Awareness and memory function during paediatric anaesthesia

Background. Previous research indicates a much higher incidence of awareness during anaesthesia in children than in adults. The present study is the first large-scale, intraoperative assessment of awareness during paediatric anaesthesia using the isolated forearm technique, and the first large-scale study of memory function during paediatric anaesthesia. Methods. One hundred and eighty-four children, 5-18 yr, underwent the isolated forearm technique during the first 17 min of surgery while receiving volatile anaesthesia. The isolated forearm technique was modified to accommodate brief or no paralysis. Bispectral index was monitored in a subset of 54 patients. Sixteen neutral words were played 20 times during surgery and, on recovery, implicit memory for these words was tested with a word identification task. Explicit memory for the surgical period was tested with a structured interview. Behavioural changes were assessed with age-appropriate questionnaires. Results. No child had explicit recall of intraoperative events on recovery, and there was no evidence of implicit memory for words presented during anaesthesia. Two of 184 children made unambiguous and verified responses on the modified isolated forearm technique, an incidence of intraoperative awareness of 1.1%. One of these children reported that he was uncomfortable and not completely unconscious during surgery. Neither child had implicit memory for the neutral words, or adverse behaviour change. Conclusions. The incidence of awareness during surgery in children is approximately eight times that measured in adults by postoperative recall. In contrast to adults, there is no evidence for preserved memory priming during anaesthesia.