By: 1 March 2013

Some types of anaesthetics cause an increase in the level of lactate production in unconscious children’s brains, causing delirium.

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

While past paediatric 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.

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

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

The research discovered that sevoflurane was associated with higher concentrations of lactate and glucose, compared to children who were anaesthetised with propofol. Exploratory analysis of the data showed children who emerged from anaesthesia 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 anaesthesia 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 anaesthesia, it is important to determine the impact inhalant and intravenous anaesthetics have on children.”

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

For more information, visit the Anesthesiology website at