Are children undergoing cardiac surgery receiving antibiotics at subtherapeutic levels?

Abstract

OBJECTIVES Perioperative antibiotics have decreased, but not eradicated post-operative infections. In patients undergoing cardiac surgery with cardiopulmonary bypass, the dilutional effect of the priming and any additional volume given during the procedure may lead to subtherapeutic antibiotic levels. Our aim was to determine whether children undergoing cardiac surgery with cardiopulmonary bypass receive subtherapeutic perioperative antibiotics. METHODS Using published pharmacokinetic data on cefuroxime, we developed a computer simulation model to generate a nomogram predicting patients at risk for subtherapeutic cefuroxime levels based on time from initial dosing and additional volume given. RESULTS A computer-generated one-compartment pharmacokinetic model was created predicting cefuroxime plasma levels over time for patients of all weights and additional volumes given for both a 25- and 50 mg/kg intravenous dose. For example, following a 25 mg/kg dose, a subject receiving an additional volume of 275 mL/kg is predicted to be subtherapeutic (<16 mg/L = 4 x mininum inhibitory concentration) at 4 hours. Our nomogram predicts all subjects will be subtherapeutic at 8 hours consistent with general pediatrics dosing schemes. Following a 50 mg/kg dose, levels are predicted to be subtherapeutic after an additional volume of 315 ml/kg at 5.5 hours. CONCLUSION Our model predicts which patients undergoing cardiac surgery with cardiopulmonary will have subtherapeutic cefuroxime levels. This nomogram enables providers to determine when to re-dose antibiotics in patients receiving large additional volumes during cardiac surgeries. This rational approach to perioperative antibiotic dosing may result in a reduction in post-operative infection in this vulnerable patient population.