Low bicarbonate replacement fluid normalizes metabolic alkalosis during continuous veno-venous hemofiltration with regional citrate anticoagulation

Abstract Background Metabolic alkalosis is a frequently occurring problem during continuous veno-venous hemofiltration (CVVH) with regional citrate anticoagulation (RCA). This study aimed to evaluate the effectiveness of switching from high to low bicarbonate (HCO3 −) replacement fluid in alkalotic critically ill patients with acute kidney injury treated by CVVH and RCA. Methods A retrospective-comparative study design was applied. Patients who underwent CVVH with RCA in the ICU between 09/2016 and 11/2017 were evaluated. Data were available from the clinical routine. A switch of the replacement fluid Phoxilium® (30 mmol/l HCO3 −) to Biphozyl® (22 mmol/l HCO3 −) was performed as blood HCO3 − concentration persisted ≥ 26 mmol/l despite adjustments of citrate dose and blood flow. Data were collected from 72 h before the switch of the replacement solutions until 72 h afterwards. Results Of 153 patients treated with CVVH during that period, 45 patients were switched from Phoxilium® to Biphozyl®. Forty-two patients (42 circuits) were available for statistical analysis. After switching the replacement fluid from Phoxilium® to Biphozyl® the serum HCO3 − concentration decreased significantly from 27.7 mmol/l (IQR 26.9–28.9) to 25.8 mmol/l (IQR 24.6–27.7) within 24 h (p