#2725 Chronic kidney disease is a risk factor for hyperchloremic metabolic acidosis after plasma exchange

Abstract

Abstract Background and Aims Observational studies have demonstrated that metabolic acidosis due to hyperchloremia is an often encountered metabolic disorder following plasma exchange (PE) with an albumin-saline solution. Because of the reduced capacity for acid and chloride excretion, we hypothesized that patients with chronic kidney disease have the highest risk for hyperchloremic metabolic acidosis, in particular when multiple PE sessions are performed in a limited period. Method We prospectively collected data from all patients who received PE at Amsterdam UMC, between February 2023, and January 2024. We collected data on demographics, exchanged plasma volume, replacement fluids, and collected blood for analysis of sodium, chloride and bicarbonate before and after plasma exchange. We selected patients who received ≥5 plasma exchanges in an intensive cycle (≥4.2 sessions/week). We excluded patients who received Omniplasma, intravenous sodium bicarbonate or dialysis during the PE period. We assessed the effect of PE and kidney function on plasma bicarbonate and chloride concentration throughout the PE period with repeated measures mixed ANOVA, corrected for baseline plasma bicarbonate concentration, volume of exchanged plasma and PE intensity. Results Data from 26 patients, corresponding to 130 plasma exchanges, were included in the analysis. The mean age was 56 ± 14 years and 46% was female. Mean eGFR was 45 ± 14 ml/min/1.73 m2. Patients with an eGFR ≤59 ml/min/1.73 m2 (n = 17) had a significantly lower baseline plasma bicarbonate concentration (19.0 ± 2.8 versus 24.0 ± 1.9 mmol/L; p < 0.001) and used oral bicarbonate supplements (29% versus 0%; p = 0.02) more often than patients with an eGFR ≥60 ml/min/1.73 m2 (n = 9). Despite the lower baseline plasma bicarbonate and more frequent use of oral bicarbonate supplements, the plasma bicarbonate levels decreased the most in subjects with an eGFR ≤59 ml/min/1.73 m2 (mean difference −4.2; 95% CI −7.1 to −1.3; p = 0.006; Fig. 1A) during a cycle of 5 PE sessions. Baseline plasma chloride concentration was similar in both groups (103 ± 7 vs 103 ± 4 mmol/L) and increased the most in patients with an eGFR ≤59 ml/min/1.73 m2 (mean difference −1.4; 95% CI −2.2 to 5.0; p = 0.426; Fig. 1B). Conclusion Repeated plasma exchange with albumin-saline as a replacement fluid is associated with a significant decrease in plasma bicarbonate concentration in patients with impaired kidney function. Future studies should determine whether this hyperchloremic metabolic acidosis has impact on the patients’ symptoms or long-term outcome.