LAUSR

INTRODUCTION: Continuous renal replacement therapy (CRRT) augments a patient's volume of distribution and clearance leading to frequent subtherapeutic levels with intermittently dosed vancomycin. Continuous infusion (CI) vancomycin may offer an advantage in CRRT. Limited studies exist comparing intermittent infusion (II) and CI vancomycin. The purpose of this study was to determine if CI vancomycin in patients receiving CRRT results in more frequent therapeutic concentrations compared to II vancomycin. METHODS: This was a single-center, retrospective chart review of critically ill adult patients receiving CI or II vancomycin while on CRRT between January 1, 2017 and March 31, 2021. The primary outcome was frequency of therapeutic vancomycin concentration (15-25 mcg/mL) at 24 ± 6 hours. Secondary outcomes included percentage of patients therapeutic at first concentration, percentage of patients with subtherapeutic and supratherapeutic concentrations, and intensive care unit (ICU) and hospital mortality. RESULTS: A total of 268 patients were screened and 59 patients met inclusion criteria. Seventeen patients received CI vancomycin and 42 patients received II vancomycin. Baseline characteristics were similar with the exception of more COVID-19 patients, more frequent vasopressor therapy, a higher mean SOFA score, and higher BUN at CRRT initiation in the CI group. The total median loading dose was 1000 mg (IQR 1000-1750 mg) in the CI group and 2000 mg (IQR 1500-2000 mg) in the II group (p=0.003). The daily maintenance dose was 1250 mg (IQR 1250-1500 mg) in CI group and 1000 mg (IQR 1000-1000 mg) in the II group (p< 0.0001). Therapeutic concentration at 24 ± 6 hours was achieved in 52.9% of CI patients compared to 47.6% of II patients (p=0.78). Subtherapeutic concentrations occurred less frequently in the CI group (11.8% vs 42.9%, p=0.03) whereas supratherapeutic concentrations occurred more frequently in the CI group (35.3% vs 2.4%, p=0.0016). ICU and hospital mortality were higher in the CI group (88.2% vs 52.4%, p=0.02). CONCLUSION: CI vancomycin was associated with less subtherapeutic concentrations as compared to II vancomycin in patients receiving CRRT. However, there was no difference in frequency of therapeutic concentrations at 24 hours and CI was associated with more frequent supratherapeutic concentrations.