High bicarbonate replacement fluid and time to pH normalization during continuous veno-venous hemofiltration with regional citrate anticoagulation: a retrospective single-center cohort study.

Abstract

Background: In critically ill patients, acid-base disorders are common before start of continuous renal replacement therapy. The aim of this study was to determine the influence of a high bicarbonate replacement fluid (30 mmol/L, Phoxilium^®) on underlying acid-base disturbances.

Methods: This single-center retrospective study included patients treated with continuous veno-venous hemofiltration (CVVH) at a medical ICU from January 2018 to May 2019. All patients received CVVH with regional citrate anticoagulation (RCA) and a high bicarbonate RF (Phoxilium^®). Patients were categorized based on their initial pH. Acid-base parameters were closely monitored over 72 h at pre-specified intervals.

Results: The study included 64 patients with a median age of 68 years. At the start of CVVH, 56.3% (n = 36) had acidemia, 12.5% (n = 8) had alkalemia and 32.3% (n = 20) had a normal pH. The median pH of patients with acidemia [0 h: 7.28 (interquartile range 7.23-7.33)] was corrected quickly to the normal range within 8 h [7.36 (interquartile range 7.29-7.4)]. The median pH of patients with alkalemia took longer (48 h) to reach normal values and patients with a normal pH showed a further pH increase within the normal range over the 72 h. All patients showed an increasing bicarbonate and base excess from 24 to 72 h.

Conclusions: The RF in CVVH with RCA appears to be one of several factors influencing acid-base balance. Patients with different pre-existing acid-base disorders showed distinct correction kinetics. Prospective studies are needed to determine the clinical relevance of these findings and to optimize RF composition for better patient outcomes.