102,627 research outputs found
Non-invasive ventilation in postoperative patients: A systematic review
No full textBackground: Postoperative pulmonary complications, generally defined as any pulmonary abnormality occurring in the postoperative period, are still a significant issue in clinical practice increasing hospital length of stay, morbidity and mortality. Non-invasive ventilation (NIV), primarily applied in cardiogenic pulmonary edema, decompensated COPD and hypoxemic pulmonary failure, is nowadays also used in perioperative settings. Objective: Investigate the application and results of preventive and therapeutic NIV in postsurgical patients. Design: A systematic review. Data sources: Medical literature databases were searched for articles about "clinical trials," "randomized controlled trials" and "meta-analyses." The keywords "cardiac surgery," "thoracic surgery," "lung surgery," "abdominal surgery," "solid organ transplantation," "thoraco-abdominal surgery" and "bariatric surgery" were combined with any of these: "non-invasive positive pressure ventilation," "continuous positive airway pressure," "bilevel ventilation," "postoperative complications," "postoperative care," "respiratory care," "acute respiratory failure," "acute lung injury" and "acute respiratory distress syndrome." Results: Twenty-nine articles (N = 2,279 patients) met the inclusion criteria. Nine studies evaluated NIV in post-abdominal surgery, three in thoracic surgery, eight in cardiac surgery, three in thoraco-abdominal surgery, four in bariatric surgery and two in post solid organ transplantation used both for prophylactic and therapeutic purposes. NIV improved arterial blood gases in 15 of the 22 prophylactic and in 4 of the 7 therapeutic studies, respectively. NIV reduced the intubation rate in 11 of the 29 studies and improved outcome in only 1. Conclusions: Despite these limited data and the necessity of new randomized trials, NIV could be considered as a prophylactic and therapeutic tool to improve gas exchange in postoperative patients. © 2011 jointly held by Springer and ESICM
Atomic-scale expressions for viscosity and fragile-strong behavior in metal alloys based on the Zwanzig-Mountain formula
No full textWe combine the shoving model ofT-dependent viscosity of supercooled liquids with the Zwanzig-Mountainformula for the high-frequency shear modulus using theg(r) of molecular dynamics simulations of metal alloysas the input. This scheme leads to a semianalytical expression for the viscosity as a function of temperature,which provides a three-parameter model fitting of experimental data of viscosity for the same alloy for whichg(r) was calculated. The model provides direct access to the influence of atomic-scale physical quantities suchas the interatomic potentialφ(r) on the viscosity and fragile-strong behavior. In particular, it is established thata steeper interatomic repulsion leads to fragile liquids, or, conversely, that “soft atoms make strong liquids.
Arsac G., Chevallard Y., Martinand J.-L., Tiberghien A. (Eds) (1994). La transposition didactique à l’épreuve. Grenoble, La Pensée Sauvage
No full textde Bueger-Van der Borght Cécile. Arsac G., Chevallard Y., Martinand J.-L., Tiberghien A. (Eds) (1994). La transposition didactique à l’épreuve. Grenoble, La Pensée Sauvage. In: Didaskalia, n°7, 1995. Enseignement des sciences et des techniques à l'école élémentaire. pp. 161-162
Static and dynamic components of esophageal and central venous pressure during intra-abdominal hypertension
No full textOBJECTIVE: To investigate the effects of intra-abdominal hypertension on esophageal and central venous pressure considering values obtained at end-expiration (i.e., in static conditions) and during tidal volume delivery (i.e., in dynamic conditions). DESIGN: Retrospective (pigs) and prospective, randomized, controlled (rats) trial. SETTING: Animal laboratory of a university hospital. SUBJECTS: Six female pigs and 15 Sprague Dawley male rats. INTERVENTIONS: During anesthesia and paralysis, animals' abdomens were inflated with helium. MEASUREMENTS AND MAIN RESULTS: Abdominal pressure was measured by intraperitoneal catheter. In pigs, esophageal pressure and central venous pressure were continuously measured while inflating the abdomen together with hemodynamic assessment. In rats, the abdomen was inflated after the random application of three levels of positive end-expiratory pressure. Data are shown as mean ± sd. At end-expiration, esophageal pressures were similar before and after abdominal inflation (p = .177). In contrast, the dynamic component significantly rose after intra-abdominal hypertension, from 3.2 ± 0.7 cm H2O to 10.0 ± 2.3 cm H2O (p < .001), and was correlated with peritoneal pressure (linear regression, R = .708, p < .001). Positive end-expiratory pressure significantly influenced static esophageal pressure during intra-abdominal hypertension (p = .002) but not dynamic pressures.Static central venous pressure rose with intra-abdominal hypertension from 4.1 ± 1.5 cm H2O to 6.7 ± 1.8 cm H2O (p = .043), more so the dynamic component (from 2.9 ± 0.8 cm H2O to 9.3 ± 3.1 cm H2O, p = .02). Dynamic changes of esophageal pressures correlated with dynamic changes of central venous pressure (linear regression, R = .679, p < .001). Mean values of central venous pressure significantly increased with intra-abdominal hypertension from 7.7 ± 1.5 cm H2O to 12.7 ± 2.6 cm H2O (p = .006), whereas transmural central venous pressure and intrathoracic blood volume did not change significantly. CONCLUSIONS: Dynamic changes of esophageal pressure occurred during intra-abdominal hypertension, whereas end-expiratory pressure was affected by high positive end-expiratory pressure levels. Provided that central venous pressure changes reflect esophageal pressure, central venous pressure itself cannot be relied on to guide resuscitation in patients with intra-abdominal hypertension, particularly when abdominal pressures are changing over short periods of time
Lactate as a marker of energy failure in critically ill patients : hypothesis
No full textLactate measurement in the critically ill has been traditionally used to stratify patients with poor outcome. However, plasma lactate levels are the result of a finely tuned interplay of factors that affect the balance between its production and its clearance. When the oxygen supply does not match its consumption, organisms such as man who are forced to produce ATP for their integrity adapt in many different ways up to the point when energy failure occurs. Lactate, being part of the adaptive response, may then be used to assess the severity of the supply/demand imbalance. In such a scenario, the time to intervention becomes relevant: early and effective treatment may allow the cell to revert to a normal state, as long as the oxygen machinery (i.e. mithocondria) is intact. Conversely, once the mithocondria are deranged, energy failure occurs even in the presence of normoxia. The lactate increase in critically ill patients may therefore be viewed as an early marker of a potentially reversible state
Benzodiazepines induce hyperglycemia in rats by affecting peripheral disposal of glucose
No full textIntroduction : In light of the interest in the relationship between glycemia control in critically ill subjects and outcome, we set up a study to investigate whether benzodiazepine, commonly used in anesthesia and ICUs, interferes with glucose metabolism and to explore the mechanism.
Methods : A total of 40 sedated and paralyzed Sprague-Dawley rats (301 ± 55 g) were investigated in four consecutive studies. (1) To investigate the effects of diazepam on blood glucose, 15 rats were randomly assigned to intraperitoneal anesthesia with tiopenthal 80 mg/kg (DZP0), tiopenthal 40 mg/kg + diazepam 5 mg/kg (DPZ5) or tiopenthal 40 mg/kg + diazepam 15 mg/kg (DZP15). Blood levels of glucose (GEM premier 3000; IL) were measured at time intervals over 2 hours. (2) Ten animals randomized to DZP0 or DZP5 underwent an intravenous glucose tolerance test with glucose bolus (0.5 g/kg). Acute insulin response, the mean value of blood insulin (Insulin ELISA kit; Millipore) from 2 to 10 minutes after glucose bolus, was measured as index of insulin secretion. (3) A hyperinsulinemic euglycemic clamp obtained by a continuous intravenous infusion of insulin (130 mUI/kg/minute) was run in 10 animals randomized to DZP0 or DZP5 and the glucose infusion rate (GIR, mg/kg/minute) was assessed [1]. (4) The effect of midazolam on blood glucose was tested in five additional animals (M5: tiophental 40 mg/kg + midazolam 5 mg/kg). Data are presented as mean ± SEM. Statistical analysis (ANOVA, t test) was conducted with Sigma Stat 3.1 (Systat Software). Conclusion : Both diazepam and midazolam significantly alter plasma glucose levels in rats. Peripheral disposal of glucose rather than altered pancreas secretion of insulin explains the benzodiazepine-associated hyperglycemia
Bibliographie Hilarion G. Petzold 1958 – 2009 mit Anhang als Einführung
No full textDieses Archiv enthält die Gesamtbibliographie der Werke des Autors nebst einiger Texte „Über H. G. Petzold“ im Schlussteil der Bibliographie sowie einen Anhang mit einer Einführung in die Architektur des Werkes in seinem wissenslogischen Aufbau als Ausarbeitung seines „Tree of Science Modells“ (2007).This archive contains the complete bibliography of the author and some texts about H. G. Petzold, moreover an epilogue with an introduction to the architecture of the works in its epistemological structure and composition and as an elaborations of Petzold’s „Tree of Science Modell (2007).https://www.fpi-publikation.de/polyloge/01-2009-petzold-h-g-gesamtbibliographie-h-g-petzold-1958-2009-updating-november2009/peerReviewedpublishedVersio
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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