Induction of anaesthesia with thiopentone and nitrous oxide. Anaesthesia was induced at (2) and the trace to the left of this was obtained whilst the patient was conscious in the anaesthetic room. At (1) the anaesthetist began to prepare for induction. The shift to beta band activity and the appearance of scalp muscle activity indicates some apprehension on the part of the patient (Note the muscle activity interferes with the impedance trace). Anaesthesia was induced with thiopentone, pancuronium, phenoperidine and 70% nitrous oxide, and was accompanied by an increase of amplitude. When this had nearly reached its peak, some 20 seconds later, there was an attenuation of beta and the appearance of theta and delta band activity. Thirty seconds later scalp muscle activity ceased. As the induction dose wore off the beta band activity returned and theta and delta band activity decreased.
Reproduced with permission from "The cerebral function analysing monitor: initial clinical experience, application and further development", D E Maynard and J L Jenkinson, Anaesthesia, 1984, Volume 39, pages 678-690.Published by Blackwell Science. http://www.blackwell-science.com/ana
