Identification of predictors of post-ictal delirium after electroconvulsive therapy.

Aim: Although electroconvulsive therapy (ECT) often causes post-ictal delirium (PID), to date, the specific risk factors of PID have not been described. The purpose of the present study was therefore to elucidate the predictors of PID via identification of the characteristics of patients with PID.

Methods: ECT was conducted in 50 patients and all patients underwent more than four sessions. A sine wave or a brief-pulse square wave ECT instrument was used. After convulsions the patients' PID was monitored for 30 min. The patients were allocated into four groups based on PID severity (none, mild, moderate or severe PID). Variables, including age, gender, duration of illness, diagnosis, clinical features (psychotic or catatonic features) and stimulus waveform (sine or brief pulse square waveform), were analyzed.

Results: Moderate to severe PID developed during the ECT sessions in 18 patients (36%). Most patients with severe delirium were successfully treated with i.v. bolus of propofol (1-2 mg/kg). Although the incidence of PID was 24% in patients without catatonic features, the incidence in patients with catatonic features was extremely high (88%; P < 0.001). Multiple regression analyses showed that the severity of PID correlated significantly with the presence of catatonic features (beta = 0.428, P < 0.01).

Conclusion: The presence of catatonic features before ECT is a predictor of PID. Propofol is useful for the treatment of PID.