Moderate Hyperventilation Prolongs Electroencephalogram Seizure Duration of the First Electroconvulsive Therapy

Abstract

Although it is controversial that seizure duration can influence the efficacy of electroconvulsive therapy (ECT), a missed or brief seizure is considered less effective ECT. Of the background in the practice of ECT, hyperventilation may augment the seizure duration. To elucidate these hypotheses, we performed double-blind randomized controlled trial for 19 patients. They were divided into 2 groups, according to the end-tidal pressure of carbon dioxide (ETCO2): The moderate hyperventilation group with ETCO2 of 30 mm Hg and the normal ventilation group with ETCO2 of 40 mm Hg. ECT was performed under general anesthesia with propofol and suxamethonium. During ECT electroencephalogram (EEG) and electromyogram were recorded. The Global Assessment of Functioning scores were also analyzed before and after 6 sequential ECT. The moderate hyperventilation group showed a significant increase in EEG seizure duration in the first treatment compared with the normal ventilation group (P < 0.05). However, EEG seizure duration in the subsequent treatments and electromyogram seizure duration in all the treatments did not differ between 2 groups. The moderate hyperventilation did not prevent the increase in seizure threshold or shortening of seizure duration. No complications or sever adverse effects were observed after ECT in any of the 6 treatments. The Global Assessment of Functioning scores were not significantly changed with moderate hyperventilation. We conclude that moderate hyperventilation is safe and may be useful for seizure augmentation before the restimulation with higher intensities.

Incidence and risk factors for oxygen desaturation during recovery from modified electroconvulsive therapy: A prospective observational study

“…As regards optimal PCO 2 , one study demonstrated that hyperventilation lead to prolongation of the seizure. [ 8 ] Both the above facts taken together, an appropriate ventilatory strategy during ECT seems to be one that employs modest increase in FiO 2 and maintenance of normocapnia.…”

Augmentation Strategies in Electroconvulsive Therapy

“…These results were recently replicated, but the results are confounded by the use of age-based dosing rather than stimulus titration. 10 Only 1 study has analyzed the effect of hyperventilation on electroencephalographic (EEG) morphology or clinical response. In a randomized, double-blind, controlled study of 25 patients with depression, the addition of hyperventilation (20 breaths during 20 seconds) to treatments 2 to 4 of a course of moderatedose right unilateral ECT had no effect on the Hamilton Depression Rating Scale score after the fourth treatment or on visual assessment of EEG morphology.…”

Changes in cardiac autonomic nervous system activity during a course of electroconvulsive therapy

“…Hyperventilation gives rise to an increase in PO 2 and a fall in PCO 2 and may improve the quality of ECT‐induced convulsions as well as the safety of ECT . Hyperventilation prior to ECT stimulation lowers the convulsive threshold, and 100% oxygenation is recommended .…”