Prof. Kessler began by explaining that the topic of how regional anaesthesia should be performed has always been an intense and somewhat emotional discussion. Should it be performed in awake, sedated and/or anaesthetised patients? He asked the audience how many of them routinely perform peripheral nerve blocks in the anaesthetised patient; around 20% said yes.
Closed-loop studies date back over 60 years. One of the early studies published in 1950 included 50 patients who received thiopental or ether using the closed-loop controller. Anaesthesiologists were already aware then of how to quantify the depth of anaesthesia using electroencephalogram (EEG) activity.