Comparison of two different bicarbonate replacement fluids during CVVH with RCA: a prospective, randomized, controlled trial.

Abstract

This study aimed to compare a high (HBF) and low (LBF) bicarbonate (HCO₃^-) replacement fluid over 96 h after continuous veno-venous hemofiltration (CVVH) initiation using regional citrate anticoagulation to determine which fluid achieved better acid-base balance. In this prospective, randomized, controlled, open-label, cross-over, single-center trial, patients were randomized to initially receive either LBF (22 mmol/l HCO₃^-) or HBF (30 mmol/l HCO₃^-) for 48 h (first phase), followed by changing to the other fluid for a further 48 h (second phase). Intracorporeal pH and HCO₃^- changes were analyzed by calculating the rates of levels outside the standard values (excursion rates). Generalized estimating equations were performed to estimate the odds ratios for at least one pH/HCO₃^- excursion. Time to normalization within the first phase for pH and HCO₃^- was assessed using Kaplan-Meier curves and log-rank tests. A total of 88 patients were included. The rates for at least one pH and HCO₃^- excursion were higher in patients treated with HBF compared to LBF (pH: first phase 52% vs. 41%; second phase 48% vs. 34%; HCO₃^-: first phase 68% vs. 43%; second phase 73% vs. 43%). Adjusted odds ratios were 1.78 (95% CI 1.12-2.82; p = 0.015) for pH and 3.60 (95% CI 2.16-5.99; p < 0.001) for HCO₃^-. The time to normalization of pH in acidotic patients and of HCO₃^- in patients with low HCO₃^- did not differ significantly between HBF and LBF (p = 0.102, p = 0.468). LBF showed significantly lower rates of pH and HCO₃^- excursions compared to HBF and no significant differences to the pH normalization in acidotic patients were observed. NCT04071171.