Controversies in pediatric anesthesia: sevoflurane and fluid management

Abstract

Purpose of review: To explore the interrelationships among the pharmacokinetics of sevoflurane, epileptiform electroencephalographic (EEG) activity and awareness in children. To also describe the revised perioperative fluid management strategy espoused by Holliday and Segar and noninvasive measures that may predict who will respond positively to fluid loading.

Recent findings: The depth of anesthesia during the early washin period with sevoflurane 8% is one-third less than during halothane. Eight percent sevoflurane rarely causes clinical seizures; more commonly, it causes epileptiform EEG activity that only weakly portends seizure activity. When preceded by nitrous oxide, midazolam or normocapnia, the risk of inducing epileptiform activity during spontaneous respiration is exceedingly small. Decreasing the inspired concentration of sevoflurane upon loss of the eyelash reflex to prevent epileptiform activity has not been shown to reduce the risk of clinical seizures, but more importantly, it may increase the risk of awareness if the child is stimulated. Isotonic intravenous solutions should be infused in volumes of 20-40 ml/kg over 2-4 h in children undergoing elective surgery. Postoperatively, these infusions may be continued at rates of 2/1/0.5 ml/kg/h; serum sodium concentration should be measured periodically. Noninvasive measures currently do not reliably identify those children who will respond positively to fluid boluses.

Summary: Sevoflurane is a well tolerated induction agent that rarely causes seizures in children, but may cause awareness if the inspired concentration is prematurely reduced. Perioperative isotonic fluids should be infused at 20-40 ml/kg over 2-4 h during elective surgery. Noninvasive metrics do not predict a child's responsiveness to fluid loading.