Methods of assessment of volume status and intercompartmental fluid shifts in hemodialysis patients: implications in clinical practice.

Determining dry weight and assessing extracellular fluid volume in hemodialysis (HD) patients is one of the greatest challenges to practicing nephrologists. The clinical examination has limited accuracy, so different strategies have been investigated to aid in this evaluation. Biochemical markers of volume overload (ANP, BNP, cGMP) are fraught with excessive variability and poor correlation with volume status. Inferior vena cava ultrasound is effective, but cumbersome and costly. Bioimpedance measurements of intra- and extracellular water have significant shortcomings when used as isolated measurements, but can be useful in following trends over time and have been shown to improve intradialytic symptoms and blood pressure control. Continuous blood volume monitoring is helpful in preventing intradialytic hypotension and may help identify patients who are volume overloaded and need increased ultrafiltration. In this review we discuss these different techniques and other developments in the evaluation of dry weight and volume status, which may enhance our ability to improve patient stability and well-being during HD sessions.