1,720,964 research outputs found
Early postoperative cognitive recovery and gas exchange patterns after balanced anesthesia with sevoflurane or desflurane in overweight and obese patients undergoing craniotomy.
No full textAbstract: Overweight and obese patients are at especially high risk for delayed awakening after general surgery. Whether this risk also applies to cerebral neurosurgical procedures remains unclear. This study evaluated early postoperative cognitive recovery and gas exchange patterns, after balanced anesthesia with sevoflurane or desflurane, in overweight and obese patients undergoing craniotomy for supratentorial expanding lesions. Fifty-six patients were consecutively enrolled, and randomly assigned to 1 of 2 study groups to receive balanced anesthesia with sevoflurane or desflurane. Cognitive function was evaluated with the Short Orientation Memory Concentration Test and the Rancho Los Amigos Scale and gas exchange patterns (pH, PaO2, and PaCO2) were recorded in all patients at 5 time-points: preoperatively and postoperatively, after patients reached an Aldrete score Z9, at 15, 30, 45, and 60 minutes. Preoperative cognitive status was similar in the 2 treatment groups. Early postoperative cognitive recovery was more delayed and Short Orientation Memory Concentration Test scores at 15 and 30 minutes postanesthesia were lower in patients receiving sevoflurane- based anesthesia than in those receiving desfluranebased anesthesia (21.5±3.5 vs. 14.9±3.5) (P<0.005) and (26.9±0.7 vs. 21.5±1.4) (P<0.005), and the postoperative Rancho Los Amigos Scalegrade 8 showed a similar trend (25/28 patients 89% vs. 8/28 patients 28% (P<0.005) and 28/28 patients (100% vs. 13/28 patients 46%) (P<0.005). Similarly, gas-exchange analysis showed higher PaCO2 at 15 and 30 minutes and lower pH up to 45 minutes postextubation in patients receiving sevoflurane-based anesthesia. In overweight and obese patients undergoing craniotomy desflurane-based anesthesia allows earlier postoperative cognitive recovery and reversal to normocapnia and normal pH. Key Words: neuroanesthesia, postoperativ
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
Postoperative cognitive dysfunction: toward the Alzheimer disease: Pathomechanism Hypothesis
No full textAlzheimer’s disease (AD), a chronic and progressive deterioration of memory and other cognitive domains, is the
most common form of dementia. Because of related health and social impact, there is growing interest in assessing potential
relationship between anesthesia and the onset and progression of chronic neurodegenerative disorders, including AD. Currently,
preclinical and clinical research is addressed to identify underlying pathomechanisms, patient risk factors, and the use of the
least provocative drugs and techniques, to minimize the incidence of chronic neurodegenerative disorders. Preclinical studies are
providing an increasing body of evidences on some of the mechanisms that link anesthetics to neuronal programmed cell death
(apoptosis) and accumulation of misfolded proteins in the aging brain. Therefore, risk factors and pathomechanisms of chronic
neurodegenerative disorders, including AD, and persistent postoperative-postanesthesia cognitive dysfunction may overla
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
Esmolol blunts postoperative hemodynamic changes after propofol-remifentanyl total intravenous fast-track neuroanesthesia for intracranial surgery.
No full textAbstract
Study Objective: To investigate whether esmolol is effective in attenuating postoperative hemodynamic
changes related to sympathetic overdrive.
Design: Clinical study.
Setting: Operating room of a university hospital.
Patients: 60 ASA physical status I, II, and III patients, age 18 to 65 years, scheduled for elective
craniotomy for supratentorial neurosurgery.
Interventions: Patients were given total intravenous anesthesia (TIVA) during emergence from
anesthesia and up to 60 minutes after extubation. Those patients who had hypertension (defined as an
increase in systolic blood pressure N20% from baseline values) and tachycardia (defined as an increase
N20% in heart rate from baseline) received a loading dose of 500 μg/kg esmolol in one minute, followed
by an infusion titrated stepwise (50, 100, 200, and 300 μg/kg per min) every two minutes.
Measurements: The mean dose and duration of esmolol therapy were measured.
Main Results: Of 60 patients, 49 (82%) who received propofol-remifentanil TIVA developed significant
tachycardia and hypertension soon after extubation. Treatment with esmolol (500 μg/kg in bolus
maintained at a mean rate of 200 ± 50 μg/kg per min) effectively controlled hypertension and
tachycardia in 45 of 49 patients (92%; P b 0.05) within a mean 4.30 ± 2.20 minutes. After extubation,
mean esmolol infusion time was 29 ± 8 minutes
Bulbar compression due to vertebrobasilar artery doliohectasia causing persistent hiccups in a patient successfully treated with diuretics and corticosteroids.
No full textVertebrobasilar artery dolichoectasia is rarely syntomatic. The reported clinical manifestation include sign of cranial nerve or brain stem compression. These complications typycally develop when the basilar artery is elongated or ectasic and lies laterally to the margin of the clivus or dorsum sellae thus leading to bulbar compression. Persitent hiccups is a rare condition frequently associated with esophagogastric irritational noxae, chest tumors or cerebral expanding lesion in posterior fossa. When we have ruled out systemic (peripheral) causes, patiens presenting with cronic persistent hiccups should undergo non invasive brain imaging (angioCT- MR) to rule out possible underlying encephalic causes requiring tailored therapy
Endotracheal lidocaine in preventing endotracheal suctioning-indiced changes in cerebral hemodynamics in patients with severe head trauma.
No full textntroduction In patients with severe head trauma, endotracheal suctioning can result in adverse reactions
including cough, systemic hypertension, increased intracranial pressure, and reduced cerebral perfusion pressure.
The aim of this prospective, blinded clinical trial in
mechanically ventilated patients with severe head trauma
whose cough reflexes were still intact was to assess the
effectiveness of endotracheally instilled lidocaine in preventing endotracheal suctioning-induced changes in
cerebral hemodynamics (increase in intracranial pressure
and reduced cerebral perfusion pressure) after a single
endotracheal suctioning.
Methods and Results Ten minutes after lidocaine instillation into the endotracheal tube, secretions were suctioned
for <30 s through a standard closed endotracheal suctioning circuit. Heart rate, arterial pressure, intracranial
pressure, and cerebral perfusion pressure were continuously monitored. The first patient studied received an
endotracheal lidocaine dose of 2.0 mg/kg. The dose for the
next study patient was titrated upwards or downwards in
0.5 mg/kg steps according to, whether the intracranial
pressure reached the predefined threshold of ‡20 mmHg. A
total of 41 patients were studied. Lidocaine instillation into
the endotracheal tube had no effect on hemodynamic and
ventilatory variables. In 21 patients lidocaine dose instilled
into the endotracheal tube effectively prevented the endotracheal suctioning-induced intracranial pressure increase
behind the predefined threshold of ‡20 mmHg and cerebral
perfusion pressure remained unchanged. In the remaining
20, although intracranial pressure rose significantly cerebral perfusion pressure remained constant.
Conclusions In mechanically ventilated patients with
severe head trauma endotracheal lidocaine instillation
effectively and dose-dependently prevents the endotracheal
suctioning-induced intracranial pressure increase and
cerebral perfusion pressure reduction
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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