1572. Evaluation of Vancomycin Levels Following Weight-Based Pre-operative and Re-warming Vancomycin Dosing in Cardiac Surgery

BACKGROUND: Weight-based dosing of vancomycin in the pre-operative setting is standard practice at our institution based on the 2013 Clinical Practice Guidelines for Antimicrobial Prophylaxis in Surgery. Our antimicrobial subcommittee recommended a weight-based dosing (15 mg/kg/dose) approach to negate the need for a subsequent vancomycin dose during rewarming in cases requiring cardiopulmonary bypass (CPB). However, after discussion with all perioperative stakeholders, administration of vancomycin 1 g intravenously for all patients on CPB at rewarming continued. The aim of this study was to determine whether subsequent rewarming vancomycin doses contributed to the development of postoperative acute kidney injury (AKI). METHODS: This was a prospective cohort study of all cardiac surgery patients undergoing surgery from April 16, 2018 through April 27, 2018 for the development of AKI as defined by RIFLE criteria. Institutional guidelines recommend vancomycin as perioperative prophylaxis in all cardiac surgery cases with a preoperative 15 mg/kg dose, a 1 g rewarming dose, and nomogram-based post-operative dosing. Vancomycin troughs were obtained prior to the first post-operative dose in the intensive care unit. Serum creatinine was recorded on the post-op day (POD) 0, POD 1, and POD 7. RESULTS: Data were collected on 54 patients over a 2-week period. The median age was 64 years of age, with 41 (76%) male patients. Seven patients (13%) had a prior diagnosis of chronic kidney disease (CKD). Post-op AKI developed in 8 patients (15%) by POD 7; two of which had CKD at baseline. All patients received appropriate preoperative and postoperative dosing. Forty-nine (91%) patients had trough levels obtained, with the median trough 7.6 μg/mL (range 2 – 15.9 μg/mL) prior to the first nomogram-based post-operative vancomycin dose. Higher rates of AKI were associated with a longer duration of CPB rather than vancomycin levels obtained. CONCLUSION: The current practice of redosing 1 g vancomycin at rewarming did not appear to contribute higher rates of AKI. In addition, all vancomycin trough levels reviewed were less than 20 μg/mL. Levels observed in this study are lower than previously described in the literature to cause nephrotoxicity. Further evaluation of vancomycin use in this setting is warranted DISCLOSURES: All authors: No reported disclosures.