Fluid volume assessment in hemodialysis patients

Abstract

Achievement of normal volume status is crucial in hemodialysis (HD), since both volume overload and volume depletion have been associated with adverse outcome and events. The main objectives of this thesis were to find out the prevalence of volume overload and to identify the best clinical parameter or set of parameters that can predict volume overload in HD patients along with the development of volume management protocol. Another objective was investigating the literature about the use of sodium profiling in alleviating intradialytic side effects. Volume status of 194 HD patients in 2 hemodialysis units was assessed by multi-frequency bio-impedance spectroscopy. Of all patients 48% (n=94) were volume expanded. ECFV depletion was present in 9% of patients (n=17). Interdialytic weight gain (IDWG) was not different between hypovolemic, normovolemic and hypervolemic patients. Only 50% of the volume overloaded patients were hypertensive (>140/90mmHg). Paradoxical hypertension was common (31% of all patients) in our HD population, however, its incidence was not different between patients. Intradialytic hypotension was relatively common and was more frequent amongst hypovolemic patients. Blood pressure was neither sensitive nor specific for volume assessment. Edema was highly specific for detection of volume overload but lacks sensitivity. In sum, the study indicates that volume overload is highly prevalent in HD population and could not be identified using clinical parameters alone. Only 4 clinical parameters (edema, SBP, lower BMI, smoking) were found to be significant predictors for volume overload. None of the 4 parameters was sensitive and specific. We found that bio-impedance was a helpful bedside method to better identify hidden volume overload.