High bicarbonate replacement fluid and time to pH normalization during continuous veno-venous hemofiltration with...

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.

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.

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.

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.