Preface

Hemodialysis (HD) treatment has undergone significant improvements in technology and quality performance in managing patients with kidney failure. These advancements include state-of-the-art HD machines, water treatment plants with ultrapure water, medical devices, disposables, and solutions. More recently, there have been significant improvements in the creation and maintenance of vascular access as well as the types, classifications, and monitoring of uremic toxins and their relationship with inflammation, atherosclerosis and vascular classification, and cardiovascular and all-cause mortality. Innovation in dialysis membranes/dialyzers resulted in the development of the medium cut-off membrane, which enables the removal of largersized uremic toxins in a safe, simple, and effective way. The HD technique that uses the medium cut-off membrane/dialyzer is known as expanded hemodialysis (HDx). HDx therapy has been shown to result in significant improvement in the quality of life of HD patients as well as reductions in hospitalization, medications, and non-fatal cardiovascular events.

*Updates on Hemodialysis* discusses different aspects of these innovations and can be used as a guide to improve daily practice and achieve best possible medical outcomes in HD patients. Chapters are clear and easy to read and include illustrations, figures, and tables to support the text.

I wish to thank the contributing authors for their excellent chapters. My thanks also go to IntechOpen and Publishing Process Managers Mrs. Blanka Gugic and Ms. Marina Dusevic for their assistance in collecting and editing the chapter manuscripts.

> **Ayman Karkar** Consultant Physician and Nephrologist, Head Medical Affairs at Baxter International Inc., Renal Care – Middle East and Africa, Dubai, United Arab Emirates

**1**

**Chapter 1**

Hemodialysis

*Ayman Karkar*

**1. Introduction**

cancer [3–6].

conventional HD modalities.

**2. Uremic toxins and hemodialysis techniques**

Introductory Chapter: Updates on

Despite the significant improvements in hemodialysis (HD) techniques over the past 40 years, patients on this therapy still suffer from the burden of HD-associated symptoms, vascular access-related issues, acute and chronic complications, poor quality of life, and the mortality rate remains unacceptably elevated [1, 2]. The European Renal Association (ERA) and the United States Renal Data System (USRDS) showed that the 5-year survival rate for patients on HD is close to only 50%, which is worse than patients with breast cancer, prostate cancer and almost like or worse than colon

The retention of large-size uremic toxins (e.g., proinflammatory cytokines, alpha 1-microglobulin, YKL-40, and kappa and lambda free light chains) has been associated with inflammation, atherosclerosis and vascular calcification, cardiovascular disease, and increased risk of mortality [7]. These uremic toxins have also been associated with poor quality of life, such as late recovery time post-HD session, impaired physical function, moderate-to-severe pruritus, and restless legs syndrome [8]. These drawbacks of HD treatment demonstrate the unmet needs in the current or

The new medium cut-off membrane/dialyzer, with its larger pore size, lower wall thickness, and smaller inner diameter of hollow fibers, has significantly improved the clearance of the large-size uremic toxins in safe, simple, and effective technique, especially when compared to conventional hemodialysis techniques [9]. For example, the low-flux HD can remove small soluble solutes less than 500 Dalton (Da), such as urea and creatinine, whereas high-flux HD is capable of efficiently removing molecules less than 15,000 Da. Diffusion is the major contributor to the clearance of smallsize molecules, but convection, as in online hemodiafiltration (HDF), is required for the efficient removal of large-size molecules, especially those above 25,000 Da [7]. Randomized controlled trials have shown the effectiveness of online HDF not only in its ability to remove large-size uremic toxins but to improve the quality of life [10] and to significantly reduce the cardiovascular and all-cause mortality, especially if the

/session [11].

used prescribed convection volume equals to or exceeds 23 liters/1.73 m2

However, successful implementation of online HDF is demanding. For example, it requires a special HD machine that has the ability to mix solutions online, a powerful high-flux dialyzer, functional vascular access with a blood flow rate of 350–400 ml/
