Articles: function.
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Beyond being a substitute for X-ray, computed tomography, and scintigraphy, magnetic resonance imaging (MRI) inherently combines morphologic and functional information more than any other technology. Lung perfusion: The most established method is first-pass contrast-enhanced imaging with bolus injection of gadolinium chelates and time-resolved gradient-echo (GRE) sequences covering the whole lung (1 volume/s). Images are evaluated visually or semiquantitatively, while absolute quantification remains challenging due to the nonlinear relation of T1-shortening and contrast material concentration. ⋯ Respiratory mechanics: Time-resolved series with high background signal such as GRE or steady-state free precession visualize the movement of chest wall, diaphragm, mediastinum, lung tissue, tracheal wall, and tumor. The assessment of volume changes allows drawing conclusions on regional ventilation. With this arsenal of functional imaging capabilities at high spatial and temporal resolution but without radiation burden, MRI will find its role in regional functional lung analysis and will therefore overcome the sensitivity of global lung function analysis for repeated short-term treatment monitoring.
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Acta Anaesthesiol Scand · Feb 2014
ReviewPopulation pharmacometrics in support of analgesics studies.
Population pharmacometric modeling is used to explain both population trends as well as the sources and magnitude of variability in pharmacokinetic and pharmacodynamics data; the later, in part, by taking into account patient characteristics such as weight, age, renal function and genetics. The approach is best known for its ability to analyze sparse data, i.e. when only a few measurements have been collected from each subject, but other benefits include its flexibility and the potential to construct more detailed models than those used in the traditional individual curve fitting approach. ⋯ In addition, the use of these models to design and optimize future studies is discussed. In this context, finding the best design factors, such as the sampling times or the dose, for future studies within pre-defined criteria using a previously constructed population pharmacokinetic model can help researchers acquire clinically meaningful data without wasting resources and unnecessarily exposing vulnerable patient groups to study drugs and additional blood sampling.
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Curr Opin Anaesthesiol · Feb 2014
ReviewUpdate on minimally invasive hemodynamic monitoring in thoracic anesthesia.
Advanced hemodynamic monitoring is indispensable for adequate management of patients undergoing major surgery. This article will summarize minimally invasive hemodynamic monitoring technologies and their potential use in thoracic anesthesia. ⋯ Many different minimally invasive hemodynamic monitoring devices have been developed and clinically introduced in the last years. They offer the advantage of being less invasive and easier to use. However, these techniques have several limitations and data are scarce in patients undergoing thoracic anesthesia, preventing their widespread use so far.
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Anesthesia and analgesia · Feb 2014
The effectiveness of different functional fibrinogen polymerization assays in eliminating platelet contribution to clot strength in thromboelastometry.
Viscoelastic tests such as functional fibrinogen polymerization assays (FFPAs) in thrombelastography (TEG®) or thromboelastometry (ROTEM®) measure clot elasticity under platelet inhibition. Incomplete platelet inhibition influences maximum clot firmness (MCF) of FFPAs. We compared the ability of existing and newly developed FFPAs to eliminate the platelet contribution to clot strength. ⋯ FFPAs based solely on glycoprotein-IIb/IIIa inhibition, such as FFTEG or EXTEM-ABC, are less effective than cytochalasin D-based assays, such as FIBTEM or FIBTEM-S, at inhibiting the platelet component of clot strength. The FIBTEM PLUS assay, and the combination of FIBTEM and abciximab, sufficiently inhibits platelet contribution to clot elasticity. The combination of a glycoprotein-IIb/IIIa receptor blocker and cytochalasin D allows evaluation of functional fibrinogen polymerization without platelet "noise." In a clinical setting, the significance of potent platelet inhibition ensures a more accurate assessment of MCF and therefore the need for fibrinogen supplementation therapy. Further studies are necessary to investigate the application and impact of these tests in a clinical situation.
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Curr Opin Anaesthesiol · Feb 2014
ReviewCerebral near-infrared spectroscopy in perioperative management of left ventricular assist device and extracorporeal membrane oxygenation patients.
Spinal cord ischemia after thoracoabdominal aortic interventions is a devastating complication because it significantly worsens the perioperative morbidity and mortality. Long-term outcome is also affected because of medical complications which are directly related to the neural deficits. Paraplegia has significant medical, social, and financial aspects. Limited mobility, the need for assistance in activities of daily living, makes paraplegia an important target for prevention. An understanding of spinal cord blood supply, risk factors for spinal ischemia, and strategies for spinal cord rescue in this setting can help minimize the negative outcome effects of this important complication. ⋯ The progression of spinal cord ischemia after thoracoabdominal aortic interventions can frequently be arrested before irreversible infarction results. This spinal cord rescue depends on the early detection and immediate multimodal intervention to maximize spinal cord oxygen supply. The devastating outcomes associated with spinal infarction in this setting offset the risks and knowledge gaps currently associated with contemporary interventions.