Effective fluid removal during hemodialysis is one of the biggest challenges in children with end-stage renal disease (ESRD). Generally, children do not tolerate having more than 3-4% of their body weight removed during each dialysis session thus necessitating multiple sessions each week to ensure effective renal replacement. Excessive fluid removal is often associated with nausea, vomiting, hypotension and cramps resulting in serious complications in patient care during and immediately after dialysis as well as reduced patient compliance. The development of novel therapies to increase the amount of fluid removed during each session without a corresponding increase in the incidence of complications is therefore very important to improve quality and compliance with hemodialysis; and eventually survival of children with ESRD. The purpose of this study is to evaluate the application of the impedance threshold device during hemodialysis in children to optimize fluid removal, reduce the incidence of complications (such as cramps,vomiting and hypotension), and device tolerance.