TBI were identified using unweighted (uILS) and weighted (wILS) inflammatory load score (ILS) formation.

METHODS

Adults with moderate-to-severe TBI (n ​= ​157) completed neuropsychological testing, the Functional Impairment Measure Cognitive Subscale (FIM-Cog) and self-reported Percent Back to Normal scale 6 months (n ​= ​139) and 12 months (n ​= ​136) post-injury. Serial serum samples were collected 1-3 months post-TBI. Cognitive composite scores were created as equally weighted means of T-scores derived from a multidimensional neuropsychological test battery. Median inflammatory marker levels associated with 6-month and 12-month cognitive composite T-scores (p ​< ​0.10) were selected for ILS formation. Markers were quartiled, and quartile ranks were summed to generate an uILS. Marker-specific β-weights were derived using penalized ridge regression, multiplied by standardized marker levels, and summed to generate a wILS. ILS associations with cognitive composite scores were assessed using multivariable linear regression. Structural equation models assessed ILS influences on functional cognition and QOL using 12-month FIM-Cog and Percent Back to Normal scales.

RESULTS

ILS component markers included: IL-1β, TNF-α, sIL-4R, sIL-6R, RANTES, and MIP-1β. Increased sIL-4R levels were positively associated with overall cognitive composite T-scores in bivariate analyses, while remaining ILS markers were negatively associated with cognition. Multivariable receiver operator curves (ROC) showed uILS added 14.98% and 31.93% relative improvement in variance captured compared to the covariates only base model (age, sex, education, Glasgow Coma Scale score) when predicting cognitive composite scores at 6 and 12 months, respectively; wILS added 33.99% and 36.87% relative improvement in variance captured. Cognitive composite mediated wILS associations with FIM-Cog scores at 12 months, and both cognitive composite and FIM-Cog scores mediated wILS associations with QOL.

CONCLUSIONS

Early chronic inflammatory burden is associated with cognitive performance post-TBI. wILS explains greater variance in cognitive composite T-scores than uILS. Linking inflammatory burden associated with cognitive deficits to functional outcome post-TBI demonstrates the potential impact of immunotherapy interventions aimed at improving cognitive recovery post-TBI.

Evaluating the Cross-Sectional and Longitudinal Relationships Predicting Suicidal Ideation Following Traumatic Brain Injury

OBJECTIVE

Characterize relationships among substance misuse, depression, employment, and suicidal ideation (SI) following moderate to severe traumatic brain injury (TBI).

DESIGN

Prospective cohort study.

SETTING

Inpatient rehabilitation centers with telephone follow-up; level I/II trauma centers in the United States.

PARTICIPANTS

Individuals with moderate to severe TBI with data in both the National Trauma Data Bank and the Traumatic Brain Injury Model Systems National Database, aged 18 to 59 years, with SI data at year 1 or year 2 postinjury (N = 1377).

MAIN OUTCOME MEASURE

Primary outcome of SI, with secondary employment, substance misuse, and depression outcomes at years 1 and 2 postinjury.

RESULTS

Cross-lagged structural equation modeling analysis showed that year 1 unemployment and substance misuse were associated with a higher prevalence of year 1 depression. Depression was associated with concurrent SI at years 1 and 2. Older adults and women had a greater likelihood of year 1 depression. More severe overall injury (injury severity score) was associated with a greater likelihood of year 1 SI, and year 1 SI was associated with a greater likelihood of year 2 SI.

CONCLUSIONS

Substance misuse, unemployment, depression, and greater extracranial injury burden independently contributed to year 1 SI; in turn, year 1 SI and year 2 depression contributed to year 2 SI. Older age and female sex were associated with year 1 depression. Understanding and mitigating these risk factors are crucial for effectively managing post-TBI SI to prevent postinjury suicide.

Impact of Invasive Quantitative Respiratory Cultures on Antimicrobial Therapy for Suspected Pneumonia in Trauma

BACKGROUND

Invasive quantitative respiratory cultures are generally not recommended because of a lack of demonstrated benefit. There is insufficient literature regarding specific populations such as trauma. The objective of this study was to evaluate the effect of invasive quantitative respiratory sampling on de-escalation to targeted antimicrobial therapy for the management of pneumonia in a trauma population.

METHODS

This was a single-center retrospective cohort study conducted at an American College of Surgeons-verified Level II Trauma Center in Nashville, TN. Adult patients admitted to the trauma service and diagnosed with pneumonia from July 2013 to August 2018 were divided into 2 groups: invasive quantitative respiratory sampling versus noninvasive respiratory sampling. The primary endpoint was rate of targeted antimicrobial therapy. Secondary endpoints included in-hospital mortality, antibiotic days of therapy, and frequency of discontinuation of antibiotics when quantitative cultures were below the diagnostic threshold.

RESULTS

A total of 88 patients were sampled, with 27 in the invasive quantitative group and 66 in the noninvasive group. There was no difference in rates of targeted therapy in patients with invasive quantitative sampling (17 [63%] vs. 35 [57%]; relative risk = 1.10; 95% confidence interval [0.76, 1.57]). No statistically significant differences were observed for in-hospital mortality (8 patients vs. 6 patients, p = .35) or antimicrobial days of therapy (10.3 ± 8.8 vs. 7.8 ± 3.6, p = .161). Only 2 patients (17%) had antibiotics withheld when below the diagnostic threshold.

CONCLUSIONS

Invasive quantitative respiratory sampling did not result in significant changes in targeted antibiotic therapy in a trauma population.

Comorbid Conditions Among Adults 50 Years and Older With Traumatic Brain Injury: Examining Associations With Demographics, Healthcare Utilization, Institutionalization, and 1-Year Outcomes

OBJECTIVES

To assess the relationship of acute complications, preexisting chronic diseases, and substance abuse with clinical and functional outcomes among adults 50 years and older with moderate-to-severe traumatic brain injury (TBI).

DESIGN

Prospective cohort study.

PARTICIPANTS

Adults 50 years and older with moderate-to-severe TBI (n = 2134).

MEASURES

Clusters of comorbid health conditions empirically derived from non-injury International Classification of Diseases, Ninth Revision codes, demographic/injury variables, and outcome (acute and rehabilitation length of stay [LOS], Functional Independence Measure efficiency, posttraumatic amnesia [PTA] duration, institutionalization, rehospitalization, and Glasgow Outcome Scale-Extended (GOS-E) at 1 year).

RESULTS

Individuals with greater acute hospital complication burden were more often middle-aged men, injured in motor vehicle accidents, and had longer LOS and PTA. These same individuals experienced higher rates of 1-year rehospitalization and greater odds of unfavorable GOS-E scores at 1 year. Those with greater chronic disease burden were more likely to be rehospitalized at 1 year. Individuals with more substance abuse burden were most often younger (eg, middle adulthood), black race, less educated, injured via motor vehicle accidents, and had an increased risk for institutionalization.

CONCLUSION

Preexisting health conditions and acute complications contribute to TBI outcomes. This work provides a foundation to explore effects of comorbidity prevention and management on TBI recovery in older adults.

Effects of hospital-acquired pneumonia on long-term recovery and hospital resource utilization following moderate to severe traumatic brain injury

BACKGROUND

Individuals with traumatic brain injury (TBI) have extended inpatient hospital stays that include prolonged mechanical ventilation, increasing risk for infections, including pneumonia. Studies show the negative short-term effects of hospital-acquired pneumonia (HAP) on hospital-based outcomes; however, little is known of its long-term effects.

METHODS

A prospective cohort study was conducted. National Trauma Databank and Traumatic Brain Injury Model Systems were merged to derive a cohort of 3,717 adults with moderate-to-severe TBI. Exposure data were gathered from the National Trauma Databank, and outcomes were gathered from the Traumatic Brain Injury Model Systems. The primary outcome was the Glasgow Outcome Scale-Extended (GOS-E), which was collected at 1, 2, and 5 years postinjury. The GOS-E was categorized as favorable (>5) or unfavorable (≤5) outcomes. A generalized estimating equation model was fitted estimating the effects of HAP on GOS-E over the first 5 years post-TBI, adjusting for age, race, ventilation status, brain injury severity, injury severity score, thoracic Abbreviated Injury Scale score of 3 or greater, mechanism of injury, intraventricular hemorrhage, and subarachnoid hemorrhage.

RESULTS

Individuals with HAP had a 34% (odds ratio, 1.34; 95% confidence interval, 1.15-1.56) increased odds for unfavorable GOS-E over the first 5 years post-TBI compared with individuals without HAP, after adjustment for covariates. There was a significant interaction between HAP and follow-up, such that the effect of HAP on GOS-E declined over time. Sensitivity analyses that weighted for nonresponse bias and adjusted for differences across trauma facilities did not appreciably change the results. Individuals with HAP spent 10.1 days longer in acute care and 4.8 days longer in inpatient rehabilitation and had less efficient functional improvement during inpatient rehabilitation.

CONCLUSION

Individuals with HAP during acute hospitalization have worse long-term prognosis and greater hospital resource utilization. Preventing HAP may be cost-effective and improve long-term recovery for individuals with TBI. Future studies should compare the effectiveness of different prophylaxis methods to prevent HAP.

LEVEL OF EVIDENCE

Prospective cohort study, level III.

Early or Late Bacterial Lung Infection Increases Mortality After Traumatic Brain Injury in Male Mice and Chronically Impairs Monocyte Innate Immune Function

OBJECTIVES

Respiratory infections in the postacute phase of traumatic brain injury impede optimal recovery and contribute substantially to overall morbidity and mortality. This study investigated bidirectional innate immune responses between the injured brain and lung, using a controlled cortical impact model followed by secondary Streptococcus pneumoniae infection in mice.

DESIGN

Experimental study.

SETTING

Research laboratory.

SUBJECTS

Adult male C57BL/6J mice.

INTERVENTIONS

C57BL/6J mice were subjected to sham surgery or moderate-level controlled cortical impact and infected intranasally with S. pneumoniae (1,500 colony-forming units) or vehicle (phosphate-buffered saline) at 3 or 60 days post-injury.

MAIN RESULTS

At 3 days post-injury, S. pneumoniae-infected traumatic brain injury mice (TBI + Sp) had a 25% mortality rate, in contrast to no mortality in S. pneumoniae-infected sham (Sham + Sp) animals. TBI + Sp mice infected 60 days post-injury had a 60% mortality compared with 5% mortality in Sham + Sp mice. In both studies, TBI + Sp mice had poorer motor function recovery compared with TBI + PBS mice. There was increased expression of pro-inflammatory markers in cortex of TBI + Sp compared with TBI + PBS mice after both early and late infection, indicating enhanced post-traumatic neuroinflammation. In addition, monocytes from lungs of TBI + Sp mice were immunosuppressed acutely after traumatic brain injury and could not produce interleukin-1β, tumor necrosis factor-α, or reactive oxygen species. In contrast, after delayed infection monocytes from TBI + Sp mice had higher levels of interleukin-1β, tumor necrosis factor-α, and reactive oxygen species when compared with Sham + Sp mice. Increased bacterial burden and pathology was also found in lungs of TBI + Sp mice.

CONCLUSIONS

Traumatic brain injury causes monocyte functional impairments that may affect the host's susceptibility to respiratory infections. Chronically injured mice had greater mortality following S. pneumoniae infection, which suggests that respiratory infections even late after traumatic brain injury may pose a more serious threat than is currently appreciated.

Interrelationships Between Post-TBI Employment and Substance Abuse: A Cross-lagged Structural Equation Modeling Analysis

OBJECTIVE

To describe the interrelationship of postinjury employment and substance abuse (SA) among individuals with traumatic brain injury.

DESIGN

Structural equation model (SEM) and logistic regression analytic approach using a merged database of the National Trauma Data Bank (NTDB) and Traumatic Brain Injury Model Systems (TBIMS) National Database, with acute care and rehabilitation hospitalization data and 1, 2, and 5 year follow-up data.

SETTING

United States Level I/II trauma centers and inpatient rehabilitation centers with telephone follow-up.

PARTICIPANTS

Individuals in the TBIMS National Database successfully matched to their NTDB data, aged 18-59 years, with trauma severity, age, sex, employment, and SA data at 1, 2, and/or 5 years postinjury (N=2890).

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURE

Employment status (employed/unemployed) and SA (present/absent) at year 1, year 2, and year 5 postinjury.

RESULTS

SEM analysis showed older age at injury predicted lower likelihood of employment at all time points postinjury (βYR1=-0.016; βYR2=-0.006; βYR5=-0.016; all P<.001), while higher injury severity score (ISS) predicted lower likelihood of employment (β=-0.008; P=.027) and SA (β=-0.007; P=.050) at year 1. Male sex predicted higher likelihood of SA at each follow-up (βYR1=0.227; βYR2=0.184; βYR5=0.161; all P<.100). Despite associations of preinjury unemployment with higher preinjury SA, postinjury employment at year 1 predicted SA at year 2 (β=0.118; P=.028). Employment and SA during the previous follow-up period predicted subsequent employment and SA, respectively.

CONCLUSIONS

Employment and SA have unique longitudinal interrelationships and are additionally influenced by age, sex, and ISS. The present work suggests the need for more research on causal, confounding, and mediating factors and appropriate screening and intervention tools that minimize SA and facilitate successful employment-related outcomes.

Healthcare-Associated Infections in the Neurocritical Care Unit

PURPOSE OF REVIEW

This article summarizes updated data and knowledge on healthcare-associated infections in the neurocritical care unit, with a focus on central nervous system infections and systemic infectious complications in patients with acute brain disease. It also reviews the concept of brain injury-induced immune modulation, an underlying mechanism to explain why the neuro-ICU population is particularly susceptible to infections.

RECENT FINDINGS

Healthcare-associated infections in the neuro-ICU are common: up to 40 % of meningitides in the developed world are now healthcare-associated. The number of gram-negative infections is rising. New diagnostic approaches attempt to aid in the diagnosis of healthcare-associated meningitis and ventriculitis. Healthcare-associated infections in the neurocritical care unit remain a challenge for diagnosis, treatment, and prevention. Gaining a better understanding of at-risk patients and development of preventative strategies will be the goal for future investigation.

Epidemiology of Comorbid Conditions Among Adults 50 Years and Older With Traumatic Brain Injury

OBJECTIVES

Aging individuals with traumatic brain injury (TBI) experience multiple comorbidities that can affect recovery from injury. The objective of this study was to describe the most commonly co-occurring comorbid conditions among adults 50 years and older with TBI.

SETTING

Level I Trauma centers.

PARTICIPANTS

Adults 50 years and older with moderate/severe TBI enrolled in the TBI-Model Systems (TBI-MS) from 2007 to 2014 (n = 2134).

DESIGN

A TBI-MS prospective cohort study.

MAIN MEASURES

International Classification of Disease-9th Revision codes collapsed into 45 comorbidity categories. Comorbidity prevalence estimates and trend analyses were conducted by age strata (50-54, 55-64, 65-74, 75-84, ≥85 years). A dimension reduction method, Treelet Transform, classified clusters of comorbidities that tended to co-occur.

RESULTS

The 3 most commonly occurring comorbid categories were hypertensive disease (52.6/100 persons), other diseases of the respiratory system (51.8/100 persons), and fluid component imbalances (43.7/100 persons). Treelet Transform classified 3 clusters of comorbid codes, broadly classified as (1) acute medical diseases/infections, (2) chronic conditions, and (3) substance abuse disorders.

CONCLUSION

This study provides valuable insight into comorbid conditions that co-occur among adults 50 years and older with TBI and provides a foundation for future studies to explore how specific comorbidities affect TBI recovery.

Incidence of post-traumatic pneumonia in poly-traumatized patients: identifying the role of traumatic brain injury and chest trauma

Purpose

Traumatic brain injury (TBI) and chest trauma are common injuries in severely injured patients. Both entities are well known to be associated with severe post-traumatic complications, including pneumonia, a common complication with a significant impact on the further clinical course. However, the relevance of TBI, chest trauma and particularly their combination as risk factors for the development of pneumonia and its impact on outcomes are not fully elucidated.

Methods

A retrospective analysis of poly-traumatized patients treated between 2010 and 2015 at a level I trauma centre was performed. Inclusion criteria were: Injury Severity Score ≥ 16 and age ≥ 18 years. TBI and chest trauma were classified according to the Abbreviated Injury Scale. Complications (i.e. acute respiratory distress syndrome (ARDS), multi-organ dysfunction syndrome (MODS) and pneumonia) were documented by a review of the medical records. The primary outcome parameter was in-hospital mortality.

Results

Over the clinical course, 19.9% of all patients developed pneumonia, and in-hospital mortality was 25.3%. Pneumonia (OR 5.142, p = 0.001) represented the strongest independent predictor of in-hospital mortality, followed by the combination of chest injury and TBI (OR 3.784, p = 0.008) and TBI (OR 3.028, p = 0.010). Chest injury alone, the combination of chest injury and TBI, and duration of ventilation were independent predictors of pneumonia [resp. OR 4.711 (p = 0.004), OR 4.193 (p = 0.004), OR 1.002 (p < 0.001)].

Conclusions

Chest trauma alone and especially its combination with TBI represent high-risk injury patterns for the development of pneumonia, which forms the strongest predictor of mortality in poly-traumatized patients.

Infections after a traumatic brain injury: The complex interplay between the immune and neurological systems

Traumatic brain injury (TBI) is a serious global health issue, being the leading cause of death and disability for individuals under the age of 45, and one of the largest causes of global neurological disability. In addition to the brain injury itself, it is increasingly appreciated that a TBI may also alter the systemic immune response in a way that renders TBI patients more vulnerable to infections in the acute post-injury period. Such infections pose an additional challenge to the patient, increasing rates of mortality and morbidity, and worsening neurological outcomes. Hospitalization, surgical interventions, and a state of immunosuppression induced by injury to the central nervous system (CNS), may all contribute to the high rate of infections seen in the population with TBI. Ongoing research to better understand the immunomodulators that underlie TBI-induced immunosuppression may aid in the development of effective therapeutic strategies to improve the recovery trajectory for patients. This review first describes the clinical scenario, posing the question of whether TBI patients are more susceptible to infections such as pneumonia, and if so, why? We then consider how cross-talk between the injured brain and the systemic immune system occurs, and further, how the additional immune challenge of an acquired infection can contribute to ongoing neuroinflammation and neurodegeneration after a TBI. Experimental models combining TBI with infection are discussed, as well as current treatment options available for this double-barreled insult. The aims of this review are to summarize current understanding of the bidirectional relationship between the CNS and the immune system when faced with a mechanical trauma combined with a concomitant infection, and to highlight key outstanding questions that remain in the field.

[Predictors of remote outcomes of brain injury]

AIM

To determine predictors of remote outcomes of complex combat brain injury.

MATERIAL AND METHODS

A survey of 145 combatants with long-term combat injury (from 1 to 10 years) was conducted. Responses were received from 30 people from 18 regions of the Russian Federation. Data analysis included nonparametric correlation analysis using Spearman coefficient.

RESULTS AND CONCLUSION

Significant correlations were between the remote functional outcome and the following predictors: the severity of injury at admission (r=0.527; p<0,01), leukocyte level at admission (r=0.594; p<0,01), presence and severity of pelvic disturbances (r=0.574; p<0,01), the duration of staying in intensive care (r=0.476; p<0,01), neurological deficit severity and scores on the Glasgow Outcome Scale (r=0.469; p<0,01). Character of remote outcome was associated with posttraumatic amnesia (r=0.491; p<0,05), concomitant injuries of abdominal cavity organs, kidney, bladder, time of starting peroral feeding (r=0.377; p<0,05), mean heart rhythm rate during the first 14 days of treatment, pneumonia (r=0.377; p<0,05) and episodes of psychomotor agitation (r=0.381; p<0,05) within a period of hospital treatment. These results need confirmation in a larger study.

Glasgow Outcome Scale Measures and Impact on Analysis and Results of a Randomized Clinical Trial of Severe Traumatic Brain Injury

The original unstructured Glasgow Outcome Scale (uGOS) and the newer structured interviews GOS and the Extended GOS (GOS-E) have been used widely as outcomes in severe traumatic brain injury (TBI) trials. We compared outcome categories (ranging from dead [D] to good recovery [GR]) for each measure in a randomized trial of transfusion threshold and the implications of measure choice and analysis methods for the results of the trial. We planned to explore patient symptomology possibly driving any discrepancies between the patient's uGOS and GOS scores. Category correspondence between uGOS and GOS scores occurred in 160 (88.4%) of the 181 analyzed cases. The GOS-E and GOS instruments incorporated more behavioral/cognitive/social and other components, leading to a worse outcome in some cases than for the uGOS. Choice of outcome measure and analysis led to incongruous conclusions. Dichotomizing uGOS into favorable outcome (GR and moderate disability [MD] categories) versus unfavorable (severe disability [SD], vegetative state [VS], and D categories), we observed a significant effect of transfusion threshold (odds ratio [OR] = 0.51, p = 0.03; adjusted OR = 0.40, p = 0.02). For the same dichotomization of GOS and GOS-E, the effect was not statistically significant but the ORs were similar (ORs between 0.57 and 0.68, p > 0.15 for all). An effect was not detected using ordinal logistic regression or sliding dichotomy method for all three measures. Differences in categorizations of subjects between moderate and severe disability among the scales impacted conclusions of the trial. In future studies, particular attention should be given to implementing GOS measures and describing the methodology for how outcomes were ascertained.

Probabilistic Matching of Deidentified Data From a Trauma Registry and a Traumatic Brain Injury Model System Center: A Follow-up Validation Study

In a previous study, individuals from a single Traumatic Brain Injury Model Systems and trauma center were matched using a novel probabilistic matching algorithm. The Traumatic Brain Injury Model Systems is a multicenter prospective cohort study containing more than 14,000 participants with traumatic brain injury, following them from inpatient rehabilitation to the community over the remainder of their lifetime. The National Trauma Databank is the largest aggregation of trauma data in the United States, including more than 6 million records. Linking these two databases offers a broad range of opportunities to explore research questions not otherwise possible. Our objective was to refine and validate the previous protocol at another independent center. An algorithm generation and validation data set were created, and potential matches were blocked by age, sex, and year of injury; total probabilistic weight was calculated based on of 12 common data fields. Validity metrics were calculated using a minimum probabilistic weight of 3. The positive predictive value was 98.2% and 97.4% and sensitivity was 74.1% and 76.3%, in the algorithm generation and validation set, respectively. These metrics were similar to the previous study. Future work will apply the refined probabilistic matching algorithm to the Traumatic Brain Injury Model Systems and the National Trauma Databank to generate a merged data set for clinical traumatic brain injury research use.

Comparison of two simple models for prediction of short term mortality in patients after severe traumatic brain injury

INTRODUCTION

The subscale motor score of Glasgow Coma Scale (msGCS) and the Abbreviated Injury Score of head region (HAIS) are validated prognostic factors in traumatic brain injury (TBI). The aim was to compare the prognostic performance of a HAIS-based prediction model including HAIS, pupil reactivity and age, and the reference prediction model including msGCS in emergency department (ED), pupil reactivity and age.

METHODS

Secondary analysis of a prospective epidemiological study including patients after severe TBI (HAIS > 3) with follow-up from the time of accident until 14 days or earlier death was performed in Switzerland. Performance of prediction, based on accuracy of discrimination [area under the receiver-operating curve (AUROC)], calibration (Hosmer-Lemeshow test) and validity (bootstrapping with 2000 repetitions to correct) for optimism of the two prediction models were investigated. A non-inferiority approach was performed and an a priori threshold for important differences was established.

RESULTS

The cohort included 808 patients [median age 56 {inter-quartile range (IQR) 33-71}, median motor part of GCS in ED 1 (1-6), abnormal pupil reactivity 29.0%] with a death rate of 29.7% at 14 days. The accuracy of discrimination was similar (AUROC HAIS-based prediction model: 0.839; AUROC msGCS-based prediction model: 0.826, difference of the 2 AUROC 0.013 (-0.007 to 0.037). A similar calibration was observed (Hosmer-Lemeshow X² 11.64, p = 0.168 vs. Hosmer-Lemeshow X² 8.66, p = 0.372). Internal validity of HAIS-based prediction model was high (optimism corrected AUROC: 0.837).

CONCLUSIONS

Performance of prediction for short-term mortality after severe TBI with HAIS-based prediction model was non-inferior to reference prediction model using msGCS as predictor.