A comparison of methods to detect awareness under anaesthesia for patients undergoing electro-convulsive therapy.

For ECT, it is common practice to use as a low an anaesthetic dose as practical as the anaesthetic induction drugs have a tendency to suppress the therapeutic ECT seizure. This leads to an increased risk of awareness under anaesthesia. Despite this increased risk, many institutions take no extra precautions. Others, such as our institution, use an isolated limb technique, where the patient's foot is isolated from the paralysing drugs with a BP cuff so if the patient is still awake they can still communicate by moving their foot, prior to treatment. The use of Bispectral index (BIS) (EEG brain monitoring to prevent awareness under anaesthesia is in common use in other areas of anaesthesia) has been described for ECT but there are no papers comparing BIS and isolated limb technique or their comparative accuracy. Our exposure will be to add a BIS monitoring to our standard isolated limb technique, and have an independent observer record the value on the BIS monitor and the presence or absence of foot movement to voice command just prior to the ECT treatment. ECT procedures typically take 20-30 mins from when the patient wheels into operating theatre to wheels out. The actual anaesthetic and ECT treatment take around 10-15 mins, with the rest of the time need for setup. This trial is not expected to increase the time per procedure as the BIS electrodes can be attached by the anaesthetist in parallel with the psychiatrist attaching the ECT electrodes. It is anticipated the majority of patients enrolled in the trial will have a single treatment observed but some may have more than one treatment session observed, the frequency of which is determined by whatever their normal treatment schedule is. For example, some patients receive fortnightly or monthly maintenance ECT, in which case they would be observed fortnightly, or monthly. Some patients receive higher frequency, for example ECT every second day. The trial does not determine in anyway how often the patient receives ECT, it only observes them during their normal treatment. The observation will be performed members of the trial team, either Dr Mackenzie, or Dr Allysan Armstrong-Brown, (both trained in Anaesthesia) who will be in the operating theatre observing. In addition, the patient will have their own treating Anaesthetist who is blinded to the BIS scores, and will be looking after their ECT patient as they normally would.