3,834 research outputs found
Cardiac output monitoring during abdominal aortic cross clamping: a comparison between Vigileo/FloTrac system and transoesophageal Doppler
Cardiac output (CO) monitoring is one of the key points in the hemodynamic evaluation of critically ill patients, and can be useful in various settings of high-risk surgery. There is a lack of evidence that the extensive use of invasive devices in the hemodynamic monitoring has a good impact in terms of outcome [1], and less invasive systems have been proposed. Our aim was to compare the CO estimated by Vigileo/FloTrac with the blood flow in thoracic aorta as measured by transoesophageal Doppler in patients undergoing open abdominal aortic aneurysm repair, during the aortic cross-clamping (AoX) phase. We have measured the Augmentation Index (AI), a parameter related to vascular stiffness, using the applanation tonometry method, in order to have a better understanding of the effect of AoX on blood pressure waves.
Methods
We enrolled 10 consecutive patients (10 men; age 66 \ub1 6 years) undergoing elective open AAA repair (ASA II to III) under general anesthesia. Radial arterial access was used for semi-invasive determination of blood pressures and CO (APCO) with the Vigileo. An esophageal Doppler was positioned after clinical stabilization. Applanation tonometry was measured just before and after the aortic clamping.
Results
We found a significant (P < 0.05) increase in CO reported by Vigileo/FloTrac system in the post-clamping phase, when compared with the pre-clamping and basal phases, while the blood flow in thoracic aorta resulted decreased, according with the theory of redistribution of fluids in the splanchnic venous vasculature [2]. There was an important contribution of the wave reflection to the aortic pulse pressure wave after the AoX, as expressed by a significant increase in the AI.
Conclusions
The Vigileo/FloTrac system appears to overestimate CO after AoX when compared with the measure of blood flow in thoracic aorta, and this result could be influenced by the pulse pressure wave reflection occurring after clamping. In high-risk surgical settings, other situations of rapid change of systemic resistance vessels could be similarly misread, thus suggesting the necessity of a more tailored Vigileo algorithm
Geometric combinatorial algebras: cyclohedron and simplex
In this paper we report on results of our investigation into the algebraic
structure supported by the combinatorial geometry of the cyclohedron. Our new
graded algebra structures lie between two well known Hopf algebras: the
Malvenuto-Reutenauer algebra of permutations and the Loday-Ronco algebra of
binary trees. Connecting algebra maps arise from a new generalization of the
Tonks projection from the permutohedron to the associahedron, which we discover
via the viewpoint of the graph associahedra of Carr and Devadoss. At the same
time that viewpoint allows exciting geometrical insights into the
multiplicative structure of the algebras involved. Extending the Tonks
projection also reveals a new graded algebra structure on the simplices.
Finally this latter is extended to a new graded Hopf algebra (one-sided) with
basis all the faces of the simplices.Comment: 23 figures, new expanded section about Hopf algebra of simplices,
with journal correction
Brain deposition of gadobutrol in children—a cross-sectional and longitudinal MRI T1 mapping study
Objectives:Depositions of linear gadolinium-based MRI contrast agents are readily visible in T1-weighted MRIs of certain brain regions in both adults and children. Macrocyclic contrast agents such as gadobutrol have so far escaped detection by qualitative MRI in children. This study aimed to assess whether there is evidence for deposition of gadobutrol in children using quantitative T1 mapping.Methods:This retrospective study included patients, naive to other gadolinium-based contrast agents than gadobutrol, who had received gadobutrol as part of a clinically indicated MRI. For each patient, T1 relaxation times at 3 T were measured using single-shot T1 mapping at two time points. In each of six brain regions, age-adjusted T1 relaxation times were correlated with a number of previous gadobutrol administrations. To combine interindividual, cross-sectional effects with intraindividual, longitudinal effects, both linear mixed model and generalized additive mixed model were applied.Results:One hundred four examinations of 52 children (age median 11.4, IQR 6.3–15, 26 female) with a median of 7 doses of gadobutrol in the history of their neurological or neurooncological disease were included. After correction for age and indeterminate disease-related effects to T1 time, a negative correlation of T1 time with the number of gadobutrol doses administered was observed in both mixed models in the putamen (beta − 1.65, p = .03) and globus pallidus (beta − 1.98, p = .012)Conclusions:The results indicate that in children, gadobutrol is deposited in the globus pallidus and putamen
Pattern Avoidance in Poset Permutations
We extend the concept of pattern avoidance in permutations on a totally
ordered set to pattern avoidance in permutations on partially ordered sets. The
number of permutations on that avoid the pattern is denoted
. We extend a proof of Simion and Schmidt to show that for any poset , and we exactly classify the posets for which
equality holds.Comment: 13 pages, 1 figure; v2: corrected typos; v3: corrected typos and
improved formatting; v4: to appear in Order; v5: corrected typos; v6: updated
author email addresse
Synchronization of the Distributed Readout Frontend Electronics of the Baby MIND Detector
Baby MIND is a new downstream muon range detector for the WGASCI experiment. This article discusses the distributed readout system and its timing requirements. The paper presents the design of the synchronization subsystem and the results of its test
Baby MIND: A magnetised spectrometer for the WAGASCI experiment
The WAGASCI experiment being built at the J-PARC neutrino beam line will
measure the difference in cross sections from neutrinos interacting with a
water and scintillator targets, in order to constrain neutrino cross sections,
essential for the T2K neutrino oscillation measurements. A prototype Magnetised
Iron Neutrino Detector (MIND), called Baby MIND, is being constructed at CERN
to act as a magnetic spectrometer behind the main WAGASCI target to be able to
measure the charge and momentum of the outgoing muon from neutrino charged
current interactions.Comment: Poster presented at NuPhys2016 (London, 12-14 December 2016). Title +
4 pages, LaTeX, 6 figure
Baby MIND Experiment Construction Status
Baby MIND is a magnetized iron neutrino detector, with novel design features,
and is planned to serve as a downstream magnetized muon spectrometer for the
WAGASCI experiment on the T2K neutrino beam line in Japan. One of the main
goals of this experiment is to reduce systematic uncertainties relevant to
CP-violation searches, by measuring the neutrino contamination in the
anti-neutrino beam mode of T2K. Baby MIND is currently being constructed at
CERN, and is planned to be operational in Japan in October 2017.Comment: Poster presented at NuPhys2016 (London, 12-14 December 2016). 4
pages, LaTeX, 7 figure
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