1,720,990 research outputs found
Non-invasive hemodynamic monitoring techniques for detecting Preload responsiveness in critically ill patients
Full text linkVolume expansion is the first-line treatment for acute circulatory failure in almost all cases. However, its inconsistent effectiveness and its side effects make it necessary to predict the effects before undertaking it. Several tests have been developed to detect this state of preload dependence, and we are interested in refining some of them and improve their use. The end expiratory occlusion (EEXPO) test consists in transiently stopping mechanical ventilation at end expiration to increase venous return and, thus, cardiac preload. In preload responder patients it is expected to increase cardiac output. We have gathered an amount of information from the existing literature, showing that its ability of detecting fluid responsiveness is very high, through a systematic review and meta-analysis. The effects of this test must be assessed on cardiac output, and several methods have already been described for this. Bioreactance is a completely non invasive technique to measure cardiac output, which has been demonstrated to be reliable in detecting preload responsiveness through a passive leg raising (PLR) maneuver. Nevertheless, its role in detecting a positive EEXPO test was never investigated. In the main study of this PhD project, we show that the current available commercial version of the bioreactance device is not
suitable for this purpose, due to its very long averaging and refreshing times (24 and 4 seconds, respectively). However, when we used a research version of the device, which allowed us to reduce both intervals (8 and 1 second for averaging and refreshing times, respectively), bioreactance proved to be a reliable method to detect preload responsiveness through the EEXPO test. We have also described an original and reliable method for measuring the effects of both PLR and EEXPO tests, which consists of measuring the perfusion index (PI), the ratio between the pulsatile and the non-pulsatile portion of the pulse oxygen saturation signal. Although the signal could not be collected stably in all patients, changes in this index during passive leg raising were able to measure the effects of the PLR test and predict the response to volume expansion. Similarly, Pl measurements could identify a positive EEXPO test, even though their changes were of lower amplitude compared to those of a PLR test. Our results open up the possibility of measuring the effects of these tests of preload responsiveness using non-invasive tools. This could prompt their use outside the intensive care unit, such as in the emergency department, where tracking changes of cardiac output during the first hours of the management of acute circulatory failure could lead to a more rational use of fluid administration
Insights from Italy: the Novara-COVID score for rapid destination of COVID-19 patients at emergency department presentation
No full textElectromagnetic Navigation Bronchoscopy: Where Are We Now? Five Years of a Single-Center Experience
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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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