Design of a Third-party Reverse Logistics Network under a Carbon Tax Scheme

© 2016 Eastern Macedonia and Thrace Institute of Technology. Reverse logistics network involves significant inherent uncertainties, which cannot be completely characterized because of a lack of adequate historical data. In this study, a multi-product and multi-period interval programming model was developed on the basis of partial information to design an effective reverse logistics network. In addition, the trade-offbetween economic benefits and the environmental burdens from carbon emissions was analyzed by considering the effect of a carbon tax scheme on the reverse logistics network design. Through an improved and modified interval linear programming method, the optimal interval solution was obtained with LINGO. Finally, numerical simulations were conducted to explore the effectiveness of the model and the effect of the carbon tax scheme. Results show that the optimal solution of the reverse logistics network design is robust. The effect of the carbon tax scheme is trivial when the carbon tax is low and significant when the carbon tax is high. As carbon tax gradually increases, carbon emissions effectively decrease, but sharply declines the total profit sharply declines. The findings indicate that the proposed model can effectively solve the reverse logistics network design with partial information under a carbon tax scheme

A dream deferred: the rise and fall of recombinant activated protein C

CITATION: Ranieri VM, Thompson BT, Barie PS, Dhainaut JF, Douglas IS, Finfer S, Gårdlund B, Marshall JC, Rhodes A, Artigas A, Payen D, Tenhunen J, Al-Khalidi HR, Thompson V, Janes J, Macias WL, Vangerow B, Williams MD: Drotrecogin alfa (activated) in adult patients with septic shock. N Engl J Med 2012, 366:2055-2064

High-frequency oscillation in early adult respiratory distress syndrome

Background\ud Previous trials suggesting that high-frequency oscillatory ventilation (HFOV) reduced mortality among adults with the acute respiratory distress syndrome (ARDS) were limited by the use of outdated comparator ventilation strategies and small sample sizes.\ud \ud Methods\ud Objective: The aim of the study was to compare HFOV with a conventional ventilation strategy that used low tidal volumes and high levels of positive end-expiratory pressure in patients with new-onset, early (<72 hours) moderate to severe ARDS.\ud \ud Design: A multicenter, randomized, controlled trial was conducted in 39 ICUs in five countries.\ud \ud Setting: Participants were adults with new-onset, moderate to severe ARDS.\ud \ud Intervention: Patients were randomly assigned to HFOV targeting lung recruitment or to a control ventilation strategy targeting lung recruitment with the use of low tidal volumes and high positive end-expiratory pressure.\ud \ud Measurements: The primary outcome was the 60-day in-hospital mortality from any cause. Secondary outcomes included ICU mortality, 28-day mortality, new barotrauma, new tracheostomy, refractory hypoxemia, refractory acidosis, mechanical ventilation duration in survivors, ICU duration in survivors, and hospitalization in survivors.\ud \ud Results\ud On the recommendation of the data monitoring committee, we stopped the trial after 548 out of a planned 1,200 patients had undergone randomization. The two study groups were well matched at baseline. The HFOV group underwent HFOV for a median of 3 days (interquartile range, 2 to 8); in addition, 34 of 273 patients (12%) in the control group received HFOV for refractory hypoxemia. In-hospital mortality was 47% in the HFOV group, as compared with 35% in the control group (relative risk of death with HFOV, 1.33; 95% confidence interval, 1.09 to 1.64; P = 0.005). This finding was independent of baseline abnormalities in oxygenation or respiratory compliance. Patients in the HFOV group received higher doses of midazolam than did patients in the control group (199 mg/day (interquartile range, 100 to 382) vs. 141 mg/day (interquartile range, 68 to 240), P < 0.001), and more patients in the HFOV group than in the control group received neuromuscular blockers (83% vs. 68%, P < 0.001). In addition, more patients in the HFOV group received vasoactive drugs (91% vs. 84%, P = 0.01) and received them for a longer period than did patients in the control group (5 days vs. 3 days, P = 0.01).\ud \ud Conclusions\ud In adults with moderate-to-severe ARDS, early application of HFOV, as compared with a ventilation strategy of low tidal volume and high positive end-expiratory pressure, does not reduce, and may increase, in-hospital mortality.\ud \ud Ventilator management is a key component of acute respiratory distress syndrome (ARDS) management. Low tidal volume (6 ml/kg) ventilation has been shown to reduce mortality [1], raising the question of whether high-frequency oscillatory ventilation (HFOV) with even lower tidal volumes will be even more beneficial. The theory behind HFOV is to couple a very small tidal volume (approximately 1 to 2 ml/kg) with a very high respiratory rate (3 to 15 breaths/second), thus providing a constant mean airway pressure, and limiting alveolar overdistension and repetitive collapse and reopening injury.\ud \ud In the United States, HFOV has been sporadically used in adult ARDS patients after the US Food and Drug Administration cleared it for pediatric use in the 1990s. A 2010 meta-analysis of HFOV versus conventional ventilation (CV) for ARDS pooled six trials. The meta-analysis included four adult trials, a total of 291 adult patients. The study concluded that HFOV might reduce hospital mortality in patients with ARDS compared with CV and is unlikely to cause harm [2]. However, some of the trials did not use lung-protective ventilation in the CV group [2, 3, 4].\ud \ud HFOV has been used in ARDS patients as a rescue therapy. More recently, HFOV has been used as primary or secondary therapy early in the disease course, with some evidence of success [5, 6]. However, the efficacy of HFOV in adults with early ARDS has not been proven. The current OSCILLATE trial sought to address this clinical question.\ud \ud The OSCILLATE trial compared HFOV with a CV strategy that used low tidal volumes and high levels of positive end-expiratory pressure in patients with new-onset, early (<72 hours since onset of respiratory failure), moderate to severe ARDS. The primary outcome was hospital mortality. Patients discharged from hospital were assumed to be alive at 60 days. Secondary outcomes were mortality at other time points, barotrauma, organ dysfunction, duration of ventilation, and duration of ICU and hospital stay. The study cohort was relatively young (mean age 55 years) and had high acuity (mean Acute Physiology and Chronic Health Evaluation II score of 29). Approximately one-half of the patients had sepsis and/or pneumonia. Close to two-thirds were on vasopressors or inotropes at baseline. In-hospital mortality was 47 % in the HFOV group, as compared with 35 % in the control group (P = 0.005).\ud \ud The OSCILLATE trial was a well-conducted, large, multicenter trial performed in several countries. The HFOV protocol was standardized based on pilot testing and consensus guidelines. There was concern for a learning curve associated with the use of HFOV, and most patients were enrolled at centers that were experienced with HFOV. However, subgroup analyses did not detect an interaction between treatment effect and the number of patients enrolled per site. Why then did the OSCILLATE trial demonstrate harm with HFOV?\ud \ud First, the HFOV group received more sedatives and vasoactive drugs (91% vs. 84%, P = 0.01). Vasoactive drugs and neuromuscular blockers were administered for longer in the HFOV group. One mechanism for hypotension in HFOV is that high intrathoracic pressures lead to decreased preload and right ventricular dysfunction, and consequently hemodynamic compromise. Sedatives and opioids (most commonly midazolam and fentanyl) that can cause vasodilatation were administered for the same duration in the two groups (median 10 days), but during the first week the median doses were higher in the HFOV group.\ud \ud Second, central venous pressure was used for volume assessment. The study used central venous pressure greater than 12 cmH2O as the cutoff point for adequate intravascular volume prior to initiating the study protocol. Central venous pressure is an imperfect surrogate for volume status and preload. Central venous pressure less than 12 cmH2O does not necessarily indicate inadequate volume status. Echocardiogram, pulse pressure variation, or other monitoring technologies could be used for more accurate intravascular volume monitoring during HFOV.\ud \ud Third, the OSCILLATE trial used recruitment maneuvers and relatively high mean airway pressure; initial mean airway pressures were 30 cmH2O and often increased up to 38 cmH2O. The OSCAR trial did not use mandatory recruitment maneuvers and set the initial mean airway pressure to 5 cmH2O above the peak plateau pressure (mean mean airway pressure 26.9 cmH2O on day 1 and 25.1 cmH2O on day 3) and showed no harm with HFOV compared with CV [7]. In contrast to results of the OSCILLATE trial, there was no difference in 30-day mortality and no significant difference in the duration of inotropic agents or pressor use between HFOV and CV in the OSCAR trial.\ud \ud The OSCILLATE trial found that HFOV did not reduce, and may increase, mortality in early ARDS patients. Further study of the ideal HFOV setting and appropriate patient population and hemodynamic monitoring during HFOV are warranted

The Adult Respiratory Distress Syndrome Cognitive Outcomes Study: long-term neuropsychological function in survivors of acute lung injury

CITATION: Mikkelsen ME, Christie JD, Lanken PN, Biester RC, Thompson BT, Bellamy SL, Localio AR, Demissie E, Hopkins RO, Angus DC: The adult respiratory distress syndrome cognitive outcomes study: long-term neuropsychological function in survivors of acute lung injury. Am J Respir Crit Care Med 2012, 185:1307-1315

Is there a role for music in the ICU?

Background\ud Alternatives to sedative medications, such as music, may alleviate the anxiety associated with ventilatory support.\ud \ud Methods\ud Objective: The aim of the study was to test whether listening to self-initiated patient-directed music (PDM) can reduce anxiety and sedative exposure during ventilatory support in critically ill patients.\ud \ud Design: This study was a randomized clinical trial.\ud \ud Setting: In 12 ICUs of five hospitals in the Minneapolis–St Paul, Minnesota area, 373 patients receiving acute mechanical ventilatory support for respiratory failure were enrolled between September 2006 and March 2011. Of the patients included in the study, 86% were white, 52% were female, and the mean age was 59 years. The patients had a mean Acute Physiology, Age and Chronic Health Evaluation III score of 63 and a mean of 5.7 study days.\ud \ud Interventions: The patients received self-initiated PDM (n =126) with preferred selections tailored by a music therapist, or self-initiated use of noise-canceling headphones (NCH; n = 122), or usual care (n = 125).\ud \ud Outcomes: Daily assessments of anxiety (on a 100 mm visual analog scale) and two aggregate measures of sedative exposure (intensity and frequency) were assessed.\ud \ud Results\ud Patients in the PDM group listened to music for a mean of 79.8 (median (range) 12 (0 to 796)) minutes/day. Patients in the NCH group wore the noise-abating headphones for a mean of 34.0 (median (range), 0 (0 to 916)) minutes/day. The mixed-models analysis showed that, at any time point, patients in the PDM group had an anxiety score that was 19.5 points lower (95% confidence interval, −32.2 to −6.8) than patients in the usual care group (P = 0.003). By the fifth study day, anxiety was reduced by 36.5% in PDM patients. The treatment × time interaction showed that PDM significantly reduced both measures of sedative exposure. Compared with usual care, the PDM group had reduced sedation intensity by −0.18 (95% confidence interval, −0.36 to −0.004) points/day (P = 0.05) and had reduced frequency by −0.21 (95% confidence interval, −0.37 to −0.05) points/day (P = 0.01). The PDM group had reduced sedation frequency by −0.18 (95% confidence interval, −0.36 to −0.004) points/day versus the NCH group (P = 0.04). By the fifth study day, the PDM patients received two fewer sedative doses (reduction of 38%) and had a reduction of 36% in sedation intensity.\ud \ud Conclusions\ud Among ICU patients receiving acute ventilatory support for respiratory failure, PDM resulted in greater reduction in anxiety compared with usual care, but not compared with NCH. Concurrently, PDM resulted in greater reduction in sedation frequency compared with usual care or NCH, and greater reduction in sedation intensity compared with usual care but not compared with NCH

ω-3 fatty acids, γ-linolenic acid, and antioxidants: immunomodulators or inert dietary supplements?

Citation: Rice TW, Wheeler AP, Thompson BT, deBoisblanc BP, Steingrub J, Rock, P. Enteral Omega-3 Fatty Acid, γ-Linolenic Acid, and Antioxidant Supplementation in Acute Lung Injury. JAMA. 2011; 306(14):1574-1581. PubMed PMID: 21976613.Background: The omega-3 (n-3) fatty acids docosahexaenoic acid and eicosapentaenoic acid, along with γ-linolenic acid and antioxidants, may modulate systemic inflammatory response and improve oxygenation and outcomes in patients with acute lung injury.Methods: Objective: To determine if dietary supplementation of these substances to patients with acute lung injury would increase ventilator-free days to study day 28.Design: The OMEGA study, a randomized, double-blind, placebo-controlled, multicenter trial conducted from January 2, 2008, through February 21, 2009. All participants had complete follow-up.Setting: This trial occurred at 44 hospitals in the National Heart, Lung, and Blood Institute ARDS Clinical Trials Network.Subjects: Participants were 272 adults within 48 hours of developing acute lung injury requiring mechanical ventilation whose physicians intended to start enteral nutrition.Intervention: Twice-daily enteral supplementation of n-3 fatty acids, γ -linolenic acid, and antioxidants compared with an isocaloric control. Enteral nutrition, directed by a protocol, was delivered separately from the study supplement.Outcomes: Ventilator-free days to study day 28.Results: The study was stopped early for futility after 143 and 129 patients were enrolled in the n-3 and control groups. Despite an 8-fold increase in plasma eicosapentaenoic acid levels, patients receiving the n-3 supplement had fewer ventilator-free days (14.0 vs 17.2; P=.02) (difference, -3.2 [95% CI, -5.8 to -0.7]) and intensive care unit-free days (14.0 vs 16.7; P=.04). Patients in the n-3 group also had fewer nonpulmonary organ failure-free days (12.3 vs 15.5; P=.02). Sixty-day hospital mortality was 26.6% in the n 3 group vs 16.3% in the control group (P=.054), and adjusted 60-day mortality was 25.1% and 17.6% in the n-3 and control groups, respectively (P=.11). Use of the n-3 supplement resulted in more days with diarrhea (29% vs 21%; P=.001).Conclusions: Twice-daily enteral supplementation of n-3 fatty acids, γ-linolenic acid, and antioxidants did not improve the primary end point of ventilator-free days or other clinical outcomes in patients with acute lung injury and may be harmful. © 2012 BioMed Central Ltd

Quantifying the accuracy and precision of a novel real-time 6 degree-of-freedom kilovoltage intrafraction monitoring (KIM) target tracking system.

Target rotation can considerably impact the delivered radiotherapy dose depending on the tumour shape. More accurate tumour pose during radiotherapy treatment can be acquired through tracking in 6 degrees-of-freedom (6 DoF) rather than in translation only. A novel real-time 6 DoF kilovoltage intrafraction monitoring (KIM) target tracking system has recently been developed. In this study, we experimentally evaluated the accuracy and precision of the 6 DoF KIM implementation. Real-time 6 DoF KIM motion measurements were compared against the ground truth motion retrospectively derived from kV/MV triangulation for a range of lung and prostate tumour motion trajectories as well as for various static poses using a phantom. The accuracy and precision of 6 DoF KIM were calculated as the mean and standard deviation of the differences between KIM and kV/MV triangulation for each DoF, respectively. We found that KIM is able to provide 6 DoF motion with sub-degree and sub-millimetre accuracy and precision for a range of realistic tumour motion

SOTER on ROS: A Run-Time Assurance Framework on the Robot Operating System

We present an implementation of SOTER, a run-time assurance framework for building safe distributed mobile robotic (DMR) systems, on top of the Robot Operating System (ROS). The safety of DMR systems cannot always be guaranteed at design time, especially when complex, off-the-shelf components are used that cannot be verified easily. SOTER addresses this by providing a language-based approach for run-time assurance for DMR systems. SOTER implements the reactive robotic software using the language P, a domain-specific language designed for implementing asynchronous event-driven systems, along with an integrated run-time assurance system that allows programmers to use unfortified components but still provide safety guarantees. We describe an implementation of SOTER for ROS and demonstrate its efficacy using a multi-robot surveillance case study, with multiple run-time assurance modules. Through rigorous simulation, we show that SOTER enabled systems ensure safety, even when using unknown and untrusted components.Comment: 20th International Conference on Runtime Verificatio