Comparison of Remimazolam and Etomidate As Induction Agents for Electroconvulsive Treatment

Patients who underwent ECT under general anesthesia between April 2023 and January 2024 were included. The exclusion criteria were as follows: (1) American Society of Anesthesiologists Physical Status ≥3; (2) age <18 or >70 years; and (3) patients with cognitive impairments, such as dementia or delirium. The study sample comprised 30 patients aged 18-70 years who were scheduled to undergo ECT for major depression, schizophrenia, and schizoaffective disorder. The sample size was calculated using G*Power to compare the recovery times between the two groups. On the basis of an effect size of 0.7 obtained from a previous pilot study and a significance level of 0.05, investigators derived a total sample size of 28. Considering a follow-up loss rate of approximately 10%, investigators designed the study to include a total of 30 participants.

The patients were divided into two groups of 15 each and randomly assigned to ei-ther group E or group R using a computer-generated random number table. To minimize variability in recovery speed and response to medication between individuals, investigators devised a crossover study design in which etomidate and remimazolam were administered alternately, with each drug administered once. Patients in group E received etomidate as the induction agent for the first ECT session, followed by remimazolam for the second ECT session a few days later. Conversely, patients in group R received remimazolam as the induction agent for the first ECT session and etomidate for the second ECT session a few days later. The patients and raters were blinded to the administered anesthetic drugs. Blinding was implemented using opaque sealed envelopes that were sequentially numbered.

ECT was conducted following the international standards approved by our institu-tion, using the SpECTrum 5000 Q device (MECTA Corporation, Lake Oswego, OR, USA).

No premedication was administered, and all patients were required to maintain nil per os for at least 8 h before the procedure. During each ECT session, all patients un-derwent non-invasive blood pressure measurement, electrocardiogram, and peripheral oxygen saturation (SpO2) monitoring, and received preoxygenation through an O2 facial mask before anesthesia.

For neuromuscular blockade, succinylcholine (0.8-1.2 mg/kg IV) was used. The an-esthetic dosages were etomidate at 0.15-0.20 mg/kg IV and remimazolam at 0.12-0.15 mg/kg IV. Following admission and monitoring of the patient, preoxygenation was per-formed until SpO2 reached 100%. Then, the induction agent, either etomidate or remi-mazolam, was administered, immediately followed by 100 mcg of remifentanil. Once the patient stopped responding on being called, a cuff was placed on one arm and inflated until the radial artery pulse was no longer detectable. After isolating one arm, succinyl-choline was administered and sufficient time was allowed for fasciculation to resolve before proceeding. After adequate time for the muscle relaxant to take effect, electrical currents were delivered to the brain through electrodes placed on the scalp. The intensity of the current was determined according to an established psychiatric protocol, and in the absence of a seizure, was increased by 10 J in three successive attempts. If a seizure lasting longer than 30 s was induced, the treatment was considered successful. The duration of the seizure and corresponding shock intensity were recorded for each patient.

Following the seizure, mask ventilation was continued until spontaneous respiration returned. The time from the end of the seizure until the patient's spontaneous tidal volume reached ≥200 mL was measured and defined as the self-respiration recovery time. Additionally, the time from the end of the seizure until the patient opened their eyes spontaneously, either in response to a gentle tap or verbal stimulation, was measured and defined as the eye-opening recovery time.

Apart from the induction agent, there were no differences between the two groups in terms of procedural techniques, anesthetic management during surgery, or cardiovascular support.