2,061 research outputs found
Cardiac-related impedance changes obtained by electrical impedance tomography: an acceptable parameter for assessment of pulmonary perfusion?
No full textComment on Borges et al. "Regional lung perfusion estimated by electrical impedance tomography in a piglet model of lung collapse"
No full textLung impedance measurements to monitor alveolar ventilation
No full textPurpose of review Electrical impedance tomography (EIT) is an attractive method of monitoring patients during mechanical ventilation because it can provide a noninvasive continuous image of pulmonary impedance, which indicates the distribution of ventilation. This article will discuss ongoing research on EIT, with a focus on methodological aspects and limitations and novel approaches in terms of pathophysiology, diagnosis and therapeutic advancements. Recent findings EIT enables the detection of regional distribution of alveolar ventilation and, thus, the quantification of local inhomogeneities in lung mechanics. By detecting recruitment and derecruitment, a positive end-expiratory pressure level at which tidal ventilation is relatively homogeneous in all lung regions can be defined. Additionally, different approaches to characterize the temporal local behaviour of lung tissue during ventilation have been proposed, which adds important information. Summary There is growing evidence that supports EIT usage as a bedside measure to individually optimize ventilator settings in critically ill patients in order to prevent ventilator-induced lung injury. A standardization of current approaches to analyse and interpret EIT data is required in order to facilitate the clinical implementation
Ida von Hahn-Hahn und Isabelle Eberhardt. Ausbruch aus Restriktionen – Auf der Suche nach sich selbst
No full textThe following thesis compares the travelogue Orientalische Briefe by the German author Ida von Hahn-Hahn with the travel journals Mes Journaliers by the French author Isabelle Eberhardt, in the context of how each woman represents herself as a female traveler and author. The comparative study analyzes whether both authors in these texts deal with the issue of breaking out of social and cultural restrictions while traveling to the ‘Orient’. The overall question of my thesis concerns what kind of filters did they use to speak about the ‘cultural other’.
The personal backgrounds of Ida von Hahn-Hahn and Isabelle Eberhardt differ in several aspects. The German author Ida von Hahn-Hahn visited the ‘Orient’ in 1843 temporarily and each place on only one occasion whereas the French author Isabelle Eberhardt constantly traveled at the end of the 19th century and at the same time she turned North Africa into her new home. These texts were analyzed in the context of gender discourse analysis, focusing on the discourse of feminity in the 19th century and the discourse of the Western world about the ‘Orient’. The comparison showed similarities and differences in the way both authors present themselves and the ‘Arab woman’ by (de-)constructing pre-existing ‘images’.
In my analysis I was able to demonstrate that both authors consciously deal with the western femininity discourse of the 19th century and the Western discourse about the ‘Orient’ by selecting similar motives. Even though their results are quite different, both authors clearly use the ‘Orient’ to express their search of one’s self
Monitoring of Regional Lung Ventilation Using Electrical Impedance Tomography After Cardiac Surgery in Infants and Children
No full textElectrical impedance tomography (EIT) is a noninvasive method to monitor regional lung ventilation in infants and children without using radiation. The objective of this prospective study was to determine the value of EIT as an additional monitoring tool to assess regional lung ventilation after pediatric cardiac surgery for congenital heart disease in infants and children. EIT monitoring was performed in a prospective study comprising 30 pediatric patients who were mechanically ventilated after cardiac surgery. Data were analyzed off-line with respect to regional lung ventilation in different clinical situations. EIT data were correlated with respirator settings and arterial carbon dioxide (CO2) partial pressure in the blood. In 29 of 30 patients, regional ventilation of the lung could sufficiently and reliably be monitored by means of EIT. The effects of the transition from mechanical ventilation to spontaneous breathing after extubation on regional lung ventilation were studied. After extubation, a significant decrease of relative impedance changes was evident. In addition, a negative correlation of arterial CO2 partial pressure and relative impedance changes could be shown. EIT was sufficient to discriminate differences of regional lung ventilation in children and adolescents after cardiac surgery. EIT reliably provided additional information on regional lung ventilation in children after cardiac surgery. Neither chest tubes nor pacemaker wires nor the intensive care unit environment interfered with the application of EIT. EIT therefore may be used as an additional real-time monitoring tool in pediatric cardiac intensive care because it is noninvasive
Electrical impedance tomography is able to track changes in respiratory function in endotoxin-challenged rodents
No full textBackground and objective: In order to assess and optimize the effect of new therapies for acute lung injury (ALI) in rodent models, a monitoring technique that continuously assesses the functional state of the lung is mandatory. Electrical impedance tomography (EIT) has been suggested as a technique for quantifying lung inflammation in ALI. However, EIT has not been evaluated in a rodent model of ALI. Methods: EIT measurements were compared in ventilated Sprague-Dawley rats (n = 14), randomly subjected to intratracheal administration of endotoxin (LPS) or saline (control). Lung mechanics, lung weight wet/dry ratio and inflammatory markers in bronchoalveolar lavage fluid were also evaluated. Results: LPS caused a significant decrease in lung compliance and TLC as compared with control (-42.0%, P = 0.04, and -27.9%, P = 0.02, respectively). These changes were paralleled by differences in mean impedance changes as detected by EIT (Spearman's rank correlation coefficient: rho = 0.66 and 0.73, respectively, P < 0.01). LPS increased the lung weight wet/dry ratio (6.35 +/- 0.42 vs 5.15 +/- 0.07, P = 0.003), and the bronchoalveolar lavage total WCC (8.96 +/- 1.87 vs 1.16 +/- 0.10 x 10(9)/L, P = 0.002) as compared with control. The lung weight wet/dry ratio was inversely related to the mean impedance change (rho = -0.76, P < 0.01). Conclusions: This study has demonstrated for the first time that eight-electrode EIT readily tracks the inflammatory response of lung tissue in a rodent model of ALI. EIT may thus provide a promising, non-invasive technique for monitoring the time-course of ALI in rodent models, and for testing novel pharmacological strategies to counter it
Characterization of the Dᵂ-Laguerre-Hahn functionals
No full text29 pages, no figures.-- MSC2000 codes: 33C45, 39A10.MR#: MR1914598 (2003e:33021)Zbl#: Zbl 1021.33007We give some characterization theorems for the DᵂLaguerre-Hahn linear functionals and we extend the concept of the class of the usual Laguerre-Hahn functionals to the Dᵂ-Laguerre-Hahn functionals, recovering the classic results when ᵂ tends to zero. Moreover, we show that some transformations carried out on the Dᵂ-Laguerre-Hahn linear functionals lead to new Dᵂ-Laguerre-Hahn linear functionals. Finally, we analyze the class of the resulting functionals and we give some applications relative to the first associated Charlier, Meixner, Krawtchouk and Hahn orthogonal polynomials.The work of the second author (FM) was supported by Ministerio de Ciencia y Tecnología (Dirección General de Investigación) of Spain under grant BFM 2000-0206-C04-01 and the INTAS project INTAS 2000-272.Publicad
The influence of callus distraction on the growth plate
No full textObjectives This study was designed to investigate the morphology, thickness and cellularity of the growth plate during callus distraction performed in the immediate vicinity of the growth plate. Methods Lengthening of the right tibia by 25% was carried out on 24 beagle dogs by callus distraction. Distraction was started at the fifth postoperative day with a distraction rate of 0.5 mm twice a day. A control group of six dogs underwent tibial osteotomy and external fixation without distraction. Half of the dogs of both groups were sacrificed at the end of the distraction phase of 25 days (Group A) and the remaining 15 dogs after an additional consolidation period of 25 days (Group B). The tibia and femur was removed from the distracted right leg and from the left control side of each animal and longitudinal sections were cut and stained with Pentachrome. The thickness and cellularity of the regeneration zone, the proliferation zone and the hypertrophic zone were determined for the proximal tibial and the distal femoral epiphysis. Results During the distraction phase the thickness of the proximal tibial growth plate and its cellularity were reduced on the distraction side. During the consolidation phase there was a slight recovery in the proximal tibial growth plate. Conclusions Callus distraction leads to a temporary reduction in growth of the affected physis
Asymptotic iteration method for solving Hahn difference equations
No full textHahn’s difference operator Dq;wf(x)=(f(qx + w) – f(x))/((q – 1)x + w), q ∈ (0, 1), w > 0,
x = w/(1 – q) is used to unify the recently established difference and q-asymptotic
iteration methods (DAIM, qAIM). The technique is applied to solve the second-order
linear Hahn difference equations. The necessary and sufficient conditions for
polynomial solutions are derived and examined for the (q;w)-hypergeometric
equation.Natural Sciences and Engineering Research Council of CanadaCanadian Network for Research and Innovation in Machining Technolog
The Approximate Jordan-Hahn Decomposition
No full textNon-commutative measure theory embraces measure theory on cr-fields of subsets of a set, on projection lattices of von Neumann algebras or JBW-algebras and on hypergraphs alike [20], [27], [33], [37], [39], [40], [41]. Due to the unifying structure of an orthoalgebra concepts can easily be transferred from one branch to the other. Additional conceptual inpetus is obtained from the logico-probabilistic foundations of quantum mechanics (see [6], [19], [21]).In the late seventies the author studied the Jordan-Hahn decomposition of measures on orthomodular posets and certain graphs. These investigations revealed an interesting geometrical aspect of this decomposition in that the Jordan-Hahn property of the convex set of probability charges on a finite orthomodular poset can be characterized in terms of the extreme points of the unit ball of the Banach space dual of the base normed space of Jordan charges.</jats:p
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