Enhancing ECT technique: the influence of anaesthetic factors on ictal seizure quality in electroconvulsive therapy

Electroconvulsive therapy (ECT) is an effective treatment for severe psychiatric disorders, particularly major depression. ECT involves the induction of a generalised seizure, under general anaesthesia. Commonly used anaesthetic agents possess anticonvulsant properties, which may reduce the quality of the induced seizure and the efficacy of ECT treatment. Preliminary evidence suggests that the time interval between anaesthetic induction and ECT stimulus administration impacts ECT seizure quality. Previously, it was unclear to what degree this was a direct consequence of the time interval, as opposed to the ventilation provided during the time interval, as hyperventilation has been shown to impact seizure quality. This thesis aimed to clarify the influence of the time interval and ventilation technique on seizure quality. Further, the importance of seizure quality for the efficacy of ECT was examined. Study 1 is a systematic review of evidence addressing the clinical relevance of ictal EEG quality, the main outcome of interest in studies 2 and 3. The review explores the relationship between ictal seizure quality, treatment technique and treatment outcomes. This review confirmed that ictal EEG quality is an important clinical measure, with evidence to support ECT dosing decisions based on changes in EEG quality across the ECT treatment course. Study 2 is a retrospective study examining the influence of the anaesthetic to ECT stimulus time interval on seizure quality, with thiopentone anaesthetic. This study confirms previous preliminary findings with propofol anaesthetic, with longer time intervals showing better seizure quality, providing further evidence of the clinical importance of the anaesthetic to ECT stimulus time interval. Study 3 is a prospective randomised trial examining the relative impact of the anaesthetic to ECT stimulus time interval, and the pre-treatment ventilation approach, on ictal seizure quality utilising a 2 x 2 factorial, crossover study design. Results confirm the significant effect of the anaesthetic to ECT stimulus time interval on seizure quality and argue strongly for the regular clinical monitoring, and potential optimisation, of this variable. By contrast, the effect of ventilation rate pre-treatment was not significant. In summary, this thesis provides new evidence demonstrating the impact of anaesthetic technique on ictal seizure quality and elucidates the clinical relevance of these novel findings