Background: Bioelectrical impedance analysis (BIA) is a non-invasive method to estimate total body water (TBW) and extracellular water (ECW) volume. Crit-Line(®) (CL), on the other hand, assesses intravascular water (IVW) volume. We evaluate continuous changes in body water composition during hemodialysis (HD) with concurrent use of BIA and CL.
Methods: BIA at the start and the end of the HD session was measured using a BIA device. To investigate the shifting pattern of body water composition, patients were subjected to simultaneous monitoring of BIA with CL.
Results: Both TBW resistance (Rt) and ECW resistance (Re) increased in response to changes in the ultrafiltration (UF) ratio. There was a positive correlation between ΔRe/Rt and the UF ratio, and the ratio of Re/Rt at the end of HD was significantly higher than that at the start of HD. Simultaneous monitoring of BIA with CL showed a parallel shift of the change in the Re (ΔRe) and the change in hematocrit (ΔHt). In one patient with increasing inflammatory response, change in ΔHt was dissociated from change in ΔRe. One hyponatremic patient showed a different pattern of changing ΔRe between the first half and the latter half of the HD session.
Conclusion: Our study suggests that the concurrent use of BIA and CL may be a useful technique to simulate water shift patterns across the different compartments in HD.