2,073 research outputs found
Model-based cardiovascular monitoring of acute pulmonary embolism in porcine trials
Introduction:
Diagnosis and treatment of cardiac and circulatory dysfunction can be error-prone and relies heavily on clinical
intuition and experience. Model-based approaches utilising measurements available in the Intensive care unit
(ICU) can provide a clearer physiological picture of a patient’s cardiovascular status to assist medical staff with
diagnosis and therapy decisions. This research tests a subject-specific cardiovascular system (CVS) modelling
technique on measurements from a porcine model of acute pulmonary embolism (APE).
Methods:
Measurements were recorded in 5 pig trials, where autologous blood clots were inserted every two hours into
the jugular vein to simulate pulmonary emboli. Of these measurements only a minimal set of clinically available or
inferable data were used in the identification process (aortic and pulmonary artery pressure, stroke volume, heart
rate, global end diastolic volume, and mitral and tricuspid valve closure times).
The CVS model was fitted to 46 sets of data taken at 30 minute intervals (t=0, 30, 60, …, 270) during the induction
of APE to identify physiological model parameters and their change over time in APE. Model parameters and
outputs were compared to experimentally derived metrics and measurements not used in the identification
method to validate the accuracy of the model and assess its diagnostic capability.
Results:
Modelled mean ventricular volumes and maximum ventricular pressures matched measured values with median
absolute errors of 4.3% and 4.4%, which are less than experimental measurement noise (~10%). An increase in
pulmonary vascular resistance, the main hemodynamic consequence of APE, was identified in all the pigs and
related well to experimental values (R=0.68). Detrimental changes in reflex responses, such as decreased right
ventricular contractility, were noticed in two pigs that died during the trial, diagnosing the loss of autonomous
control. Increases in the ratio of the modelled right to left ventricular end diastolic volumes, signifying the
leftward shift of the intra-ventricular septum seen in APE, compared well to the clinically measured index
(R=0.88).
Conclusions:
Subject-specific CVS models can accurately and continuously diagnose and track acute disease dependent
cardiovascular changes resulting from APE using readily available measurements. Human trials are underway to
clinically validate these animal trial results
Pulmonary embolism diagnostics from the driver function
Ventricular driver functions are not readily measured in the ICU, but can clearly indicate the development of pulmonary embolism (PE) otherwise difficult to diagnose. Recent work has developed accurate methods of
measuring these driver functions from readily available ICU measurements. This research tests those methods by assessing the ability of these driver functions to diagnose the evolution of PE
Model-based cardiovascular monitoring of large pore hemofiltration during endotoxic shock in pigs
peer reviewe
Quantum Memories. A Review based on the European Integrated Project "Qubit Applications (QAP)"
We perform a review of various approaches to the implementation of quantum
memories, with an emphasis on activities within the quantum memory sub-project
of the EU Integrated Project "Qubit Applications". We begin with a brief
overview over different applications for quantum memories and different types
of quantum memories. We discuss the most important criteria for assessing
quantum memory performance and the most important physical requirements. Then
we review the different approaches represented in "Qubit Applications" in some
detail. They include solid-state atomic ensembles, NV centers, quantum dots,
single atoms, atomic gases and optical phonons in diamond. We compare the
different approaches using the discussed criteria.Comment: 22 pages, 12 figure
Surgical treatment of scoliosis in a rare disease: arthrogryposis
<p>Abstract</p> <p>Background</p> <p>The reported incidence of scoliosis in arthrogryposis varies from 30% to 67% and, in most cases, the curves progress rapidly and become stiff from early age.</p> <p>The authors report six cases of scoliosis in arthrogryposis to assess the role of surgical treatment.</p> <p>Methods</p> <p>Six cases (3 males, 3 females; mean age at surgery 13.2 years) with arthrogryposis multiplex congenita associated with the characteristic amyoplasia were reviewed: they were operated on for scoliosis at the authors' Spine Surgery Department between 1987 and 2008.</p> <p>Surgery was performed using the Harrington-Luque instrumentation (2 cases), the Luque system (1), a hybrid segmental technique with hooks and screws (1) and spinal anchoring with pedicle screws (2).</p> <p>Results</p> <p>The patients were clinically and radiologically reviewed at a mean follow-up of 4.2 years, ± 2.7 (range, 1 to 9 years). Three minor postoperative complications were encountered; a long-term pulmonary complication was seen in one case after reintervention and was successfully resolved after 10 days. Surgery was successful in the other 5 cases, where solid arthrodesis was achieved and no significant curve progression was observed at follow-up.</p> <p>Conclusions</p> <p>The experience acquired with the present case series leads the authors to assert that prompt action should be taken when treating such aggressive forms of scoliosis. In case of mild spinal deformities in arthrogryposis, brace treatment should be attempted, the evolution of the curves being unpredictable; however, when the curve exceeds 40° and presents with marked hyperkyphosis, hyperlordosis or pelvic obliquity, surgery should not be delayed.</p
Exoplanet Atmosphere Measurements from Transmission Spectroscopy and other Planet-Star Combined Light Observations
It is possible to learn a great deal about exoplanet atmospheres even when we
cannot spatially resolve the planets from their host stars. In this chapter, we
overview the basic techniques used to characterize transiting exoplanets -
transmission spectroscopy, emission and reflection spectroscopy, and full-orbit
phase curve observations. We discuss practical considerations, including
current and future observing facilities and best practices for measuring
precise spectra. We also highlight major observational results on the
chemistry, climate, and cloud properties of exoplanets.Comment: Accepted review chapter; Handbook of Exoplanets, eds. Hans J. Deeg
and Juan Antonio Belmonte (Springer-Verlag). 22 pages, 6 figure
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