Chronic dialysis patients receive repeated treatments in an outpatient hemodialysis unit (Chronic). Their dialysis needs are often well known and predictable. Occasionally patients need emergency dialysis performed in the hospital or emergency department (Acute). Their treatment conditions may not be known to the medical staff. Compartment fluid volume removal data from patients during acute and chronic dialysis would be helpful in gaining insight into the specific hemodialysis operating characteristics needed under these conditions. Such volume from the intracellular (V c ), interstitial (V i ), and intravascular (V b ) information does not seem to be available in the literature. ObjectiveThe aim of this study was to use electrical impedance spectroscopy (EIS) to measure V c , V i , and V b volume changes during hemodialysis (HD) in End-Stage Renal Disease ((ESRD) patients in an outpatient or Chronic Unit (CU) and in an inpatient or Acute Unit (AU) setting and create pattern profiles for each treatment center. Methods Electrical Impedance Spectrograph DescriptionThe EIS (Z-Scan-2, U.F.I. Inc, Morro Bay, CA) used in this study, combines two bioimpedance instruments into a single device. It combines a fixed frequency Impedance Plethysmograph (IPG)