Predictors of Seizure Threshold in Right Unilateral Ultrabrief Electroconvulsive Therapy: Role of Concomitant Medications and Anaesthesia Used

Abstract Background An individualized approach to maximize electroconvulsive therapy (ECT) efficacy and minimize cognitive side effects is to treat patients relative to their seizure threshold (ST). However, although Right Unilateral-Ultrabrief (0.3 ms) (RUL-UB) ECT is increasingly used in clinical settings as an effective form of ECT with minimal cognitive effects, there is sparse data regarding predictors of ST. Objective To analyze the relationship between ST and clinical and demographic factors in a sample of patients treated with RUL-UB ECT. Methods Clinical, demographic and ECT data from 179 patients in ECT research studies were examined. Seizure threshold was titrated at the first ECT session. ECT was performed with a Thymatron ® or Mecta ® device, with thiopentone (2.5–5 mg/kg) or propofol (1–2 mg/kg) anaesthesia. Medications taken at the time of ST titration were documented. The association between ST and candidate predictor variables was examined with regression analysis. Results Multiple regression analyses showed that 34% of the variance in ST ( P R 2  = 0.194, P R 2  = 0.029, P  ≤ 0.01) and higher anaesthetic dose (mg in propofol equivalents) ( R 2  = 0.029, P R 2  = 0.043, P R 2  = 0.019, P Conclusions Empirical titration is recommended for accurate determination of ST in patients receiving RUL-UB ECT. Novel findings of this study are that propofol anaesthesia resulted in higher ST than thiopentone and concomitant treatment with lithium treatment lowered ST.