Impact of acute lung injury and acute respiratory distress syndrome after traumatic brain injury in the United States

Ischaemic stroke in mice induces lung inflammation but not acute lung injury

Stroke is a major cause of death worldwide and ischemic stroke is the most common subtype accounting for approximately 80% of all cases. Pulmonary complications occur in the first few days to weeks following ischemic stroke and are a major contributor to morbidity and mortality. Acute lung injury (ALI) occurs in up to 30% of patients with subarachnoid haemorrhage but the incidence of ALI after ischemic stroke is unclear. As ischemic stroke is the most common subtype of stroke, it is important to understand the development of ALI following the initial ischemic injury to the brain. Therefore, this study investigated whether focal ischemic stroke causes lung inflammation and ALI in mice. Ischemic stroke caused a significant increase in bronchoalveolar lavage fluid (BALF) macrophages and neutrophils and whole lung tissue proinflammatory IL-1β mRNA expression but this did not translate into histologically evident ALI. Thus, it appears that lung inflammation, but not ALI, occurs after experimental ischemic stroke in mice. This has significant implications for organ donors as the lungs from patient's dying of ischemic stroke are not severely damaged and could thus be used for transplantation in people awaiting this life-saving therapy.

Inhibition of Cerebral High-Mobility Group Box 1 Protein Attenuates Multiple Organ Damage and Improves T Cell-Mediated Immunity in Septic Rats

Sepsis remains one of the leading causes of mortality in intensive care units, but there is a shortage of effective treatments. A dysregulated host immune response and multiple organ injury are major factors for the pathogenesis and progression of sepsis, which require specific mechanism and treatment. In the present study, we performed an intracerebroventricular (ICV) injection of BoxA, a specific antagonist of high-mobility group box 1 protein (HMGB1), in septic rats that were produced by cecal ligation and puncture surgery; we further assessed the functional changes of multiple organs and splenic T lymphocytes. We found that the inhibition of cerebral HMGB1 significantly alleviated multiple organ damage under septic exposure, including damage to the heart, liver, lungs, and kidneys; reversed the immune dysfunction of T cells; and increased the survival of septic rats. These data suggest that central HMGB1 might be a potential therapeutic target for septic challenge and that inhibition of brain HMGB1 can protect against multiple organ dysfunction induced by sepsis.

Combined lung and brain ultrasonography for an individualized "brain-protective ventilation strategy" in neurocritical care patients with challenging ventilation needs

When intracranial hypertension and severe lung damage coexist in the same clinical scenario, their management poses a difficult challenge, especially as concerns mechanical ventilation management. The needs of combined lung and brain protection from secondary damage may conflict, as ventilation strategies commonly used in patients with ARDS are potentially associated with an increased risk of intracranial hypertension. In particular, the use of positive end-expiratory pressure, recruitment maneuvers, prone positioning, and protective lung ventilation can have undesirable effects on cerebral physiology: they may positively or negatively affect intracranial pressure, based on the final repercussions on PaO₂ and cerebral perfusion pressure (through changes in cardiac output, mean arterial pressure, venous return, PaO₂ and PaCO₂), also according to the baseline conditions of cerebral autoregulation. Lung ultrasound (LUS) and brain ultrasound (BUS, as a combination of optic nerve sheath diameter assessment and cerebrovascular Doppler ultrasound) have independently proven their potential in respectively monitoring lung aeration and brain physiology at the bedside. In this narrative review, we describe how the combined use of LUS and BUS on neurocritical patients with demanding mechanical ventilation needs can contribute to ventilation management, with the aim of a tailored "brain-protective ventilation strategy."

TBI Rehabilomics Research: Conceptualizing a humoral triad for designing effective rehabilitation interventions

Most areas of medicine use biomarkers in some capacity to aid in understanding how personal biology informs clinical care. This article draws upon the Rehabilomics research model as a translational framework for programs of precision rehabilitation and intervention research focused on linking personal biology to treatment response using biopsychosocial constructs that broadly represent function and that can be applied to many clinical populations with disability. The summary applies the Rehabilomics research framework to the population with traumatic brain injury (TBI) and emphasizes a broad vision for biomarker inclusion, beyond typical brain-derived biomarkers, to capture and/or reflect important neurological and non-neurological pathology associated with TBI as a chronic condition. Humoral signaling molecules are explored as important signaling and regulatory drivers of these chronic conditions and their impact on function. Importantly, secondary injury cascades involved in the humoral triad are influenced by the systemic response to TBI and the development of non-neurological organ dysfunction (NNOD). Biomarkers have been successfully leveraged in other medical fields to inform pre-randomization patient selection for clinical trials, however, this practice largely has not been utilized in TBI research. As such, the applicability of the Rehabilomics research model to contemporary clinical trials and comparative effectiveness research designs for neurological and rehabilitation populations is emphasized. Potential points of intervention to modify inflammation, hormonal, or neurotrophic support through rehabilitation interventions are discussed. This article is part of the Special Issue entitled "Novel Treatments for Traumatic Brain Injury".

Adult Firearm-Related Traumatic Brain Injury in United States Trauma Centers

Civilian firearm injury is an important public health concern in the United States. Gunshot wounds to the head (GSWH) remain in need of update and systematic characterization. We identify predictors of prolonged hospital length of stay (HLOS), intensive care unit length of stay (ICU LOS), medical complications, mortality, and discharge disposition from a population-based sample using the National Sample Program (NSP) of the National Trauma Data Bank (NTDB), years 2003-2012. Statistical significance was assessed at α < 0.001 to correct for multiple comparisons. In total, 8148 adult GSWH patients were included extrapolating to 32,439 national incidents. Age was 36.6 ± 16.4 years and 64.4% were severe traumatic brain injury (TBI; Glasgow Coma Scale [GCS] score 3-8). Assault (49.2%), handgun (50.3%), and residential injury (43.2%) were of highest incidence. HLOS and ICU LOS were 7.7 ± 14.2 and 5.7 ± 13.4 days, respectively. Overall mortality was 54.6%; suicide/self-injury was associated with the highest mortality rate (71.6%). GCS, Injury Severity Score, and hypotension were significant predictors for outcomes overall. Medicare/Medicaid patients had longer HLOS compared to private/commercial insured (mean increase, 4.4 days; 95% confidence interval [2.6-6.3]). Compared to the Midwest, the South had longer HLOS (mean increase, 3.7 days; [2.0-5.4]) and higher odds of complications (odds ratio [OR], 1.7 [1.4-2.0]); the West had lower odds of complications (OR, 0.6; [0.5-0.7]). Versus handgun, shotgun (OR, 0.3; [0.2-0.4]) and hunting rifle (OR, 0.5; [0.4-0.8]) resulted in lower mortality. Patients with government/other insurance had higher odds of discharging home compared to private/commercially insured (OR, 1.7; [1.3-2.3]). In comparison to level I trauma centers, level II trauma centers had lower odds of discharge to home (OR, 0.7; [0.5-0.8]). Our results support hypotension, injury severity, injury intent, firearm type, and U.S. geographical location as important prognostic variables in firearm-related TBI. Improved understanding of civilian GSWH is critical to promoting increased awareness of firearm injuries as a public health concern and reducing its debilitating injury burden to patients, families, and healthcare systems.

Dexmedetomidine Protects Against Traumatic Brain Injury-Induced Acute Lung Injury in Mice

Background

Traumatic brain injury (TBI) leads to acute lung injury (ALI), in which the inflammatory response plays an important role in its pathophysiology. Recent studies suggest that dexmedetomidine (Dex) plays a protective role in acute inflammatory diseases. However, whether Dex has a protective effect on TBI-induced ALI is not clear. The aim of this study was to investigate the effect of Dex on TBI-induced ALI in mice.

Material/Methods

Mice were randomly divided into 5 groups: 1) sham group; 2) TBI group; 3) TBI+Dex group; 4) TBI+atipamezole (Atip) group; and 5) TBI+Dex+Atip group. Dex (50 μg/kg) was intraperitoneal injected immediately after TBI. The α₂ adrenergic antagonist Atip (250 μg/kg) was intraperitoneal injected 15 minutes prior to Dex treatment. Then 24 hours later, the protein concentration in the bronchoalveolar lavage fluid (BALF), lung wet to dry weight ratio, hematoxylin and eosin (H&E) staining of lungs, the level of high-mobility group box protein 1(HMGB1) in serum, and the receptor for advanced glycation end products (RAGE) expression in lung were detected.

Results

Dex ameliorated the score of lung histological examination, as well as the severity of pulmonary edema and permeability. Moreover, Dex was observed to significantly suppress the expression of HMGBI and RAGE. However, the protective effects of Dex were partially reversed by the administration of Atip.

Conclusions

Dex may protect against TBI-induced ALI via the HMGB1-RAGE signal pathway, and this protective effect is partly dependent on its α₂ adrenoceptor agonist action.

National incidence rates for Acute Respiratory Distress Syndrome (ARDS) and ARDS cause-specific factors in the United States (2006-2014)

PURPOSE

To estimate the incidence of Acute Respiratory Distress Syndrome (ARDS) and ARDS-related mortality rates.

METHODS

We identified patients with a risk factor for ARDS in the National Inpatient Sample (NIS) (2006-2014). Using survey-weighted descriptive statistics we estimated annual and overall proportions of ARDS cases.

RESULTS

From over 69 million discharges, 1,151,969 ARDS discharges and 969,567 ARDS discharges with a risk factor were identified. Sepsis (46.8%), pneumonia (44.9%) and shock (44.4%) were the most common ARDS risk factor. Pancreatitis (3.4%), pulmonary contusion (1.4%) and drowning (0.2%) were the least frequently reported. Incidence rates increased from 180.7 (2006) to 220.8 (2011) and again from 182.8 (2012) to 193.4 (2014). Incidence for pneumonia, shock and sepsis-associated ARDS increased steadily, while transfusion and trauma-associated ARDS declined. Trends for gastric aspiration and pancreatitis-related ARDS remained unchanged. Shock, sepsis and transfusion-associated ARDS had higher mortality rates compared to other factors. Except for transfusion and trauma-associated ARDS, mortality rates for other factors declined.

CONCLUSION

Although increasing incidence for ARDS was observed, mortality rates declined for most risk factors. Mortality for transfusion and trauma-associated ARDS increased in the later study period, research is needed to examine reasons for the increasing in-hospital deaths associated with these risk factors.

Elevated plasma levels of TIMP-3 are associated with a higher risk of acute respiratory distress syndrome and death following severe isolated traumatic brain injury

Background:

Complications after injury, such as acute respiratory distress syndrome (ARDS), are common after traumatic brain injury (TBI) and associated with poor clinical outcomes. The mechanisms driving non-neurologic organ dysfunction after TBI are not well understood. Tissue inhibitor of matrix metalloproteinase-3 (TIMP-3) is a regulator of matrix metalloproteinase activity, inflammation, and vascular permeability, and hence has plausibility as a biomarker for the systemic response to TBI.

Methods:

In a retrospective study of 182 patients with severe isolated TBI, we measured TIMP-3 in plasma obtained on emergency department arrival. We used non-parametric tests and logistic regression analyses to test the association of TIMP-3 with the incidence of ARDS within 8 days of admission and in-hospital mortality.

Results:

TIMP-3 was significantly higher among subjects who developed ARDS compared with those who did not (median 2810 pg/mL vs. 2260 pg/mL, p=0.008), and significantly higher among subjects who died than among those who survived to discharge (median 2960 pg/mL vs. 2080 pg/mL, p<0.001). In an unadjusted logistic regression model, for each SD increase in plasma TIMP-3, the odds of ARDS increased significantly, OR 1.5 (95% CI 1.1 to 2.1). This association was only attenuated in multivariate models, OR 1.4 (95% CI 1.0 to 2.0). In an unadjusted logistic regression model, for each SD increase in plasma TIMP-3, the odds of death increased significantly, OR 1.7 (95% CI 1.2 to 2.3). The magnitude of this association was greater in a multivariate model adjusted for markers of injury severity, OR 1.9 (95% CI 1.2 to 2.8).

Discussion:

TIMP-3 may play an important role in the biology of the systemic response to brain injury in humans. Along with clinical and demographic data, early measurements of plasma biomarkers such as TIMP-3 may help identify patients at higher risk of ARDS and death after severe isolated TBI.

Level of evidence

III.

Traumatic Brain Injury-Induced Acute Lung Injury: Evidence for Activation and Inhibition of a Neural-Respiratory-Inflammasome Axis

Approximately 20-25% of traumatic brain injury (TBI) subjects develop acute lung injury (ALI), but the pathomechanisms of TBI-induced ALI remain poorly defined. Our previous work has shown that the inflammasome plays a critical role in TBI-induced secondary pathophysiology and that inflammasome proteins are released in extracellular vesicles (EV) after TBI. Here we investigated whether EV-mediated inflammasome signaling contributed to the etiology of TBI-induced ALI. C57/BL6 male mice were subjected to controlled cortical impact (CCI), and the brains and lungs were examined for inflammasome activation and ALI at 4 and 24 h after TBI. We show that TBI releases EV containing inflammasome proteins into serum that target the lung to cause ALI, supporting activation of a neural-respiratory-inflammasome axis. Administration of a low-molecular-weight heparin (enoxaparin, a blocker of EV uptake) or treatment with a monoclonal antibody against apoptosis speck-like staining protein containing a caspase recruitment domain (anti-ASC) after adoptive transfer of EV isolated from TBI-injured mice significantly inhibited inflammasome activation in the lungs of recipient mice resulting in improved ALI scores.This axis constitutes an important arm of the innate inflammatory response in lung pathology after TBI and targeting this axis represents a novel therapeutic treatment for TBI-induced ALI.

Effect of Cerebral Perfusion Pressure on Acute Respiratory Distress Syndrome

BACKGROUND

Increased cerebral perfusion pressure (CPP)>70 mmHg has been associated with acute respiratory distress syndrome (ARDS) after traumatic brain injury (TBI). Since this reported association, significant changes in ventilation strategies and fluid management have been accepted as routine critical care. Recently, individualized perfusion targets using autoregulation monitoring suggest CPP titration>70 mmHg. Given these clinical advances, the association between ARDS and increased CPP requires further delineation.

OBJECTIVE

To determine the association between ARDS and increased CPP after TBI.

METHODS

We conducted a single-center historical cohort study investigating the association of increased CPP and ARDS after TBI. We collected demographic data and physiologic data for CPP, intracranial pressure, mechanical ventilation, cumulative fluid balance and delta/driving pressure (ΔP). We collected outcomes measures pertaining to duration of ventilation, intensive care unit admission length, hospitalization length and 6-month neurological outcome.

RESULTS

In total, 113 patients with severe TBI and multimodal neuromonitoring were included. In total, 16 patients (14%) developed ARDS according to the Berlin definition. There was no difference in the mean CPP during the first 7 days of admission between patients who developed ARDS (74 mmHg SD 18 vs. 73 mmHg SD 18, p=0.86) versus those who did not. Patients who developed ARDS had a higher ΔP (15 mmHg [5] vs. 12 mmHg [4], p=0.016) and lower lung compliance (35 ml/cmH2O [10] vs. 49 ml/cmH2O [18], p=0.024) versus those who did not.

CONCLUSION

We did not observe an association between increased CPP and ARDS. Patients with ARDS had higher ΔP and lower lung compliance.

Valproic acid attenuates the risk of acute respiratory failure in patients with subarachnoid hemorrhage

BACKGROUND

Valproic acid (VPA) has shown potent anti-inflammatory effect and attenuates acute lung injury.

AIM

To determine whether the use of VPA is associated with a decreased risk of acute respiratory failure (ARF) in patients with subarachnoid hemorrhage (SAH).

DESIGN

The Taiwan National Health Insurance Research Database was used to analyse all patients newly diagnosed with SAH from 2000 to 2010. The VPA users were matched for age, gender and index date in 1:2 ratios with randomly selected non-VPA users as a comparison group.

METHODS

Multivariate Cox regression was used to identify the predictors of ARF and to compare the incidence rates of ARF among SAH patients using and not using VPA.

RESULTS

The study cohort included 16 228 newly diagnosed SAH patients, from which 521 VPA users and 1042 matched non-VPA-exposed individuals were selected. In the VPA-treated cohort and the non-VPA-treated cohort, 117 and 289 patients developed ARF, respectively. Any use of VPA was associated with a 16% decreased risk of ARF requiring mechanical ventilation in 30-day tracking of the SAH patients (adjusted hazard ratio [HR], 0.840, 95% confidence interval [CI], 0.676-0.945). Age, sepsis and pneumonia were identified as independent predictors of ARF in patients with SAH. After stratification, VPA users showed a lower risk of ARF among SAH patients complicated with pneumonia compared with non-users of VPA (adjusted HR, 0.816, 95% CI, 0.652-0.921).

CONCLUSIONS

Any use of VPA was associated with a reduced risk of ARF in patients with SAH. VPA may be beneficial for decreasing the risk of pneumonia-induced ARF in patients with SAH.

Blood Glutamate Levels Are Closely Related to Acute Lung Injury and Prognosis after Stroke

Background

Acute lung injury (ALI) is a serious complication of stroke that occurs with a high incidence. Our preclinical results indicated that ALI might be related to blood glutamate levels after brain injury. The purpose of this study was to assess dynamic changes in blood glutamate levels in patients with stroke and to determine the correlation between blood glutamate levels, ALI, and long-term prognosis after stroke.

Methods

Venous blood samples were collected from controls and patients with stroke at admission and on the third and seventh day after the onset of stroke. Patients were followed for 3 months. The correlations among blood glutamate levels, severities of stroke and ALI, and long-term outcomes were analyzed, and the predictive values of blood glutamate levels and severity scores for ALI were assessed.

Results

In this study, a total of 384 patients with stroke were enrolled, with a median age of 59 years. Patients showed significantly increased blood glutamate levels within 7 days of stroke onset (p < 0.05), and patients with more severe injuries showed higher blood glutamate levels. Moreover, blood glutamate levels were closely related to the occurrence (adjusted odds ratio, 3.022, p = 0.003) and severity (p < 0.001) of ALI and the long-term prognosis after stroke (p < 0.05), and they were a more accurate predictor of ALI than the more commonly used severity scores (p < 0.01).

Conclusion

These results indicated that an increased blood glutamate level was closely related to the development of ALI and a poor prognosis after stroke.

Clinical Trial Registration

http://www.chictr.org.cn, identifier ChiCTR-RPC-15006770.

Protective effect of hydrogen-saturated saline on acute lung injury induced by oleic acid in rats

Background

The purpose of the study is to investigate the role and mechanisms of hydrogen-saturated saline (HSS) in the acute lung injury (ALI) induced by oleic acid (OA) in rats.

Methods

Rats were treated with OA (0.1 mL/kg) to induce ALI and then administered with HSS (5 mL/kg) by intravenous (iv) and intraperitoneal (ip) injection, respectively. Three hours after the injection with OA, the arterial oxygen partial pressure (PaO₂), arterial oxygen saturation (SaO₂), carbon dioxide partial pressure (PaCO₂), and bicarbonate (HCO₃⁻) levels were analyzed using blood gas analyzer. In addition, the levels of malondialdehyde (MDA), tumor necrosis factor-α (TNF-α), and interleukin 1β (IL-1β) and myeloperoxidase (MPO) activity were measured by commercial kits, and pathological changes of lung tissue were examined by HE staining. Finally, the correlations of MPO activity or MDA level with the levels of TNF-α or IL-1β were analyzed by Pearson’s correlation analysis.

Results

We found decreased PaO₂ levels and the pathological changes of lung tissue of ALI after OA injection. In addition, OA increased the levels of MDA, TNF-α, and IL-1β, as well as MPO activity in lung tissues (P < 0.05). However, after treatment with HSS, all of these changes were alleviated (P < 0.05), and these changes were mitigated when treated with HSS by ip then iv injection (P < 0.05). Furthermore, MDA level and MPO activity were positively correlated with TNF-α and IL-1β levels in the lung tissue, respectively (P < 0.01).

Conclusion

HSS attenuated ALI induced by OA in rats and might protect against ALI through selective resistance to oxidation and inhibiting inflammatory infiltration.

Association between chronic exposure to air pollution and mortality in the acute respiratory distress syndrome

The impact of chronic exposure to air pollution and outcomes in the acute respiratory distress syndrome (ARDS) is unknown. The Nationwide Inpatient Sample (NIS) from 2011 was utilized for this analysis. The NIS is a national database that captures 20% of all US in-patient hospitalizations from 47 states. Patients with ARDS who underwent mechanical ventilation from the highest 15 ozone pollution cities were compared with the rest of the country. Secondary analyses assessed outcomes of ARDS patients for ozone pollution and particulate matter pollution on a continuous scale by county of residence. A total of 8,023,590 hospital admissions from the 2011 NIS sample were analyzed. There were 93,950 patients who underwent mechanical ventilation for ARDS included in the study. Patients treated in high ozone regions had significantly higher unadjusted hospital mortality (34.9% versus 30.8%, p < 0.01) than patients in cities with control levels of ozone. After controlling for all variables in the model, treatment in a hospital located in a high ozone pollution area was associated with an increased odds of in-hospital mortality (OR 1.11, 95% CI 1.08-1.15, p < 0.01). After adjustment for all variables in the model, for each increase in ozone exposure by 0.01 ppm the OR for death was 1.07 (95% CI 1.06-1.08, p < 0.01). Similarly, for each increase in particulate matter exposure by 10 μg/m³, the OR for death was 1.08 (95% CI 1.02-1.16, p < 0.01). Chronic exposure to both ozone and particulate matter pollution is associated with higher rates of mortality in ARDS. These preliminary findings need to be confirmed by further detailed studies.

The Effect of Positive End-Expiratory Pressure on Intracranial Pressure and Cerebral Hemodynamics

BACKGROUND

Lung protective ventilation has not been evaluated in patients with brain injury. It is unclear whether applying positive end-expiratory pressure (PEEP) adversely affects intracranial pressure (ICP) and cerebral perfusion pressure (CPP). We aimed to evaluate the effect of PEEP on ICP and CPP in a large population of patients with acute brain injury and varying categories of acute lung injury, defined by PaO2/FiO2.

METHOD

Retrospective data were collected from 341 patients with severe acute brain injury admitted to the ICU between 2008 and 2015. These patients experienced a total of 28,644 paired PEEP and ICP observations. Demographic, hemodynamic, physiologic, and ventilator data at the time of the paired PEEP and ICP observations were recorded.

RESULTS

In the adjusted analysis, a statistically significant relationship between PEEP and ICP and PEEP and CPP was found only among observations occurring during periods of severe lung injury. For every centimeter H2O increase in PEEP, there was a 0.31 mmHg increase in ICP (p = 0.04; 95 % CI [0.07, 0.54]) and a 0.85 mmHg decrease in CPP (p = 0.02; 95 % CI [-1.48, -0.22]).

CONCLUSION

Our results suggest that PEEP can be applied safely in patients with acute brain injury as it does not have a clinically significant effect on ICP or CPP. Further prospective studies are required to assess the safety of applying a lung protective ventilation strategy in brain-injured patients with lung injury.

Neuropulmonology

Neuropulmonology refers to the complex interconnection between the central nervous system and the respiratory system. Neurologic injury includes traumatic brain injury, hemorrhage, stroke, and seizures, and in each there are far-reaching effects that can result in pulmonary dysfunction. Systemic changes can induce impairment of pulmonary function due to changes in the core structure and function of the lung. The conditions and disorders that often occur in these patients include aspiration pneumonia, neurogenic pulmonary edema, and acute respiratory distress syndrome, but also several abnormal respiratory patterns and sleep-disordered breathing. Lung infections, pulmonary edema - neurogenic or cardiogenic - and pulmonary embolus all are a serious barrier to recovery and can have significant effects on outcomes such as hospital course, prognosis, and mortality. This review presents the spectrum of pulmonary abnormalities seen in neurocritical care.

Association between ventilatory settings and development of acute respiratory distress syndrome in mechanically ventilated patients due to brain injury

PURPOSE

In neurologically critically ill patients with mechanical ventilation (MV), the development of acute respiratory distress syndrome (ARDS) is a major contributor to morbidity and mortality, but the role of ventilatory management has been scarcely evaluated. We evaluate the association of tidal volume, level of PEEP and driving pressure with the development of ARDS in a population of patients with brain injury.

MATERIALS AND METHODS

We performed a secondary analysis of a prospective, observational study on mechanical ventilation.

RESULTS

We included 986 patients mechanically ventilated due to an acute brain injury (hemorrhagic stroke, ischemic stroke or brain trauma). Incidence of ARDS in this cohort was 3%. Multivariate analysis suggested that driving pressure could be associated with the development of ARDS (odds ratio for unit increment of driving pressure 1.12; confidence interval for 95%: 1.01 to 1.23) whereas we did not observe association for tidal volume (in ml per kg of predicted body weight) or level of PEEP. ARDS was associated with an increase in mortality, longer duration of mechanical ventilation, and longer ICU length of stay.

CONCLUSIONS

In a cohort of brain-injured patients the development of ARDS was not common. Driving pressure was associated with the development of this disease.

Low-Dose Heparin Anticoagulation During Extracorporeal Life Support for Acute Respiratory Distress Syndrome in Conscious Sheep

Background:

Over 32% of burned battlefield causalities develop trauma-induced hypoxic respiratory failure, also known as acute respiratory distress syndrome (ARDS). Recently, 9 out of 10 US combat soldiers’ survived life-threatening trauma-induced ARDS supported with extracorporeal membrane oxygenation (ECMO), a portable form of cardiopulmonary bypass. Unfortunately, the size, incidence of coagulation complications, and the need for systematic anticoagulation for traditional ECMO devices have prevented widespread use of this lifesaving technology. Therefore, a compact, mobile, ECMO system using minimal anticoagulation may be the solution to reduce ARDS in critically ill military and civilian patients.

Methods:

We conducted a prospective cohort laboratory investigation to evaluate the coagulation function in an ovine model of oleic acid induced ARDS supported with veno-venous ECMO. The experimental design approximated the time needed to transport from a battlefield setting to an advanced facility and compared bolus versus standard heparin anticoagulation therapy.

Results:

Comprehensive coagulation and hemostasis assays did not show any difference because of ECMO support over 10 h between the two groups but did show changes because of injury. Platelet count and function did decrease with support on ECMO, but there was no significant bleeding or clot formation during the entire experiment.

Conclusions:

A bolus heparin injection is sufficient to maintain ECMO support for up to 10 h in an ovine model of ARDS. With a reduced need for systematic anticoagulation, ECMO use for battlefield trauma could reduce significant morbidity and mortality from ventilator-induced lung injury and ARDS. Future studies will investigate the mechanisms and therapies to support patients for longer periods on ECMO without coagulation complications.

Level of Evidence:

V—therapeutic animal experiment.

The acute respiratory distress syndrome following isolated severe traumatic brain injury

BACKGROUND

Acute respiratory distress syndrome (ARDS) is common after traumatic brain injury (TBI) and is associated with worse neurologic outcomes and longer hospitalization. However, the incidence and associated causes of ARDS in isolated TBI have not been well studied.

METHODS

We performed a subgroup analysis of 210 consecutive patients with isolated severe TBI enrolled in a prospective observational cohort at a Level 1 trauma center between 2005 and 2014. Subjects required endotracheal intubation and had isolated severe TBI defined by a head Abbreviated Injury Scale (AIS) score of 3 or greater and AIS score lower than 3 in all other categories. ARDS within the first 8 days of admission was rigorously adjudicated using Berlin criteria. Regression analyses were used to test the association between predictors of interest and ARDS.

RESULTS

The incidence of ARDS in the first 8 days after severe isolated TBI was 30%. Patients who developed ARDS were administered more crystalloids (4.3 L vs. 3.5 L, p = 0.005) and blood products in the first 12 hours of admission. Patients with ARDS had significantly worse clinical outcomes measured at 28 days, including longer median intensive care unit and hospital stays (4 days vs. 13 days, p < 0.001, and 7.5 days vs. 14.5 days, p < 0.001, respectively). In unadjusted logistic regression analyses, the odds of developing ARDS were significantly associated with head AIS score (odds ratio [OR], 1.8; p = 0.018), male sex (OR, 2.9; p = 0.012), and early transfusion of platelets (OR, 2.8; p = 0.003). These associations were similar in a multivariate logistic regression model.

CONCLUSION

In the era of balanced hemostatic resuscitation practices, severity of head injury, male sex, early crystalloids, and early transfusion of platelets are associated with a higher risk of ARDS after severe isolated TBI. Early transfusion of platelets after severe TBI may be a modifiable risk factor for ARDS, and these findings invite further investigation into causal mechanisms driving this observed association.

LEVEL OF EVIDENCE

Prognostic/epidemiologic study, level III.

Transplantation of bone marrow-derived mesenchymal stem cells (BMSCs) improves brain ischemia-induced pulmonary injury in rats associated to TNF-α expression

Background

Bone marrow mesenchymal stem cell (BMSCs)-based therapy seems to be a promising treatment for acute lung injury, but the therapeutic effects of BMSCs transplantation on acute lung injury induced by brain ischemia and the mechanisms have not been totally elucidated. This study explores the effects of transplantation of BMSCs on acute lung injury induced by focal cerebral ischemia and investigates the underlying mechanism.

Methods

Acute lung injury model was induced by middle cerebral artery occlusion (MCAO). BMSCs (with concentration of 1 × 10⁶/ml) were transplanted into host through tail vein 1 day after MCAO. Then, the survival, proliferation and migration of BMSCs in lung were observed at 4 days after transplantation, and histology observation and lung function were assessed for 7 days. Meanwhile, in situ hybridization (ISH), qRT-PCR and western blotting were employed to detect the expression of TNF-α in lung.

Results

Neurobehavioral deficits and acute lung injury could be seen in brain ischemia rats. Implanted BMSCs could survive in the lung, and relieve pulmonary edema, improve lung function, as well as down regulate TNF-α expression.

Conclusions

The grafted BMSCs can survive and migrate widespread in lung and ameliorate lung injury induced by focal cerebral ischemia in the MCAO rat models. The underlying molecular mechanism, at least partially, is related to the suppression of TNF-α.

The incidence of ARDS and associated mortality in severe TBI using the Berlin definition

BACKGROUND

The incidence of adult respiratory distress syndrome (ARDS) in severe traumatic brain injury (TBI) is poorly reported. Recently, a new definition for ARDS was proposed, the Berlin definition. The percentage of patients represented by TBI in the Berlin criteria study is limited. This study describes the incidence and associated mortality of ARDS in TBI patients.

METHODS

The study was an analysis of the safety of erythropoietin administration and transfusion threshold on the incidence of ARDS in severe TBI patients. Three reviewers independently assessed all patients enrolled in the study for acute lung injury/ARDS using the Berlin and the American-European Consensus Conference (AECC) definitions. A Cox proportional hazards model was used to assess the relationship between ARDS and mortality and 6-month Glasgow Outcome Scale (GOS) score.

RESULTS

Two hundred patients were enrolled in the study. Of the patients, 21% (41 of 200) and 26% (52 of 200) developed ARDS using the AECC and Berlin definitions, respectively, with a median time of 3 days (interquartile range, 3) after injury. ARDS by either definition was associated with increased mortality (p = 0.04) but not with differences in functional outcome as measured by the GOS score at 6 months. Adjusted analysis using the Berlin criteria showed an increased mortality associated with ADS (p = 0.01).

CONCLUSION

Severe TBI is associated with an incidence of ARDS ranging from 20% to 25%. The incidence is comparable between the Berlin and AECC definitions. ARDS is associated with increased mortality in severe TBI patients, but further studies are needed to validate these findings.

LEVEL OF EVIDENCE

Epidemiologic study, level II.

Increased Risk of Post-Trauma Stroke after Traumatic Brain Injury-Induced Acute Respiratory Distress Syndrome

This study determines whether acute respiratory distress syndrome (ARDS) is an independent risk factor for an increased risk of post-traumatic brain injury (TBI) stroke during 3-month, 1-year, and 5-year follow-ups, respectively, after adjusting for other covariates. Clinical data for the analysis were from the National Health Insurance Database 2000, which covered a total of 2121 TBI patients and 101 patients with a diagnosis of TBI complicated with ARDS (TBI-ARDS) hospitalized between January 1, 2001 and December 31, 2005. Each patient was tracked for 5 years to record stroke occurrences after discharge from the hospital. The prognostic value of TBI-ARDS was evaluated using a multivariate Cox proportional hazard model. The main outcome found that stroke occurred in nearly 40% of patients with TBI-ARDS, and the hazard ratio for post-TBI stroke increased fourfold during the 5-year follow-up period after adjusting for other covariates. The increased risk of hemorrhagic stroke in the ARDS group was considerably higher than in the TBI-only cohort. This is the first study to report that post-traumatic ARDS yielded an approximate fourfold increased risk of stroke in TBI-only patients. We suggest intensive and appropriate medical management and intensive follow-up of TBI-ARDS patients during the beginning of the hospital discharge.

Lateral (Parasagittal) Fluid Percussion Model of Traumatic Brain Injury

Fluid percussion was first conceptualized in the 1940s and has evolved into one of the leading laboratory methods for studying experimental traumatic brain injury (TBI). Over the decades, fluid percussion has been used in numerous species and today is predominantly applied to the rat. The fluid percussion technique rapidly injects a small volume of fluid, such as isotonic saline, through a circular craniotomy onto the intact dura overlying the brain cortex. In brief, the methods involve surgical production of a circular craniotomy, attachment of a fluid-filled conduit between the dura overlying the cortex and the outlet port of the fluid percussion device. A fluid pulse is then generated by the free-fall of a pendulum striking a piston on the fluid-filled cylinder of the device. The fluid enters the cranium, producing a compression and displacement of the brain parenchyma resulting in a sharp, high magnitude elevation of intracranial pressure that is propagated diffusely through the brain. This results in an immediate and transient period of traumatic unconsciousness as well as a combination of focal and diffuse damage to the brain, which is evident upon histological and behavioral analysis. Numerous studies have demonstrated that the rat fluid percussion model reproduces a wide range of pathological features associated with human TBI.

Predictors of Outcomes in Traumatic Brain Injury

INTRODUCTION

The purpose of this study was to retrospectively evaluate patients treated for traumatic brain injuries (TBI) to determine how multiple organ trauma (MOT) and lung injuries sustained at the time of initial injury affect outcome.

METHODS

A single institution retrospective review of all patients diagnosed with TBI at a level I trauma center from 2000 to 2014 was conducted. Clinical outcome was based on Glasgow Outcome Scale at hospital discharge. Lung injury was defined as the presence of pulmonary contusions, pneumothorax, hemothorax, rib fractures, or diaphragmatic rupture proven by x-ray or computed tomography scan. MOT was defined as trauma to one body region with an Abbreviated Injury Scale (AIS) score ≥3 plus trauma to 2 additional body regions with AIS scores ≥1. Regression analysis was conducted with SPSS 21.

RESULTS

There were 409 patients reviewed. The majority of patients were male (73%), average age was 46 years (range, 16-94 years), average Glasgow Coma Scale (GCS) score was 7, and 71% had a severe TBI (GCS ≤8). Thirty percent of patients had poor outcome (Glasgow Outcome Scale = 1-2) Regression analysis indicated age (odds ratio [OR] 1.03, P < 0.001), initial GCS (OR 0.88, P < 0.001), Injury Severity Score (OR 1.03, P = 0.021), and head AIS ≥5 (OR 0.55, P = 0.019) were significant independent predictors of poor outcome. Sex, MOT, lung injury, and lung injury severity were not significant predictors of outcome.

CONCLUSIONS

Age, GCS, Injury Severity Score, and critical head injuries (AIS ≥5) were significant tools in predicting outcome in this patient cohort. MOT and traumatic lung injury may cause significant damage to a patient suffering from a severe TBI, but these injuries do not predict mortality in this patient population.

The HMGB1-RAGE Inflammatory Pathway: Implications for Brain Injury-Induced Pulmonary Dysfunction

SIGNIFICANCE

Deceased patients who have suffered severe traumatic brain injury (TBI) are the largest source of organs for lung transplantation. However, due to severely compromised pulmonary lung function, only one-third of these patients are eligible organ donors, with far fewer capable of donating lungs (∼ 20%). As a result of this organ scarcity, understanding and controlling the pulmonary pathophysiology of potential donors are key to improving the health and long-term success of transplanted lungs.

RECENT ADVANCES

Although the exact mechanism by which TBI produces pulmonary pathophysiology remains unclear, it may be related to the release of damage-associated molecular patterns (DAMPs) from the injured tissue. These heterogeneous, endogenous host molecules can be rapidly released from damaged or dying cells and mediate sterile inflammation following trauma. In this review, we highlight the interaction of the DAMP, high-mobility group box protein 1 (HMGB1) with the receptor for advanced glycation end-products (RAGE), and toll-like receptor 4 (TLR4).

CRITICAL ISSUES

Recently published studies are reviewed, implicating the release of HMGB1 as producing marked changes in pulmonary inflammation and physiology following trauma, followed by an overview of the experimental evidence demonstrating the benefits of blocking the HMGB1-RAGE axis.

FUTURE DIRECTIONS

Targeting the HMGB1 signaling axis may increase the number of lungs available for transplantation and improve long-term benefits for organ recipient patient outcomes.

Extracorporeal decarboxylation in patients with severe traumatic brain injury and ARDS enables effective control of intracranial pressure

INTRODUCTION

Acute respiratory distress syndrome (ARDS) with concomitant impairment of oxygenation and decarboxylation represents a complex problem in patients with increased intracranial pressure (ICP). Permissive hypercapnia is not an option to obtain and maintain lung-protective ventilation in the presence of elevated ICP. Pumpless extracorporeal lung assist (pECLA) devices (iLA Membrane Ventilator; Novalung, Heilbronn, Germany) can improve decarboxylation without aggravation associated with invasive ventilation. In this pilot series, we analyzed the safety and efficacy of pECLA in patients with ARDS and elevated ICP after severe traumatic brain injury (TBI).

METHODS

The medical records of ten patients (eight male, two female) with severe ARDS and severe TBI concurrently managed with external ventricular drainage in the neurointensive care unit (NICU) were retrospectively analyzed. The effect of pECLA on enabling lung-protective ventilation was evaluated using the difference between plateau pressure and positive end-expiratory pressure, defined as driving pressure (ΔP), during the 3 days preceding the implant of pECLA devices until 3 days afterward. The ICP threshold was set at 20 mmHg. To evaluate effects on ICP, the volume of daily cerebrospinal fluid (CSF) drainage needed to maintain the set ICP threshold was compared pre- and postimplant.

RESULTS

The ΔP values after pECLA implantation decreased from a mean 17.1 ± 0.7 cm/H2O to 11.9±0.5 cm/H2O (p = 0.011). In spite of this improved lung-protective ventilation, carbon dioxide pressure decreased from 46.6 ± 3.9 mmHg to 39.7 ± 3.5 mmHg (p = 0.005). The volume of daily CSF drainage needed to maintain ICP at 20 mmHg decreased significantly from 141.5 ± 103.5 ml to 62.2 ± 68.1 ml (p = 0.037).

CONCLUSIONS

For selected patients with concomitant severe TBI and ARDS, the application of pECLA is safe and effective. pECLA devices improve decarboxylation, thus enabling lung-protective ventilation. At the same time, potentially detrimental hypercapnia that may increase ICP is avoided. Larger prospective trials are warranted to further elucidate application of pECLA devices in NICU patients.

Incidence and Outcomes of Acute Respiratory Distress Syndrome: A Nationwide Registry-Based Study in Taiwan, 1997 to 2011

Most epidemiological studies of acute respiratory distress syndrome (ARDS) have been conducted in western countries, and studies in Asia are limited. The aim of our study was to evaluate the incidence, in-hospital mortality, and 1-year mortality of ARDS in Taiwan.We conducted a nationwide inpatient cohort study based on the Taiwan National Health Insurance Research Database between 1997 and 2011. A total of 40,876 ARDS patients (68% male; mean age 66 years) were identified by International Classification of Diseases, 9th edition coding and further analyzed for clinical characteristics, medical costs, and mortality.The overall crude incidence of ARDS was 15.74 per 100,000 person-years, and increased from 2.53 to 19.26 per 100,000 person-years during the study period. The age-adjusted incidence of ARDS was 15.19 per 100,000 person-years. The overall in-hospital mortality was 57.8%. In-hospital mortality decreased from 59.7% in 1997 to 47.5% in 2011 (P < 0.001). The in-hospital mortality rate was lowest (33.5%) in the youngest patients (age 18-29 years) and highest (68.2%) in the oldest patients (>80 years, P < 0.001). The overall 1-year mortality rate was 72.1%, and decreased from 75.8% to 54.7% during the study period. Patients who died during hospitalization were older (69 ± 17 versus 62 ± 19, P < 0.001) and predominantly male (69.8% versus 65.3%, P < 0.001). In addition, patients who died during hospitalization had significantly higher medical costs (6421 versus 5825 US Dollars, P < 0.001) and shorter lengths of stay (13 versus 19 days, P < 0.001) than patients who survived.We provide the first large-scale epidemiological analysis of ARDS incidence and outcomes in Asia. Although the overall incidence was lower than has been reported in a prospective US study, this may reflect underdiagnosis by International Classification of Diseases, 9th edition code and identification of only patients with more severe ARDS in this analysis. Overall, there has been a decreasing trend in in-hospital and 1-year mortality rates in recent years, likely because of the implementation of lung-protective ventilation.

Moderate/severe acute respiratory distress syndrome in patients with or without traumatic brain injury

Introduction

Patients with traumatic brain injury are at risk of developing acute respiratory distress syndrome, which significantly increases morbidity. This study aimed to assess functional difference (respiratory mechanics) and morbidity and mortality of moderate/severe acute respiratory distress syndrome among patients with traumatic brain injury compared with those with other non-traumatic aetiologies, besides assessing the outcomes of patients with severe traumatic brain injury with or without moderate/severe acute respiratory distress syndrome.

Methods

A prospective cohort study analysed consecutive patients with moderate/severe acute respiratory distress syndrome (PaO2/FiO2 < 200) and consecutive patients with traumatic brain injury during a 14-month period in the general intensive care unit of a teaching hospital in Cascavel, southern Brazil.

Results

Overall, 85 patients were assessed: 30 with traumatic brain injury without acute respiratory distress syndrome, 17 with traumatic brain injury and acute respiratory distress syndrome and 38 with non-traumatic brain injury (other aetiologies) acute respiratory distress syndrome. Acute respiratory distress syndrome in patients with traumatic brain injury resulted in a longer intensive care unit length of stay and slightly higher mortality. When acute respiratory distress syndrome patients with and without traumatic brain injury are compared, the latter required higher values of positive end expiratory pressure and showed a trend to lower lung static compliance, with slightly higher mortality.

Conclusions

In patients with traumatic brain injury, the presence of acute respiratory distress syndrome increased hospitalisation time. Patients with non-traumatic brain injury acute respiratory distress syndrome showed lower respiratory compliance and required higher values of positive end expiratory pressure than those with traumatic brain injury – acute respiratory distress syndrome, with higher mortality.

Sepsis in intensive care unit patients with traumatic brain injury: factors associated with higher mortality

Objective

Patients with traumatic brain injury are particularly susceptible to sepsis, which may exacerbate the systemic inflammatory response and lead to organ dysfunction. The influence of clinical variables on the mortality of intensive care unit patients with traumatic brain injury and sepsis was investigated.

Methods

The present investigation was a retrospective study involving 175 patients with traumatic brain injury who were treated in a period of 1 year at a reference hospital for trauma and who had sepsis, severe sepsis, or septic shock. Demographic and clinical data were obtained, and the SOFA score was calculated at the time sepsis was found and after 72 hours.

Results

There was a predominance of young men with severe traumatic brain injury, multiple head injuries, sepsis with a pulmonary focus, prolonged hospital stay, and high mortality (37.7%). Circulatory and respiratory failure had a high incidence, but renal and coagulation failure were less frequent, and liver failure was not observed. After logistic regression, the presence of septic shock and respiratory failure 72 hours after the sepsis diagnosis was associated with higher mortality, with an odds ratio of 7.56 (95%CI=2.04-27.31, p=0.0024) and 6.62 (95%CI=1.93-22.78, p=0.0027), respectively. In addition, there was a higher mortality among patients who had no organ failure on D1 but who developed the condition after 72 hours of sepsis and in those patients who already had organ failure at the time sepsis was diagnosed and remained in this condition after 72 hours.

Conclusion

Septic shock and progressive organ (particularly respiratory) dysfunction increases the mortality of patients with traumatic brain injury and sepsis.

In Vivo Effects of Mesenchymal Stromal Cells in Two Patients With Severe Acute Respiratory Distress Syndrome

Mesenchymal stromal cells (MSCs) have been investigated as a treatment for various inflammatory diseases because of their immunomodulatory and reparative properties. However, many basic questions concerning their mechanisms of action after systemic infusion remain unanswered. We performed a detailed analysis of the immunomodulatory properties and proteomic profile of MSCs systemically administered to two patients with severe refractory acute respiratory distress syndrome (ARDS) on a compassionate use basis and attempted to correlate these with in vivo anti-inflammatory actions. Both patients received 2×10(6) cells per kilogram, and each subsequently improved with resolution of respiratory, hemodynamic, and multiorgan failure. In parallel, a decrease was seen in multiple pulmonary and systemic markers of inflammation, including epithelial apoptosis, alveolar-capillary fluid leakage, and proinflammatory cytokines, microRNAs, and chemokines. In vitro studies of the MSCs demonstrated a broad anti-inflammatory capacity, including suppression of T-cell responses and induction of regulatory phenotypes in T cells, monocytes, and neutrophils. Some of these in vitro potency assessments correlated with, and were relevant to, the observed in vivo actions. These experiences highlight both the mechanistic information that can be gained from clinical experience and the value of correlating in vitro potency assessments with clinical effects. The findings also suggest, but do not prove, a beneficial effect of lung protective strategies using adoptively transferred MSCs in ARDS. Appropriate randomized clinical trials are required to further assess any potential clinical efficacy and investigate the effects on in vivo inflammation.

SIGNIFICANCE

This article describes the cases of two patients with severe refractory adult respiratory syndrome (ARDS) who failed to improve after both standard life support measures, including mechanical ventilation, and additional measures, including extracorporeal ventilation (i.e., in a heart-lung machine). Unlike acute forms of ARDS (such in the current NIH-sponsored study of mesenchymal stromal cells in ARDS), recovery does not generally occur in such patients.

Brain-lung crosstalk: Implications for neurocritical care patients

Major pulmonary disorders may occur after brain injuries as ventilator-associated pneumonia, acute respiratory distress syndrome or neurogenic pulmonary edema. They are key points for the management of brain-injured patients because respiratory failure and mechanical ventilation seem to be a risk factor for increased mortality, poor neurological outcome and longer intensive care unit or hospital length of stay. Brain and lung strongly interact via complex pathways from the brain to the lung but also from the lung to the brain. Several hypotheses have been proposed with a particular interest for the recently described “double hit” model. Ventilator setting in brain-injured patients with lung injuries has been poorly studied and intensivists are often fearful to use some parts of protective ventilation in patients with brain injury. This review aims to describe the epidemiology and pathophysiology of lung injuries in brain-injured patients, but also the impact of different modalities of mechanical ventilation on the brain in the context of acute brain injury.

CD11d integrin blockade reduces the systemic inflammatory response syndrome after traumatic brain injury in rats

Traumatic CNS injury triggers a systemic inflammatory response syndrome (SIRS), in which circulating inflammatory cells invade body organs causing local inflammation and tissue damage. We have shown that the SIRS caused by spinal cord injury is greatly reduced by acute intravenous treatment with an antibody against the CD11d subunit of the CD11d/CD18 integrin expressed by neutrophils and monocyte/macrophages, a treatment that reduces their efflux from the circulation. Traumatic brain injury (TBI) is a frequently occurring injury after motor vehicle accidents, sporting and military injuries, and falls. Our studies have shown that the anti-CD11d treatment diminishes brain inflammation and oxidative injury after moderate or mild TBI, improving neurological outcomes. Accordingly, we examined the impact of this treatment on the SIRS triggered by TBI. The anti-CD11d treatment was given at 2h after a single moderate (2.5-3.0 atm) or 2 and 24h after each of three consecutive mild (1.0-1.5 atm) fluid percussion TBIs. Sham-injured, saline-treated rats served as controls. At 24h, 72 h, and 4 or 8 weeks after the single TBI and after the third of three TBIs, lungs of rats were examined histochemically, immunocytochemically and biochemically for downstream effects of SIRS including inflammation, tissue damage and expression of oxidative enzymes. Lung sections revealed that both the single moderate and repeated mild TBI caused alveolar disruption, thickening of inter-alveolar tissue, hemorrhage into the parenchyma and increased density of intra-and peri-alveolar macrophages. The anti-CD11d treatment decreased the intrapulmonary influx of neutrophils and the density of activated macrophages and the activity of myeloperoxidase after these TBIs. Moreover, Western blotting studies showed that the treatment decreased lung protein levels of oxidative enzymes gp91(phox), inducible nitric oxide synthase and cyclooxygenase-2, as well as the apoptotic pathway enzyme caspase-3 and levels of 4-hydroxynonenal-bound proteins (an indicator of lipid peroxidation). Decreased expression of the cytoprotective transcription factor Nrf2 reflected decreased lung oxidative stress. Anti-CD11d treatment also diminished the lung concentration of free radicals and tissue aldehydes. In conclusion, the substantial lung component of the SIRS after single or repeated TBIs is significantly decreased by a simple, minimally invasive and short-lasting anti-inflammatory treatment.

Differences in degree, differences in kind: characterizing lung injury in trauma

BACKGROUND

Acute lung injury following trauma remains a significant source of morbidity and mortality. Although multiple trauma studies have used hypoxemia without radiographic adjudication as a surrogate for identifying adult respiratory distress syndrome (ARDS) cases, the differences between patients with hypoxemia alone and those with radiographically confirmed ARDS are not well described in the literature. We hypothesized that nonhypoxemic, hypoxemic, and ARDS patients represent distinct groups with unique characteristics and predictors.

METHODS

Laboratory, demographic, clinical, and outcomes data were prospectively collected from 621 intubated, critically injured patients at an urban Level 1 trauma center from 2005 to 2013. Hypoxemia was defined as PaO2/FIO2 ratio of 300 or lower. ARDS was adjudicated using Berlin criteria, with blinded two-physician consensus review of chest radiographs. Group comparisons were performed by hypoxemia and ARDS status. Logistic regression analyses were performed to separately assess predictors of hypoxemia and ARDS.

RESULTS

Of the 621 intubated patients, 64% developed hypoxemia; 46% of these hypoxemic patients developed ARDS by chest radiograph. Across the three groups (no hypoxemia, hypoxemia, ARDS), there were no significant differences in age, sex, or comorbidities. However, there was an increase in severity of shock, injury, and chest injury by group, with corresponding trends in transfusion requirements and volume of early fluid administration. Outcomes followed a similar stepwise pattern, with pneumonia, multiorgan failure, length of intensive care unit stay, number of ventilator days, and overall mortality highest in ARDS patients. In multiple logistic regression, early plasma transfusion, delayed crystalloid administration, body mass index, and head and chest injury were independent predictors of hypoxemia, while head and chest injury, early crystalloid infusion, and delayed platelet transfusion were independent predictors of ARDS.

CONCLUSION

Hypoxemia and ARDS exist on a spectrum of respiratory dysfunction following trauma, with increasing injury severity profiles and resuscitation requirements. However, they also represent distinct clinical states with unique predictors, which require directed research approaches and targeted therapeutic strategies.

LEVEL OF EVIDENCE

Prognostic and epidemiologic study, level III.

The HMGB1-RAGE axis mediates traumatic brain injury-induced pulmonary dysfunction in lung transplantation

Traumatic brain injury (TBI) results in systemic inflammatory responses that affect the lung. This is especially critical in the setting of lung transplantation, where more than half of donor allografts are obtained postmortem from individuals with TBI. The mechanism by which TBI causes pulmonary dysfunction remains unclear but may involve the interaction of high-mobility group box-1 (HMGB1) protein with the receptor for advanced glycation end products (RAGE). To investigate the role of HMGB1 and RAGE in TBI-induced lung dysfunction, RAGE-sufficient (wild-type) or RAGE-deficient (RAGE(-/-)) C57BL/6 mice were subjected to TBI through controlled cortical impact and studied for cardiopulmonary injury. Compared to control animals, TBI induced systemic hypoxia, acute lung injury, pulmonary neutrophilia, and decreased compliance (a measure of the lungs' ability to expand), all of which were attenuated in RAGE(-/-) mice. Neutralizing systemic HMGB1 induced by TBI reversed hypoxia and improved lung compliance. Compared to wild-type donors, lungs from RAGE(-/-) TBI donors did not develop acute lung injury after transplantation. In a study of clinical transplantation, elevated systemic HMGB1 in donors correlated with impaired systemic oxygenation of the donor lung before transplantation and predicted impaired oxygenation after transplantation. These data suggest that the HMGB1-RAGE axis plays a role in the mechanism by which TBI induces lung dysfunction and that targeting this pathway before transplant may improve recipient outcomes after lung transplantation.

Lung protective ventilation (ARDSNet) versus airway pressure release ventilation: ventilatory management in a combined model of acute lung and brain injury

BACKGROUND

Concomitant lung/brain traumatic injury results in significant morbidity and mortality. Lung protective ventilation (Acute Respiratory Distress Syndrome Network [ARDSNet]) has become the standard for managing adult respiratory distress syndrome; however, the resulting permissive hypercapnea may compound traumatic brain injury. Airway pressure release ventilation (APRV) offers an alternative strategy for the management of this patient population. APRV was hypothesized to retard the progression of acute lung/brain injury to a degree greater than ARDSNet in a swine model.

METHODS

Yorkshire swine were randomized to ARDSNet, APRV, or sham. Ventilatory settings and pulmonary parameters, vitals, blood gases, quantitative histopathology, and cerebral microdialysis were compared between groups using χ2, Fisher's exact, Student's t test, Wilcoxon rank-sum, and mixed-effects repeated-measures modeling.

RESULTS

Twenty-two swine (17 male, 5 female), weighing a mean (SD) of 25 (6.0) kg, were randomized to APRV (n = 9), ARDSNet (n = 12), or sham (n = 1). PaO2/FIO2 ratio dropped significantly, while intracranial pressure increased significantly for all three groups immediately following lung and brain injury. Over time, peak inspiratory pressure, mean airway pressure, and PaO2/FIO2 ratio significantly increased, while total respiratory rate significantly decreased within the APRV group compared with the ARDSNet group. Histopathology did not show significant differences between groups in overall brain or lung tissue injury; however, cerebral microdialysis trends suggested increased ischemia within the APRV group compared with ARDSNet over time.

CONCLUSION

Previous studies have not evaluated the effects of APRV in this population. While our macroscopic parameters and histopathology did not observe a significant difference between groups, microdialysis data suggest a trend toward increased cerebral ischemia associated with APRV over time. Additional and future studies should focus on extending the time interval for observation to further delineate differences between groups.

Analysis of Hypoxemia in Early Ventilator-Associated Pneumonia Secondary to Haemophilus in Trauma Patients

BACKGROUND

Haemophilus species bacteria (HSB) are known pathogens responsible for early pneumonia in intubated trauma patients. The primary goal of this study was to examine the incidence and extent of hypoxemia in intubated trauma patients who develop early ventilator-associated pneumonia (VAP) secondary to HSB. On the basis of our clinical experiences, we hypothesized that patients with Haemophilus species bacteria pneumonia (HSBP) would have a high rate of hypoxemia but that the effect would be transient.

METHODS

Retrospective review of intubated trauma patients from an urban level I trauma center with HSBP diagnosed by deep tracheal aspirate or bronchoalveolar lavage from April 2007 to November 2012. Collected variables included day of HSBP diagnosis; PaO2 to FIO2 ratio (P:F) at HSBP diagnosis as well as HSBP day three and HSBP day seven; injury severity score (ISS) and its component parts; admission Glasgow Coma Scale (GCS) score; and mortality. Hypoxemia was defined as P:F <200. χ(2) Tests were utilized to assess factors that differed between hypoxemic and non-hypoxemic patients; data are presented as median (interquartile range, IQR).

RESULTS

Sixty-nine patients were identified (80% male; age, 35 y [range, 24-49]; ISS 27 [9-59]). Diagnosis of HSBP occurred early (hospital day 4 [range, 3-5]). Forty-three percent of patients had acute respiratory distress syndrome (ARDS) on HSBP day 1; this decreased to 26% on day three and to 30% on day seven. Forty patients (77%) had a tracheostomy performed. Patients with hypoxemia were significantly less likely to have a severe head injury (GCS<9), p<0.05. Patients with hypoxemia had similar hospital length of stay and mortality to patients who did not develop hypoxemia.

CONCLUSION

Haemophilus species bacteria pneumonia in trauma patients is associated with high rates of transient hypoxemia and a high tracheostomy rate, although subsequent outcomes are not affected. Patients with head injuries had a lower incidence of hypoxemia from pneumonia.

When birds can't fly: an analysis of interfacility ground transport using advanced life support when helicopter emergency medical service is unavailable

BACKGROUND

Helicopter emergency medical service (HEMS) transport of trauma patients is costly and of unproven benefit. Recent retrospective studies fail to control for crew expertise and therefore compare highly trained advance life support with less-trained basic life support crews. The purpose of our study was to compare HEMS with ground, interfacility transport while controlling for crew training. We hypothesized that patients transported by HEMS would experience shorter interhospital transport time and reduced mortality.

METHODS

Our National Trauma Registry of the American College of Surgeons database was retrospectively queried to identify consecutive interfacility, hospital transfers (January 1, 2008, to November 1, 2012) to our Level I trauma center. Transfers were stratified by transportation vehicle (i.e., HEMS vs. ground transport). Cohorts were compared across standard demographic and clinical variables using univariate analysis. Multivariate logistic regression was performed to determine the association of these variables with mortality.

RESULTS

The HEMS (n = 2,190) and ground (n = 223) cohorts were well matched overall, with no significant differences for demographics, injury severity, physiology, hospital length of stay, or complications. Median (interquartile range) time to definitive care was significantly lower for HEMS (150 [114] minutes vs. 255 [157] minutes, p < 0.001), without change in mortality (9.0% vs. 8.1%, p = 0.71). Multivariate logistic regression did not identify an association between transport mode and mortality.

CONCLUSION

Despite faster interfacility transport times, HEMS offered no mortality benefit compared with ground when crew expertise was controlled for, contradicting recent large, retrospective National Trauma Data Bank studies. Our study may represent the best approximation of a prospective study by focusing on patients deemed worthy of HEMS by referring providers. Although HEMS may seem intuitively beneficial for time-dependent injuries, larger studies with a similar methodology are warranted to justify the cost and risk of HEMS and identify subsets of patients who may benefit.

LEVEL OF EVIDENCE

Prognostic/epidemiologic study, level III.

The epidemiology of spontaneous fever and hypothermia on admission of brain injury patients to intensive care units: a multicenter cohort study

OBJECTIVES

Fever and hypothermia (dysthermia) are associated with poor outcomes in patients with brain injuries. The authors sought to study the epidemiology of dysthermia on admission to the intensive care unit (ICU) and the effect on in-hospital case fatality in a mixed cohort of patients with brain injuries.

METHODS

The authors conducted a multicenter retrospective cohort study in 94 ICUs in the United States. Critically ill patients with neurological injuries, including acute ischemic stroke (AIS), aneurysmal subarachnoid hemorrhage (aSAH), intracerebral hemorrhage (ICH), and traumatic brain injury (TBI), who were older than 17 years and consecutively admitted to the ICU from 2003 to 2008 were selected for analysis.

RESULTS

In total, 13,587 patients were included in this study; AIS was diagnosed in 2973 patients (22%), ICH in 4192 (31%), aSAH in 2346 (17%), and TBI in 4076 (30%). On admission to the ICU, fever was more common among TBI and aSAH patients, and hypothermia was more common among ICH patients. In-hospital case fatality was more common among patients with hypothermia (OR 12.7, 95% CI 8.4-19.4) than among those with fever (OR 1.9, 95% CI 1.7-2.1). Compared with patients with ICH (OR 2.0, 95% CI 1.8-2.3), TBI (OR 1.5, 95% CI 1.3-1.8), and aSAH (OR 1.4, 95% CI 1.2-1.7), patients with AIS who developed fever had the highest risk of death (OR 3.1, 95% CI 2.5-3.7). Although all hypothermic patients had an increased mortality rate, this increase was not significantly different across subgroups. In a multivariable analysis, when adjusted for all other confounders, exposure to fever (adjusted OR 1.3, 95% CI 1.1-1.5) or hypothermia (adjusted OR 7.8, 95% CI 3.9-15.4) on admission to the ICU was found to be significantly associated with in-hospital case fatality.

CONCLUSIONS

Fever is frequently encountered in the acute phase of brain injury, and a small proportion of patients with brain injuries may also develop spontaneous hypothermia. The effect of fever on mortality rates differed by neurological diagnosis. Both early spontaneous fever and hypothermia conferred a higher risk of in-hospital death after brain injury.

Variation in the BDNF gene interacts with age to predict mortality in a prospective, longitudinal cohort with severe TBI

BACKGROUND

Mortality predictions following traumatic brain injury (TBI), and our understanding of TBI pathology, may be improved by including genetic risk in addition to traditional prognostic variables. One promising target is the gene coding for brain-derived neurotrophic factor (BDNF), a ubiquitous neurotrophin important for neuronal survival and neurogenesis.

OBJECTIVE

We hypothesized the addition of BDNF genetic variation would improve mortality prediction models and that BDNF Met-carriers (rs6265) and C-carriers (rs7124442) would have the highest mortality rates post-TBI.

METHODS

This study examined BDNF functional single nucleotide polymorphisms rs6265 (val66met) and rs7124442 (T>C) in relation to mortality in a prospective, longitudinal cohort with severe TBI. We examined 315 individuals receiving care for a closed head injury within the University of Pittsburgh Medical Center, aged 16 to 74 years. Mortality was examined acutely (0-7 days postinjury) and postacutely (8-365 days postinjury). A gene risk score (GRS) was developed to examine both BDNF loci. Cox proportional hazards models were used to calculate hazard ratios for survivability post-TBI while controlling for covariates.

RESULTS

BDNF GRS was significantly associated with acute mortality, regardless of age. Interestingly, subjects in the hypothesized no-risk allele group had the lowest survival probability. Postacutely, BDNF-GRS interacted with age such that younger participants in the no-risk group had the highest survival probability, while older participants in the hypothesized no-risk group had the lowest probability of survival.

CONCLUSIONS

These data suggest complex relationships between BDNF and TBI mortality that interact with age to influence survival predictions beyond clinical variables alone. Evidence supporting dynamic, temporal balances of pro-survival/pro-apoptotic target receptors may explain injury and age-related gene associations.

The epidemiology, risk factors, and impact on hospital mortality of status epilepticus after subdural hematoma in the United States

Introduction

Subdural hematoma (SDH) is a well described risk factor in the development of Status Epilepticus (SE), however the epidemiology of SE after SDH is unknown. In this study, we sought to determine the epidemiology of SE, the prevalence of risk factors, and impact on hospital mortality using a large administrative dataset.

Methods

Data was derived from the Nationwide Inpatient Sample from 1988 through 2011. We queried the NIS database for patients older than 18 years, with a diagnosis of SDH and SE. Diagnoses were defined by ICD 9 CM codes 432.1, 852.2, 852.3 and 345.3 for SE. Adjusted incidence rates of admission and prevalence proportions were calculated. Multivariate logistic models were then fitted to assess for the impact of status epilepticus on hospital mortality.

Results

Over the 23-year period, we identified more than 1,583,255 admissions with a diagnosis of SDH. The prevalence of SE in this cohort was 0.5% (7,421 admissions). The population adjusted incidence rate of admissions of SDH increased from 13/100,000 in 1988 to 38/100,000 in 2011. The prevalence of SE in SDH, increased from 0.5% in 1988 to 0.7% in 2011. In hospital mortality of patients with SDH and without SE decreased from 17.9% to 10.3% while in hospital mortality of patients with SDH and SE did not statistically change. Mortality increased over the same period (2.3/100,000 in 1988 to 3.9/100.000 in 2011) and the diagnosis of SE increased mortality in this cohort (OR 2.17, p < 0.0001). The risk of SE remained stable throughout the study period, but was higher among older patients, blacks, and in those with respiratory, metabolic, hematological, and renal system dysfunction.

Conclusion

Our study demonstrates that the incidence of admissions of SDH is increasing in the United States. Despite a decline in the overall SDH related mortality, SE increased the risk of in-hospital death in patients with a primary diagnosis of SDH.

Extracranial hypothermia during cardiac arrest and cardiopulmonary resuscitation is neuroprotective in vivo

There is increasing evidence that ischemic brain injury is modulated by peripheral signaling. Peripheral organ ischemia can induce brain inflammation and injury. We therefore hypothesized that brain injury sustained after cardiac arrest (CA) is influenced by peripheral organ ischemia and that peripheral organ protection can reduce brain injury after CA and cardiopulmonary resuscitation (CPR). Male C57Bl/6 mice were subjected to CA/CPR. Brain temperature was maintained at 37.5°C ± 0.0°C in all animals. Body temperature was maintained at 35.1°C ± 0.1°C (normothermia) or 28.8°C ± 1.5°C (extracranial hypothermia [ExHy]) during CA. Body temperature after resuscitation was maintained at 35°C in all animals. Behavioral testing was performed at 1, 3, 5, and 7 days after CA/CPR. Either 3 or 7 days after CA/CPR, blood was analyzed for serum urea nitrogen, creatinine, alanine aminotransferase, aspartate aminotransferase, and interleukin-1β; mice were euthanized; and brains were sectioned. CA/CPR caused peripheral organ and brain injury. ExHy animals experienced transient reduction in brain temperature after resuscitation (2.1°C ± 0.5°C for 4 minutes). Surprisingly, ExHy did not change peripheral organ damage. In contrast, hippocampal injury was reduced at 3 days after CA/CPR in ExHy animals (22.4% ± 6.2% vs. 45.7% ± 9.1%, p=0.04, n=15/group). This study has two main findings. Hypothermia limited to CA does not reduce peripheral organ injury. This unexpected finding suggests that after brief ischemia, such as during CA/CPR, signaling or events after reperfusion may be more injurious than those during the ischemic period. Second, peripheral organ hypothermia during CA reduces hippocampal injury independent of peripheral organ protection. While it is possible that this protection is due to subtle differences in brain temperature during early reperfusion, we speculate that additional mechanisms may be involved. Our findings add to the growing understanding of brain-body cross-talk by suggesting that peripheral interventions can protect the brain even if peripheral organ injury is not altered.

The epidemiology of admissions of nontraumatic subarachnoid hemorrhage in the United States

BACKGROUND

Subarachnoid hemorrhage (SAH) is the cause of 5% to 10% of strokes annually in the United States.

OBJECTIVE

To study the incidence and mortality trends of admissions of SAH from 1979 to 2008 using a nationally representative sample of all nonfederal acute-care hospitals in the United States: The National Hospital Discharge Survey.

METHODS

The sample was obtained from the hospital discharge records according to the International Classification of Disease, 9th Revision, Clinical Modification code 430.

RESULTS

We reviewed data on approximately 1 billion hospitalizations in the United States over a 30-year study period and identified 612,500 cases of SAH, which was more common in women (relative risk 1.71, 95% confidence interval 1.7-1.72) and nonwhite persons than white persons (relative risk 1.46, 95% confidence interval 1.4-1.5). The estimated incidence rate of admission after SAH was 7.2 to 9.0 per 100,000/year and did not significantly change over the study period. Overall, in-hospital mortality after SAH fell from 30% during the period from 1979 to 1983 to 20% during the subperiod from 2004 to 2008 (P = .03) and was lower in larger treating hospitals. The average days of care for SAH hospitalizations decreased, but the rate of discharge to long-term care facilities increased.

CONCLUSION

The incidence rate of admission after SAH has remained stable over the past 30 years. Total deaths and in-hospital mortality after SAH have decreased significantly. In-hospital mortality after SAH is lower in larger treating hospitals.

Acute lung injury in patients with subarachnoid hemorrhage: a nationwide inpatient sample study

OBJECTIVE

To determine national trends for patients with subarachnoid hemorrhage (SAH) and pulmonary complications including acute respiratory distress syndrome (ARDS).

METHODS

The Nationwide Inpatient Sample database was used to sample 193,209 admissions for SAH with and without ARDS during the period 1993-2008 using International Classification of Diseases, Ninth Revision, Clinical Modification coding. A multivariate stepwise regression analysis was performed.

RESULTS

The incidence of ARDS in patients with SAH increased from 35.51% in 1993 to 37.60% in 2008. However, the overall mortality in patients with SAH and in patients with SAH and ARDS decreased in the same period, from 42.30% to 31.99% and from 75.13% to 60.76%, respectively. Multivariate analysis showed that the predictors of developing ARDS in patients with SAH include older age; larger hospital size; and comorbidities such as epilepsy, cardiac arrest, sepsis, congestive heart failure, hypertension, chronic obstructive pulmonary disease, hematologic dysfunction, renal dysfunction, and neurologic dysfunction. Predictors of mortality in patients with SAH include age and hospital complications, such as coronary artery disease, ARDS, cancer, hematologic dysfunction, and renal dysfunction.

CONCLUSIONS

Patients with SAH are at increased risk of developing ARDS. The identification of certain risk factors may alert and aid practitioners in preventing worsening disease.

Understanding changes in established practice: pulmonary artery catheter use in critically ill patients

OBJECTIVE

Multiple studies suggest that routine use of pulmonary artery catheters is not beneficial in critically ill patients. Little is known about the patterns of "uptake" of practice change that involves removal of a device previously considered standard of care, rather than adoption of a new technique or technology. Our objective was to assess recent pulmonary artery catheter use across ICUs and identify factors associated with high use.

DESIGN

Cohort study.

SETTING

U.S. ICUs in Project IMPACT.

PATIENTS

Adult ICU admissions from 2001 to 2008.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Trends in pulmonary artery catheter use from 2001 to 2008 were assessed. For 2006-2008, we compared pulmonary artery catheter use across ICUs. We assessed characteristics of ICUs and hospitals in the top quartile for in-ICU pulmonary artery catheter placement (vs the bottom quartile) using chi-square and t tests and factors associated with in-ICU pulmonary artery catheter insertion using multilevel mixed effects logistic regression. Total pulmonary artery catheter use decreased from 10.8% of patients (2001-2003) to 6.2% (2006-2008; p < 0.001); insertion of pulmonary artery catheters in ICU decreased from 4.2% to 2.2% (p < 0.001). In 2006-2008, ICUs in the top quartile for in-ICU pulmonary artery catheter insertion (3.4-25.0% of patients) were more often surgical (54.2% vs 21.7% in the lowest quartile, p = 0.070), teaching hospitals (54.2% vs 4.3%, p = 0.001), and had surgeon leadership (40.9% vs 13.0%, p = 0.067). After multivariable regression, surgical patients (p < 0.001) and all patients in surgical ICUs (p = 0.057) were more likely to have pulmonary artery catheters placed in ICU.

CONCLUSIONS

Use of pulmonary artery catheters in ICU patients has declined but with significant variation across units. Removal of this technology has occurred most in nonsurgical ICUs and patients.

Mesenchymal stromal cell injection protects against oxidative stress in Escherichia coli-induced acute lung injury in mice

BACKGROUND AIMS

Stem cells may be a promising therapy for acute respiratory distress syndrome. Recent in vivo and in vitro studies suggested that the mesenchymal stromal cells (MSCs) have anti-oxidative stress properties. We hypothesized that intravenous injection of bone marrow-derived mesenchymal stem cells (MSCs) could attenuate Escherichia coli-induced acute lung injury (ALI) in mice by controlling the oxidative stress status.

METHODS

Eighty mice were randomly divided into four groups: group 1 (control group) received 25 μL of saline as a vehicle; group 2 contained E coli-induced ALI mice; group 3 included mice that received MSCs before induction of ALI; group 4 included mice that received MSCs after induction of ALI. Lung samples were isolated and assayed for oxidative stress variables and histopathologic analysis. Total anti-oxidant capacity was measured in broncho-alveolar lavage.

RESULTS

Pre- and post-injury MSC injection increased survival, reduced pulmonary edema and attenuated lung injuries in ALI mice. Histologically, MSCs exhibited a considerable degree of preservation of the pulmonary alveolar architecture. An increase of anti-oxidant enzyme activities and a decrease of myeloperoxidase activity and malondialdehyde levels in the MSC recipient groups versus the ALI group were found. Furthermore, the total anti-oxidant capacity and reduced glutathione levels were significantly increased in MSCs recipient groups versus the ALI group. Weak +ve inducible nitric oxide synthase immuno-expression in groups that received MSCs was detected. Pre-injury MSC injection showed better effects than did post-injury MSC injection.

CONCLUSIONS

Systemic bone marrow-derived MSC injection was effective in modulating the oxidative stress status in E coli-induced acute lung injury in mice.

Traumatic brain injury in rats induces lung injury and systemic immune suppression

Traumatic brain injury (TBI) is frequently complicated by acute lung injury, which is predictive for poor outcome. However, it is unclear whether lung injury develops independently or as a result of mechanical ventilation after TBI. Further, TBI is strongly associated with the development of pneumonia, suggesting a specific vulnerability for the development of nosocomial infections in the lung after TBI. In this study, we evaluated whether indeed pulmonary injury and immune suppression develop spontaneously in an animal model of mild TBI (mTBI). TBI was induced in male PVG rats by closed-head trauma using a weight-drop device. Subsequently, we evaluated the effects of this on the lungs as well as on the excitability of the systemic immune system. Finally, we performed an experiment in which TBI was followed by induction of pneumonitis and evaluated whether TBI affects the severity of subsequent pneumonitis induced by intratracheal instillation of heat-killed Staphylococcus aureus. mTBI resulted in significant lung injury, as evidenced by pulmonary edema, protein leakage to the alveolar compartment, and increased concentrations of interleukin-1 and -6 in broncho alveolar lavage fluid (all p<0.05 vs. sham-treated animals). Further, after TBI, the release of tumor necrosis factor alpha was decreased when whole blood was stimulated ex vivo (p<0.05 TBI vs. sham), indicating systemic immune suppression. When TBI was followed by pneumonitis, the severity of subsequent pneumonitis was not different in rats previously subjected to TBI or sham treatment (p>0.05), suggesting that systemic immune suppression is not translated toward the pulmonary compartment in this specific model. We here show that during mild experimental TBI, acute pulmonary injury, as well as a decrease in the excitability of the systemic immune system, can be observed.

Hospital mortality in primary admissions of septic patients with status epilepticus in the United States*

OBJECTIVE

To determine the prevalence of status epilepticus, associated factors, and relationship with in-hospital mortality in primary admissions of septic patients in the United States.

DESIGN

Cross-sectional study.

SETTING

Primary admissions of adult patients more than 18 years old with a diagnosis of sepsis and status epilepticus from 1988 to 2008 identified through the Nationwide Inpatient Sample.

PARTICIPANTS

A total of 7,669,125 primary admissions of patients with sepsis.

INTERVENTIONS

None.

RESULTS

During the 21-year study period, the prevalence of status epilepticus in primary admissions of septic patients increased from 0.1% in 1988 to 0.2% in 2008 (p < 0.001). Status epilepticus was also more common among later years, younger admissions, female gender, Black race, rural hospital admissions, and in those patients with organ dysfunctions. Mortality of primary sepsis admissions decreased from 20% in 1988 to 18% in 2008 (p < 0.001). Mortality in status epilepticus during sepsis decreased from 43% in 1988 to 28% in 2008. In-hospital mortality after admissions for sepsis was associated with status epilepticus, older age, and Black and Native American/Eskimo race; patients admitted to a rural or urban private hospitals; and patients with organ dysfunctions.

CONCLUSION

Our analysis demonstrates that status epilepticus after admission for sepsis in the United States was rare. Despite an overall significant reduction in mortality after admission for sepsis, status epilepticus carried a higher risk of death. More aggressive electrophysiological monitoring and a high level of suspicion for the diagnosis of status epilepticus may be indicated in those patients with central nervous system organ dysfunction after sepsis.