Impact of hyperventilation on stimulus efficiency during the early phase of an electroconvulsive therapy course: a...

The question whether hyperventilation during electroconvulsive therapy (ECT) can improve stimulus efficiency is as yet unanswered.

Twenty-five consecutive consenting patients (N = 25) with major depression who were administered ECT entered into the study. Right unilateral ECT at thrice the threshold dose was administered using Mecta spECTrum 5000Q (Mecta Corp, Lake Oswego, Ore), with standard titration procedures and stimulus configurations. At the second ECT session, they were randomly allocated to ECT either with hyperventilation or with no hyperventilation. Hyperventilation was actively administered by an anesthetist just after anesthetic paralysis and before the ECT stimulus during the second, third, and fourth ECT sessions. Assessments were double-blind and performed at baseline and 24 to 48 hours after the fourth ECT session. Time to reorient after ECT was assessed during the first up to the fourth ECT session. Ictal electroencephalogram (EEG) quality was visually assessed using standard scales.

There were no significant differences across the 2 groups about depression severity and global cognitive impact. However, the orientation time was 34% longer among those who did not receive hyperventilation. The ratio of orientation time without hyperventilation to that with hyperventilation equals 1.34 (95% confidence interval, 0.94-1.92; P = 0.103). There was a significant increase in threshold over time across both groups (mean difference, 16.4; SE, 5.5; P = 0.006) with no significant main effect for the groups (P = 0.399). There were no significant group differences in the EEG quality.

The addition of hyperventilation during the early phase of the ECT course shows a trend to lessen the impact on immediate orientation without impeding clinical response. This does not seem to be mediated by differential threshold changes or change to the ictal EEG quality.