Customized anesthetic preservation of ictal threshold in electroconvulsive therapy: role of adjunctive remifentanil with etomidate

We present a case of anesthesia for electroconvulsive (ECT) therapy that was complicated by emetic sensitivity to etomidate, fragile ictal threshold, and mild pseudocholinesterase deficiency. The anesthetic was designed in this patient taking all his issues in consideration. The mild pseudocholinesterase deficiency necessitated a (50-75%) reduction in succinylcholine dosage, careful monitoring of the train of four, and postictal amnestic coverage to prevent paralysis upon waking. The significant emetic response to etomidate prompted substitution to propofol and preemptive ondansetron. Propofol significantly raised the ictal threshold but significantly reduced the postprocedural emesis. Eventually, this clinical challenge was resolved with adjunctive use of low-dose etomidate and remifentanil. This combination preserved the ictal parameters, providing patient comfort, good clinical response, and therapeutic efficacy. Although seizure duration and quality often are restored with hyperventilation and caffeine, this case necessitated a return to etomidate for the restoration of satisfactory ictal parameters. Although this effect of remifentanil has been described with methohexital, and etomidate with alfentanil, to the best of our knowledge, this is the first reported case of adjunctive remifentanil with etomidate for preserving ictal threshold. The outpatient course of ECT was thus completed with all psychiatric and anesthetic goals satisfied: adequate seizure quality and duration, no paralysis upon waking, no post-ECT nausea and vomiting, and patient satisfaction. Anesthesiologists should be aware of factors influencing the seizure duration and, keeping in mind the coexisting medical conditions of the patient, adjustments should be made to get the best possible outcome.

A retrospective comparison of remifentanil versus methohexital for anesthesia in electroconvulsive therapy

The electroconvulsive therapy (ECT) service at West Virginia University conducted a retrospective analysis of 24 patients who received bilateral ECT between November 1998 and December 2003. Patients were treated with a standard methohexital-based anesthetic. Twenty-four patients became completely or relatively refractory to maximum settings on the ECT device and were then switched to remifentanil as the sole induction agent. Seizure threshold was established by stimulus dose retitration. Stimulus dose in total charge (mC) and dynamic energy (J) was significantly lower with the remifentanil anesthetic versus methohexital. (P < 0.0001) Resulting motor and EEG seizure duration in patients was significantly longer receiving the remifentanil anesthetic versus methohexital. (P < 0.0001) Previous reports describe a rise in seizure threshold in patients for repeated ECT. Although this rise occurred during the treatment course using a methohexital anesthetic, this effect was greatly diminished when remifentanil was used as the sole anesthetic agent. We conclude that remifentanil can provide improved seizure response to ECT in patients who are refractory to seizure induction after a standard methohexital anesthetic. We also conclude that the increase in stimulus dose typically required with repeated treatments is related to the anesthetic regimen.

Augmentation of seizure induction in electroconvulsive therapy: a clinical reappraisal

OBJECTIVE

Missed or abortive seizures during electroconvulsive therapy (ECT) may preclude completion of an effective course of treatment in some cases. Seizure augmentation, using proconvulsant agents, has been used to overcome resistance to the induction and continuation of seizure activity. In this review, we analyze published clinical data on the effects and safety of seizure augmentation techniques.

METHOD

Clinical studies and case reports were obtained through a MEDLINE literature search from 1966 to 2001, cross-referencing ECT and proconvulsant agents. Article references were also scanned for relevant studies.

RESULTS AND CONCLUSIONS

Data from clinical trials indicate that augmentation facilitates seizure induction when maximal electrical stimuli fail. Anesthetic modifications, including hyperventilation and substitution with etomidate, ketamine, or other agents, often are successful in overcoming seizure resistance and compare favorably with the use of caffeine. In a few studies, augmentation enabled the use of lower stimulus intensities and fewer treatments without loss of efficacy, even in patients not resistant to seizure induction. However, effects of proconvulsants must be reconciled with increasing evidence of the importance of stimulus dosing relative to seizure threshold and other parameters, now considered key to the efficacy of ECT. Further investigations of pharmacologic augmentation could facilitate the administration of ECT and could provide further insights concerning parameters of seizure efficacy and the mechanism of action underlying convulsive therapies.