(584) Extracorporeal Membrane Oxygenation and Continuous Renal Replacement Therapy Impact on Vancomycin

Introduction: Vancomycin, an antibiotic used for coverage of gram-positive organisms has antibacterial activity dependent on both time and concentration. Evaluating therapeutic drug levels is imperative. In patients on extracorporeal membrane oxygenation (ECMO) or continuous renal replacement therapy (CRRT), achieving therapeutic levels may be challenging due to the increase in the volume of distribution via hemodilution, altered clearance, and circuit sequestration. The objective of this study is to evaluate the impact of ECMO and CRRT compared to CRRT alone on vancomycin levels.

Methods: This was a single-center, retrospective cohort study performed at an academic medical center. Patients included were adults (≥18 years) who received vancomycin while on ECMO and CRRT or CRRT alone for at least 48 hours between August 2018 to March 2024. Patients were excluded if vancomycin was discontinued prior to obtaining a level or if a significant interruption to CRRT of > 4 hours occurred. The primary outcome was the number of patients who achieved an initial therapeutic vancomycin level. Key secondary outcomes evaluated were total assessment of all levels and dose of vancomycin.

Results: Forty patients were included with equal numbers in each group. All baseline characteristics were similar between the two groups with the exception of lower median age (48 years vs. 63 years; p=0.035) and less end-stage renal disease at baseline (0% vs 40%; p=0.003) in the ECMO plus CRRT group compared to the CRRT alone group. The number of patients that achieved an initial therapeutic level was 11 (55%) in the ECMO plus CRRT group and 10 (50%) in the CRRT alone group (p=0.752) with the median total number of therapeutic levels being 1 in both groups. The median weight-based dose in the ECMO plus CRRT group was similar to the CRRT alone group (15.5 mg/kg vs. 13.7 mg/kg; p=0.061).

Conclusions: Dosing vancomycin in ECMO or CRRT can be challenging due to unpredictable pharmacokinetics. There was no difference in achievement of therapeutic levels between the two groups, but the initial rate of non-therapeutic levels was high. Given the importance of optimal antimicrobial dosing in critically ill patients, education and further investigation is warranted to ensure therapeutic dosing of vancomycin in patients on CRRT with or without ECMO.