Sympathetic Hyperactivity After Traumatic Brain Injury and the Role of Beta-Blocker Therapy

Preclinical Studies on Mechanisms Underlying the Protective Effects of Propranolol in Traumatic Brain Injury: A Systematic Review

Traumatic brain injury (TBI) is a leading cause of mortality and morbidity amongst trauma patients. Its treatment is focused on minimizing progression to secondary injury. Administration of propranolol for TBI maydecrease mortality and improve functional outcomes. However, it is our sense that its use has not been universally adopted due to low certainty evidence. The literature was reviewed to explore the mechanism of propranolol as a therapeutic intervention in TBI to guide future clinical investigations. Medline, Embase, and Scopus were searched for studies that investigated the effect of propranolol on TBI in animal models from inception until June 6, 2023. All routes of administration for propranolol were included and the following outcomes were evaluated: cognitive functions, physiological and immunological responses. Screening and data extraction were done independently and in duplicate. The risk of bias for each individual study was assessed using the SYCLE's risk of bias tool for animal studies. Three hundred twenty-three citations were identified and 14 studies met our eligibility criteria. The data suggests that propranolol may improve post-TBI cognitive and motor function by increasing cerebral perfusion, reducing neural injury, cell death, leukocyte mobilization and p-tau accumulation in animal models. Propranolol may also attenuate TBI-induced immunodeficiency and provide cardioprotective effects by mitigating damage to the myocardium caused by oxidative stress. This systematic review demonstrates that propranolol may be therapeutic in TBI by improving cognitive and motor function while regulating T lymphocyte response and levels of myocardial reactive oxygen species. Oral or intravenous injection of propranolol following TBI is associated with improved cerebral perfusion, reduced neuroinflammation, reduced immunodeficiency, and cardio-neuroprotection in preclinical studies.

Alcohol-Intoxicated Patients With Blunt Trauma and Head Injuries Have Better Outcomes Than Sober Patients

BACKGROUND

Although alcohol-intoxicated patients have difficulties evaluating their consciousness level and being transported prehospital, there is some evidence that the survival outcomes for alcohol-intoxicated patients with head injuries are better. The present study evaluated whether the survival and brain function outcomes in alcohol-intoxicated trauma patients with head injuries were better than those in sober patients using the Japan Trauma Data Bank (JTDB), a nationwide trauma registry in Japan.

METHODS

The 17,823 patients with blunt trauma, including head injuries, who were registered in the JTDB database between January 2019 and December 2021 were retrospectively analyzed. Logistic regression analyses were performed for in-hospital survival in patients with blunt trauma, including those with head injuries, and for good brain function based on the Glasgow outcome scale (GOS) in patients with only head injuries. Survival rates by head injury score using the abbreviated injury scale (AIS) 2008 or injury severity score (ISS) categories were compared between drinking and nondrinking groups.

RESULTS

Drinking significantly affected survival (odds ratio 1.800, p<0.001) and good brain function (odds ratio 1.546, p<0.001), as indicated by logistic regression analysis using head injuries alone or blunt multisite trauma (including head injuries), respectively. According to analyses by the ISS category or head AIS score, there were significant differences between the drinking and non-drinking groups in several categories (ISS 9-15, 16-24, and 25-40 and AIS 3 and 5) regarding survival rates with blunt trauma, including head injuries, or good GOS rates with head injuries alone.

CONCLUSIONS

The survival rates for blunt trauma, including head injuries, and the prognosis for brain function based on the GOS were better in the drinking group than in the control group for cases with head injuries alone. A multivariate analysis also showed that alcohol consumption was significantly associated with better outcomes.

Neuromodulation Therapies in Pre-Clinical Models of Traumatic Brain Injury: Systematic Review and Translational Applications

Traumatic brain injury (TBI) has been associated with several lasting impairments that affect quality of life. Pre-clinical models of TBI have been studied to further our understanding of the underlying short-term and long-term symptomatology. Neuromodulation techniques have become of great interest in recent years as potential rehabilitative therapies after injury because of their capacity to alter neuronal activity and neural circuits in targeted brain regions. This systematic review aims to provide an overlook of the behavioral and neurochemical effects of transcranial direct current stimulation (tDCS), transcranial magnetic stimulation (TMS), deep brain stimulation (DBS), and vagus nerve stimulation (VNS) in pre-clinical TBI models. After screening 629 abstracts, 30 articles were pooled for review. These studies showed that tDCS, TMS, DBS, or VNS delivered to rodents restored TBI-induced deficits in coordination, balance, locomotor activity and improved cognitive impairments in memory, learning, and impulsivity. Potential mechanisms for these effects included neuroprotection, a decrease in apoptosis, neuroplasticity, and the restoration of neural circuit abnormalities. The translational value, potential applicability, and the interpretation of these findings in light of outcome data from clinical trials in patients with TBI are discussed.

Beta-blockers reduce intestinal permeability and early mortality following traumatic brain injury in Drosophila

Traumatic brain injury (TBI) frequently leads to non-neurological consequences such as intestinal permeability. The beta-blocker drug labetalol, which inhibits binding of catecholamine neurotransmitters to adrenergic receptors, reduces intestinal permeability in a rat TBI model. Using a Drosophila melanogaster TBI model, we previously found a strong positive correlation between intestinal permeability and mortality within 24 hours of TBI in a standard laboratory line (w¹¹¹⁸ ) and across genetically diverse inbred lines from the Drosophila Genetic Reference Panel (DGRP). Here, we report that feeding injured w¹¹¹⁸ flies the beta-blockers labetalol and metoprolol reduced intestinal permeability and mortality. Additionally, metoprolol reduced intestinal permeability when 18 DGRP fly lines were analyzed in aggregate, but neither beta-blocker affected mortality. These data indicate that the mechanism underlying disruption of the intestinal barrier by adrenergic signaling following TBI is conserved between humans and flies and that mortality following TBI in flies is not strictly dependent on disruption of the intestinal barrier. Thus, the fly TBI model is useful for shedding light on the mechanism and consequences of adrenergic signaling between the brain and intestine following TBI in humans.

Sepsis or sympathetics? Paroxysmal sympathetic hyperactivity after pontine stroke

A 64-year-old man from nursing home with a pontine stroke 3 months ago, ventilator-dependent, presented with episodic fever, tachycardia and tachypnoea occurring several times a day. He was evaluated for sepsis and pulmonary embolism and was treated empirically with broad-spectrum antibiotics. But these episodes persisted. Due to the episodic nature and typical symptoms of sympathetic overactivity, in the setting of prior brain injury, paroxysmal sympathetic hyperactivity was considered. His antibiotics were discontinued, and he was treated symptomatically with baclofen and bromocriptine, which resulted in a partial reduction of these episodes.

Hydrogen Sulfide Subchronic Treatment Improves Hypertension Induced by Traumatic Brain Injury in Rats through Vasopressor Sympathetic Outflow Inhibition

Traumatic brain injury (TBI) represents a critical public health problem around the world. To date, there are no accurate therapeutic approaches for the management of cardiovascular impairments induce by TBI. In this regard, hydrogen sulfide (H₂S), a novel gasotransmitter, has been proposed as a neuro- and cardioprotective molecule. This study was designed to determine the effect of subchronic management with sodium hydrosulfide (NaHS) on hemodynamic, vasopressor sympathetic outflow and sensorimotor alterations produced by TBI. Animals underwent a lateral fluid percussion injury, and changes in hemodynamic variables were measured by pletismographic methods. In addition, vasopressor sympathetic outflow was assessed by a pithed rat model. Last, sensorimotor impairments were evaluated by neuroscore test and beam-walking test. At seven, 14, 21, and 28 days after moderate-severe TBI, the animals showed: (1) a decrease on sensorimotor function in the neuroscore test and beam-walking test; (2) an increase in heart rate, systolic, diastolic, and mean blood pressure; (3) progressive sympathetic hyperactivity; and (4) a decrease in vasopressor responses induced by noradrenaline (α_1/2-adrenoceptors agonist) and UK 14,304 (selective α₂-adrenoceptor agonist). Interestingly, intraperitoneal daily injections of NaHS, an H₂S donor (3.1 and 5.6 mg/kg), during seven days after TBI prevented the development of the impairments in hemodynamic variables, which were similar to those obtained in sham animals. Moreover, NaHS treatment prevented the sympathetic hyperactivity and decreased noradrenaline-induced vasopressor responses. No effects on sensorimotor dysfunction were observed, however. Taken together, our results suggest that H₂S ameliorates the hemodynamic and sympathetic system impairments observed after TBI.

Traumatic brain injury induced temperature dysregulation: What is the role of β blockers?

BACKGROUND

Traumatic brain injury (TBI) is associated with sympathetic discharge that leads to posttraumatic hyperthermia (PTH). Beta blockers (ββ) are known to counteract overactive sympathetic discharge. The aim of our study was to evaluate the effect of ββ on PTH in critically-ill TBI patients.

METHODS

We performed retrospective cohort analysis of the Medical Information Mart for Intensive Care database. We included all critically ill TBI patients with head Abbreviated Injury Scale (AIS) score of 3 or greater and other body region AIS score less than 2 who developed PTH (at least one febrile episode [T > 38.3°C] with negative microbiological cultures (blood, urine, and bronchoalveolar lavage). Patients on preinjury ββ were excluded. Patients were stratified into (ββ+) and (ββ-) groups. Propensity score matching was performed (1:1 ratio) controlling for patient demographics, injury parameters and other medications that influence temperature. Outcomes were the number of febrile episodes, maximum temperature, and the time interval between febrile episodes. Multivariate linear regression was performed.

RESULTS

We analyzed 4,286 critically ill TBI patients. A matched cohort of 1,544 patients was obtained: 772 ββ + (metoprolol, 60%; propranolol, 25%; and atenolol, 15%) and 772 ββ-. Mean age was 63.4 ± 15.4 years, median head AIS score of 3 (3-4), and median Injury Severity Score of 10 (9-16). Patients in the ββ+ group had a lower number of febrile episodes (8 episodes vs. 12 episodes; p = 0.003), lower median maximum temperature (38.0°C vs. 38.5°C; p = 0.025), and a longer median time between febrile episodes (3 hours vs. 1 hour; p = 0.013). On linear regression, propranolol was found to be superior in terms of reducing the number of febrile episodes and the maximum temperature. However, there was no significant difference between the three ββ in terms of reducing the time interval between febrile episodes (p = 0.582).

CONCLUSION

Beta blockers attenuate PTH by decreasing the frequency of febrile episodes, increasing the time interval between febrile episodes, and reducing the maximum rise in temperature. ββ may be a potential therapeutic modality in PTH.

LEVEL OF EVIDENCE

Therapeutic, level IV.

Efficacy of trazodone for treating paroxysmal sympathetic hyperactivity presenting after left temporal subcortical hemorrhage

Paroxysmal sympathetic hyperactivity (PSH) is a clinical condition characterized by abnormal paroxysmal surges in sympathetic nervous system activity. PSH is known to occur after severe head injury and hypoxic encephalopathy. Cases of PSH that develop after stroke have been reported worldwide; however, PSH is not commonly reported in the field of stroke research in Japan. Some studies have suggested that gabapentin may improve the symptoms of PSH. To our knowledge, this is the first case report demonstrating the efficacy of trazodone for the treatment of PSH that developed after temporal subcortical hemorrhage. A 49-year-old woman presented to our clinic with mild confusion and sensory aphasia after experiencing left temporal subcortical hemorrhage; a conservative treatment was initiated at our hospital. Immediately upon hospitalization, she developed prolonged consciousness disorder, high fever, tachycardia, malignant hypertension, tachypnea, constipation, and overactive bladder. The patient's symptoms improved after the administration of trazodone. She was diagnosed with PSH after intracranial hemorrhage and was subsequently transferred to a recovery and rehabilitation hospital unit where the oral administration of trazodone continued. Prolonged PSH contributes significantly to the impairment of daily activities in patients with stroke; therefore, early diagnosis and treatment are critical. Here, we report on the efficacy of trazodone as an effective treatment option for improving clinical outcomes and reducing the stay in the stroke care unit.

Beta-Blocker Therapy in Severe Traumatic Brain Injury: A Prospective Randomized Controlled Trial

Background

Observational studies have demonstrated improved outcomes in TBI patients receiving in-hospital beta-blockers. The aim of this study is to conduct a randomized controlled trial examining the effect of beta-blockers on outcomes in TBI patients.

Methods

Adult patients with severe TBI (intracranial AIS ≥ 3) were included in the study. Hemodynamically stable patients at 24 h after injury were randomized to receive either 20 mg propranolol orally every 12 h up to 10 days or until discharge (BB+) or no propranolol (BB−). Outcomes of interest were in-hospital mortality and Glasgow Outcome Scale-Extended (GOS-E) score on discharge and at 6-month follow-up. Subgroup analysis including only isolated severe TBI (intracranial AIS ≥ 3 with extracranial AIS ≤ 2) was carried out. Poisson regression models were used.

Results

Two hundred nineteen randomized patients of whom 45% received BB were analyzed. There were no significant demographic or clinical differences between BB+ and BB− cohorts. No significant difference in in-hospital mortality (adj. IRR 0.6 [95% CI 0.3–1.4], p = 0.2) or long-term functional outcome was measured between the cohorts (p = 0.3). One hundred fifty-four patients suffered isolated severe TBI of whom 44% received BB. The BB+ group had significantly lower mortality relative to the BB− group (18.6% vs. 4.4%, p = 0.012). On regression analysis, propranolol had a significant protective effect on in-hospital mortality (adj. IRR 0.32, p = 0.04) and functional outcome at 6-month follow-up (GOS-E ≥ 5 adj. IRR 1.2, p = 0.02).

Conclusion

Propranolol decreases in-hospital mortality and improves long-term functional outcome in isolated severe TBI. This randomized trial speaks in favor of routine administration of beta-blocker therapy as part of a standardized neurointensive care protocol.

Level of evidence

Level II; therapeutic.

Study type

Therapeutic study.

Efficacy of trazodone for treating paroxysmal sympathetic hyperactivity presenting after thalamic hemorrhage: A case report

Paroxysmal sympathetic hyperactivity (PSH) is a clinical condition characterized by abnormal paroxysmal surges in sympathetic nervous system activity. PSH is known to occur after severe head injury and hypoxic encephalopathy. Cases of PSH that develop after stroke have been reported worldwide; however, PSH is not commonly reported in the field of stroke research in Japan. Some studies have suggested that gabapentin may improve the symptoms of PSH. To our knowledge, this is the first case report demonstrating the efficacy of trazodone for the treatment of PSH that developed after thalamic hemorrhage. A 45-year-old woman presented to our clinic with headache and paralysis of the left side of her body after experiencing right thalamic hemorrhage; a conservative treatment was initiated at our hospital. Immediately upon hospitalization, she developed high fever, tachycardia, tachypnea, constipation, and overactive bladder and had breathing difficulties. Blood sampling revealed elevated levels of myocardial escape enzymes; however, coronary angiography did not show any significant stenosis or occlusion. The patient's symptoms improved after the administration of trazodone. She was diagnosed with catecholamine cardiomyopathy associated with PSH after intracranial hemorrhage and was subsequently transferred to a recovery and rehabilitation hospital unit where the oral administration of trazodone continued. Prolonged PSH contributes significantly to the impairment of daily activities in patients with stroke; therefore, early diagnosis and treatment are critical. Here, we report on the efficacy of trazodone as an effective treatment option for improving clinical outcomes and reducing the stay in the stroke care unit.

Multiple organ dysfunction after trauma

Background

The nature of multiple organ dysfunction syndrome (MODS) after traumatic injury is evolving as resuscitation practices advance and more patients survive their injuries to reach critical care. The aim of this study was to characterize contemporary MODS subtypes in trauma critical care at a population level.

Methods

Adult patients admitted to major trauma centre critical care units were enrolled in this 4‐week point‐prevalence study. MODS was defined by a daily total Sequential Organ Failure Assessment (SOFA) score of more than 5. Hierarchical clustering of SOFA scores over time was used to identify MODS subtypes.

Results

Some 440 patients were enrolled, of whom 245 (55·7 per cent) developed MODS. MODS carried a high mortality rate (22·0 per cent versus 0·5 per cent in those without MODS; P < 0·001) and 24·0 per cent of deaths occurred within the first 48 h after injury. Three patterns of MODS were identified, all present on admission. Cluster 1 MODS resolved early with a median time to recovery of 4 days and a mortality rate of 14·4 per cent. Cluster 2 had a delayed recovery (median 13 days) and a mortality rate of 35 per cent. Cluster 3 had a prolonged recovery (median 25 days) and high associated mortality rate of 46 per cent. Multivariable analysis revealed distinct clinical associations for each form of MODS; 24‐hour crystalloid administration was associated strongly with cluster 1 (P = 0·009), traumatic brain injury with cluster 2 (P = 0·002) and admission shock severity with cluster 3 (P = 0·003).

Conclusion

Contemporary MODS has at least three distinct types based on patterns of severity and recovery. Further characterization of MODS subtypes and their underlying pathophysiology may lead to future opportunities for early stratification and targeted interventions.

Beta-adrenergic blockade for attenuation of catecholamine surge after traumatic brain injury: a randomized pilot trial

Background

Beta-blockers have been proven in multiple studies to be beneficial in patients with traumatic brain injury. Few prospective studies have verified this and no randomized controlled trials. Additionally, most studies do not titrate the dose of beta-blockers to therapeutic effect. We hypothesize that propranolol titrated to effect will confer a survival benefit in patients with traumatic brain injury.

Methods

A randomized controlled pilot trial was performed during a 24-month period. Patients with traumatic brain injury were randomized to propranolol or control group for a 14-day study period. Variables collected included demographics, injury severity, physiologic parameters, urinary catecholamines, and outcomes. Patients receiving propranolol were compared with the control group.

Results

Over the study period, 525 patients were screened, 26 were randomized, and 25 were analyzed. Overall, the mean age was 51.3 years and the majority were male with blunt mechanism. The mean Injury Severity Score was 21.8 and median head Abbreviated Injury Scale score was 4. Overall mortality was 20.0%. Mean arterial pressure was higher in the treatment arm as compared with control (p=0.021), but no other differences were found between the groups in demographics, severity of injury, severity of illness, physiologic parameters, or mortality (7.7% vs. 33%; p=0.109). No difference was detected over time in any variables with respect to treatment, urinary catecholamines, or physiologic parameters. Glasgow Coma Scale (GCS), Sequential Organ Failure Assessment, and Acute Physiology and Chronic Health Evaluation scores all improved over time. GCS at study end was significantly higher in the treatment arm (11.7 vs. 8.9; p=0.044). Finally, no difference was detected with survival analysis over time between groups.

Conclusions

Despite not being powered to show statistical differences between groups, GCS at study end was significantly improved in the treatment arm and mortality was improved although not at a traditional level of significance. The study protocol was safe and feasible to apply to an appropriately powered larger multicenter study.

Level of evidence

Level 2—therapeutic.

Significance of Cardiac Troponin I Elevation in Traumatic Brain Injury Patients

Background

Myocardial dysfunction is frequently described as an underlying cause of mortality in traumatic brain injury (TBI) known as brain-cardiac link. However the impact on prognosis of a disease remains uncertain.

Objectives

The current study aimed at investigating the correlation between TBI and cardiac troponin I (cTnI) rise and in-hospital mortality rate among patients with TBI.

Methods

In the current prospective study TBI patients with abbreviated injury scale score (AIS) > 3 and Glasgow coma scale (GCS) score ≤ 8 with cTnI measurement within the first 24 hours of admission were evaluated. Chi-square, Kruskal-Wallis, Mann-Whitney U and Logistic Regression tests were used for data analysis.

Results

A total of 166 eligible patients were studied .The mean age of the cases was 37.64 ± 17.21 years, largely under 65 (93.4%) and male (86.7%).The most common injuries were cerebral contusion (35.1%), while motor vehicle crash (MVC) was the most common cause of injuries (83.73%); 59 % of the patients showed detectable cTnI concentrations within 24 hours of admission; 65.7% of the patients expired; they showed higher levels of cTnI compared to survivors that showed lower levels, 0.148 ± 0.074 vs 0.057 ± 0.055, respectively (P < 0.001). Moreover, a significant association was observed between mortality rate and lower admission GCS 3.49 ± 1.08 vs 6.79 ± 1.66, respectively (P < 0.001).

Conclusions

Increased cTnI levels could be a predictor of mortality among patients with TBI. Its measurement and investigation for therapeutic strategies could lead to better management of these cases.

Geriatric Polytrauma-Cardiovascular and Immunologic Response in a Murine Two-Hit Model of Trauma

BACKGROUND

The aims of the present study were to establish a clinically relevant two-hit model with trauma/hemorrhage followed by sepsis in older mice and investigate age-dependent cardiovascular and immunologic specificities under these conditions.

MATERIALS AND METHODS

In aged mice (12, 18, and 24 mo old), a femur fracture followed by hemorrhage was induced. After resuscitation, animals were monitored for 72 h before sepsis was induced. Vital signs were monitored during shock. Systemic interleukin (IL)-6 levels were measured daily. Expression of sarcoplasmic or endoplasmic reticulum calcium ATPase (SERCA) and IL-6 receptor were analyzed in heart, lung, and liver tissues.

RESULTS

After induction of shock, mean arterial pressure decreased significantly in all groups (12 mo, P < 0.001; 18 mo, P < 0.001; 24 mo, P = 0.013). Compared with younger animals, 24-mo old mice were not able to adequately compensate for hypovolemia by an increase of heart rate (P = 0.711). Expression of SERCA2 (P = 0.002) and IL-6 receptor on myocytes (P = 0.037), lung (P = 0.005), and liver (P = 0.009) tissues were also lowest in this group. Systemic IL-6 values showed the most distinct posttraumatic response in 24-mo-old mice (P = 0.016). Survival rate decreased significantly with increased age (P = 0.005).

CONCLUSIONS

The increased mortality rate in older animals was associated with a limited compensatory physiological response and a more distinct immunologic reaction after trauma and sepsis. A decreased SERCA2 expression and missing feedback loops due to a reduced density of organ bound immune receptors might represent possible explanations for the observed age-dependent differences.

Paroxysmal Sympathetic Hyperactivity After Severe Traumatic Brain Injury in Children: Prevalence, Risk Factors, and Outcome

OBJECTIVE

To describe paroxysmal sympathetic hyperactivity in pediatric patients with severe traumatic brain injury using the new consensus definition, the risk factors associated with developing paroxysmal sympathetic hyperactivity, and the outcomes associated with paroxysmal sympathetic hyperactivity.

DESIGN

Retrospective cohort study.

SETTING

Academic children's hospital PICU.

PATIENTS

All pediatric patients more than 1 month and less than 18 years old with severe traumatic brain injury between 2000 and 2016. We excluded patients if they had a history of five possible confounders for paroxysmal sympathetic hyperactivity diagnosis or if they died within 24 hours of admission for traumatic brain injury.

MEASUREMENTS AND MAIN RESULTS

Our primary outcome was PICU mortality. One hundred seventy-nine patients met inclusion criteria. Thirty-six patients (20%) had at least eight criteria and therefore met classification of "likelihood of paroxysmal sympathetic hyperactivity." Older age was the only factor independently associated with developing paroxysmal sympathetic hyperactivity (odds ratio, 1.08; 95% CI, 1.00-1.16). PICU mortality was significantly lower for those with paroxysmal sympathetic hyperactivity compared with those without paroxysmal sympathetic hyperactivity (odds ratio, 0.08; 95% CI, 0.01-0.52), but PICU length of stay was greater in those with paroxysmal sympathetic hyperactivity (odds ratio, 4.36; 95% CI, 2.94-5.78), and discharge to an acute care or rehabilitation setting versus home was higher in those with paroxysmal sympathetic hyperactivity (odds ratio, 5.59; 95% CI, 1.26-24.84; odds ratio, 5.39; 95% CI, 1.87-15.57, respectively). When paroxysmal sympathetic hyperactivity was diagnosed in the first week of admission, it was not associated with discharge disposition.

CONCLUSIONS

Our study suggests that the rate of paroxysmal sympathetic hyperactivity in patients with severe traumatic brain injury is higher than previously reported. Older age was associated with an increased risk for developing paroxysmal sympathetic hyperactivity, but severity of the trauma and the brain injury were not. For survivors of severe traumatic brain injury beyond 24 hours who developed paroxysmal sympathetic hyperactivity, there was a lower PICU mortality but also greater PICU length of stay and a lower likelihood of discharge home from the admitting hospital, suggesting that functional outcome in survivors with paroxysmal sympathetic hyperactivity is worse than survivors without paroxysmal sympathetic hyperactivity.

Beta blockers in critically ill patients with traumatic brain injury: Results from a multicenter, prospective, observational American Association for the Surgery of Trauma study

BACKGROUND

Beta blockers, a class of medications that inhibit endogenous catecholamines interaction with beta adrenergic receptors, are often administered to patients hospitalized after traumatic brain injury (TBI). We tested the hypothesis that beta blocker use after TBI is associated with lower mortality, and secondarily compared propranolol to other beta blockers.

METHODS

The American Association for the Surgery of Trauma Clinical Trial Group conducted a multi-institutional, prospective, observational trial in which adult TBI patients who required intensive care unit admission were compared based on beta blocker administration.

RESULTS

From January 2015 to January 2017, 2,252 patients were analyzed from 15 trauma centers in the United States and Canada with 49.7% receiving beta blockers. Most patients (56.3%) received the first beta blocker dose by hospital day 1. Those patients who received beta blockers were older (56.7 years vs. 48.6 years, p < 0.001) and had higher head Abbreviated Injury Scale scores (3.6 vs. 3.4, p < 0.001). Similarities were noted when comparing sex, admission hypotension, mean Injury Severity Score, and mean Glasgow Coma Scale. Unadjusted mortality was lower for patients receiving beta blockers (13.8% vs. 17.7%, p = 0.013). Multivariable regression determined that beta blockers were associated with lower mortality (adjusted odds ratio, 0.35; p < 0.001), and propranolol was superior to other beta blockers (adjusted odds ratio, 0.51, p = 0.010). A Cox-regression model using a time-dependent variable demonstrated a survival benefit for patients receiving beta blockers (adjusted hazard ratio, 0.42, p < 0.001) and propranolol was superior to other beta blockers (adjusted hazard ratio, 0.50, p = 0.003).

CONCLUSION

Administration of beta blockers after TBI was associated with improved survival, before and after adjusting for the more severe injuries observed in the treatment cohort. This study provides a robust evaluation of the effects of beta blockers on TBI outcomes that supports the initiation of a multi-institutional randomized control trial.

LEVEL OF EVIDENCE

Therapeutic/care management, level III.

Acute Traumatic Brain Injury Induces CD4+ and CD8+ T Cell Functional Impairment by Upregulating the Expression of PD-1 via the Activated Sympathetic Nervous System

OBJECTIVE

Traumatic brain injury (TBI) induces immunosuppression in the acute phase, and the activation of the sympathetic nervous system (SNS) might play a role in this process, but the mechanism involved is unknown. Herein, we explored the impact of acute (a)TBI on the peripheral immune system and its correlation with the SNS and the T cell exhaustion marker, PD-1 (programmed cell death-1).

METHODS

Flow cytometry (FCM) was performed to analyze the expression of T cell markers and intracellular cytokines, interferon-γ and tumor necrosis factor-α, and the T cell exhaustion marker, PD-1, in the peripheral blood mononuclear cells (PBMCs) of TBI rats. Enzyme-linked immunosorbent assay (ELISA) was performed to analyze the concentration of norepinephrine (NE) in the serum. Propranolol was administrated to block the SNS in vivo and NE stimulation was used to imitate the activation of the SNS in vitro.

RESULTS

We found that the concentration of NE was significantly elevated after TBI, and the dysfunction of CD4+ and CD8+ T cells was reversed by the SNS blocker propranolol in vivo and imitated by the SNS neurotransmitter NE in vitro. The expression of PD-1 on CD4+ and CD8+ T cells was upregulated after aTBI, which was reversed by propranolol administration in vivo and imitated by NE stimulation in vitro. Furthermore, the PD-1 blocker reversed the dysfunction of CD4+ and CD8+T cells in vitro.

CONCLUSION

Our findings demonstrated that aTBI activated the SNS, and further upregulated the expression of PD-1 on CD4+ and CD8+ T cells, which, in turn, impaired their function and contributed to immunosuppression.

Brain-Heart Interactions in Traumatic Brain Injury

The cardiovascular manifestations associated with nontraumatic head disorders are commonly known. Similar manifestations have been reported in patients with traumatic brain injury (TBI); however, the underlying mechanisms and impact on the patient's clinical outcomes are not well explored. The neurocardiac axis theory and neurogenic stunned myocardium phenomenon could partly explain the brain-heart link and interactions and can thus pave the way to a better understanding and management of TBI. Several observational retrospective studies have shown a promising role for beta-adrenergic blockers in patients with TBI in reducing the overall TBI-related mortality. However, several questions remain to be answered in clinical randomized-controlled trials, including population selection, beta blocker type, dosage, timing, and duration of therapy, while maintaining the optimal mean arterial pressure and cerebral perfusion pressure in patients with TBI.

Autonomic Nervous System Dysfunctions as a Basis for a Predictive Model of Risk of Neurological Disorders in Subjects with Prior History of Traumatic Brain Injury: Implications in Alzheimer's Disease

Autonomic dysfunction is very common in patients with dementia, and its presence might also help in differential diagnosis among dementia subtypes. Various central nervous system structures affected in Alzheimer's disease (AD) are also implicated in the central autonomic nervous system (ANS) regulation. For example, deficits in central cholinergic function in AD could likely lead to autonomic dysfunction. We recently developed a simple, readily applicable evaluation for monitoring ANS disturbances in response to traumatic brain injury (TBI). This ability to monitor TBI allows for the possible detection and targeted prevention of long-term, detrimental brain responses caused by TBI that lead to neurodegenerative diseases such as AD. We randomly selected and extracted de-identified medical record information from subjects who have been assessed using the ANS evaluation protocol. Using machine learning strategies in the analysis of information from individual as well as a combination of ANS evaluation protocol components, we identified a novel prediction model that is effective in correctly segregating between cases with or without a documented history of TBI exposure. Results from our study support the hypothesis that trauma-induced ANS dysfunctions may contribute to clinical TBI features. Because autonomic dysfunction is very common in AD patients it is possible that TBI may also contribute to AD and/or other forms of dementia through these novel mechanisms. This study provides a novel prediction model to physiologically assess the likelihood of subjects with prior history of TBI to develop clinical TBI complications, such as AD.

β-Blockade use for Traumatic Injuries and Immunomodulation: A Review of Proposed Mechanisms and Clinical Evidence

Sympathetic nervous system activation and catecholamine release are important events following injury and infection. The nature and timing of different pathophysiologic insults have significant effects on adrenergic pathways, inflammatory mediators, and the host response. Beta adrenergic receptor blockers (β-blockers) are commonly used for treatment of cardiovascular disease, and recent data suggests that the metabolic and immunomodulatory effects of β-blockers can expand their use. β-blocker therapy can reduce sympathetic activation and hypermetabolism as well as modify glucose homeostasis and cytokine expression. It is the purpose of this review to examine either the biologic basis for proposed mechanisms or to describe current available clinical evidence for the use of β-blockers in traumatic brain injury, spinal cord injury, hemorrhagic shock, acute traumatic coagulopathy, erythropoietic dysfunction, metabolic dysfunction, pulmonary dysfunction, burns, immunomodulation, and sepsis.

Beta-blockers and Traumatic Brain Injury: A Systematic Review, Meta-analysis, and Eastern Association for the Surgery of Trauma Guideline

OBJECTIVE

To determine if beta-(β)-blockers improve outcomes after acute traumatic brain injury (TBI).

BACKGROUND

There have been no new inpatient pharmacologic therapies to improve TBI outcomes in a half-century. Treatment of TBI patients with β-blockers offers a potentially beneficial approach.

METHODS

Using MEDLINE, EMBASE, and CENTRAL databases, eligible articles for our systematic review and meta-analysis (PROSPERO CRD42016048547) included adult (age ≥ 16 years) blunt trauma patients admitted with TBI. The exposure of interest was β-blocker administration initiated during the hospitalization. Outcomes were mortality, functional measures, quality of life, cardiopulmonary morbidity (e.g., hypotension, bradycardia, bronchospasm, and/or congestive heart failure). Data were analyzed using a random-effects model, and represented by pooled odds ratio (OR) with 95% confidence intervals (CI) and statistical heterogeneity (I).

RESULTS

Data were extracted from 9 included studies encompassing 2005 unique TBI patients with β-blocker treatment and 6240 unique controls. Exposure to β-blockers after TBI was associated with a reduction of in-hospital mortality (pooled OR 0.39, 95% CI: 0.27-0.56; I = 65%, P < 0.00001). None of the included studies examined functional outcome or quality of life measures, and cardiopulmonary adverse events were rarely reported. No clear evidence of reporting bias was identified.

CONCLUSIONS

In adults with acute TBI, observational studies reveal a significant mortality advantage with β-blockers; however, quality of evidence is very low. We conditionally recommend the use of in-hospital β-blockers. However, we recommend further high-quality trials to answer questions about the mechanisms of action, effectiveness on subgroups, dose-response, length of therapy, functional outcome, and quality of life after β-blocker use for TBI.

β-Blocker after severe traumatic brain injury is associated with better long-term functional outcome: a matched case control study

PURPOSE

Severe traumatic brain injury (TBI) is the predominant cause of death and disability following trauma. Several studies have observed improved survival in TBI patients exposed to β-blockers, however, the effect on functional outcome is poorly documented.

METHODS

Adult patients with severe TBI (head AIS ≥ 3) were identified from a prospectively collected TBI database over a 5-year period. Patients with neurosurgical ICU length of stay <48 h and those dying within 48 h of admission were excluded. Patients exposed to β-blockers ≤ 48 h after admission and who continued with treatment until discharge constituted β-blocked cases and were matched to non β-blocked controls using propensity score matching. The outcome of interest was Glasgow Outcome Scores (GOS), as a measure of functional outcome up to 12 months after injury. GOS ≤ 3 was considered a poor outcome. Bivariate analysis was deployed to determine differences between groups. Odds ratio and 95% CI were used to assess the effect of β-blockers on GOS.

RESULTS

362 patients met the inclusion criteria with 21% receiving β-blockers during admission. After propensity matching, 76 matched pairs were available for analysis. There were no statistical differences in any variables included in the analysis. Mean hospital length of stay was shorter in the β-blocked cases (18.0 vs. 26.8 days, p < 0.01). The risk of poor long-term functional outcome was more than doubled in non-β-blocked controls (OR 2.44, 95% CI 1.01-6.03, p = 0.03).

CONCLUSION

Exposure to β-blockers in patients with severe TBI appears to improve functional outcome. Further prospective randomized trials are warranted.

Thromboelastography After Murine TBI and Implications of Beta-Adrenergic Receptor Knockout

BACKGROUND

The source of coagulopathy in traumatic brain injury (TBI) is multifactorial and may include adrenergic stimulation. The aim of this study was to assess coagulopathy after TBI using thromboelastography (TEG), and to investigate the implications of β-adrenergic receptor knockout.

METHODS

Adult male wild type c57/bl6 (WT) and β1/β2-adrenergic receptor knockout (BKO) mice were assigned to either TBI (WT-TBI, BKO-TBI) or sham injury (WT-sham, BKO-sham). Mice assigned to TBI were subject to controlled cortical impact (CCI). At 24 h post-injury, whole blood samples were obtained and taken immediately for TEG.

RESULTS

At 24 h after injury, a trend toward increased fibrinolysis was seen in WT-TBI compared to WT-sham although this did not reach significance (EPL 8.1 vs. 0 %, p = 0.18). No differences were noted in fibrinolysis in BKO-TBI compared to BKO-sham (LY30 2.6 vs. 2.5 %, p = 0.61; EPL 3.4 vs. 2.9 %, p = 0.61). In addition BKO-TBI demonstrated increased clot strength compared to BKO-sham (MA 76.6 vs. 68.6, p = 0.03; G 18.2 vs. 11.3, p = 0.03).

CONCLUSIONS

In a mouse TBI model, WT mice sustaining TBI demonstrated a trend toward increased fibrinolysis at 24 h after injury while BKO mice did not. These findings suggest β-blockade may attenuate the coagulopathy of TBI and minimize progression of intracranial hemorrhage by reducing fibrinolysis and increasing clot strength.

[High blood pressure during the autonomic crises in children in intensive care unit: Etiologic circumstances and modality therapeutic]

The dysautonomic (DC) or neurovegetative crisis remains an imperfectly known entity; it associates in a paroxysmal manner a reaction of sympathetic hyperreactivity that can lead to the prognosis. Our objective is to specify the etiological circumstances (DC) and their modality of treatment in pediatric intensive care unit.

MATERIALS-METHODS

Descriptive study on files of children admitted in the intensive care unit of 2010-2015 who presented a DC acquired during their hospitalization.

RESULTS

In total, 41 patients included with an average age of 56.92 months presented DC. Among the etiological circumstances Guillain-Barré syndrome and head trauma are noted. Observed symptoms occur on average at one week of admission; they are related to the consequences of DC. The manifestations are polymorphic: a systolic hypertension is present in all cases with an average PAS of 141.24±13.48mmHg, an average PAD of 86.80±11.01mmHg, a vasomotor disorder, a hyperthermia are noted. Cerebral anoxia post cardiac arrest in 4 patients preceded the onset of DC. Apart from the etiologic treatment, 39 patients were intubated with mechanical ventilation, sedated with morphinomimetic and benzodiazepine±lioresal (baclofen). Treatment of hypertension resulted in the administration of a central antihypertensive. Evolution is good in addition to 5 deaths related to neurovegetative disorders.

CONCLUSION

DC is a poorly understood situation in pediatric intensive care unit, and the circumstances of the disease are variable. The diagnosis must be made with careful consideration because the prognosis may be fatal.

Dexmedetomidine attenuates acute paroxysmal sympathetic hyperactivity

We evaluated the curative effect of dexmedetomidine on paroxysmal sympathetic hyperactivity (PSH) in a retrospective study of 72 PSH patients after neurosurgery. Our results showed that dexmedetomidine was superior to propofol for treatment of PSH with respect to: average time needed to reduce paroxysmal hypertension (PH) to <140/90 mmHg (29.03±8.86 vs. 42.0±14.77 min), average remission time of PH (3.97±1.73 vs. 5.65±1.51 min), PH remission rate (61.22±10.8% vs. 41.52±14.15%), PH duration (9.31±2.66 vs. 13.05±4.19 days), average time for body temperature to return to normal (10.62±4.14 vs. 15.31±4.58 days), average time for heartrate to return to normal (11.34±3.90 vs. 15.72±4.10 days), and average time of respiratory rate below 25 breaths per minute (BPM) (7.00±1.74 vs. 15.32±5.87 days). Multiple logistic regression analyses showed that dexmedetomidine did not protect against the recurrence of PSH. Age and Glasgow Coma Score were the main factors predicting PSH recurrence. There was no difference in Glasgow Outcome Score (GOS) between the two groups during the 6 months of postoperative follow-up (p>0.05). These data suggest dexmedetomidine effectively controls an acute attack of PSH, but it does not improve the long-term prognosis of patients compared with propofol.

Evaluation of major trauma in elderly patients - a single trauma center analysis

BACKGROUND

The objective of the study was to gather information about elderly major trauma patients admitted to one particular Slovenian trauma centre in Celje and examine this group of polytrauma patients, specifically with respect to mechanisms of injury, injury severity and distribution of injuries. Further on, to identify morbidity and mortality rates and compare these to the younger population and, finally, to determine the factors that have the most impact on treatment results.

METHODS

The study gathered and evaluated data of 532 patients included in the Trauma Register DGU® of the German Trauma Society (TR-DGU) during a 10-year period and two distinct groups of patients were established, separated on account of age as older or younger than 65 years. The differences between these two groups were analyzed with respect to demographics, comorbidities, preclinical management, injury patterns, relevant clinical and laboratory findings. Furthermore, differences between deceased and surviving elderly patients were also analyzed.

RESULTS

The majority of elderly patients suffered from a blunt mechanism of trauma (96.6%) and of these simple falls represented 47.9% within this injury mechanism. There were two body regions, which were most frequently represented, namely head and thorax injuries, accounting for 54.7% each. Complications were more frequent among the elderly, with sepsis being present in 29.9% and multiple organ failure (MOF) in 19.7% of cases. Cardiovascular failure was also high in both the elderly and young, accounting for 45.3% of the elderly and 31.3% of the younger population. The in-hospital mortality rate for the elderly group was 25.6% and was significantly higher compared to the younger counterparts (14.7%). Low fall mechanism of injury, coma and the new injury severity score (NISS) were statistically important factors for the mortality of seriously injured elderly patients during the acute phase of treatment.

CONCLUSIONS

Despite advances in care, morbidity and mortality in elderly patients after major trauma remains considerably higher than in younger populations with head injuries accounting for the majority of fatalities. The elderly patient population in this study mostly suffered from blunt mechanisms of injury, with simple falls representing a high proportion of injury mechanisms. Generally, the injury severity scale (ISS) in the elderly is not statistically higher than with the younger population. Likewise, the distribution of injuries according to body regions is also similar; however, the elderly are more prone to complications (e. g. sepsis and MOF), which is likely due to a lower physiological reserves.

Attenuation of cardiovascular stress with sympatholytics does not improve survival in patients with severe isolated traumatic brain injury

BACKGROUND

Studies have shown improved survival after traumatic brain injury (TBI) with the administration of sympatholytics, including β-blockers and clonidine, which is thought to attenuate the cardiovascular stress response. However, the use of sympatholytics has not been studied in patients with isolated severe TBI (ISTBI). We hypothesized that ISTBI patients receiving sympatholytics who demonstrated a reduction in cardiovascular stress would have improved outcomes compared with similarly injured patients without these cardiovascular changes.

METHODS

We reviewed the medical records of 338 ISTBI patients (head Abbreviated Injury Scale [AIS] score > 3 and associated injury AIS score < 1) admitted to a Level I trauma center from 2010 through 2014. All patients were managed according to Brain Trauma Foundation guidelines. Demographic, clinical, and survival probability data were gathered. The primary outcome was inpatient mortality. Cardiovascular stress was assessed using the rate-pressure product (RPP = systolic blood pressure × heart rate / 100) calculated both before and after sympatholytic administration. Associations between independent variables and mortality were adjusted for total hospital length of stay.

RESULTS

Among ISTBI patients, observed mortality was 6% (n = 20), while predicted mortality by Trauma and Injury Severity Score (TRISS) was 11% (n = 38). Administration of sympatholytics was associated with reduction in RPP in univariate analysis (p = 0.035). After adjusting for length of stay, neither receipt of β-blockers nor reduction in RPP was associated with survival. Mean reduction in RPP among survivors was not different from that among nonsurvivors (-4.0% vs. -11.9%, p = 0.148). In addition, RPP reduction among patients who received sympatholytics occurred at the same rate in survivors as nonsurvivors (67% vs. 68%, p = 0.894). Severity of head injury, intraventricular hemorrhage, and any intracranial operative intervention were significantly associated with mortality.

CONCLUSION

Although sympatholytic administration is associated with a significant decrease in RPP, the survival benefit seen in patients with multiple injuries with TBI is not observed among ISTBI patients. Further research on the role of sympatholysis in the management of ISTBI is warranted.

LEVEL OF EVIDENCE

Therapeutic study, level IV.

Early propranolol after traumatic brain injury is associated with lower mortality

BACKGROUND

β-Adrenergic receptor blockers (BBs) administered after trauma blunt the cascade of immune and inflammatory changes associated with injury. BBs are associated with improved outcomes after traumatic brain injury (TBI). Propranolol may be an ideal BB because of its nonselective inhibition and ability to cross the blood-brain barrier. We determined if early administration of propranolol after TBI is associated with lower mortality.

METHODS

All adults (age ≥ 18 years) with moderate-to-severe TBI (head Abbreviated Injury Scale [AIS] score, 3-5) requiring intensive care unit (ICU) admission at a Level I trauma center from January 1, 2013, to May 31, 2015, were prospectively entered into a database. Administration of early propranolol was dosed within 24 hours of admission at 1 mg intravenous every 6 hours. Patients who received early propranolol after TBI (EPAT) were compared with those who did not (non-EPAT). Data including demographics, hospital length of stay (LOS), ICU LOS, and mortality were collected.

RESULTS

Over 29 months, 440 patients with moderate-to-severe TBI met inclusion criteria. Early propranolol was administered to 25% (109 of 440) of the patients. The EPAT cohort was younger (49.6 years vs. 60.4 years, p < 0.001), had lower Glasgow Coma Scale (GCS) score (11.7 vs. 12.4, p = 0.003), had lower head AIS score (3.6 vs. 3.9, p = 0.001), had higher admission heart rate (95.8 beats/min vs. 88.4 beats/min, p = 0.002), and required more days on the ventilator (5.9 days vs. 2.6 days, p < 0.001). Similarities were noted in sex, Injury Severity Score (ISS), admission systolic blood pressure, hospital LOS, ICU LOS, and mortality rate. Multivariate regression showed that EPAT was independently associated with lower mortality (adjusted odds ratio, 0.25; p = 0.012).

CONCLUSION

After adjusting for predictors of mortality, early administration of propranolol after TBI was associated with improved survival. Future studies are needed to identify additional benefits and optimal dosing regimens.

LEVEL OF EVIDENCE

Therapeutic study, level IV.

Impact of Beta-Blockers on Nonhead Injured Trauma Patients

Catecholamine surge after traumatic injury may lead to dysautonomia with increased morbidity. Small retrospective studies have shown potential benefit of beta-blockers (BB) in trauma patients with and without traumatic brain injury (TBI). This study evaluates a large multiply injured cohort without TBI that received BB. Patients were identified from the trauma registry from January 1, 2003 to December 31, 2011. Patients who received >1 dose of BB were compared to controls. Patients with TBI, length of stay (LOS) < 2 days, and prehospital BB were excluded. Outcomes were mortality, intensive care unit (ICU) LOS, and LOS. Stepwise multivariable regression was used to identify variables significantly associated with mortality. During the study period, 19,151 eligible patients were admitted. The mean age was 39 years. Most were male (74%) and most sustained blunt mechanism (75%). A total of 1854 (11%) patients received BB. BB patients had longer LOS (16 vs 6 days), ICU LOS (7 vs 1 days), and higher mortality (2.8 vs 0.5%) (all P < 0.001). Multivariable regression demonstrated no benefit to BB after adjusting for potential confounding characteristics [odds ratio (OR) 0.952; confidence interval (CI) 0.620–1.461]. In conclusion, in this largest study to date, patients receiving BB were older, more severely injured, and had a higher mortality. Unlike TBI patients, multivariable regression showed no benefit from BB in this population.

Optimizing sedation in patients with acute brain injury

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

Propranolol and Mesenchymal Stromal Cells Combine to Treat Traumatic Brain Injury

More than 6.5 million patients are burdened by the physical, cognitive, and psychosocial deficits associated with traumatic brain injury (TBI) in the U.S. Despite extensive efforts to develop neuroprotective therapies for this devastating disorder, there have been no successful outcomes in human clinical trials to date. Retrospective studies have shown that β-adrenergic receptor blockers, specifically propranolol, significantly decrease mortality of TBI through mechanisms not yet fully elucidated but are thought to counterbalance a hyperadrenergic state resulting from a TBI. Conversely, cellular therapies have been shown to improve long-term behavior following TBI, likely by reducing inflammation. Given the nonredundancy in their therapeutic mechanisms, we hypothesized that a combination of acute propranolol followed by mesenchymal stem cells (MSCs) isolated from human bone marrow would have additive effects in treating a rodent model of TBI. We have found that the treatments are well-tolerated individually and in combination with no adverse events. MSCs decrease BBB permeability at 96 hours after injury, inhibit a significant accumulation of activated microglia/macrophage in the thalamic region of the brain both short and long term, and enhance neurogenesis short term. Propranolol decreases edema and reduces the number of fully activated microglia at 7 days and the number of semiactivated microglia at 120 days. Combinatory treatment improved cognitive and memory functions 120 days following TBI. Therefore, the results here suggest a new, efficacious sequential treatment for TBI may be achieved using the β-blocker propranolol followed by MSC treatment.

SIGNIFICANCE

Despite continuous efforts, traumatic brain injury (TBI) remains the leading cause of death and disability worldwide in patients under the age of 44. In this study, an animal model of moderate-severe TBI was treated with an acute dose of propranolol followed by a delayed dose of human mesenchymal stem cells (MSCs), resulting in improved short- and long-term measurements. These results have direct translational application. They reinforce the inevitable clinical trial of MSCs to treat TBI by demonstrating, among other benefits, a notable decrease in chronic neuroinflammation. More importantly, these results demonstrate that MSCs and propranolol, which is increasingly being used clinically for TBI, are compatible treatments that improve overall outcome.

Chemical sympathectomy attenuates inflammation, glycocalyx shedding and coagulation disorders in rats with acute traumatic coagulopathy

Acute traumatic coagulopathy (ATC) may trigger sympathoadrenal activation associated with endothelial damage and coagulation disturbances. Overexcitation of sympathetic nerve in this state would disrupt sympathetic-vagal balance, leading to autonomic nervous system dysfunction. The aim of this study was to evaluate the autonomic function in ATC and its influence on inflammation, endothelial and coagulation activation. Male Sprague-Dawley rats were randomly assigned to sham, ATC control (ATCC) and ATC with sympathectomy by 6-hydroxydopamine (ATCS) group. Sham animals underwent the same procedure without trauma and bleeding. Following trauma and hemorrhage, rats underwent heart rate variability (HRV) test, which predicts autonomic dysfunction through the analysis of variation in individual R-R intervals. Then, rats were euthanized at baseline, and at 0, 1 and 2 h after shock and blood gas, conventional coagulation test and markers of inflammation, coagulation, fibrinolysis, endothelial damage and catecholamine were measured. HRV showed an attenuation of total power and high frequency, along with a rise of low frequency and low frequency : high frequency ratio in the ATC rats, which both were reversed by sympathectomy in the ATCS group. Additionally, sympathetic denervation significantly suppressed the increase of proinflammatory cytokines, tumor necrosis factor-α and the fibrinolysis markers including tissue-type plasminogen activator and plasmin-antiplasmin complex. Serum catecholamine, soluble thrombomodulin and syndecan-1 were also effectively inhibited by sympathectomy. These data indicated that autonomic dysfunction in ATC involves both sympathetic activation and parasympathetic inhibition. Moreover, sympathectomy yielded anti-inflammatory, antifibrinolysis and endothelial protective effects in rats with ATC. The role of autonomic neuropathy in ATC should be explored further.

Impact of age on the clinical outcomes of major trauma

PURPOSE

In view of demographic changes over the past few decades, the average age of trauma patients is progressively increasing. We therefore aimed to summarize the specific characteristics of geriatric trauma and to identify potential fields for further research to improve the care of elderly trauma patients.

METHODS

Review of the literature.

RESULTS

Due to the diverse risk factors (e.g., pre-existing conditions, limited physiological reserve), geriatric patients are prone to developing severe complications, even after less severe trauma. Yet, age is not considered as the only predictor of worse outcomes, and it should not be considered the only criterion for limiting care in those patients. It is crucial that age-specific treatment guidelines are developed to optimize the outcomes for senior trauma patients. Based on the current literature, these guidelines should emphasize the importance of field triage directly to a trauma center, along with the activation of the trauma team. Furthermore, early intensive monitoring, aggressive resuscitation, and time of surgical intervention are of upmost importance to reduce mortality.

CONCLUSION

The impact of several factors [age, premedical conditions (PMC), decreased physiological reserves, and impaired immune function] on the post-traumatic course of elderly trauma patients needs to be clarified in future experimental and clinical studies for the early identification of geriatric high-risk patients and for the development of age-adapted therapeutic strategies.

Prospective evaluation of early propranolol after traumatic brain injury

BACKGROUND

Although beta-adrenergic receptor blockade may improve outcomes after traumatic brain injury (TBI), its early use is not routine. We hypothesize that judicious early low-dose propranolol after TBI (EPAT) will improve outcomes without altering bradycardia or hypotensive events.

METHODS

We conducted a prospective, observational study on all patients who presented with moderate-to-severe TBI from March 2010-August 2013. Ten initial patients did not receive propranolol (control). Subsequent patients received propranolol at 1-mg intravenous every 6 h starting within 12 h of intensive care unit (ICU) admission (EPAT) for a minimum of 48 h. Heart rate and blood pressure were recorded hourly for the first 72 h. Bradycardia and hypotensive events, mortality, and length of stay (LOS) were compared between cohorts to determine significant differences.

RESULTS

Thirty-eight patients were enrolled; 10 control and 28 EPAT. The two cohorts were similar when compared by gender, emergency department (ED) systolic blood pressure, ED heart rate, and mortality. ED Glasgow coma scale was lower (4.2 versus 10.7, P < 0.01) and injury severity score higher in control. EPAT patients received a mean of 10 ± 14 doses of propranolol. Hypotensive events were similar between cohorts, whereas bradycardia events were higher in control (5.8 versus 1.6, P = 0.05). ICU LOS (15.4 versus 30.4 d, P = 0.02) and hospital LOS (10 versus 19.1 d, P = 0.05) were lower in EPAT. Mortality rates were similar between groups (10% versus 10.7%, P = 0.9). The administration of propranolol led to no recorded complications.

CONCLUSIONS

Although bradycardia and hypotensive events occur early after TBI, low-dose intravenous propranolol does not increase their number or severity. Early use of propranolol after TBI appears to be safe and may be associated with decreased ICU and hospital LOS.

Early diagnosis of paroxysmal sympathetic hyperactivity in the ICU

BACKGROUND

Paroxysmal sympathetic hyperactivity (PSH) is a complication of acquired brain injury manifesting with episodic tachycardia, tachypnea, hypertension, diaphoresis, hypertonia, and posturing. No universally accepted diagnostic criteria exist and diagnosis is often delayed until the rehabilitation phase.

METHODS

Electronic records were screened to identify consecutive cases of PSH diagnosed in an intensive care unit (ICU) between 1/2006 and 8/2012 and assess the validity of early clinical diagnosis against formal diagnostic criteria. Data collected included patient demographics, brain injury etiology, symptoms noted by the clinician to support the diagnosis of PSH, PSH manifestations, therapeutic interventions, relevant brain imaging, and investigations to exclude alternative diagnoses. An operational set of diagnostic criteria based on previous literature was used for comparison.

RESULTS

Fifty-three consecutive patients with PSH were identified. Mean age was 33.6 ± 14.5 years (range 16-67). Traumatic brain injury was the most common etiology (30 patients, 56.6 %) but causes were diverse. Mean time to diagnosis was 8.3 ± 11.0 days; 31 patients (59 %) were diagnosed within 7 days and 20 patients (38 %) within 3 days of admission. Tachycardia was almost uniformly present, and diaphoresis, fever, hypertension, and tachypnea were also present in most cases. Dystonia and posturing were present in less than half of patients. 89 % of clinically diagnosed cases met formal diagnostic criteria.

CONCLUSIONS

Paroxysmal sympathetic hyperactivity can be diagnosed early in the ICU. Strict diagnostic criteria supported the clinician's diagnosis in the majority of cases. Diagnosis should not be rejected because of any particular sign's absence, especially dystonia and posturing.

Perioperative implications of the patient with autonomic dysfunction

PURPOSE OF REVIEW

The autonomic nervous system functions to control heart rate, blood pressure, respiratory rate, gastrointestinal motility, hormone release, and body temperature on a second-to-second basis. Here we summarize some of the latest literature on autonomic dysfunction, focusing primarily on the perioperative implications.

RECENT FINDINGS

The variety of autonomic dysfunction now extends to a large number of clinical conditions in which the cause or effect of the autonomic component is blurred. Methods for detecting dysautonomia can be as simple as performing a history and physical examination that includes orthostatic vital signs measured in both recumbent and vertical positions; however, specialized laboratories are required for definitive diagnosis. Heart rate variability monitoring is becoming more commonplace in the assessment and understanding of autonomic instability. Degenerative diseases of the autonomic nervous system include Parkinson's disease and multiple system atrophy, with the most serious manifestations being postural hypotension and paradoxical supine hypertension. Other conditions occur in which the autonomic dysfunction is only part of a larger disease process, such as diabetic autonomic neuropathy, traumatic brain injury, and spinal cord injury.

SUMMARY

Patients with dysautonomia often have unpredictable and paradoxical physiological responses to various perioperative stimuli. Knowledge of the underlying pathophysiology of their condition is required in order to reduce symptom exacerbation and limit morbidity and mortality during the perioperative period.

Catecholamines, steroids and immune alterations in ischemic stroke and other acute diseases

The outcome of stroke patients is not only determined by the extent and localization of the ischemic lesion, but also by stroke-associated infections. Stroke-induced immune alterations, which are related to stroke-associated infections, have been described over the last decade. Here we review the evidence that catecholamines and steroids induced by stroke result in stroke-induced immune alterations. In addition, we compare the immune alterations observed in other acute diseases such as myocardial infarction, brain trauma, and surgical trauma with the changes seen in stroke-induced immune alterations.

Decreasing adrenergic or sympathetic hyperactivity after severe traumatic brain injury using propranolol and clonidine (DASH After TBI Study): study protocol for a randomized controlled trial

Background

Severe TBI, defined as a Glasgow Coma Scale ≤ 8, increases intracranial pressure and activates the sympathetic nervous system. Sympathetic hyperactivity after TBI manifests as catecholamine excess, hypertension, abnormal heart rate variability, and agitation, and is associated with poor neuropsychological outcome. Propranolol and clonidine are centrally acting drugs that may decrease sympathetic outflow, brain edema, and agitation. However, there is no prospective randomized evidence available demonstrating the feasibility, outcome benefits, and safety for adrenergic blockade after TBI.

Methods/Design

The DASH after TBI study is an actively accruing, single-center, randomized, double-blinded, placebo-controlled, two-arm trial, where one group receives centrally acting sympatholytic drugs, propranolol (1 mg intravenously every 6 h for 7 days) and clonidine (0.1 mg per tube every 12 h for 7 days), and the other group, double placebo, within 48 h of severe TBI. The study uses a weighted adaptive minimization randomization with categories of age and Marshall head CT classification. Feasibility will be assessed by ability to provide a neuroradiology read for randomization, by treatment contamination, and by treatment compliance. The primary endpoint is reduction in plasma norepinephrine level as measured on day 8. Secondary endpoints include comprehensive plasma and urine catecholamine levels, heart rate variability, arrhythmia occurrence, infections, agitation measures using the Richmond Agitation-Sedation Scale and Agitated Behavior scale, medication use (anti-hypertensive, sedative, analgesic, and antipsychotic), coma-free days, ventilator-free days, length of stay, and mortality. Neuropsychological outcomes will be measured at hospital discharge and at 3 and 12 months. The domains tested will include global executive function, memory, processing speed, visual-spatial, and behavior. Other assessments include the Extended Glasgow Outcome Scale and Quality of Life after Brain Injury scale. Safety parameters evaluated will include cardiac complications.

Discussion

The DASH After TBI Study is the first randomized, double-blinded, placebo-controlled trial powered to determine feasibility and investigate safety and outcomes associated with adrenergic blockade in patients with severe TBI. If the study results in positive trends, this could provide pilot evidence for a larger multicenter randomized clinical trial. If there is no effect of therapy, this trial would still provide a robust prospective description of sympathetic hyperactivity after TBI.

Trial registration

ClinicalTrials.gov NCT01322048

β-adrenergic receptor inhibition affects cerebral glucose metabolism, motor performance, and inflammatory response after traumatic brain injury

BACKGROUND

The purpose of this study was to evaluate how β-adrenergic receptor inhibition after traumatic brain injury (TBI) alters changes in early cerebral glucose metabolism and motor performance, as well as cerebral cytokine and heat shock protein (HSP) expression.

METHODS

Mouse cerebral glucose metabolism was measured by microPET fluorodeoxyglucose uptake and converted into standardized uptake values (SUV). Four groups of C57/Bl6 mice (wild type [WT]) were initially evaluated: sham or TBI, followed by tail vein injection of either saline or a nonselective β-adrenergic receptor inhibitor (propranolol, 4 mg/kg). Then motor performance, cerebral cytokine, and HSP70 expression were studied at 12 hours and 24 hours after sham injury or TBI in WT mice treated with saline or propranolol and in β1-adrenergic/β2-adrenergic receptor knockout (BARKO) mice treated with saline.

RESULTS

Cerebral glucose metabolism was significantly reduced after TBI (mean SUV TBI, 1.63 vs. sham 1.97, p < 0.01) and propranolol attenuated this reduction (mean SUV propranolol, 1.89 vs. saline 1.63, p < 0.01). Both propranolol and BARKO reduced motor deficits at 24 hours after injury, but only BARKO had an effect at 12 hours after injury. TBI WT mice treated with saline performed worse than propranolol mice at 24 hours after injury on rotarod (23 vs. 44 seconds, p < 0.01) and rearing (130 vs. 338 events, p = 0.01) results. At 24 hours after injury, sham BARKO and TBI BARKO mice were similar on rotarod (21 vs. 19 seconds, p = 0.53), ambulatory testing (2,891 vs. 2,274 events, p = 0.14), and rearing (129 vs. 64 events, p = 0.09) results. Interleukin 1β expression was affected by BARKO and propranolol after TBI; attenuation of interleukin 6 and increased HSP70 expression were noted only with BARKO.

CONCLUSION

β-adrenergic receptor inhibition affects cerebral glucose metabolism, motor performance, as well as cerebral cytokine and HSP expression after TBI.

[Cardiac complications of acute brain injury]

The clinical importance of cardiovascular consequences resulting from cerebral injury has long been recognized. However, interactions between the brain and the cardiovascular system remain poorly defined and their importance for the management of patients suffering from acute brain injury is largely underestimated. This should have profound consequences on treatment strategies during anaesthesia and intensive cares of these patients, taking into account not only brain perfusion, but also cardiovascular optimisation. This report summarizes the main data available regarding the cardiovascular consequences of brain death, traumatic brain injury, stroke and epilepsy.

Elevated systolic blood pressure after trauma: tolerated in the elderly

BACKGROUND

We undertook the current study to determine the impact of elevated admission systolic blood pressure (SBP) on trauma patients without severe brain injury.

MATERIALS AND METHODS

We conducted a retrospective review of the Los Angeles County Trauma System database to identify all patients with moderate to severe injuries (injury severity score >9) admitted between 2003 and 2008. Patients with head abbreviated injury score >3 were excluded. We divided the remaining patients into three age cohorts and conducted multivariate regression modeling at increasing SBP thresholds to identify independent predictors of mortality.

RESULTS

A total of 23,931 patients met inclusion criteria. Overall mortality was 8.6% and it increased with age across the three groups. The admission SBP thresholds associated with significantly increased mortality in the young and middle-aged were >190 mm Hg (AOR 1.5, P = 0.04) and >180 mm Hg (AOR 1.5, P = 0.01), respectively. In the elderly, no admission SBP threshold was associated with significantly increased mortality. Interestingly, several elevated admission SBP thresholds were associated with significantly reduced mortality in the elderly (>150 mm Hg AOR 0.6, P < 0.01; >160 mm Hg AOR 0.6, P < 0.01; and >170 mm Hg AOR 0.7, P = 0.02).

CONCLUSIONS

The admission SBP thresholds that predicted higher mortality for the young and middle-aged were >190 mm Hg and >180 mm Hg, respectively. Elderly trauma patients tolerated higher admission SBP than their younger counterparts and multiple elevated SBP thresholds were associated with significantly reduced mortality in the elderly.

Efficacy of beta-blockade after isolated blunt head injury: does race matter?

BACKGROUND

Several retrospective clinical studies and recent prospective animal models demonstrate improved outcomes with beta-blocker administration after isolated blunt head injury. However, no investigations to date have examined the influence of race on the potential therapeutic effectiveness of these medications. Our hypothesis was that mortality benefits associated with beta-blocker exposure after isolated blunt head injury varies based on ethnicity.

METHODS

The trauma registry and the surgical intensive care unit (ICU) databases of an academic Level I trauma center were used to identify all patients sustaining blunt head injury requiring ICU admission from July 1998 to December 2009. Patients sustaining major associated extracranial injuries (Abbreviated Injury Scale [AIS] score ≥ 3 in any body region) were excluded. Patient demographics, injury profile, Injury Severity Score, and beta-blocker exposure were abstracted. The primary outcome evaluated was in-hospital mortality stratified by ethnicity.

RESULTS

During the 11-year study period, 3,750 patients were admitted to the Los Angeles County + University of Southern California Medical Center trauma ICU because of blunt trauma. Of these, 65% (n = 2,446) had an "isolated" head injury. When stratified by race, most patients were Hispanics (60%), followed by Whites (21%), Asians (11%), and African Americans (8%). After adjusting for confounding variables with multivariate regression, only those of Asian and Hispanic descent demonstrated significantly improved outcomes associated with beta-blocker administration.

CONCLUSIONS

Our results indicate that beta-blockade after traumatic brain injury may not benefit all races equally. Further prospective research is necessary to assess this discrepancy in treatment benefit and explore other possible therapeutic interventions.

Gender influences outcomes in trauma patients with elevated systolic blood pressure

BACKGROUND

This analysis explored the association between gender and systolic blood pressure (SBP) in trauma patients and then established how gender influenced outcomes in those with elevated SBP.

METHODS

Demographics and outcomes were compared using the Los Angeles County Trauma System Database and multivariable modeling determined predictors for SBP, pneumonia, and mortality.

RESULTS

Age and male sex were significant predictors for increased SBP, whereas the Injury Severity Score (ISS) ≥16 was a significant predictor for decreased SBP. In both male and female TBI patients, SBP ≥160 mmHg was associated with increased pneumonia (Adjusted odds ratio [AOR] = 1.74, P = .002 and AOR = 2.37, P = .046, respectively), whereas SBP ≥160 mmHg was a predictor for mortality only among male TBI patients (AOR = 1.48, P = .03). In non-TBI patients, SBP ≥160 mmHg was not a predictor for pneumonia or mortality in either sex.

CONCLUSIONS

In this retrospective review of trauma registry data, men presented with higher SBP. In patients with TBI, regardless of gender, increased SBP was associated with increased pneumonia, and in men with TBI increased SBP was associated with increased mortality. The cause and relevance of these epidemiological findings require further investigation.