1,720,968 research outputs found
Prospective Clinical and Fiberoptic Evaluation of the Supreme Laryngeal Mask Airway ™
No full textBackground In March 2007, a new disposable laryngeal mask airway (LMA) became available. The LMA Supreme (The Laryngeal Mask Company Limited, St. Helier, Jersey, Channel Islands) aims to combine the LMA Fastrach feature of easy insertion with the gastric access and high oropharyngeal leak pressures of the LMA ProSeal. Methods The authors performed an evaluative study with the LMA Supreme, size 4, on 100 women to measure the ease of insertion, determinate the laryngeal fit by fiberoptic classification, evaluate the oropharyngeal leak pressure, and report adverse events. Results Insertion of the LMA Supreme was possible in 94 patients (94%) during the first attempt, and in 5 patients (5%) during the second attempt. In one small patient, the LMA Supreme could not be inserted because of limited pharyngeal space. This patient was excluded from further analysis. Insertion of a gastric tube was possible in all patients at the first attempt. The median time for LMA Supreme insertion was 10.0 s (+/-4.7 s; range, 8-30 s). Laryngeal fit, evaluated by fiberscopic view, was rated as optimal in all patients, both immediately after insertion of the LMA Supreme and at the end of surgery. After equalization to room pressure, the mean cuff volume needed to achieve 60 cm H2O cuff pressure was 18.4 ml (+/-3.8 ml; range, 8-31 ml). The mean oropharyngeal leak pressure at the level of 60 cm H2O cuff pressure was 28.1 cm H2O (+/-3.8 cm H2O, range, 21-35 cm H2O). Eight patients (8.1%) complained of a mild sore throat. No patient reported dysphagia or dysphonia. Conclusions Clinical evaluation of the LMA Supreme showed easy insertion, optimal laryngeal fit, and low airway morbidity. Oropharyngeal leak pressure results were comparable to earlier data from the LMA ProSeal
Reduced sevoflurane loss during cardiopulmonary bypass when using a polymethylpentane versus a polypropylene oxygenator
No full textPurpose: The goal of this investigation was to examine the influence of two oxygenators with different membranes, made of either polypropylene (PPL) or polymethylpentane (PMP), on the plasma concentration of sevoflurane during cardiopulmonary bypass. Methods: The concentrations of sevoflurane during cardiopulmonary bypass were examined in patient plasma, endotracheal tubes, cardiotomy reservoirs and the outlets of the heart-lung oxygenators in twenty patients who underwent elective heart surgery. Results: The sevoflurane losses are smaller in cardiopulmonary bypass when using a polymethylpentane versus a polypropylene oxygenator. Ten minutes after beginning cardiopulmonary bypass, the sevoflurane plasma concentration in the PPL oxygenator group compared to the PMP oxygenator group fell significantly (PPL 0.48-1.79 (0.93) vs. PMP 0.80-2.15 (1.56) mu L x 100 mL(-1), p = 0.02). This difference persisted until ten minutes after the termination of cardiopulmonary bypass. Conclusion: The results of this study show that using a polymethylpentane membrane oxygenator rather than a polypropylene oxygenator significantly reduces the losses of sevoflurane, resulting in higher plasma concentrations and greater depth of anesthesia
Moderate Hyperventilation during Intravenous Anesthesia Increases Net Cerebral Lactate Efflux
Full text linkBackground: Hyperventilation is known to decrease cerebral blood flow (CBF) and to impair cerebral metabolism, but the threshold in patients undergoing intravenous anesthesia is unknown. The authors hypothesized that reduced CBF associated with moderate hyperventilation might impair cerebral aerobic metabolism in patients undergoing intravenous anesthesia. Methods: Thirty male patients scheduled for coronary surgery were included in a prospective, controlled crossover trial. Measurements were performed under fentanyl-midazolam anesthesia in a randomized sequence aiming at partial pressures of carbon dioxide of 30 and 50 mmHg. Endpoints were CBF, blood flow velocity in the middle cerebral artery, and cerebral metabolic rates for oxygen, glucose, and lactate. Global CBF was measured using a modified Kety-Schmidt technique with argon as inert gas tracer. CBF velocity of the middle cerebral artery was recorded by transcranial Doppler sonography. Data were presented as mean (SD). Two-sided paired t tests and one-way ANOVA for repeated measures were used for statistical analysis. Results: Moderate hyperventilation significantly decreased CBF by 60%, blood flow velocity by 41%, cerebral oxygen delivery by 58%, and partial pressure of oxygen of the jugular venous bulb by 45%. Cerebral metabolic rates for oxygen and glucose remained unchanged; however, net cerebral lactate efflux significantly increased from -0.38 (2.18) to -2.41(2.43) mu mol min(-1) 100 g(-1). Conclusions: Moderate hyperventilation, when compared with moderate hypoventilation, in patients with cardiovascular disease undergoing intravenous anesthesia increased net cerebral lactate efflux and markedly reduced CBF and partial pressure of oxygen of the jugular venous bulb, suggesting partial impairment of cerebral aerobic metabolism at clinically relevant levels of hypocapnia
Prospective Clinical and Fiberoptic Evaluation of the Supreme Laryngeal Mask Airway (TM)
No full textBackground: In March 2007, a new disposable laryngeal mask airway (LMA) became available. The LMA Supreme (TM) (The Laryngeal Mask Company Limited, St. Helier, Jersey, Channel islands) aims to combine the LMA Fastrach (TM) feature of easy insertion with the gastric access and high oropharyngeal leak pressures of the LMA ProSeal (TM). Methods: The authors performed an evaluative study with the LMA Supreme (TM), size 4, on 100 women to measure the case of insertion, determinate the laryngeal fit by fiberoptic classification, evaluate the oropharyngeal leak pressure, and report adverse events. Results: Insertion of the LMA Supreme (TM) was possible in 94 patients (94%) during the first attempt, and in 5 patients (5%) during the second attempt. lit one small patient, the LMA Supreme (TM) could not be inserted because of limited pharyngeal space. This patient was excluded from further analysis. Insertion of a gastric tube was possible in all patients at the first attempt. The median time for LMA Supreme (TM) insertion was 10.0 s (+/- 4.7 s; range, 8-30 s). Laryngeal fit, evaluated by fiberscopic view, was rated as optimal in all patients, both immediately after insertion of the LMA Supreme (TM) and at the end of surgery. After equalization to room pressure, the mean cuff volume needed to achieve 60 cm H(2)O cuff pressure was 18.4 ml (+/- 3.8 ml; range, 8-31 ml). The mean oropharyngeal leak pressure at the level of 60 cm H(2)O cuff pressure was 28.1 cut H(2)O (+/- 3.8 cm H(2)O, range, 21-35 cm H(2)O). Eight patients (8.1%) complained of a mild sore throat. No patient reported dysphagia or dysphonia. Conclusions: Clinical evaluation of the LMA Supreme (TM) showed easy insertion, optimal laryngeal lit, and low airway morbidity. Oropharyngeal leak pressure results were comparable to earlier data from the LMA ProSeal (TM)
Prospective Clinical and Fiberoptic Evaluation of the Supreme Laryngeal Mask Airway (TM)
No full textBackground: In March 2007, a new disposable laryngeal mask airway (LMA) became available. The LMA Supreme (TM) (The Laryngeal Mask Company Limited, St. Helier, Jersey, Channel islands) aims to combine the LMA Fastrach (TM) feature of easy insertion with the gastric access and high oropharyngeal leak pressures of the LMA ProSeal (TM). Methods: The authors performed an evaluative study with the LMA Supreme (TM), size 4, on 100 women to measure the case of insertion, determinate the laryngeal fit by fiberoptic classification, evaluate the oropharyngeal leak pressure, and report adverse events. Results: Insertion of the LMA Supreme (TM) was possible in 94 patients (94%) during the first attempt, and in 5 patients (5%) during the second attempt. lit one small patient, the LMA Supreme (TM) could not be inserted because of limited pharyngeal space. This patient was excluded from further analysis. Insertion of a gastric tube was possible in all patients at the first attempt. The median time for LMA Supreme (TM) insertion was 10.0 s (+/- 4.7 s; range, 8-30 s). Laryngeal fit, evaluated by fiberscopic view, was rated as optimal in all patients, both immediately after insertion of the LMA Supreme (TM) and at the end of surgery. After equalization to room pressure, the mean cuff volume needed to achieve 60 cm H(2)O cuff pressure was 18.4 ml (+/- 3.8 ml; range, 8-31 ml). The mean oropharyngeal leak pressure at the level of 60 cm H(2)O cuff pressure was 28.1 cut H(2)O (+/- 3.8 cm H(2)O, range, 21-35 cm H(2)O). Eight patients (8.1%) complained of a mild sore throat. No patient reported dysphagia or dysphonia. Conclusions: Clinical evaluation of the LMA Supreme (TM) showed easy insertion, optimal laryngeal lit, and low airway morbidity. Oropharyngeal leak pressure results were comparable to earlier data from the LMA ProSeal (TM)
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
Carbon dioxide induced changes in cerebral blood flow and flow velocity: Role of cerebrovascular resistance and effective cerebral perfusion pressure
No full textIn addition to cerebrovascular resistance (CVR) zero flow pressure (ZFP), effective cerebral perfusion pressure (CPPe) and the resistance area product (RAP) are supplemental determinants of cerebral blood flow (CBF). Until now, the interrelationship of PaCO2 -induced changes in CBF, CVR, CPPe, ZFP, and RAP is not fully understood. In a controlled crossover trial, we investigated 10 anesthetized patients aiming at PaCO2 levels of 30, 37, 43, and 50 mm Hg. Cerebral blood flow was measured with a modified Kety-Schmidt-technique. Zero flow pressure and RAP was estimated by linear regression analysis of pressure-flow velocity relationships of the middle cerebral artery. Effective cerebral perfusion pressure was calculated as the difference between mean arterial pressure and ZFP, CVR as the ratio CPPe/CBF. Statistical analysis was performed by one-way RM-ANOVA. When comparing hypocapnia with hypercapnia, CBF showed a significant exponential reduction by 55% and mean V MCA by 41%. Effective cerebral perfusion pressure linearly decreased by 17% while ZFP increased from 14 to 29 mm Hg. Cerebrovascular resistance increased by 96% and RAP by 39%; despite these concordant changes in mean CVR and Doppler-derived RAP correlation between these variables was weak (r=0.43). In conclusion, under general anesthesia hypocapnia-induced reduction in CBF is caused by both an increase in CVR and a decrease in CPPe, as a consequence of an increase in ZFP
- …
