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Abstract
Electroconvulsive Therapy (ECT) remains an essential therapeutic tool in modern psychiatry. ECT involves the administration of an electrical stimulus via two electrodes placed on the scalp to produce generalised seizure activity, under controlled anaesthetic conditions. Adequate seizure elicitation and quality are important, as they can contribute to cognitive and efficacy outcomes with ECT. However, general anaesthetics used for ECT have anticonvulsant properties, potentially interfering with the elicitation and quality of the ECT seizures. This thesis presents three studies that investigated the impact of different aspects of anaesthesia technique (anaesthetic type, dose, timing, addition of opioids) on seizure outcomes and inferred methods to reduce the anticonvulsant burden of intravenous anaesthetics on ECT seizure production and quality.
Study 1 examined the effects of several variables, including different anaesthetic regimens (propofol vs thiopentone) and doses, on the elicitation of seizures with Right Unilateral Ultrabrief (RUL UB) ECT, a relatively new ECT modality. Results from this study suggest that the type of anaesthesia used and its dose can impact on seizure threshold.
Study 2 assessed the effect of naturalistically varying the anaesthetic-ECT time interval on the quality of the ECT seizures, in the context of using propofol anaesthesia for RUL brief pulse ECT. Results from study 2 suggest that the time interval between the start of anaesthesia induction and the commencement of the ECT stimulus (anaesthetic-ECT time interval) can significantly impact on the quality of the seizures and highlight that this factor should be taken into account in ECT practice.
Study 3 explored the effects of the addition of co-adjuvant remifentanil to the main anaesthetic ECT agent (propofol, thiopentone) on seizure quality, when the dose of the latter was maintained (i.e, not reduced). Findings suggest that the addition of co-adjuvant remifentanil to standard anaesthetic doses does not have a positive effect on seizure quality, thus remifentanil should not be considered a seizure enhancer or augmenter.
In summary, this thesis presented novel clinical findings in relation to the anaesthetic approach in ECT that represent a potential step forward in the improvement of anaesthetic ECT procedures.