Ketamine Pharmacokinetics in Children Having Heart Surgery

The role of ketamine in pediatric anesthesia is well established. It is one of the most commonly used agents for conscious sedation in pediatrics. Its widespread use stems for its abrupt onset of action and brief duration of sedation. There is limited ketamine pharmacokinetic data in children and none to our knowledge in infants and young children who will be given an intravenous bolus dose before a surgical procedure that includes cardiopulmonary bypass. Ketamine is marketed as a racemic mixture (50:50 mixture of S- and R-ketamine enantiomers). Ketamine undergoes N-demethylation (CYP3B6, 2C9, and 3A4) to its primary active metabolite,norketamine, with minor inactive metabolites, dehydroxynorketamine, generated secondary to direct oxidation. Ketamine exhibits a high intrinsic clearance with hepatic clearance dependent on hepatic blood flow under normal circumstances. One inherent disadvantage associated with the use of cardiopulmonary bypass (CPB) is the potential for organ dysfunction post-operatively. We propose an open-label controlled study describing the disposition of ketamine in 28 infants and children who will be undergoing cardiac surgery with (n=16) and without (n=12) CPB. We anticipate that cardiopulmonary bypass alters the pharmacokinetics of ketamine.