Bioimpedance-guided fluid management in maintenance hemodialysis: a pilot randomized controlled trial

Abstract

Background: Chronic subclinical volume overload happens very frequently in hemodialysis patients and is associated directly with hypertension, increased arterial stiffness, left ventricular hypertrophy, and ultimately higher mortality.

Study design: Randomized controlled parallel-group trial.

Setting & participants: 131 patients from one hemodialysis center, randomly assigned into 2 groups.

Intervention: Dry weight prescription using results derived from repeated 3-month bioimpedance measurements to guide ultrafiltration for strict volume control (bioimpedance group; n=62) compared with clinical judgment without bioimpedance measures (clinical-methods group; n=69) for 2.5 years.

Outcomes: The primary outcome was all-cause mortality over 2.5 years (the duration of the intervention). Secondary outcomes were change in relative arterial stiffness, fluid overload, and blood pressure (BP) over 2.5 years.

Measurements: Bioimpedance measurements were performed using a Body Composition Monitor device. Pulse wave velocity analysis was performed at baseline, 2.5 years (end of intervention), and 3.5 years (end of study). Relative fluid overload and BP were assessed at 3-month intervals.

Results: The unadjusted HR for all-cause death in the bioimpedance group (vs the clinical-methods group) was 0.100 (95% CI, 0.013-0.805; P=0.03). After 2.5 years, we found a greater decline in arterial stiffness, relative fluid overload, and systolic BP in the bioimpedance group than the clinical-methods group. Between-group differences in change from baseline to the end of intervention were -2.78 (95% CI, -3.75 to 1.80)m/s for pulse wave velocity (P<0.001), -2.99% (95% CI, -5.00% to -0.89%) for relative fluid overload (P=0.05), and -2.43 (95% CI, -7.70 to 2.84)mmHg for systolic BP (P=0.4).

Limitations: Echocardiography was not performed as cardiovascular assessment and the caregivers were not masked to the intervention.

Conclusions: Our study showed improvement in both surrogate and hard end points after strict volume control using bioimpedance to guide dry weight adjustment. These findings need to be confirmed in a larger trial.

Trial registration: ClinicalTrials.gov NCT01828658.

Keywords: Bioimpedance; hemodialysis; pulse wave velocity; survival.