To determine the effectiveness of early, routine antioxidant supplementation using alpha-tocopherol and ascorbic acid in reducing the rate of pulmonary morbidity and organ dysfunction in critically ...ill surgical patients.
Oxidative stress has been associated with the development of the acute respiratory distress syndrome (ARDS) and organ failure through direct tissue injury and activation of genes integral to the inflammatory response. In addition, depletion of endogenous antioxidants has been associated with an increased risk of nosocomial infections. The authors postulated that antioxidant supplementation in critically ill surgical patients may reduce the incidence of ARDS, pneumonia, and organ dysfunction.
This randomized, prospective study was conducted to compare outcomes in patients receiving antioxidant supplementation (alpha-tocopherol and ascorbate) versus those receiving standard care. The primary endpoint for analysis was pulmonary morbidity (a composite measure of ARDS and nosocomial pneumonia). Secondary endpoints included the development of multiple organ failure, duration of mechanical ventilation, length of ICU stay, and mortality.
Five hundred ninety-five patients were enrolled and analyzed, 91% of whom were victims of trauma. The relative risk of pulmonary morbidity was 0.81 (95% confidence interval 0.60-1.1) in patients receiving antioxidant supplementation. Multiple organ failure was significantly less likely to occur in patients receiving antioxidants than in patients receiving standard care, with a relative risk of 0.43 (95% confidence interval 0.19-0.96). Patients randomized to antioxidant supplementation also had a shorter duration of mechanical ventilation and length of ICU stay.
The early administration of antioxidant supplementation using alpha-tocopherol and ascorbic acid reduces the incidence of organ failure and shortens ICU length of stay in this cohort of critically ill surgical patients.
This paper is concerned with spatially-varying acoustic liner impedance in aeroacoustic ducts, in the presence of a high sound pressure level. It is shown that impedance discontinuity is a leading ...order parameter in the definition of the impedance variation. A large impedance discontinuity yields a high normal velocity variation, leading to significant nonlinear effects. An iterative numerical strategy is proposed to predict the spatially-varying acoustic impedance over a liner. A Bayesian inference process is coupled with a surrogate model to validate the model with measurements of the acoustic velocity fields above a liner at a high sound intensity, obtained using laser Doppler velocimetry.
•Impedance discontinuities affect the nonlinear response of acoustic liners at grazing incidence.•An iterative process is proposed to model the liner nonlinearity at grazing incidence.•The convergence of the iteration depends on the liner resistance value.•The nonlinear impedance effect is less pronounced in ducts having a lower duct height.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
IMPORTANCE: Traumatic brain injury (TBI) is the leading cause of death and disability due to trauma. Early administration of tranexamic acid may benefit patients with TBI. OBJECTIVE: To determine ...whether tranexamic acid treatment initiated in the out-of-hospital setting within 2 hours of injury improves neurologic outcome in patients with moderate or severe TBI. DESIGN, SETTING, AND PARTICIPANTS: Multicenter, double-blinded, randomized clinical trial at 20 trauma centers and 39 emergency medical services agencies in the US and Canada from May 2015 to November 2017. Eligible participants (N = 1280) included out-of-hospital patients with TBI aged 15 years or older with Glasgow Coma Scale score of 12 or less and systolic blood pressure of 90 mm Hg or higher. INTERVENTIONS: Three interventions were evaluated, with treatment initiated within 2 hours of TBI: out-of-hospital tranexamic acid (1 g) bolus and in-hospital tranexamic acid (1 g) 8-hour infusion (bolus maintenance group; n = 312), out-of-hospital tranexamic acid (2 g) bolus and in-hospital placebo 8-hour infusion (bolus only group; n = 345), and out-of-hospital placebo bolus and in-hospital placebo 8-hour infusion (placebo group; n = 309). MAIN OUTCOMES AND MEASURES: The primary outcome was favorable neurologic function at 6 months (Glasgow Outcome Scale-Extended score >4 moderate disability or good recovery) in the combined tranexamic acid group vs the placebo group. Asymmetric significance thresholds were set at 0.1 for benefit and 0.025 for harm. There were 18 secondary end points, of which 5 are reported in this article: 28-day mortality, 6-month Disability Rating Scale score (range, 0 no disability to 30 death), progression of intracranial hemorrhage, incidence of seizures, and incidence of thromboembolic events. RESULTS: Among 1063 participants, a study drug was not administered to 96 randomized participants and 1 participant was excluded, resulting in 966 participants in the analysis population (mean age, 42 years; 255 74% male participants; mean Glasgow Coma Scale score, 8). Of these participants, 819 (84.8%) were available for primary outcome analysis at 6-month follow-up. The primary outcome occurred in 65% of patients in the tranexamic acid groups vs 62% in the placebo group (difference, 3.5%; 90% 1-sided confidence limit for benefit, −0.9%; P = .16; 97.5% 1-sided confidence limit for harm, 10.2%; P = .84). There was no statistically significant difference in 28-day mortality between the tranexamic acid groups vs the placebo group (14% vs 17%; difference, −2.9% 95% CI, −7.9% to 2.1%; P = .26), 6-month Disability Rating Scale score (6.8 vs 7.6; difference, −0.9 95% CI, −2.5 to 0.7; P = .29), or progression of intracranial hemorrhage (16% vs 20%; difference, −5.4% 95% CI, −12.8% to 2.1%; P = .16). CONCLUSIONS AND RELEVANCE: Among patients with moderate to severe TBI, out-of-hospital tranexamic acid administration within 2 hours of injury compared with placebo did not significantly improve 6-month neurologic outcome as measured by the Glasgow Outcome Scale-Extended. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT01990768
BACKGROUND:Thrombelastography (TEG) fibrinolysis shutdown after trauma is associated with increased mortality due to hypercoagulability-associated organ failure. However, a lack of mechanistic data ...has precluded the development of novel interventions to treat shutdown.
OBJECTIVES:To define the pathophysiology of TEG shutdown in severely injured, bleeding patients through secondary analysis of the PROPPR trial.
METHODS:Fibrinolysis was characterized in PROPPR subjects using admission TEG lysis at 30 min (LY30) or plasmin-antiplasmin (PAP) levels. LY30 categories were low (<0.9%), moderate (0.9–2.9%), or high (≥ 3%). PAP was classified as low (<1,500 μg/L), moderate (1,500–20,000 μg/L), or high (>20,000 μg/L). Demographics, outcomes, admission TEG values, platelet count and function, standard coagulation tests, and coagulation proteins were compared.
RESULTS:Five hundred forty-seven patients had TEG data and 549 patients had PAP data available. Low LY30 was associated with reduced platelet count and aggregation, poorer TEG clot formation, prolonged clotting times, and reduced fibrinogen and alpha2 antiplasmin. Compared to moderate PAP, low PAP subjects had similar platelet parameters, TEG values, fibrinogen, and alpha2 antiplasmin, but reduced tPA, and elevated PAI-1. D-Dimer values increased as PAP increased, however patients with low LY30 had elevated D-Dimer compared with moderate LY30 patients. Most low LY30 deaths were due to TBI (45%) and hemorrhage (42%) versus one of each cause (TBI, hemorrhage, MOF) in low PAP patients.
CONCLUSIONS:Low TEG LY30 does not reflect shutdown of enzymatic fibrinolysis with hypercoagulability, but rather a coagulopathic state of moderate fibrinolysis with fibrinogen consumption and platelet dysfunction that is associated with poor outcomes.
Thermal engineering deals with the estimation of the temperature at different spatial points and different instants for a given set of boundary and initial conditions. For this purpose, the reference ...model is a numerical simulation model but it is time-consuming. Consequently we build a surrogate model in order to replace it. This surrogate model is a recursive multilayer perceptron, independent of the boundary conditions and parametrized by the statistical learning of multidimensional temporal trajectories computed with the reference model. It emulates the outputs of the reference model over time from the only knowledge of initial conditions and exogenous variables. Moreover this model is able to predict these outputs in steady state, even if its formulation is time-dependent.
A new methodology is proposed so as to overcome the learning problem associated to the very weak number of trajectories available for the surrogate model construction. The first step attempts to build a more robust surrogate model by considering it as the average of local models resulting from the V-folds cross-validation technique. This new kind of multilayer perceptron is much more robust and accurate, in particular when the learning dataset is very small. The second step consists in the creation of a new learning dataset which is made up of each time observation coming from each trajectory. In this way, we artificially obtain a sizeable sample allowing all the classic neural networks constructions.
Furthermore, many approaches exist in order to select the best hidden neurons number but most of them are costly or require a lot of observations. We consider here a non-asymptotic approach based on the minimization of a penalized criterion providing accurate results in an economical computational way. In order to calibrate precisely the penalty term, we use the slope heuristic or the dimension jump, recently introduced in a regression framework. The validation of the method is performed on a toy function.
The prediction ability of the surrogate model built with the new methodology is successfully compared to usual constructions on a simplified problem and then applied to thermal engineering.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The transfusion of older packed RBCs may be harmful in critically ill patients. We seek to determine the association between packed RBC age and mortality among trauma patients requiring massive ...packed RBC transfusion.
We analyzed data from the Pragmatic, Randomized Optimal Platelet and Plasma Ratios trial. Subjects in the parent trial included critically injured adult patients admitted to 1 of 12 North American Level I trauma centers who received at least 1 unit of packed RBCs and were predicted to require massive blood transfusion. The primary exposure was volume of packed RBC units transfused during the first 24 hours of hospitalization, stratified by packed RBC age category: 0 to 7 days, 8 to 14 days, 15 to 21 days, and greater than or equal to 22 days. The primary outcome was 24-hour mortality. We evaluated the association between transfused volume of each packed RBC age category and 24-hour survival, using random-effects logistic regression, adjusting for total packed RBC volume, patient age, sex, race, mechanism of injury, Injury Severity Score, Revised Trauma Score, clinical site, and trial treatment group.
The 678 patients included in the analysis received a total of 8,830 packed RBC units. One hundred patients (14.8%) died within the first 24 hours. On multivariable analysis, the number of packed RBCs greater than or equal to 22 days old was independently associated with increased 24-hour mortality (adjusted odds ratio OR 1.05 per packed RBC unit; 95% confidence interval CI 1.01 to 1.08): OR 0.97 for 0 to 7 days old (95% CI 0.88 to 1.08), OR 1.04 for 8 to 14 days old (95% CI 0.99 to 1.09), and OR 1.02 for 15 to 21 days old (95% CI 0.98 to 1.06). Results of sensitivity analyses were similar only among patients who received greater than or equal to 10 packed RBC units.
Increasing quantities of older packed RBCs are associated with increased likelihood of 24-hour mortality in trauma patients receiving massive packed RBC transfusion (≥10 units), but not in those who receive fewer than 10 units.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Endotheliopathy of trauma is characterized by breakdown of the endothelial glycocalyx. Elevated biomarkers of endotheliopathy, such as serum syndecan-1 (Synd-1) ≥ 40 ng/mL, have been associated with ...increased need for transfusions, complications, and mortality. We hypothesized that severely injured trauma patients who exhibit elevated Synd-1 levels shortly after admission have an increased likelihood of developing sepsis.
We analyzed a subset of patients from the Pragmatic, Randomized Optimal Platelet and Plasma Ratios (PROPPR) trial who survived at least 72 hours after hospital admission, and we determined elevated Synd-1 levels (≥ 40 ng/mL) 4 hours after hospital arrival. Sepsis was defined a priori as meeting systemic inflammatory response criteria and having a known or suspected infection. Univariate analysis was performed to identify variables associated with elevated Synd-1 levels and sepsis. Significant variables at a value of p < 0.2 in the univariate analysis were chosen by purposeful selection and analyzed in a mixed effects multivariate logistic regression model to account for the 12 different study sites.
We included 512 patients. Of these, 402 (79%) had elevated Synd-1 levels, and 180 (35%) developed sepsis. Median Synd-1 levels at 4 hours after admission were 70 ng/dL (interquartile range IQR 36 to 157 ng/dL) in patients who did not develop sepsis, and 165 ng/dL IQR 67 to 336 ng/dL in those who did (p < 0.001). Adjusting for treatment arm and site, multivariable analyses revealed that elevated Synd-1 status, Injury Severity Score (ISS), and total blood transfused were significantly associated with an increased likelihood of developing sepsis.
Elevated Synd-1 levels 4 hours after admission in severely injured adult trauma patients who survived the initial 72 hours after hospital admission are associated with subsequent sepsis.
Rib fractures are common and associated with significant pulmonary morbidity. We hypothesized that epidural analgesia would provide superior pain relief, and reduce the risk of subsequent pneumonia.
...A prospective, randomized trial of epidural analgesia versus IV opioids for the management of chest wall pain after rib fractures was carried out. Entry criteria included patients older than 18 years with more than 3 rib fractures and no contraindications to epidural catheter placement.
From March 2000 to December 2003, 408 patients were admitted with more than 3 rib fractures; 282 met exclusion criteria, 80 could not be consented, and 46 were enrolled (epidural n=22, opioids n=24). The groups were comparable for mean age, injury severity score, gender, chest Abbreviated Injury Scale, and mean number of rib fractures. The epidural group tended to have more flail segments (38% vs 21%, P=.20) and pulmonary contusions (59% vs 38%, P=.14), and required more chest tubes (95% vs 71%, P=.03) Despite the greater direct pulmonary injury in the epidural group, their rate of pneumonia was 18% versus 38% for the intravenous opioid group. When adjusted for direct pulmonary injury, there was a greater risk of pneumonia in the opioid group: OR, 6.0; 95% CI, 1.0-35; P=.05. When stratified for the presence of pulmonary contusion there was a 2.0-fold increase in the number of ventilator days for the opioid group: incident rate ratio, 2.0; 95% CI, 1.6-2.6; P<.001.
The use of epidural analgesia is limited in the trauma population due to numerous exclusion criteria. However, when feasible, epidural analgesia is associated with a decrease in the rate of nosocomial pneumonia and a shorter duration of mechanical ventilation after rib fractures.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Disruption of the vascular endothelium and endothelial glycocalyx (EG) has been described after severe trauma. Plasma has been suggested to restore microvascular integrity by preservation and repair ...of the EG. We sought to evaluate whether plasma administered in a 1:1:1 ratio was associated with less endothelial marker circulation than a 1:1:2 ratio.
This is a secondary analysis of the PROPPR trial, which investigated post-traumatic resuscitation with platelets, plasma, and red blood cells in a 1:1:1 ratio compared with a 1:1:2 ratio. Syndecan-1, soluble thrombomodulin (sTM), and receptor for advanced glycation end products (RAGE) were quantified for each treatment group on admission and at 2 hours, 4 hours, 6 hours, 12 hours, 24 hours, 48 hours, and 72 hours. Patients were excluded if they did not survive longer than 3 hours or had data from fewer than two time points.
Three hundred eight patients in the 1:1:1 group and 291 in the 1:1:2 group were analyzed. There were no statistically significant differences in syndecan-1, sTM, or RAGE between treatment groups at any time point ( p > 0.05). Patients who developed acute respiratory distress syndrome, acute kidney injury, and death had significantly elevated biomarker expression at most time points when compared with patients who did not develop these sequelae ( p < 0.05).
Administration of FFP in a 1:1:1 ratio does not consistently affect circulation of endothelial biomarkers following significant trauma when compared with a 1:1:2 ratio. The development of post-traumatic ARDS, AKI, and death was associated with increased endothelial biomarker circulation.
Therapeutic/Care Management; Level III.
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