Effects of the Anaesthetic-ECT time interval and ventilation rate on seizure quality in electroconvulsive therapy: A...

The anaesthetic approach adopted in ECT practice has the potential to influence patient outcomes. However, the impact of the time interval between anaesthetic induction and ECT stimulus administration has not been studied prospectively to date. This variable may represent an indirect measure of anaesthetic concentration at the time of stimulation, and therefore may influence the quality of seizures induced.

To examine the impact of the anaesthetic to ECT stimulus time interval, and ventilation rate pre-treatment, on ictal seizure quality.

In a prospective, crossover trial, 54 depressed participants were randomised to variations in anaesthetic technique at four sequential ECT treatment sessions, in a 2 x 2 design: randomisation to a short or long anaesthetic-ECT time interval, and randomisation to normal ventilation or hyperventilation during anaesthetic induction with thiopentone. Ictal EEG data were collected at each study session and assessed by a blinded rater for ictal quality (seizure amplitude, regularity, post-ictal suppression and general seizure quality), using a quantitative-qualitative structured rating scale. Linear mixed effects models were used to analyse the effect of the anaesthetic-ECT time interval, and that of ventilation rate, on seizure quality indices.

The anaesthetic-ECT time interval had a significant impact on ictal EEG quality indices (p < 0.01), with longer time intervals producing higher quality seizures. Ventilation rate did not significantly influence quality measures.

The time between anaesthetic induction and ECT stimulus administration has a significant impact on ictal EEG seizure quality. Conversely, manipulations of ventilation rate did not significantly affect seizure quality. These results suggest the anaesthetic-ECT time interval should be routinely monitored clinically and potentially optimised for maximising seizure quality with ECT.