Assessment of dry weight in hemodialysis: An overview

Fluid balance is an integral component of hemodialysis treatments to preven t under- or overhydration, both of which have been demonstrated to have sig nificant effects on intradialytic morbidity and long-term cardiovascular co mplications. Fluid removal is usually achieved by ultrafiltration to achiev e a clinically derived value for "dry weight." Unfortunately, there is no s tandard measure of dry weight and as a consequence it is difficult to ascer tain adequacy of fluid removal for an individual patient. Additionally, the re is a lack of information on the effect of ultrafiltration on fluid shift s in the extracellular and intracellular fluid spaces. It is evident that a better understanding of both interdialytic fluid status and fluid changes during hemodialysis is required to develop a precise measure of fluid balan ce. This article describes the current status of dry weight estimation and reviews emerging techniques for evaluation of fluid shifts. Additionally, i t explores the need for a marker of adequacy for fluid removal.