Two commonly used anesthetics produce different metabolic patterns in the brains of unconscious children, according to a study from the November issue of a Anesthesiology. Researchers from Stony Brook University, New York, found the inhalant gas anesthetic sevoflurane produced more lactate, a marker for enhanced or changed brain metabolism, compared to the intravenous anesthetic propofol.

While past pediatric literature has reported that sevoflurane may be associated with emergence delirium, a state of consciousness in which a child is inconsolable, irritable or uncooperative, the study explored the potential association between emergence delirium and specific brain metabolites like lactate.

About the Study

Applied proton magnetic resonance spectroscopy (1HMRS) was used to investigate the metabolic consequences of general anesthesia in the brains of rodents. Findings revealed inhalant gas anesthetic was characterized with higher concentrations of lactate, glutamate and glucose in the brains compared to propofol.

Next, researchers analyzed 59 children, ages 2 to 7 years, who underwent magnetic resonance imaging under anesthesia with either sevoflurane or propofol. 1HMRS scans were acquired in the parietal cortex after approximately 60 minutes of anesthesia. Upon consciousness, children were assessed using the pediatric anesthesia emergence delirium scale.

The research discovered that sevoflurane was associated with higher concentrations of lactate and glucose, compared to children who were anesthetized with propofol. Exploratory analysis of the data showed children who emerged from anesthesia with more agitation and dissociative behavior had the highest levels of brain lactate.

"Higher levels of lactate in the brain could lead to anxiety and/or delirium during emergence from anesthesia and in the immediate post-operative period," said lead study authors Helene Benveniste, M.D., Ph.D. and Zvi Jacob, M.D. "As an increasingly young patient population continues to have a growing need for general anesthesia, it is important to determine the impact inhalant and intravenous anesthetics have on children."

While millions of children safely undergo anesthesia without any evidence of harm, the researchers hope the study will provide understanding as to why some children have delirium after anesthesia.