Bioimpedance-guided fluid management in hemodialysis patients

Abstract

Background and objectives: Achieving and maintaining optimal fluid status remains a major challenge in hemodialysis therapy. The aim of this interventional study was to assess the feasibility and clinical consequences of active fluid management guided by bioimpedance spectroscopy in chronic hemodialysis patients.

Design, setting, participants, & measurements: Fluid status was optimized prospectively in 55 chronic hemodialysis patients over 3 months (November 2011 to February 2012). Predialysis fluid overload was measured weekly using the Fresenius Body Composition Monitor. Time-averaged fluid overload was calculated as the average between pre- and postdialysis fluid overload. The study aimed to bring the time-averaged fluid overload of all patients into a target range of 0.5 ± 0.75 L within the first month and maintain optimal fluid status until study end. Postweight was adjusted weekly according to a predefined protocol.

Results: Time-averaged fluid overload in the complete study cohort was 0.9 ± 1.6 L at baseline and 0.6 ± 1.1 L at study end. Time-averaged fluid overload decreased by -1.20 ± 1.32 L (P<0.01) in the fluid-overloaded group (n=17), remained unchanged in the normovolemic group (n=26, P=0.59), and increased by 0.59 ± 0.76 L (P=0.02) in the dehydrated group (n=12). Every 1 L change in fluid overload was accompanied by a 9.9 mmHg/L change in predialysis systolic BP (r=0.55, P<0.001). At study end, 76% of all patients were either on time-averaged fluid overload target or at least closer to target than at study start. The number of intradialytic symptoms did not change significantly in any of the subgroups.

Conclusions: Active fluid management guided by bioimpedance spectroscopy was associated with an improvement in overall fluid status and BP.

Figures

Figure 1.

Fluid overload (FO) over 1 week in three times per week ultrafiltrationtreatment. Pre- and post-FO is typically higher after the long interval and lower after the short intervals. Weekly time-averaged fluid overload (TAFO) is defined as the average fluid overload throughout 1 complete week.

Figure 2.

Study flow diagram.

Figure 3.

Development of TAFO over the study period. Bars indicate median, 95% confidence interval for the median (dark gray), and 1 SD (light gray). The range in the background depicts the TAFO target range of 0.5±0.75 L. The change in SD from ±1.6 L at baseline to ±1.1 L at study end was significant (P<0.001).

Figure 4.

Change in predialysis systolic BP (BPsys) over change in TAFO between baseline and study end.