Prediction of venous thromboembolism using clinical and serum biomarker data from a military cohort of trauma patients.

INTRODUCTION: Venous thromboembolism (VTE) is a frequent complication of trauma associated with high mortality and morbidity. Clinicians lack appropriate tools for stratifying trauma patients for VTE, thus have yet to be able to predict when to intervene. We aimed to compare random forest (RF) and logistic regression (LR) predictive modelling for VTE using (1) clinical measures alone, (2) serum biomarkers alone and (3) clinical measures plus serum biomarkers. METHODS: Data were collected from 73 military casualties with at least one extremity wound and prospectively enrolled in an observational study between 2007 and 2012. Clinical and serum cytokine data were collected. Modelling was performed with RF and LR based on the presence or absence of deep vein thrombosis (DVT) and/or pulmonary embolism (PE). For comparison, LR was also performed on the final variables from the RF model. Sensitivity/specificity and area under the curve (AUC) were reported. RESULTS: Of the 73 patients (median Injury Severity Score=16), nine (12.3%) developed VTE, four (5.5%) with DVT, four (5.5%) with PE, and one (1.4%) with both DVT and PE. In all sets of predictive models, RF outperformed LR. The best RF model generated with clinical and serum biomarkers included five variables (interleukin-15, monokine induced by gamma, vascular endothelial growth factor, total blood products at resuscitation and presence of soft tissue injury) and had an AUC of 0.946, sensitivity of 0.992 and specificity of 0.838. CONCLUSIONS: VTE may be predicted by clinical and molecular biomarkers in trauma patients. This will allow the development of clinical decision support tools which can help inform the management of high-risk patients for VTE.

Ethical considerations in the collection of genetic data from critically ill patients: what do published studies reveal about potential directions for empirical ethics research?

Critical illness trials involving genetic data collection are increasingly commonplace and pose challenges not encountered in less acute settings, related in part to the precipitous, severe and incapacitating nature of the diseases involved. We performed a systematic literature review to understand the nature of such studies conducted to date, and to consider, from an ethical perspective, potential barriers to future investigations. We identified 79 trials enrolling 24 499 subjects. Median (interquartile range) number of participants per study was 263 (116.75-430.75). Of these individuals, 16 269 (66.4%) were Caucasian, 1327 (5.4%) were African American, 1707 (7.0%) were Asian Pacific Islanders and 139 (0.6%) were Latino. For 5020 participants (20.5%), ethnicity was not reported. Forty-eight studies (60.8%) recruited subjects from single centers and all studies examined a relatively small number of genetic markers. Technological advances have rendered it feasible to conduct clinical studies using high-density genome-wide scanning. It will be necessary for future critical illness trials using these approaches to be of greater scope and complexity than those so far reported. Empirical research into issues related to greater ethnic inclusivity, accuracy of substituted judgment and specimen stewardship may be essential for enabling the conduct of such trials.

Epithelial apoptosis in mechanistically distinct methods of injury in the murine small intestine.

Gut epithelial apoptosis is involved in the pathophysiology of multiple diseases. This study characterized intestinal apoptosis in three mechanistically distinct injuries with different kinetics of cell death. FVB/N mice were subjected to gamma radiation, Pseudomonas aeruginosa pneumonia or injection of monoclonal anti-CD3 antibody and sacrificed 4, 12, or 24 hours post-injury (n=10/time point). Apoptosis was quantified in the jejunum by hematoxylin and eosin (H&E), active caspase-3, terminal deoxynucleotidyl transferase dUTP-mediated nick end labeling (TUNEL), in situ oligoligation reaction (ISOL,) cytokeratin 18, and annexin V staining. Reproducible results were obtained only for H&E, active caspase-3, TUNEL and ISOL, which were quantified and compared against each other for each injury at each time point. Kinetics of injury were different with early apoptosis highest following radiation, late apoptosis highest following anti CD3, and more consistent levels following pneumonia. ISOL was the most consistent stain and was always statistically indistinguishable from at least 2 stains. In contrast, active caspase-3 demonstrated lower levels of apoptosis, while the TUNEL assay had higher levels of apoptosis in the most severely injured intestine regardless of mechanism of injury. H&E was a statistical outlier more commonly than any other stain. This suggests that regardless of mechanism or kinetics of injury, ISOL correlates to other quantification methods of detecting gut epithelial apoptosis more than any other method studied and compares favorably to other commonly accepted techniques of quantifying apoptosis in a large intestinal cross sectional by balancing sensitivity and specificity across a range of times and levels of death.

Interleukin-1 receptor antagonist as therapy for inflammatory disorders.

IL-1 is a pivotal mediator of the immune response and has been implicated in inflammatory and infectious diseases. As a consequence, the administration of IL-1 receptor antagonist (IL-1ra), a recombinantly synthesised endogenous inhibitor of IL-1, has appeal as a therapeutic strategy in these conditions. To date, the largest clinical experiences with IL-1ra have been in the setting of sepsis and rheumatoid arthritis (RA). Like other anti-inflammatory agents that target a specific mediator, IL-1ra was found to lack efficacy when given in conjunction with standard therapy in patients with sepsis and septic shock. In contrast, recent studies enrolling patients with RA suggest that IL-1ra significantly ameliorates disease activity and retards joint destruction. Whether the respective lack of efficacy and success of IL-1ra in these two diseases is a result of differences in the pathologic processes involved, or reflects the nature in which the clinical studies were conducted, is unclear. Further, the effectiveness of IL-1ra compared to other anticytokine and conventional treatments in RA remains to be clarified. Nonetheless, the recent finding that IL-1ra has the ability to favourably influence a chronic inflammatory disease supports the hypothesis that inhibition of a single mediator of the immune response may have clinical impact.

Complex systems analysis: a tool for shock research.

For the past century, students of shock have focused research efforts to illuminate specific mechanisms that cause, or fail as a consequence of, circulatory collapse. Although clinical strategies aimed at supporting or restoring individual organ systems have proven effective, many patients succumb to more generalized multiple organ system failure. We suggest that general biological systems failure cannot be interpreted through reliance on reductionist science. We propose that complex systems analysis is an essential tool for shock research and we evaluate its application to genomic technologies.

Shock at the millennium II. Walter B. Cannon and Lawrence J. Henderson.

Walter B. Cannon and Lawrence J. Henderson, students of shock in the early twentieth century, were contemporaries for four decades in the Harvard Department of Physiology. While their discoveries continue to have important clinical applications, both men established complementary methods of scientific investigation and description. Both men were inspired by Claude Bernard, hewing to his principle of the stability of the milieu intérieur. Cannon, the traditional experimentalist, employed a reductionist approach by holding constant the confounding variables of his experiments; in contrast, Henderson, the strategist of theoretical analysis, deduced patterns and relationships from less constrained models, focusing on complexity using mathematics and graphs. In delineation, Cannon described mechanisms; Henderson described the organization of systems. Cannon's emphasis on homeostasis with the identification of feedback arcs dominated shock research for the balance of the twentieth century. Henderson's perspective designating the importance of organization to those restorative mechanisms could well reemerge to dominate the twenty-first.

Association between heart rate variability recorded on postoperative day 1 and length of stay in abdominal aortic surgery patients.

OBJECTIVE: To determine whether heart rate variability (HRV) measured in the surgical intensive care unit (ICU) on the first postoperative day predicts clinical outcome in patients undergoing abdominal aortic surgery. DESIGN: Prospective study. SETTING: Eighteen-bed surgical ICU of a 1,442-bed university hospital. PATIENTS: One hundred and six patients admitted to the ICU after abdominal aortic surgery. MEASUREMENTS AND MAIN RESULTS: Twenty-four-hour Holter recordings were analyzed for standard time and frequency domain indices and one nonlinear index (slope) of HRV. Clinical and demographic data were collected from medical records. Patients were dichotomized into short (< or = 7 days) and long (> 7 days) length of stay (LOS) by median split. Patients with long LOS had increased heart rates and decreased short- and intermediate-term HRV but no difference in overall HRV, which primarily reflects circadian rhythm. Independent predictors of LOS were increased age, insulin-dependent diabetes, and decreased HRV. CONCLUSIONS: Increased heart rates and decreased intermediate-term HRV indices measured on postoperative day 1 were independent predictors of complicated recovery. The strongest HRV predictors of outcome were natural logarithm very-low-frequency power measured over 24 hrs and during the daytime. Results support the potential use of HRV for the prediction of postsurgical resource utilization.

Extreme warfarin sensitivity in siblings associated with multiple cytochrome P450 polymorphisms.

Warfarin use is complicated by an erratic dose response. Warfarin is metabolized by two distinct subfamilies of the cytochrome P450 (CYP) complex. We describe two siblings with extreme sensitivity to warfarin who share an unusual CYP genotype. These individuals illustrate both the importance of genetics in influencing the metabolism of warfarin as well as the potential utility of genetic testing as a guide to prescribing this medication.

A prospective, randomized study comparing percutaneous with surgical tracheostomy in critically ill patients.

OBJECTIVE: To determine the relative cost-effectiveness of percutaneous dilational tracheostomy (PDT) and surgical tracheostomy (ST) in critically ill patients. DESIGN: Prospective randomized study. SETTING: Medical, surgical, and coronary intensive care units at Barnes-Jewish Hospital, a tertiary care medical center. PATIENTS: Eighty critically ill mechanically ventilated patients requiring elective tracheostomy. INTERVENTIONS: Randomization to either PDT performed in the intensive care unit or ST performed in the operating room. MEASUREMENTS AND MAIN RESULTS: Treatment groups were well matched with respect to age (PDT, 65.44 +/- 2.82 [mean +/- se] years; ST, 61.4 +/- 2.89 years, p = Ns), gender (PDT, 45% males; ST, 47.5% males, p = NS), severity of illness (Acute Physiology and Chronic Health Evaluation II score: PDT, 16.87 +/- 0.84; ST, 17.88 +/- 0.92, p = NS), and principle diagnosis. PDT was performed more quickly (PDT, 20.1 +/- 2.0 mins; ST, 41.7 +/- 3.9 mins, p < .0001) and was associated with lower patient charges than ST (total patient charges: PDT, 1,569 dollars +/- 157 dollars vs. ST, 3,172 dollars +/- 114 dollars; equipment/supply charges: PDT, 688 dollars +/- 103 dollars vs. ST, 1,526 dollars +/- 87 dollars; professional charges: PDT, 880 dollars +/- 54 dollars vs. ST, 1,647 dollars +/- 50 dollars; p < .0001 for all). There were no differences in days intubated before tracheostomy (PDT, 12.7 +/- 1.1 days; ST, 15.6 +/- 1.9, p = .20), intensive care unit length of stay (PDT, 24.5 +/- 2.5 days; ST, 28.5 +/- 3.1 days, p = .33), or hospital length of stay (PDT 49.7 +/- 4.2 days; ST, 43.7 +/- 3.5 days, p = .28) when we compared these two techniques. CONCLUSIONS: PDT is a cost-effective alternative to ST. The reduction in patient charges associated with PDT in this study resulted from the procedure being performed in the intensive care unit, thus eliminating the need for operating room facilities and personnel. PDT may become the procedure of choice for electively establishing tracheostomy in the appropriately selected patient who requires long-term mechanical ventilation.

Sepsis-induced apoptosis causes progressive profound depletion of B and CD4+ T lymphocytes in humans.

Patients with sepsis have impaired host defenses that contribute to the lethality of the disorder. Recent work implicates lymphocyte apoptosis as a potential factor in the immunosuppression of sepsis. If lymphocyte apoptosis is an important mechanism, specific subsets of lymphocytes may be more vulnerable. A prospective study of lymphocyte cell typing and apoptosis was conducted in spleens from 27 patients with sepsis and 25 patients with trauma. Spleens from 16 critically ill nonseptic (3 prospective and 13 retrospective) patients were also evaluated. Immunohistochemical staining showed a caspase-9-mediated profound progressive loss of B and CD4 T helper cells in sepsis. Interestingly, sepsis did not decrease CD8 T or NK cells. Although there was no overall effect on lymphocytes from critically ill nonseptic patients (considered as a group), certain individual patients did exhibit significant loss of B and CD4 T cells. The loss of B and CD4 T cells in sepsis is especially significant because it occurs during life-threatening infection, a state in which massive lymphocyte clonal expansion should exist. Mitochondria-dependent lymphocyte apoptosis may contribute to the immunosuppression in sepsis by decreasing the number of immune effector cells. Similar loss of lymphocytes may be occurring in critically ill patients with other disorders.

Injury in the era of genomics.

The traditional approach to the study of biology employs small-scale experimentation that results in the description of a molecular sequence of known function or relevance. In the era of the genome the reverse is true, as large-scale cloning and gene sequencing come first, followed by the use of computational methods to systematically determine gene function and regulation. The overarching goal of this new approach is to translate the knowledge learned from a systematic, global analysis of genomic data into a complete understanding of biology. For investigators who study shock, the specific goal is to increase understanding of the adaptive response to injury at the level of the entire genome. This review describes our initial experience using DNA microarrays to profile stress-induced changes in gene expression. We conclude that efforts to apply genomics to the study of injury are best coordinated by multi-disciplinary groups, because of the extensive expertise required.

The heat shock paradox: does NF-kappaB determine cell fate?

Cellular injury induces an adaptive response whether the insult is physical (e.g., heat, radiation), chemical (e.g., reactive oxygen species), infectious (e.g., bacteria), or inflammatory (e.g., lipopolysaccharide). Recent data indicate that the interactions of these responses are not predictable and that sequence permutations can have opposite effects on outcome after injury. Our overarching hypothesis is that interactions among stress responses contribute to the fate of cells, tissues, and organisms and that modulation of these interactions can have important affects on both function and survival. For example, whereas it is well known that a prior heat shock stress can protect cells against inflammatory stress both in vitro and in vivo, we and others have shown that induction of a subsequent heat stress in cells 'primed' by inflammation can precipitate cell death by apoptosis. We call this seemingly paradoxical ability of heat shock to induce cytoprotection and cytotoxicity the heat shock paradox. The molecular mechanisms by which cells integrate responses to these and other stresses are poorly understood. We present data linking the heat shock paradox to the activity of the acute-phase transcription factor nuclear factor kappa B (identifying an 'NF-kappaB paradox') and hypothesize that the mechanism is linked to the downstream effects of induction of NF-kappaB's endogenous inhibitor, IkappaBalpha, a putative heat shock protein.

A meta-analysis of prospective trials comparing percutaneous and surgical tracheostomy in critically ill patients.

STUDY OBJECTIVES: Tracheostomy is one of the most commonly performed procedures in the patient receiving long-term mechanical ventilation. While percutaneous dilational tracheostomy (PDT) is becoming increasingly utilized as an alternative to conventional surgical tracheostomy, most literature evaluating these two techniques is neither prospective nor controlled. We performed a meta-analysis of available prospective controlled studies comparing PDT and surgical tracheostomy in critically ill patients to more fully understand the relative benefits and risks of these two procedures in this population. DESIGN: Meta-analysis using Mantel-Haenszel fixed effect model. INTERVENTIONS: We performed searches of MEDLINE, Current Contents, Best Evidence, Cochrane, and HealthSTAR databases from 1985 to present to identify prospective controlled studies comparing PDT and surgical tracheostomy in critically ill patients. After establishing clinical and statistical homogeneity (Q: statistic), studies were analyzed by a Mantel-Haenszel fixed effect model. For each clinical end point examined, PDT and surgical tracheostomy were compared by calculating either absolute differences or odds ratios (ORs) with 95% confidence intervals (CIs) for continuous or discrete variables, respectively. MEASUREMENTS AND RESULTS: We pooled data from five studies (236 patients) satisfying our search criteria to analyze eight clinical end points. Operative time was shorter for PDT than surgical tracheostomy: absolute difference with 95% CI, 9. 84 min (7.83 to 10.85 min). There was no difference comparing PDT and surgical tracheostomy with respect to overall operative complication rates: OR with 95% CI, 0.732 (0.05 to 9.37). However, relative to surgical tracheostomy, PDT was associated with less perioperative bleeding (OR with 95% CI, 0.14 [0.02 to 0.39]), a lower overall postoperative complication rate (OR with 95% CI, 0.14 [0.07 to 0.29]), as well as a lower postoperative incidence of bleeding (OR with 95% CI, 0.39 [0.17 to 0.88]), and stomal infection (OR with 95% CI, 0.02 [0.01 to 0.07]). No difference was identified in days intubated prior to tracheostomy (absolute difference with 95% CI, 0.16 days [- 0.9 to 1.22 days]), overall procedure-related complications (OR with 95% CI, 0.73 [0.06 to 9.37]), or death (OR with 95% CI, 0.63 [0.18 to 2.20]) comparing these two techniques. CONCLUSIONS: Despite its popularity, there are currently only a limited number of small studies prospectively evaluating PDT and surgical tracheostomy. Our meta-analysis of these studies suggests potential advantages of PDT relative to surgical tracheostomy, including ease of performance, and lower incidence of peristomal bleeding and postoperative infection. If confirmed by additional, adequately powered prospective trials, these findings support PDT as the procedure of choice for the establishment of elective tracheostomy in the appropriately selected critically ill patient.

Injection of iron compounds followed by induction of the stress response causes tissue injury and apoptosis.

To determine whether iron-laden tissue subsequently stimulated to produce the stress ("heat shock") response-sustained injury, hindlimbs of male ND4 mice were injected with iron salts, hemin, or hemoglobin. The stress response was induced with sodium arsenite or with heat. Ulcers appeared at the injection site. Tissues were analyzed by three distinct techniques-electron microscopy, TUNEL stain, and agarose gel electrophoresis of low molecular weight DNA-which collectively suggest that the tissue injury is, at least in part, the consequence of accelerated apoptosis. The data suggest that the toxicity of free iron is amplified by induction of the stress (heat shock) response to signal a programmed response. This model and mechanism may have implications in pathological processes ranging from the cutaneous wounds of venous stasis disease to the tissue failure of multiple organ dysfunction.

Rapid onset of intestinal epithelial and lymphocyte apoptotic cell death in patients with trauma and shock.

OBJECTIVE: Apoptosis is a cellular suicide program that can be activated by cell injury or stress. Although a number of laboratory studies have shown that ischemia/reperfusion injury can induce apoptosis, few clinical studies have been performed. The purpose of this study was to determine whether apoptosis is a major mechanism of cell death in intestinal epithelial cells and lymphocytes in patients who sustained trauma, shock, and ischemia/ reperfusion injury. DESIGN: Intestinal tissues were obtained intraoperatively from 10 patients with acute traumatic injuries as a result of motor vehicle collisions or gun shot wounds. A control population consisted of six patients who underwent elective bowel resections. Apoptosis was evaluated by conventional light microscopy, laser scanning confocal microscopy using the nuclear staining dye Hoechst 33342, immunohistochemical staining for active caspase-3, and immunohistochemical staining for cytokeratin 18. SETTING: Academic medical center. PATIENTS: Patients with trauma or elective bowel resections. MEASUREMENTS AND MAIN RESULTS: Extensive focal crypt epithelial and lymphocyte apoptosis were demonstrated by multiple methods of examination in the majority of trauma patients. Trauma patients having the highest injury severity score tended to have the most severe apoptosis. Repeat intestinal samples obtained from two of the trauma patients who had a high degree of apoptosis on initial evaluation were negative for apoptosis at the time of the second operation. Tissue lymphocyte apoptosis was associated with a markedly decreased circulating lymphocyte count in 9 of 10 trauma patients. CONCLUSIONS: Focal apoptosis of intestinal epithelial and lymphoid tissues occurs extremely rapidly after injury. Apoptotic loss of intestinal epithelial cells may compromise bowel wall integrity and be a mechanism for bacterial or endotoxin translocation into the systemic circulation. Apoptosis of lymphocytes may impair immunologic defenses and predispose to infection.