Abstract:

Objective To evaluate the fluid balance and dry weight with whole body bioelectrical impedance analysis (BIA) in patients with maintenance hemodialysis (MHD）. Methods Twenty patients in stable condition with MHD for more than one year were selected (MHD group). Extra-cellular water (ECW) and intra-cellular water (ICW) were measured by BIA before hemodialysis, after hemodialysis and at intervals of hemodialysis (24 h and 48 h after hemodialysis), and related parameters were calculated. Whether patients with MHD achieved dry weight at 0 h was analysed, and the effects of average daily urine volume on ECW and ICW were explored. Another 20 healthy volunteers were served as controls. Results Compared with control group, ECW retrieved by ideal body weight was significantly higher before hemodialysis in MHD group (P<0.05）. In MHD group, ECW was significantly lower after hemodialysis than that before hemodialysis (P<0.05）. ECW/total body water (TBW) was significantly lower and ICW/TBW was significantly higher after hemodialysis than those before hemodialysis and at intervals of hemodialysis(P<0.05）. ICW and ECW at each time point were significantly related to body weight. ICW and ECW retrieved by ideal body weight at 0 h and 24 h of those who achieved dry weight were significantly higher than those who did not achieve dry weight (P<0.05）. ECW and ICW before hemodialysis and 24 h after hemodialysis were significantly lower in those with urine volume ＜400 mL/d than those with urine volume ≥400 mL/d (P<0.05）. Conclusion BIA analysis indicates that changes of fluid balance before hemodialysis, after hemodialysis and at intervals of hemodialysis in patients with MHD are characterized by ECW, and ECW/TBW is a more sensitive parameter. ICW and ECW retrieved by ideal body weight may be sensitive parameters to determine the dry weight in patients with MHD.

Key words: maintenance hemodialysis, bioelectrical impedance analysis, dry weight, intra-cellular water, extra-cellular water