High-frequency oscillation and tracheal gas insufflation in patients with severe acute respiratory distress syndrome and traumatic brain injury: an interventional physiological study

In acute respiratory distress syndrome (ARDS), combined high-frequency oscillation (HFO) and tracheal gas insufflation (TGI) improves gas exchange compared with conventional mechanical ventilation (CMV). We evaluated the effect of HFO-TGI on PaO2/fractional inspired O2 (FiO2) and PaCO2, systemic hemodynamics, intracranial pressure (ICP), and cerebral perfusion pressure (CPP) in patients with traumatic brain injury (TBI) and concurrent severe ARDS

The effect of high frequency oscillatory ventilation combined with tracheal gas insufflation on extravascular lung water in patients with acute respiratory distress syndrome: a randomized, crossover, physiological study.

Purpose: High frequency oscillation combined with tracheal gas insufflation (HFO-TGI) improves oxygenation in patients with Acute Respiratory Distress Syndrome (ARDS). There is limited physiologic data regarding the effects of HFO-TGI on hemodynamics and pulmonary edema during ARDS. The aim of this study was to investigate the effect of HFO-TGI on extravascular lung water (EVLW). Materials and Methods: We conducted a prospective, randomized, crossover study. Consecutive eligible patients with ARDS received sessions of conventional mechanical ventilation (CMV) with recruitment maneuvers (RMs), followed by HFO-TGI with RMs, or vice versa. Each ventilatory technique was administered for 8 hours. The order of administration was randomly assigned. Arterial/central venous blood gas analysis and measurement of hemodynamic parameters and EVLW were performed at baseline and after each 8-hour period using the single-indicator thermodilution technique. Results: Twelve patients received 32 sessions. PaO2/FiO2 and respiratory system compliance were higher (p<0.001 for both), while EVLW indexed to predicted body weight (EVLWI) and oxygenation index were lower (p=0.021 and 0.029, respectively) in HFO-TGI compared with CMV. There was a significant correlation between PaO2/FiO2 improvement and EVLWI drop during HFO-TGI (Rs=-0.452, p= 0.009). Conclusions: HFO-TGI improves gas exchange and lung mechanics in ARDS, and potentially attenuates EVLW accumulation

Gauged D=7 Supergravity on the S**1/Z_2 Orbifold

We construct the most general couplings of a bulk seven-dimensional Yang-Mills-Einstein N=2 supergravity with a boundary six-dimensional chiral N=(0,1) theory of vectors and charged hypermultiplets. The boundary consists of two brane worlds sitting at the fixed points of an S^1/Z_2 compactification of the seven-dimensional bulk supergravity. The resulting 6D massless spectrum surviving the orbifold projection is anomalous. By introducing boundary fields at the orbifold fixed points, we show that all anomalies are cancelled by a Green-Schwarz mechanism. In addition, all couplings of the boundary fields to the bulk are completely specified by supersymmetry. We emphasize that there is no bulk Chern-Simons term to cancel the anomalies. The latter is traded for a Green-Schwarz term which emerges in the boundary theory after a duality transformation implemented to construct the bulk supergravity.Comment: LaTeX, 42 pages; typos corrected, reference added, version to appear in Phys. Rev.

Advances in the Clinical Management of Cardiac Arrest

Cardiac arrest constitutes an extremely life-threatening condition that inevitably and promptly results in death if left untreated. Cardiac arrest outcomes still remain very poor, especially when the presenting cardiac rhythm is nonshockable. Important, recent, clinical research has focused on the quality of cardiopulmonary resuscitation (CPR), the mechanical augmentation of the circulation during CPR, CPR drugs, and therapeutic hypothermia. Chest compression depth of at least 51 mm increases the probability of neurologically favorable survival. Despite initially promising results, a large effectiveness study failed to confirm the efficacy of the mechanical augmentation of the circulation. Epinephrine has finally been shown to slightly improve functional outcome after out-of-hospital cardiac arrest, especially when given early. In a recent, in-hospital study of 268 patients, the addition of vasopressin and methylprednisolone during CPR and the administration of hydrocortisone in postresuscitation shock improved functional outcome after vasopressor-requiring cardiac arrest; however, corticosteroid efficacy still needs to be separately confirmed in a large, international trial. Lastly, preliminary human data may support the conduct of high quality trials evaluating the efficacy of beta adrenergic antagonists in shockable cardiac arrest. The purpose of this paper is to review these potentially important advances in the management of cardiac arrest.

Current Pharmacological Advances in the Treatment of Cardiac Arrest

Cardiac arrest requires immediate treatment, in order to prevent patient death. Cardiac arrest outcomes still remain very poor, especially when the patient requires vasopressor treatment. Vasopressors have been advocated, in order to increase the coronary and cerebral perfusion pressure during cardiopulmonary resuscitation (CPR). Recent data suggest an epinephrine-related benefit with respect to short- and long-term outcomes, only when epinephrine is administered within the first 10 min of collapse. Also, increasing the epinephrine dosing interval from 3-5 to 6-10 min during CPR may be associated with improved long-term outcomes. In the in-hospital setting, the combination of vasopressin, epinephrine, and corticosteroid supplementation during and after CPR (in the presence of postresuscitation shock) may be superior to epinephrine alone during CPR. The use of new formulations of amiodarone, potentially devoid of serious hypotensive effects, may contribute to increased rates of sustained return of spontaneous circulation in patients with ventricular fibrillation / pulseless ventricular tachycardia cardiac arrest. Encouraging preliminary results have been reported on the use of beta blockers in patients with shockable cardiac arrest. Other potentially promising pharmacological interventions include the use of cariporide, nitrates (and particularly inhaled nitric oxide), noble gases, levosimendan, and erythropoietin. The purpose of the current paper is to review the clinical and laboratory evidence that support new and potentially useful pharmacological interventions during CPR

On the velocity and chemical-potential dependence of the heavy-quark interaction in N=4 SYM plasmas

We consider the interaction of a heavy quark-antiquark pair moving in N=4 SYM plasma in the presence of non-vanishing chemical potentials. Of particular importance is the maximal length beyond which the interaction is practically turned off. We propose a simple phenomenological law that takes into account the velocity dependence of this screening length beyond the leading order and in addition its dependence on the R-charge. Our proposal is based on studies using rotating D3-branes.Comment: 24 pages, 10 figures; v2: energy regularization discussed in detail, references added, version to appear in Phys. Rev.

Improvement of source and wind field input of atmospheric dispersion model by assimilation of concentration measurements: Method and applications in idealized settings

AbstractThe problem of correcting the pollutant source emission rate and the wind velocity field inputs in a puff atmospheric dispersion model by data assimilation of concentration measurements has been considered. Variational approach to data assimilation has been used, in which the specified cost function is minimized with respect to source strength and/or wind field. The analyzed wind field satisfied the constraints derived from the conditions of mass conservation and linearized flow equations for perturbations from the first guess wind field. ‘Identical twin’ numerical experiments have been performed for the validation of the method. The first guess estimation errors of source emission rate and wind field were set to a factor of up to 10 and up to 6m/s respectively. The calculations results showed that in most studied cases an improvement of vector wind difference (VWD) error by about 0.7–1m/s could be achieved. The resulting normalized mean square error (NMSE) of concentration field was also reduced significantly

MODELLING THE CONCENTRATION FLUCTUATION AND INDIVIDUAL EXPOSURE IN COMPLEX URBAN ENVIRONMENTS

The concentrations fluctuations of a dispersing hazardous gaseous pollutant in the atmospheric boundary layer, and the hazard associated with short-term concentration levels, demonstrate the necessity of estimating the magnitude of these fluctuations using predicting models. Moreover the computation of concentration fluctuations and individual exposure in case of dispersion in realistic situations, such as built-up areas or street canyons, is of special practical interest for hazard assessment purposes. In order to predict or/and estimate the maximum expected dosage and the exposure time within which the dosage exceeds certain health limits, the knowledge of the behaviour of concentration fluctuations at the point under consideration is needed. In this study the whole effort is based on the ‘Mock Urban Setting Test – MUST’, an extensive field test carried out on a test site of the US Army in the Great Basin Desert in 2001 (Biltoft, 2001; Yee, 2004). The experimental data that was used for the model evaluation concerned the dispersion of a passive gas between street canyons which have been created by 120 standard size shipping containers. The computational simulations have been performed using the laboratory CFD code ADREA, which has been developed for simulating the dispersion and exposure of pollutants over complex geometries. The ADREA model is evaluated by comparing the model’s predictions with the observations utilizing statistical metrics and scatter plots. The present study has been performed in the frame of the Action COST 732 “Quality Assurance and Improvement of Micro-Scale Meteorological Models”