Validation of Changes in Extracellular Volume Measured During Hemodialysis Using a Segmental Bioimpedance Technique

Segment-specific resistivity improves body fluid volume estimates from bioimpedance spectroscopy in hemodialysis patients

“…The traditional algorithms for calculation of segmental ECV and ICV (Eqs. 7 and 8) from SBIS take into account tissue resistance data specific for each segment but employ only a uniform value for segmental resistivity (33,34). In a previous study (33), our laboratory reported that these traditional SBIS equations underestimate trunk ECV due to inhomogeneous distribution of current throughout the trunk, and we have been able to improve the accuracy of the equation by introduction of a compensatory factor.…”

“…Tissues containing a combination of water and electrolytes are more conductive than bone, air-filled spaces, and fat. Nevertheless, several reports show that current bioimpedance methods may not be accurate enough for clinical use (8,14,34).…”

The feasibility of using compression bioimpedance measurements to quantify peripheral edema

“…19. A segmental BIS measuring device has been previously used in the hemodialysis setting [28,31,42]. Measurements could be performed using a constant stress in conjunction with single channel, tetrapolar BIS spectroscopy to generate compressive BIS measurements in the clinic.…”

Air displacement plethysmography can detect moderate changes in body composition

“…The absence of X-ray exposure is an advantage of APD over DEXA when repeated measurements are performed, or for the study of women during pregnancy. The ability of BIA to detect the fluid loss after a hemodialysis session (Svendsen et al, 1993) or the fluid changes during peritoneal dialysis (Formica et al, 1993) is less clear: fluid removal is underestimated by BIA when hypotension develops during the session (Zaluska et al, 1998), and a segmental analysis may be required to detect truncal fluid changes (Zhu et al, 1998(Zhu et al, , 2003.…”