The effectiveness of water balance correction disorders by multifrequency bioimpedance spectroscopy and vector analysis of bioimpedance in hemodialysis patients: a randomized clinical trial

Introduction. Bioimpedance is a promising method for assessing hydration status in hemodialysis patients. However, the optimal algorithm for "dry" weight correction and its effectiveness – particularly with respect to hard outcomes – remains to be clarified.

Patients and methods. In a single-center, open-label randomized trial involving 98 patients, we evaluated both the short-term (weight dynamics, peridialysis blood pressure, and intradialysis complications) and long-term outcomes (five-year survival from study initiation) of dry weight correction guided by clinical and instrumental data compared with correction based solely on clinical indicators. Weight correction was performed according to a newly developed algorithm incorporatinh multi-frequency bioimpedance spectroscopy and vector bioimpedance analysis for six months, followed by a five-year observation period.

Results. 51 patients were assigned to study group (SG), and 47 to the control group (CG). Baseline clinical and laboratory parameters did no differ between the groups. In the SG, target weight increased in 13 patients by 1.3±0.9 kg, decreased in 26 patients (-1.1±0.4 kg), and remained unchanged in 12. In the CG, during the three-month follow-up period, target weight increased in 19 patients (1.3±0.9 kg), decreased in 26 (-1.2±0.8 kg), and remained unchanged in 2. The SG demonstrated a significant reduction in the number of complications per month (32 vs. 52, p=0.033), primary due to a reduction in intradialysis hypertension (15 vs. 34, p=0.009). A greater intradialytic blood pressure decrease was achieved in the SG; an effect size of 5.3 mmHg compared to CG (p=0.04). Moreover, 65% of SG patients did not require a second adjustment of target weight. Five-year survival rate was significantly higher in the in SG (χ²=4.096; p=0.043). Active dehydration was not associated with reduced survival compared with maintaining or increasing target weight (χ²=2.454, p=0.117).

Conclusions. A comprehensive algorithm for "dry" weight correction – incorporating a calculated hyperhydration coefficient, bioimpedance spectroscopy with vector analysis, and clinical signs of impaired hydration – can reduce the complications rates and the hypertension severity, improve hemodynamic stability during dialysis, and enhance patient survival.

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