PSYCHOTROPIC DRUGS AND THEIR EFFECTS ON SEIZURE DURATION IN PATIENTS RECEIVING ELECTROCONVULSIVE THERAPY

Abstract Objective To examine the effects of psychotropic drugs on seizure duration in patients receiving electroconvulsive therapy (ECT). Methods The medical records of patients who received ECT at a university hospital in Bangkok from March 2014 to February 2017 were retrospectively reviewed. Demographic data, psychotropic drug use, ECT stimulus parameters, and motor seizure duration were recorded. The daily dose of drugs with antipsychotic properties and benzodiazepine in each patient was converted into a risperidone equivalent dose and a diazepam equivalent dose, respectively. Beside descriptive statistics, regression analyses were performed with SPSS using a generalized estimating equation to examine the association between seizure duration and the use and daily dose of psychotropic drugs. Results All 647 ECT sessions were delivered in a general psychiatry ward in 249 patients, 99.1% (n = 641) in which thiopental was used for anesthesia induction. After 7 ECT sessions with anesthesia induction agents other than thiopental were excluded, 641 ECT sessions remained for statistical analysis; 436 (68.0%) and 205 (32.0%) sessions were in the acute phase and maintenance phase, respectively. Most ECT treatments achieved adequate EEG seizures (n = 581; 90.6%) as well as motor seizure duration (n = 509; 79.4%). Seizure duration was associated with the benzodiazepine equivalent dose (p = 0.001), especially when the daily diazepam equivalent dose was 20 mg or higher (p = 0.035). Risperidone equivalent dose and clozapine use did not show any significant association with seizure duration. Doses of anesthetic agents for the ECT procedure, thiopental (p <0.001) and succinylcholine (p = 0.027), and ECT stimulus parameters (i.e., charge (p <0.001), frequency (p <0.001), and train duration (p = 0.002) were significantly associated with seizure duration. After adjustment for those, the benzodiazepine equivalent dose (OR 0.921, p = 0.001) and the diazepam equivalent dose of 20 mg or higher (p = 0.014) remained significantly associated with seizure duration. Conclusion The benzodiazepine dose was associated with seizure duration in patients receiving ECT, particularly at a diazepam equivalent dose of 20 mg or higher. Clinicians should be cautious when prescribing benzodiazepine to patients receiving ECT.