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Search Results: 1 - 10 of 52928 matches for " David Fagnoul "
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Cardiac output measurements using the bioreactance technique in critically ill patients
David Fagnoul, Jean-Louis Vincent, De Daniel Backer
Critical Care , 2012, DOI: 10.1186/cc11481
Abstract: Measurement of cardiac output (CO) requires use of invasive or minimally invasive devices; the use of noninvasive and minimally invasive devices has gained popularity in recent years. The bioreactance technique is a relatively new, continuous, totally non-invasive technique for measuring CO that is easily implemented. This new technique involves analyzing phase shifts of a delivered oscillating current that occur when the current traverses the thoracic cavity [1], and differs from traditional bioimpedance techniques that rely on analysis of changes in signal amplitude. Most validation studies in critically ill patients have shown good correlation and/or agreement of bioreactance values compared with CO values obtained using other devices in patients admitted after cardiac surgery [2-4]. However, validation in critically ill patients is lacking.As part of the internal evaluation of a bioreactance device before its implementation in the unit (evaluation of new non-invasive monitoring systems before introduction in the unit does not require the approval of the ethics committee in our institution), we compared CO values obtained using the bioreactance technique (NICOM system; Cheetah Medical Inc., Portland, OR, USA) with those measured using semi-continuous cardiac output by thermodilution (CCO) with a pulmonary artery catheter (Vigilance, Edwards LifeSciences, Irvine, CA, USA). In 11 patients the CO values were compared at study inclusion and each time a relevant change in hemodynamics and/or in therapeutics (for example, fluid challenge, inotrope or vasopressor infusions) was observed (Table 1).We recorded bioreactance CO (average of five values over a 5-minute period) just after obtaining the pulmonary artery catheter CCO (average of five CCO values over a 5-minute period). We collected 141 pairs of measurements (3 to 23 per patient); the duration of monitoring was at least 3 hours but never exceeded 24 hours. The pulmonary artery catheter CCO values ranged from 3.9
Cerebral oximetry during extracorporeal cardiopulmonary resuscitation
Fabio Taccone, David Fagnoul, Benoit Rondelet, Jean-Louis Vincent, Daniel de Backer
Critical Care , 2013, DOI: 10.1186/cc11929
Abstract: Brain damage remains the most important cause of morbidity and mortality among survivors after cardiac arrest. However, it remains unclear how systemic hemodynamics should be adjusted to ensure adequate cerebral oxygenation. Cerebral oximetry has been used to optimize cerebral perfusion during conventional CPR [1], and very low cerebral saturation (<40%) may predict poor neurological outcomes at hospital discharge in patients with OHCA [2]. ECMO has been shown to be effective to resuscitate adult patients following refractory cardiac arrest with intact neurological outcomes in 15% to 30% of cases [3,4]. Nevertheless, only scarce data are available on the adequacy of cerebral oxygenation during eCPR, and most of them focus on pediatric patients. In one retrospective study, Wong and colleagues [5] described their experience with cerebral oximetry monitoring in 20 adult patients with ECMO; in this population, low cerebral saturation occurred in all patients and was corrected in 80% of them by various interventions to optimize brain perfusion, including increasing MAP or ECMO blood flow [5]. In our patient, cerebral saturation remained very low during CPR and only just exceeded 40% with initial ECMO settings, and both of these factors probably were implicated in the irreversible brain damage.We suggest that cerebral oximetry be used to rapidly adjust ECMO blood flow to provide adequate brain oxygenation in patients undergoing eCPR. The impact of such an approach on outcomes warrants further evaluation.CPR: cardiopulmonary resuscitation; ECMO: extracorporeal membrane oxygenation; eCPR: extracorporeal cardiopulmonary resuscitation; MAP: mean arterial pressure; OHCA: out-of-hospital cardiac arrest; PaO2: arterial partial oxygen pressure; StO2' tissue hemoglobin saturation.The authors declare that they have no competing interests.DF, DdB, and BR were directly involved in the medical management of the patient. FST was responsible for cerebral oximetry monitoring. All authors
The influence of the different elements of an organic molecule structure on the main kinetic parameters of its unimolecular reaction in the high-pressure region  [PDF]
David Krinkin
Natural Science (NS) , 2011, DOI: 10.4236/ns.2011.38090
Abstract: The most general dynamic tendencies of the energy redistribution in the high-pressure region are considered. Their influence on the possible deviations from the kinetic conceptions, which is now generally accepted, is examined. In this way, the structural elements of an organic molecule that promote internal energy mobilization in the high-pressure region and, conversely, hamper it, are defined. The first of these elements reduces both the Arrhenius parameters of the unimolecular reactions while the second leads to the opposite results. Some well-known exceptions to existing kinetic theories, which find an explanation in the framework of these proposed concepts, is considered. The proposed concept is very general as distinct from the existing dynamic studies, which investigate more particular details of the separate bond behaviors. The proposed general concept can broaden the study of chemical kinetics.
Raising Engagement and Enhancing Learning: School Community Partnerships That Work for Students at Promise  [PDF]
David Zyngier
Creative Education (CE) , 2011, DOI: 10.4236/ce.2011.24053
Abstract: This paper reports on a pilot study that investigates the widely reported issue of underachievement of students from Culturally Linguistically and Economically Diverse (CLED) backgrounds. It involves 15 university education faculty student volunteers and over 40 students and their families in primary (elementary) schools situated in disadvantaged communities of Victoria whose students come from 40 different nationalities, speaking 36 languages and with 75 per cent of its student cohort coming from Non English Speaking Backgrounds. A partnership was formed to focus on the problem of CLED children’s disengagement from their academic learning. We focus on how a productive partnership between schools and a university impact on inclusive teaching and learning practices both at the school and the university level. We investigate whether such an intervention can have an impact on engagement levels and the learning and social outcomes of students from refugee, migrant and working class families. Privileging participant voice we analyze data from interviews, surveys and focus groups with students, teachers and parents to argue that such a program has the capacity to re-engage underachieving students at a minimal cost to the community as an alternative model to other expensive and unsuccessful intervention programs. We conclude that at the core of this successful program is the need for both participants to feel they are empowered in the process. We know that student outcomes can be enhanced when the students feel connected to and involved in their community. Through this project, the students have the opportunity to experience greater community engagement leading to improved school attendance and retention, as well as better academic outcomes.
A Simple Proof That the Curl Defined as Circulation Density Is a Vector-Valued Function, and an Alternative Approach to Proving Stoke’s Theorem  [PDF]
David McKay
Advances in Pure Mathematics (APM) , 2012, DOI: 10.4236/apm.2012.21007
Abstract: This article offers a simple but rigorous proof that the curl defined as a limit of circulation density is a vector-valued function with the standard Cartesian expression.
“Your Guide to Paediactric Anesthesia” by Sims and Johnson: A Book Review  [PDF]
David Faraoni
Open Journal of Anesthesiology (OJAnes) , 2012, DOI: 10.4236/ojanes.2012.21003
Abstract: “Your Guide to Paediatric Anaesthesia”by Sims and Johnson is the first edition of a book written for fellow or non-pediatric anesthetists. The authors give a practical approach for daily practice in pediatric anesthesia. This \"book review\" describes a general presentation and an objective evaluation of this recently published book.
On Choosing Fourier Transforms for Practical Geoscience Applications  [PDF]
David Boteler
International Journal of Geosciences (IJG) , 2012, DOI: 10.4236/ijg.2012.325096
Abstract: The variety of definitions of Fourier transforms can create confusion for practical applications. This paper examines the choice of formulas for Fourier transforms and determines the appropriate choices for geoscience applications. One set of Discrete Fourier Transforms can be defined that approximate Fourier integrals and provide transforms between sampled continuous functions in both domains. For applications involving transforms between a continuous function and a discrete function a second set of Discrete Fourier Transforms is needed with different scaling factors. Two classes of application are presented: those where either form of transforms can be used and those where it is necessary to use a particular transform to obtain the correct results.
Investment Incentives under Price-Cap Regulation  [PDF]
David Bartolini
Theoretical Economics Letters (TEL) , 2012, DOI: 10.4236/tel.2012.25105
Abstract: In the literature on price regulation, the price-cap mechanism is seen as a very powerful incentive mechanism towards efficiency improvements. What about quality investments? The empirical literature is not univocal: Some studies suggest a deterioration of quality, while others do not find any statistically significant impact. We analyze the incentive provided by price-cap regulation in a setting in which the investment decisions of the regulated firm suffer from hold-up, and contacts are incomplete. We show that the incentives to invest in cost-saving innovations can be fostered by a price-cap contract with a “sufficient” regulatory lag, while for other types of investments, such as quality enhancement, the same contract does not help. Furthermore, we show that if the firm faces a binding resource constraint the price-cap contract generates a crowding-out effect between the two types of investment. This might explain the non univocal empirical evidence.


IMPEX: An Approach to Analyze Source Code Changes on Software Run Behavior  [PDF]
David Nemer
Journal of Software Engineering and Applications (JSEA) , 2013, DOI: 10.4236/jsea.2013.64020
Abstract:

The development of software nowadays is getting more complex due to the need to use software programs to accomplish more elaborated tasks. Developers may have a hard time knowing what could happen to the software when making changes. To support the developer in reducing the uncertainty of the impact on the software run behavior due to changes in the source code, this paper presents a tool called IMPEX which analyzes the differences in the source code and differences on the run behavior of two subsequent software versions, in the entire repository, demonstrating to the developer the impact that a change in the source code has had on the software run, over the whole software history. This impact helps the developers in knowing what is affected during execution due to their changes in the source code. This study verifies that the software runs that are most impacted by a given change in the source code, have higher chances in being impacted in the future whenever this part of the code is changed again. The approach taken in this paper was able to precisely predict what would be impacted on the software execution when a change in the source code was made in 70% of the cases.

Raymond Carver and the Ethos of Drinking  [PDF]
David McCracken
Advances in Literary Study (ALS) , 2013, DOI: 10.4236/als.2013.12004
Abstract: In Raymond Carver’s “Careful”, “Gazebo”, and “Chef’s House”, characters depend on the process of drinking as a paradigm to understand their lives. In these three stories, the characters rely upon alcohol as a solution to problems paradoxically caused by their addiction to alcohol.
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