Non-Imaging Acoustical Properties in Monitoring Arteriovenous Hemodialysis Access. a Review

The limitations of the gold standard angiography technique in arteriovenous access surveillance have opened a gap for researchers to find the best way to monitor this condition with low-cost, non-invasive and continuous bedside monitoring. The phonoangiography technique has been developed prior to these limits. This measurement and monitoring technique, associated with intelligence signal processing, promises better analysis for early detection of hemodialysis access problems, such as stenosis and thrombosis. Some research groups have shown that the phonoangiography technique could identify as many as 20% of vascular diameter changes and also its frequency characteristics due to hemodialysis access problems. The frequency characteristics of these acoustical signals are presented and discussed in detail to understand the association with the stenosis level, blood flows, sensor locations, fundamental frequency bands of normal and abnormal conditions, and also the spectral energy produced. This promising technique could be used in the near future as a tool for pre-diagnosis of arteriovenous access before any further access correction by surgical techniques is required. This paper provides an extensive review of various arteriovenous access monitoring techniques based on non-imaging acoustical properties

Assessment of Arteriovenous Shunt Pathway Function and Hypervolemia for Hemodialysis Patients by Using Integrated Rapid Screening System

Currently, the hemodialysis patients received body weight measurement by themselves, vital sign checking by nursing staffs before dialysis. Whenever, the arteriovenous routes with problems doubted, the patients needed to be referred to surgeon for vascular echography checking and then to be corrected. How to integrate these three tasks in one time is a very important issue. The project proposes to combine our previous study of audio-phono angiographic technology in detecting vascular stenosis with rapid screening system to evaluate dialysis patients’ arteriovenous routes function and their status of excess body fluids: inspecting and integrating the blood pressure, body weight, and fistula function work into a rapid screening system, and using the quantization of fistula phono angiography pitch to achieve assessing arteriovenous routes. Future hoping is developed a complete integrated intelligence system by combining the arteriovenous fistula signal processing with feature extraction with wireless sensor network technology

Progress in Hemodialysis

Hemodialysis (HD) represents the first successful long-term substitutive therapy with an artificial organ for severe failure of a vital organ. Because HD was started many decades ago, a book on HD may not appear to be up-to-date. Indeed, HD covers many basic and clinical aspects and this book reflects the rapid expansion of new and controversial aspects either in the biotechnological or in the clinical field. This book revises new technologies and therapeutic options to improve dialysis treatment of uremic patients. This book consists of three parts: modeling, methods and technique, prognosis and complications

Computational studies of oxygen transport in arterio-venous fistulae

Arterio-venous-fistulae (AVF) are surgically-formed connections between an artery and a vein and are regarded as the “gold standard” method of vascular access, for haemodialysis. Nonetheless, up to 60% fail within three months of creation. Their principal failure mechanism is intimal hyperplasia (IH), an adverse inflammatory process causing AVF to block and fail. Evidence suggests that IH is a multifactorial process, attributable to an altered vascular environment, including increased metabolic stress, flow disturbances, mechanical stress, and wall hypoxia (low oxygen levels). The present work focuses on studying wall hypoxia in idealised AVF. Vascular walls are oxygenated by transport from both luminal oxygenated blood and adventitial vasa vasorum (VV), the microvascular network supplying large vessels. Luminal oxygen supply is affected by the altered AVF haemodynamics, while altered wall-mechanics can prevent adequate VV perfusion. The aim of this thesis is to ascertain what is most important in determining wall-oxygen levels: (i) modified luminal flow field; (ii) mechanically-modified VV perfusion. Hence, a model of oxygen transport, capable of accounting for VV damage/hypoperfusion, was developed. Geometries and VV perfusion fields obtained from mechanical simulations were used to provide the oxygen transport model with a VV oxygen source. Results suggest that for a given set of wall parameters, the local wall-oxygen levels are governed by the flow field, while spatial distributions of mechanically-modified VV perfusion are shown to have negligible effects on the local wall-oxygen levels. However, overall wall-oxygen levels are highly sensitive to changes in bulk wall parameters, particularly oxygen consumption rates. Finally, these results were used to develop a simplified oxygen transport model, that is combined with a mesh-adaptive-direct-search approach to identify an optimal AVF configuration with reduced hypoxia levels. The configuration features a non-planar anastomosis and a helical shaped vein.Open Acces

Fighting against atherosclerotic disease: From the endothelium to invasive cardiology

An insight into in vitro strategies to improve endothelial function and response to ischemia and into clinical strategies to improve the outcome after percutaneous interventions

Neuroimaging - Clinical Applications

Modern neuroimaging tools allow unprecedented opportunities for understanding brain neuroanatomy and function in health and disease. Each available technique carries with it a particular balance of strengths and limitations, such that converging evidence based on multiple methods provides the most powerful approach for advancing our knowledge in the fields of clinical and cognitive neuroscience. The scope of this book is not to provide a comprehensive overview of methods and their clinical applications but to provide a "snapshot" of current approaches using well established and newly emerging techniques