الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Chronic kidney disease is a worldwide public health problem and is now recognized as a common condition that is associated with an increased risk of cardiovascular disease and chronic renal failure(Aroraand Verrelli, 2009).
All patients with evidence of persisting kidney damage for> 90 days, are defined as having chronic kidney disease (CKD) ( SIGN Guidelines., 2008).
CKD results from a large number of diseases that either are systemic and damage the kidney or are intrinsic to the kidney. The most common causes of ESKD are diabetic nephropathy, hypertension & glomerulonephritis accounting for 80% of the causes (Levey et al., 2009).
Proteinuria is the most common marker of kidney damage, indicating glomerular damage ( Levey et al., 2009).
The goals of Optimal management of CKD rest on its early diagnosis, timely referral to nephrological care and treatments which slow progression of the disease and prevent cardiovascular complications. To accomplish these goals, it is important to estimate GFR and measure albuminuria regularly in those patients at risk of CKD, implement early referral of recent diagnosed cases for conjunct follow up with nephrology specialists, and guarantee good treatment of blood pressure, proteinuria, diabetes, weight, anemia, secondary hyperparathyroidism, dyslipidemia and malnutrition(Bastos and Kirsztajn, 2011).
Hemodialysis (HD) constitutes the most common form of renalreplacement therapy (RRT) worldwide. The goal of dialysis in patients with end stage kidney disease (ESKD) is to restore body’s extracellular and intracellular composition to that of normal to the greatest extent possible (Sultania et al., 2009).
The primary goal of HD is to restore the intracellular and extracellular fluid environment that is characteristic of normal kidney function. This is accomplished by the transport of solutes, such as urea, from the blood into the dialysate, and by the transport of solutes, such as bicarbonate, from the dialysate into the blood. During ultrafiltration (UF), there is no change in solute concentrations; its primary purpose is the removal of excess total body water(Meyer &Hostetter, 2007).
Peritoneal Dialysis is achieved by instilling dialysis solution into the peritoneal cavity using a percutaneous abdominal catheter. Water and solutes are exchanged between the capillary blood and the intraperitoneal dialysate across the peritoneum, comprising vascular endothelium, its basement membrane, underlying connective tissue interstitium and a mesothelial monolayer (Saxena et al., 2006).Automated PD is a two-step therapy. During the night session, a variable number of short exchanges are carried out by the cycler while, during the daytime, none to three (one or two is most common) longer fluid dwells are allowed(Perez - Fontan and Rodriguez - Carmona 2007).
There is a multidimensional rationale for a development of a WAK system. The outcomes of chronic renal replacement therapy remain dismal regarding the quality of life, morbidity and mortality. A growing body of literature indicates that more frequent and prolonged dialysis treatment is associated with strikingly improved outcomes (Blagg et al.,2004).
A wearable artificial kidney is a wearable dialysis machine that a person with end-stage renal disease can use daily or even continuously. In order to be truly wearable,the device must be small, light and capable of operating independently of an electrical outlet.it must also be affordable. Minimal amounts of dialysate should be used and regenerated by aneffective, cheap and safe sorbent-based process.The design must be ergonomic and combine a user-friendly interface with a small, easy to-wear device(Ronco, et al.,2008).
The development of a wearable dialysis devices requires a deep knowledge of the common technical and clinical problems of ESKD patients together with an effort to think ”out of the box” in order to pursue innovative pathways(Ronco et al.,2011).
PD is the most common form of home-based renal replacement therapy. A wearable PD system would probably represent a new option to increase the use of PD and to expand the PD program worldwide(Ronco,et al.,2009).
Currently, two new designs have been proposed to increase patient freedom from additional dialysate fluid exchanges. First, the Vicenza wearable artificial kidney (ViWAK) and the second is the automated wearable artificial kidney (AWAK) (Ronco&Fecondini,2007).
The Vicenza wearable artificial kidney (ViWAK) utilizes a dual lumen catheter, allowing continuous flow PD powered by a small lightweight battery-powered pump. After an initial 2-h dwell with standard glucose-based dialysate, peritoneal dialysate is then continuously recycled by the passage of spent dialysate through a series of sorbents. Sorbents have traditionally contained microporous carbon, zirconium, or polystyrene(Ronco&Fecondini,2007).
The automated wearable artificial kidney (AWAK) is another continuous PD device designed for continued use, which differs from the ViWAK in having single catheter lumen access, and as such dialysate flow is discontinuous, depending upon a tidal regimen requiring a reservoir for refreshed dialysate (Figure 6). Whereas the ViWAK is proposed to use two conventional peritoneal dialysate exchanges each day(Lee,2008).
The challenges to design and produce a wearable continuous hemodialysis treatment are similar to those for PD, but are complicated by the requirement for blood access. Although continuous renal replacement therapy (CRRT) can deliversignificantly higher solute clearances than conventional three times weekly standard hemodialysis, simple miniaturization of the CRRT circuit is not without technical challenges(Gura et al.,2009).
The current WAK uses the same sorbents as the REDY system. this sorbent based dialysate regeneration system has been effectively applied to the treatment of acute and chronic kidney failure patients for many years(Gura et al.,2009).
Currently, a wearable hemodialysis device has been extensively trialed in pig models of acute kidney injury, and also used in two proof-of-concept human clinical trials, first as an ultrafiltration device, and second for hemodialysis (Gura et al.,2008).