(865) Vancomycin Toxicity After Sternal Washout for Mediastinitis in a Pediatric Patient With CKD

Introduction: Mediastinitis after surgery for congenital heart disease has a great impact on morbidity and mortality. Treatment includes sternal debridement, and irrigation with antibiotics.
Nephrotoxicity from supratherapeutic vancomycin plasma levels have been widely reported in pediatric patients with chronic kidney disease (CKD) receiving intravenous vancomycin. However, there have been no reports of vancomycin toxicity following wound debridement and irrigation.

Description: We present a 9 month old male with a history of Tetralogy of Fallot/Bicuspid aortic valve and renal dysplasia leading to CKD stage IV. He underwent stage 1 palliation with transannular patch, MPA band and aortic valve repair at 1 month of age and most recently VSD/ASD closure with placement of RV-PA conduit. He developed mediastinitis on post op-day 3 with initiation of intravenous cefepime and trough based vancomycin at renal dosing. 51 hours before mediastinal washout, the patient's vancomycin trough was 9.5mcg/mL and he was given a single renally adjusted dose. His trough 32 hours and 8 hours prior to the procedure were 18.8mcg/mL and 16.7 mcg/ml respectively. He did not receive further vancomycin doses. At the time of washout the patient's creatinine was 1.31mg/dL. A standard mediastinal washout media of 1000mg of vancomycin in 1000mL of normal saline was utilized. Vancomycin levels were trended with intent of continuing antibiotics until final culture results. A trough collected 16 hours after washout was elevated to 54.9 mcg/mL with a creatinine of 2.4mg/dL. Patient had not received intravenous vancomycin for 72 hours prior to this. His only vancomycin exposure was from the mediastinal washout. Wound cultures grew Serratia and Stenotrophomonas species. He was placed on intermittent hemodialysis for vancomycin toxicity with a downtrend in vancomycin level to 14.4 mcg/mL. He continued to improve off dialysis with a trough level of 0.5 mcg/ml on POD 6 and improvement in creatinine to 0.61mg/dL.

Discussion: We hypothesize that this patient’s toxicity was from vancomycin administration into the mediastinum during his procedure. Pediatric patients with CKD would benefit from further research regarding the possibility of systemic absorption of vancomycin after mediastinal washout.