Haemorrhage control in severely injured patients

Most surgeons have adopted damage control surgery for severely injured patients, in which the initial operation is abbreviated after control of bleeding and contamination to allow ongoing resuscitation in the intensive-care unit. Developments in early resuscitation that emphasise rapid control of bleeding, restrictive volume replacement, and prevention or early management of coagulopathy are making definitive surgery during the first operation possible for many patients. Improved topical haemostatic agents and interventional radiology are becoming increasingly useful adjuncts to surgical control of bleeding. Better understanding of trauma-induced coagulopathy is paving the way for the replacement of blind, unguided protocols for blood component therapy with systemic treatments targeting specific deficiencies in coagulation. Similarly, treatments targeting dysregulated inflammatory responses to severe injury are under investigation. As point-of-care diagnostics become more suited to emergency environments, timely targeted intervention for haemorrhage control will result in better patient outcomes and reduced demand for blood products. Our Series paper describes how our understanding of the roles of the microcirculation, inflammation, and coagulation has shaped new and emerging treatment strategies.

Benchmarking outcomes in the critically injured trauma patient and the effect of implementing standard operating procedures

OBJECTIVE

To determine and compare outcomes with accepted benchmarks in trauma care at 7 academic level I trauma centers in which patients were treated on the basis of a series of standard operating procedures (SOPs).

BACKGROUND

Injury remains the leading cause of death for those younger than 45 years. This study describes the baseline patient characteristics and well-defined outcomes of persons hospitalized in the United States for severe blunt trauma.

METHODS

We followed 1637 trauma patients from 2003 to 2009 up to 28 hospital days using SOPs developed at the onset of the study. An extensive database on patient and injury characteristics, clinical treatment, and outcomes was created. These data were compared with existing trauma benchmarks.

RESULTS

The study patients were critically injured and were in shock. SOP compliance improved 10% to 40% during the study period. Multiple organ failure and mortality rates were 34.8% and 16.7%, respectively. Time to recovery, defined as the time until the patient was free of organ failure for at least 2 consecutive days, was developed as a new outcome measure. There was a reduction in mortality rate in the cohort during the study that cannot be explained by changes in the patient population.

CONCLUSIONS

This study provides the current benchmark and the overall positive effect of implementing SOPs for severely injured patients. Over the course of the study, there were improvements in morbidity and mortality rates and increasing compliance with SOPs. Mortality was surprisingly low, given the degree of injury, and improved over the duration of the study, which correlated with improved SOP compliance.

A genomic storm in critically injured humans

Critical injury in humans induces a genomic storm with simultaneous changes in expression of innate and adaptive immunity genes.

Human survival from injury requires an appropriate inflammatory and immune response. We describe the circulating leukocyte transcriptome after severe trauma and burn injury, as well as in healthy subjects receiving low-dose bacterial endotoxin, and show that these severe stresses produce a global reprioritization affecting >80% of the cellular functions and pathways, a truly unexpected “genomic storm.” In severe blunt trauma, the early leukocyte genomic response is consistent with simultaneously increased expression of genes involved in the systemic inflammatory, innate immune, and compensatory antiinflammatory responses, as well as in the suppression of genes involved in adaptive immunity. Furthermore, complications like nosocomial infections and organ failure are not associated with any genomic evidence of a second hit and differ only in the magnitude and duration of this genomic reprioritization. The similarities in gene expression patterns between different injuries reveal an apparently fundamental human response to severe inflammatory stress, with genomic signatures that are surprisingly far more common than different. Based on these transcriptional data, we propose a new paradigm for the human immunological response to severe injury.

Pre-hospital intubation factors and pneumonia in trauma patients

BACKGROUND

We reported similar rates of ventilator-associated pneumonia (VAP) previously in trauma patients intubated either in a pre-hospital (PH) venue or the emergency department. A subset of PH intubations with continuous quality assessment was re-examined to identify the intubation factors associated with VAP.

METHODS

The subgroup was derived from an existing data set of consecutive adult trauma patients intubated prior to Level I trauma center admission July 2007-July 2008. Intubation details recorded included bag-valve mask ventilation (BVM) and the presence of material in the airway. The diagnosis of VAP was made preferentially by quantitative bronchoalveolar lavage (BAL) cultures (≥ 10⁴ colony-forming units indicating infection). Baseline data, injury characteristics, and circumstances of intubation of patients with and without VAP were compared by univariable analysis.

RESULTS

Detailed data were available for 197 patients; 32 (16.2%) developed VAP, on average 6.0±0.7 days after admission. Baseline characteristics were similar in the groups, but diabetes mellitus was more common in the VAP group (4 [12.5%] vs. 5 [3.0%]; p=0.02). There was a higher rate of blunt injury in the VAP patients (28 [87.5%] vs. 106 [64.2%]; p=0.01) and higher injury severity scores (33.1±2.8 vs. 23.0±1.0; p=0.0002) and chest Abbreviated Injury Scores (2.6±0.3 vs. 1.5±0.1; p=0.002). Lower Glasgow Coma Scale scores (7.9±0.9 vs. 9.9±0.4; p=0.04) and greater use of BVM (18 [56.3%] vs. 56 [34.0%]; p=0.02) were observed in patients who developed VAP. Among aspirations, 10 (31.3%) of patients with emesis developed VAP compared with only 4 (12.5%) with blood in the airway (p=0.003).

CONCLUSION

Aspiration, along with depressed consciousness and greater injury severity, may predispose trauma patients to VAP. Prospective studies should focus on the quality and timing of aspiration relative to intubation to determine if novel interventions can prevent aspiration or decrease the risk of VAP after aspiration.

The Glue Grant experience: characterizing the post injury genomic response

Despite ongoing improvements in resuscitation, care, and outcomes, traumatic injury remains a significant health care and economic burden. The causes are multifactorial, but our approach to the clinical management of these patients remains limited by our current understanding of the pathobiology of the disease. A multicenter, multidisciplinary program known as the "Inflammation and the Host Response to Injury" Large Scale Collaborative Research Program was created by the National Institute of General Medical Sciences (NIGMS, U54 GM062119-10) in 2001 in a 10-year effort to address some of these issues. Its primary goal is to describe the human genomic response to severe trauma and burns, and to examine changes in gene expression in the context of different clinical outcomes. The Program has not only successfully implemented clinical care guidelines for managing the severe trauma patient based on the best available evidence to minimize iatrogenic variability, but it has also examined the genome-wide, immune-inflammatory response in total and isolated blood leukocyte populations. This review will address current milestones as well as future directions for the Program.

Dissecting inflammatory complications in critically injured patients by within-patient gene expression changes: a longitudinal clinical genomics study

BACKGROUND

Trauma is the number one killer of individuals 1-44 y of age in the United States. The prognosis and treatment of inflammatory complications in critically injured patients continue to be challenging, with a history of failed clinical trials and poorly understood biology. New approaches are therefore needed to improve our ability to diagnose and treat this clinical condition.

METHODS AND FINDINGS

We conducted a large-scale study on 168 blunt-force trauma patients over 28 d, measuring ∼400 clinical variables and longitudinally profiling leukocyte gene expression with ∼800 microarrays. Marshall MOF (multiple organ failure) clinical score trajectories were first utilized to organize the patients into five categories of increasingly poor outcomes. We then developed an analysis framework modeling early within-patient expression changes to produce a robust characterization of the genomic response to trauma. A quarter of the genome shows early expression changes associated with longer-term post-injury complications, captured by at least five dynamic co-expression modules of functionally related genes. In particular, early down-regulation of MHC-class II genes and up-regulation of p38 MAPK signaling pathway were found to strongly associate with longer-term post-injury complications, providing discrimination among patient outcomes from expression changes during the 40-80 h window post-injury.

CONCLUSIONS

The genomic characterization provided here substantially expands the scope by which the molecular response to trauma may be characterized and understood. These results may be instrumental in furthering our understanding of the disease process and identifying potential targets for therapeutic intervention. Additionally, the quantitative approach we have introduced is potentially applicable to future genomics studies of rapidly progressing clinical conditions.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00257231

Timing of intubation and ventilator-associated pneumonia following injury

HYPOTHESIS

In an emergency medical system with established rapid-sequence intubation protocols, prehospital (PH) intubation of patients with trauma is not associated with a higher rate of ventilator-associated pneumonia (VAP) than emergency department (ED) intubation.

DESIGN

Retrospective observational cohort.

SETTING

Level I trauma center.

PATIENTS

Adult patients with trauma intubated in a PH or an ED setting from July 1, 2007, through July 31, 2008.

MAIN OUTCOME MEASURES

Diagnosis of VAP by means of bronchoscopic alveolar lavage or clinical assessment when bronchoscopic alveolar lavage was impossible. Secondary outcomes included time to VAP, length of hospitalization, and in-hospital mortality.

RESULTS

Of 572 patients, 412 (72.0%) underwent PH intubation. The ED group was older than the PH group (mean ages, 46.4 vs 39.1 years; P < .001) and had a higher incidence of blunt injury (142 [88.8%] vs 322 [78.2%]; P = .002). The mean (SD) lowest recorded ED systolic blood pressure was lower in the ED group (102.8 [1.9] vs 111.4 [1.2] mm Hg; P < .001), despite similar mean injury severity scores in both groups (27.2 [0.7] vs 27.0 [1.1]; P = .94). There was no difference in the mean rate of VAP (30 [18.8%] vs 71 [17.2%]; P = .66) or mean time to diagnosis (8.1 [1.2] vs 7.8 [1.0] days; P = .89). Logistic regression analysis identified history of drug abuse, lowest recorded ED systolic blood pressure, and injury severity score as 3 independent factors predictive of VAP.

CONCLUSIONS

Prehospital intubation of patients with trauma is not associated with higher risk of VAP. Further investigation of intubation factors and the incidence and timing of aspiration is required to identify potentially modifiable factors to prevent VAP.

Gossypiboma: tales of lost sponges and lessons learned

OBJECTIVE

To review the details surrounding cases of patients found to have retained laparotomy sponges after surgical procedures and share policy changes that have led to process improvements at one academic medical center.

DESIGN

Retrospective medical record review as part of a quality improvement process.

SETTING

Single academic medical center.

PATIENTS

Patients identified through the quality improvement process as having had retained foreign bodies after surgery.

CONCLUSIONS

Sentinel events such as retained foreign bodies after surgery require intensive review to identify systems problems. This can lead to protocol changes to improve the process. After a series of incidents, protocol changes at our institution have led to no further incidents of retained foreign bodies.

Role of the mTOR pathway in LPS-activated monocytes: influence of hypertonic saline

BACKGROUND

As heightened protein synthesis is the hallmark of many inflammatory syndromes, we hypothesize that the mammalian target of rapamycin (mTOR) pathway, which control the cap-dependent translation initiation phase, was activated by lipopolysaccharide (LPS). In addition, we studied the effect of hypertonic saline solution (HTS) on the mTOR cascade in peripheral blood mononuclear cells (PBMCs).

MATERIALS AND METHODS

PBMCs were isolated from healthy volunteers and treated with LPS. Cells were pretreated with phosphatidylinositol 3-kinase (PI3K) and mTOR inhibitors, or with HTS. Supernatants were harvested 20 h following LPS treatment, and interleukin-10 (IL-10), interleukin-6 (IL-6) and tumor necrosis alpha (TNFα) were analyzed by ELISA. Immunoblot experiments were performed for components of the PI3K/Akt/mTOR pathway at various time points. RNA was extracted after 90 min for real-time RT-PCR quantification.

RESULTS

The mTOR pathway is activated in PBMCs within 1 h of LPS stimulation. Pretreatment with rapamycin, a specific inhibitor of mTOR, resulted in a significant decrease of IL-10 and IL-6 translation and expression but did not affect the LPS-induced TNFα production. Both the mTOR pathway and the LPS-induced IL-6 production were down-regulated by HTS pretreatment.

CONCLUSIONS

The PI3k/Akt/mTOR cascade modulates LPS-induced cytokines production differentially. IL-10 and IL-6 expression are both up-regulated by activation of the mTOR pathway in response to LPS in PBMCs, while TNFα is not controlled by the mTOR cascade. Meanwhile, pretreatment of PBMCs with a HTS solution suppresses mTOR activity as well as LPS-induced IL-6, suggesting a more central role for mTOR as a regulator of the immuno-inflammatory response.

Differences in outcome between obese and nonobese patients following severe blunt trauma are not consistent with an early inflammatory genomic response

OBJECTIVES

Obesity has been demonstrated to alter a number of acute and chronic medical conditions. The effect of obesity on severely injured patients, however, remains incompletely defined. We sought to unravel potential physiologic and genomic alterations induced by obesity in severely injured blunt trauma patients.

DESIGN

A retrospective review of clinical and genomic information contained in the Inflammation and the Host Response to Injury multicenter trauma-related database examining the relationship between body mass index and the early genomic response from peripheral blood leukocytes to patient outcome following severe blunt trauma was performed.

SETTING

Multicenter collaboration between university-based academic trauma centers.

PATIENTS

Severely injured blunt trauma patients enrolled in the database.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Univariate analysis of 455 severely injured trauma patients using the National Institutes of Health/World Health Organization body mass index classification system revealed significant increases in morbidity, including longer intensive care unit stays and a greater number of ventilator days, cardiac arrests, episodes of acute renal failure, and patients developing multiple organ failure. Regression modeling identified body mass index class as being independently associated with adverse outcomes and increased morbidity but an inverse relationship with mortality in patients who suffered severe blunt traumatic injury. Initial leukocyte genomic expression patterns between 163 patients in the four different body mass index groupings did not differ; however, analysis of gene differences between body mass index classes occurring over time demonstrated significant changes in 513 probe sets with significant pathway differences being related to cellular metabolism.

CONCLUSIONS

Increasing body mass index is associated with increased morbidity following severe blunt trauma. The initial blood leukocyte inflammatory response to blunt trauma does not appear to differ significantly between patients despite increasing body mass index. Resolution of the inflammatory response may differ between patients on the basis of body mass index; however, additional work is needed to clarify the potential causality of this finding.

Oxidant alterations in CD16 expression are cytoskeletal induced

Oxidative stress during reperfusion of ischemia is associated with a phenotypic change in circulating monocytes from CD14++CD16- to a proinflammatory CD14+CD16+ subpopulation resulting in altered immunity and development of organ failure. However, the mechanism responsible remains unknown. We hypothesize that this phenotypic change, modeled by hydrogen peroxide exposure in vitro, is due to oxidative-induced intracellular calcium flux and distinct cytoskeletal and lipid raft changes. Peripheral blood monocytes obtained from healthy volunteers underwent 100 mM H2O2 exposure for 0 to 24 h. Selected cells were pretreated with 2 microM cytochalasin D, 1 microM lactrunculin A, or 30 microM 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid for 30 min. Cells underwent fluorescence-activated cell sorter for CD14, CD16, and cytokine expression. Cellular and lipid raft CD16 expression was determined by immunoblot and confocal microscopy. H2O2 exposed monocytes underwent a rapid time-dependent increase in the surface expression of CD16 from 12.81% +/- 3.53% to 37.12% +/- 7.61% at 24 h (P = 0.001). Total cellular CD16 was not changed by H2O2, but an increase in lipid raft and decrease in intracellular CD16 expression were seen after H2O2 exposure. This increase in CD16 expression was associated with a 27% increase in intracellular TNF-alpha, an alteration in actin polymerization, and the formation of raft macrodomains. These changes induced by H2O2 were inhibited by inhibition of actin polymerization (cytochalasin D and lactrunculin A) and intracellular calcium flux [1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid]. This study provides the first evidence that phenotypic alterations induced by oxidative stress during reperfusion may occur as a result of changes in cytoskeletal architecture due to calcium flux that result in lipid raft alterations rather than solely from demargination and/or production of bone marrow-derived CD16+ monocytes.

Complication rates among trauma centers

BACKGROUND

The goal of this study was to examine the association between patient complications and admission to Level I trauma centers (TC) compared with nontrauma centers (NTC).

STUDY DESIGN

This was a retrospective cohort study of data derived from the National Study on the Costs and Outcomes of Trauma (NSCOT). Patients were recruited from 18 Level I TCs and 51 NTCs in 15 regions encompassing 14 states. Trained study nurses, using standardized forms, abstracted the medical records of the patients. The overall number of complications per patient was identified, as was the presence or absence of 13 specific complications.

RESULTS

Patients treated in TCs were more likely to have any complication compared with patients in NTCs, with an adjusted relative risk (RR) of 1.34 (95% CI, 1.03, 1.74). For individual complications, only the urinary tract infection RR of 1.94 (95% CI, 1.07, 3.17) was significantly higher in TCs. TC patients were more likely to have 3 or more complications (RR, 1.83; 95% CI, 1.16, 2.90). Treatment variables that are surrogates for markers of injury severity, such as use of pulmonary artery catheters, multiple operations, massive transfusions (> 2,500 mL packed red blood cells), and invasive brain catheters, occurred significantly more often in TCs.

CONCLUSIONS

Trauma centers have a slightly higher incidence rate of complications, even after adjusting for patient case mix. Aggressive treatment may account for a significant portion of TC-associated complications. Pulmonary artery catheter use and intubation had the most influence on overall TC complication rates. Additional study is needed to provide accurate benchmark measures of complication rates and to determine their causes.

Preinjury statin use is associated with a higher risk of multiple organ failure after injury: a propensity score adjusted analysis

BACKGROUND

Recent studies suggest that statin use may improve outcome in critically ill patients. This has been attributed to the pleiomorphic effect and modulation of inflammatory mediators that occurs with statin use. We sought to determine whether preinjury statin (PIS) use was associated with improved outcome in severely injured blunt trauma patients.

METHODS

Data were obtained from a multicenter prospective cohort study evaluating outcomes in blunt injured adults with hemorrhagic shock. Patients aged 55 years and older were analyzed. Those with isolated traumatic brain injury, cervical cord injury, and those who survived <24 hours were excluded. A propensity score predicting statin use was created using logistic regression. Cox proportional hazard regression was then used to evaluate the effects of PIS use on mortality and the development of multiple organ failure (MOF, multiple organ dysfunction syndrome >5) and nosocomial infection (NI) after adjusting for important injury characteristics and the propensity of taking PISs.

RESULTS

Overall mortality and MOF rates for the study cohort (n = 295) were 21% and 50%, respectively. Over 24% of patients (n = 71) reported PIS use. Kaplan-Meier analysis revealed no difference in NI or mortality over time but did show a significant higher incidence of MOF in those with PIS use (p = 0.04). Regression analysis verified PIS was independently associated with an 80% higher risk of MOF (hazard ratio: 1.8; 95% confidence interval, 1.1-2.9) and was found to be one of the strongest independent risk factors for the development of MOF.

CONCLUSION

PIS use was independently associated with a higher risk of MOF postinjury. These results are contrary to previous analyses. The protective effect of statins may be lost in the severely injured, and modulation of the inflammatory response may result in higher morbidity. Further studies are required to better understand the impact and potential therapeutic utility of this commonly prescribed medication both before and after injury.

A genomic score prognostic of outcome in trauma patients

Traumatic injuries frequently lead to infection, organ failure, and death. Health care providers rely on several injury scoring systems to quantify the extent of injury and to help predict clinical outcome. Physiological, anatomical, and clinical laboratory analytic scoring systems (Acute Physiology and Chronic Health Evaluation [APACHE], Injury Severity Score [ISS]) are utilized, with limited success, to predict outcome following injury. The recent development of techniques for measuring the expression level of all of a person's genes simultaneously may make it possible to develop an injury scoring system based on the degree of gene activation. We hypothesized that a peripheral blood leukocyte gene expression score could predict outcome, including multiple organ failure, following severe blunt trauma. To test such a scoring system, we measured gene expression of peripheral blood leukocytes from patients within 12 h of traumatic injury. cRNA derived from whole blood leukocytes obtained within 12 h of injury provided gene expression data for the entire genome that were used to create a composite gene expression score for each patient. Total blood leukocytes were chosen because they are active during inflammation, which is reflective of poor outcome. The gene expression score combines the activation levels of all the genes into a single number which compares the patient's gene expression to the average gene expression in uninjured volunteers. Expression profiles from healthy volunteers were averaged to create a reference gene expression profile which was used to compute a difference from reference (DFR) score for each patient. This score described the overall genomic response of patients within the first 12 h following severe blunt trauma. Regression models were used to compare the association of the DFR, APACHE, and ISS scores with outcome. We hypothesized that patients with a total gene response more different from uninjured volunteers would tend to have poorer outcome than those more similar. Our data show that for measures of poor outcome, such as infections, organ failures, and length of hospital stay, this is correct. DFR scores were associated significantly with adverse outcome, including multiple organ failure, duration of ventilation, length of hospital stay, and infection rate. The association remained significant after adjustment for injury severity as measured by APACHE or ISS. A single score representing changes in gene expression in peripheral blood leukocytes within hours of severe blunt injury is associated with adverse clinical outcomes that develop later in the hospital course. Assessment of genome-wide gene expression provides useful clinical information that is different from that provided by currently utilized anatomic or physiologic scores.

Effect of immediate enteral feeding on trauma patients with an open abdomen: protection from nosocomial infections

BACKGROUND

Damage-control laparotomy has become increasingly common after operative resuscitation of severe hemorrhagic shock after injury. Despite increased use, uncertainty exists about the safety and timing of enteral nutrition. The purpose of this study was to determine the safety and effect of immediate enteral nutrition.

STUDY DESIGN

Data were obtained from a multicenter prospective cohort study evaluating clinical outcomes in adults with hemorrhagic shock after injury and were limited to patients with an open abdomen and no hollow viscus injury. The immediate enteral nutrition cohort was defined as initiation of enteral feeds within 36 hours after acute resuscitation completion. Multivariate stepwise logistic regression was used to evaluate factors associated with immediate enteral nutrition.

RESULTS

One hundred subjects met inclusion criteria; 32 immediate enteral nutrition and 68 nonimmediate enteral nutrition. Nearly all patients underwent fascial closure (93.8% immediate enteral nutrition versus 94.1% nonimmediate enteral nutrition), with an average closure day of 6.47 +/- 0.83 with immediate enteral nutrition and 8.55 +/- 0.85 with nonimmediate enteral nutrition (p = 0.129). No significant difference in multiorgan dyfunction syndrome, length of ventilator days, ICU days, hospital days, or mortality was seen between groups. The rate of pneumonia was significantly different: 14 (43.8%) in immediate enteral nutrition and 49 (72.1%) in nonimmediate enteral nutrition (p = 0.008). Immediate enteral nutrition remained independently associated with a reduction in pneumonia within our stepwise regression (odds ratio = 0.32; 95% CI, 0.13 to 0.79).

CONCLUSIONS

Immediate enteral nutrition after damage control appears safe, with no effect on abdominal closure rate. In addition, the reduction in pneumonia associated with immediate enteral nutrition suggests a tangible benefit. Immediate enteral nutrition should be considered in patients with open abdomens after severe trauma.

Insulin regulates macrophage activation through activin A

Strict control of serum glucose with insulin has been associated with a reduction in the development of multiple organ dysfunction syndrome potentially through alterations in macrophage activation. Although the mechanism responsible for this effect remains poorly elucidated, recent work has suggested that this may occur through the PI3K/AKT pathway. As a result, we set out to investigate the role and means of activation of this pathway by insulin on endotoxin-mediated activation of tissue-fixed macrophages.

METHODS

THP-1 cells were stimulated with endotoxin with or without 24 h of insulin pretreatment. Cellular protein was extracted and analyzed by immunoblot for factors essential to Toll-like receptor 4 signaling. Supernatants were analyzed by enzyme-linked immunosorbent assay for TNF-alpha and IL-8 production. In addition, potential effect of the transforming growth factor superfamily was analyzed through selective inhibition of either the transforming growth factor beta or activin A receptors.

RESULTS

Endotoxin exposure resulted in the activation of extracellular signal-regulated kinase 1/2, p38 and Jun kinase, the degradation of IkappaB, the activation of nuclear factor kappaB, and the production of TNF-alpha and IL-8. Insulin pretreatment delayed endotoxin-mediated extracellular signal-regulated kinase 1/2, p38 and Jun kinase, the degradation of IkappaB, the activation of nuclear factor kappaB, and the production of TNF-alpha and IL-8. Insulin alone was associated with an increase in cytoplasmic SH2-containing inositol 5'-phosphatase (SHIP) but a decrease in lipid raft bound SHIP. The changes induced by insulin on SHIP and endotoxin-mediated signaling were reversed by activin A blockade.

CONCLUSIONS

Insulin results in regulation of macrophage activity in response to endotoxin through the release of activin A and subsequent production of SHIP. This increase in cytoplasmic SHIP results in attenuated endotoxin-mediated intracellular signaling and inflammatory mediator production.

Early supplemental parenteral nutrition is associated with increased infectious complications in critically ill trauma patients

BACKGROUND

Parenteral nutrition (PN) is often used in severely injured patients when caloric goals are not achieved enterally. The purpose of this study is to determine whether early administration of parenteral nutrition is associated with an increased risk for infection after severe injury.

STUDY DESIGN

Retrospective cohort study of severely injured blunt trauma patients enrolled from eight trauma centers participating in the "Inflammation and the Host Response to Injury" (Glue Grant) study. We compared patients receiving PN within 7 days after injury with a control group that did not receive early PN. We then focused on patients who tolerated at least some enteral nutrition (EN) during the first week and evaluated the potential influence of supplemental PN on outcomes in this "enteral tolerant" subgroup. Primary outcomes included occurrence of a nosocomial infection after the first postinjury week. Secondary outcomes included type of infection and hospital mortality.

RESULTS

Of 567 patients enrolled, 95 (17%) received early PN. Early PN use was associated with a greater risk of nosocomial infection (relative risk [RR] = 2.1; 95% CI, 1.6 to 2.6; p < 0.001). In the enteral-tolerant subgroup (n = 249), early PN was also associated with an increase in nosocomial infections (RR = 1.6; 95% CI, 1.2 to 2.1; p = 0.005) in part because of an increased risk of bloodstream infection (RR = 2.8; 95% CI, 1.5 to 5.3; p = 0.002). Mortality tended to be higher in patients receiving additional EN and PN versus EN alone (RR = 2.3; 95% CI, 1.0 to 5.2; p = 0.06).

CONCLUSIONS

In critically ill trauma patients who are able to tolerate at least some EN, early PN administration can contribute to increased infectious morbidity and worse clinical outcomes.

Microfluidic leukocyte isolation for gene expression analysis in critically ill hospitalized patients

BACKGROUND

Microarray technology is becoming a powerful tool for diagnostic, therapeutic, and prognostic applications. There is at present no consensus regarding the optimal technique to isolate nucleic acids from blood leukocyte populations for subsequent expression analyses. Current collection and processing techniques pose significant challenges in the clinical setting. Here, we report the clinical validation of a novel microfluidic leukocyte nucleic acid isolation technique for gene expression analysis from critically ill, hospitalized patients that can be readily used on small volumes of blood.

METHODS

We processed whole blood from hospitalized patients after burn injury and severe blunt trauma according to the microfluidic and standard macroscale leukocyte isolation protocol. Side-by-side comparison of RNA quantity, quality, and genome-wide expression patterns was used to clinically validate the microfluidic technique.

RESULTS

When the microfluidic protocol was used for processing, sufficient amounts of total RNA were obtained for genome-wide expression analysis from 0.5 mL whole blood. We found that the leukocyte expression patterns from samples processed using the 2 protocols were concordant, and there was less variability introduced as a result of harvesting method than there existed between individuals.

CONCLUSIONS

The novel microfluidic approach achieves leukocyte isolation in <25 min, and the quality of nucleic acids and genome expression analysis is equivalent to or surpasses that obtained from macroscale approaches. Microfluidics can significantly improve the isolation of blood leukocytes for genomic analyses in the clinical setting.

Acid sphingomyelinase is required for lipid Raft TLR4 complex formation

BACKGROUND

Lipid rafts, composed of sphingolipids, are critical to Toll-like receptor 4 (TLR4) assembly during lipopolysaccharide (LPS) exposure as a result of phosphokinase C (PKC)-zeta activation. However, the mechanism responsible for these events remains unknown.

PURPOSE

We determined whether LPS-induced TLR4 assembly and activation are dependent on the sphingolipid metabolite ceramide, produced by acid sphingomyelinase following the initial binding of LPS to CD14.

METHODS

Cultured THP-1 cells were stimulated with LPS, exogenous C(2) ceramide, or both. Selected cells were pretreated with the acid sphingomyelinase inhibitor imipramine or CD14 neutralizing antibody.

RESULTS

Exposure to LPS led to activation of acid sphingomyelinase, production of ceramide, phosphorylation of PKCzeta, and assembly of the TLR4 receptor within lipid rafts. This was followed by activation of the MAPK family of products and the liberation of tumor necrosis factor-alpha. Pretreatment with imipramine or CD14 blockade was associated with attenuation of all of these LPS-induced events. Simultaneous treatment with C(2) ceramide and LPS reversed all the inhibitory effects induced by imipramine, but not those associated with CD14 blockade.

CONCLUSION

Assembly and activation of the TLR4 receptor following LPS binding to CD14 requires the production of ceramide by acid sphingomyelinase.

Vitamin E inhibits endotoxin-mediated transport of phosphatases to lipid rafts

The production and release of inflammatory mediators is regulated by the coordinated activity of kinases and phosphatases. These proteins are known to regulate one another through an unknown mechanism. Previously, we have demonstrated that autocrine release of oxidants regulates macrophage activation in a similar fashion. The purpose of this study is to determine if attenuated oxidant activity by antioxidant exposure can regulate endotoxin-mediated kinase and phosphatase activity. Human promonocytic THP-1 cells were stimulated with lipopolysaccharide. Selected cells were pretreated with alpha-tocopherol succinate, LY294002, or an AKT inhibitor (1L-6-hydroxymethyl-chiro-inositol 2-(R)-2-O-methyl-3-O-octadecylcarbonate). Lipid raft and cellular protein were analyzed for lipid raft toll-like receptor 4 (TLR4) receptor formation and mitogen-activated protein kinase (MAPK) activation. Harvested supernatants were analyzed for tumor necrosis factor (TNF)-alpha production. Lipopolysaccharide stimulation led to the lipid raft mobilization of TLR4 and heat shock protein 70. This was followed by lipid raft mobilization of SH related complex homology 2 domain-containing inositol-5-phosphate (SHIP), activation of the MAPK, and production of TNF-alpha. Pretreatment with alpha-tocopherol succinate did not affect mobilization of TLR4 or heat shock protein 70, but did result in attenuated mobilization of SHIP, activation of the MAPK, and production of TNF-alpha. In addition, alpha-tocopherol succinate was associated with increased activation of the counter-regulatory kinase protein kinase B. Pretreatment with LY294002 or 1L-6-hydroxymethyl-chiro-inositol 2-(R)-2-O-methyl-3-O-octadecylcarbonate reversed the effects of alpha-tocopherol succinate. Thus, it seems that endotoxin-mediated activation requires the coordinated activity of kinases and phosphatases. Antioxidant exposure in the form of vitamin E seems to attenuate endotoxin-mediated SHIP activation resulting in increased AKT activity, and attenuated MAPK activation and TNF-alpha production.