Modified electroconvulsive therapy (ECT) is commonly used for treatment of depression, mania and affective disorders (1). The mechanism of action is not clearly understood but seizures are necessary for a therapeutic response (2). Prolonged seizures may be more efficacious (3) and a motor seizure duration of greater than 25 s has been recommended to ensure clinical adequacy of treatment (4). Cognitive side-effects and the duration of the period of disorientation are no more prominent with increased seizure duration but rather correlate to the amount of electrical stimulation and electrode placement used during treatment (5-7).

General anesthesia is used during ECT (8). Since most short-acting anaesthetics have anticonvulsant effects, they can increase the threshold and inhibit spread of the seizure, thus modifying the seizure activity and shortening its duration (9).

Fentanyl is a rapid-acting opioid with a moderate duration of action and has no known anticonvulsant effect. Combining fentanyl with propofol produces loss of consciousness with a smaller induction dose of propofol and thus could potentially increase seizure duration (10). Fentanyl is widely used as analgesic in ECT anesthesia because of characteristics such as minimal postoperative confusion and a lower incidence of hypertension or tachycardia during induction of anesthesia. 

Remifentanil is a potent ultra short-acting opioid and has no known anticonvulsant effect. Recently, administration of remifentanil in combination with propofol was reported to increase the duration of seizure activity in patients undergoing ECT (5).

The goal of this study was to evaluate and compare effects of remifentanil and fentanyl on seizure duration, recovery parameters and degree of stimulus amplitude in patients undergoing ECT.