Anesthesia for Electroconvulsive Therapy

Background

Electroconvulsive therapy (ECT) inducing a generalized tonic-clonic epileptic seizure is established as an effective and safe treatment option for severe psychiatric disorders. Today, ECT is in worldwide use in both inpatient and outpatient settings. The main indications for ECT are unipolar major depression as well as manic episodes mostly not responding to psychopharmacological therapies. ^, Further indications include some other forms of psychiatric illness such as schizophrenic disorders, catatonia, suicidality, and neuroleptic malignant syndrome. ^, ECT can be combined with other treatment modalities. Since its introduction in 1938 by Italian scientists, there have been some changes in the administration of ECT to patients. While ECT was originally performed without sedation or anesthesia, a “modified technique” is presently most often used with general anesthesia, neuromuscular blockade, and mechanical ventilation providing more safety and patient comfort along with fewer procedure-associated adverse events. Currently, severe complications occur in less than 1 in 10,000 treatments, which require specific therapy. The mortality rate is very low and varies between 1:50,000 and 1:25,000 treatments, and is therewith comparable to the anesthetic-related mortality associated with minor procedures involving general anesthesia. These treatment-related cases of death are mostly caused by cardiovascular and, to a lesser extent, pulmonary complications. Although the safety and practice of ECT has improved for over 70 years, the underlying mechanisms responsible for the therapeutic effectiveness in psychiatric disorders are still under investigation and not yet clear to date. ^, Despite proven success, ECT remains the most pilloried treatment in psychiatry.

Technique of Electroconvulsive Therapy

To induce a generalized seizure that constitutes the therapeutic agent of ECT, an electrical current is applied to the brain via two surface electrodes. These are typically positioned either unilaterally or bilaterally on the scalp. The latter, also known as bitemporal or bifrontotemporal, is used today particularly in urgent clinical situations when the speed of clinical response is most important. Unilateral stimulation performed on the nondominant hemisphere avoids stimulation of the hemisphere responsible for language function and minimizes cognitive adverse effects and is therefore at present the preferred technique used for the majority of treatments. Modifications in electrode placement as well as energies and waveforms of the electrical current affect the seizure quality, which is crucial for treatment success. To date, the most accepted criteria for adequate seizure are at least 20 s of tonic-clonic movement or 25 s of electroencephalographic (EEG) seizure activity; seizures lasting less than 15 s are generally considered to be ineffective, and prolonged seizures may be associated with increased cognitive impairment. Seizure characteristics are monitored by an EEG on the ECT device.

Patients chosen for ECT most often need multiple treatments. ECT is usually administered up to two to three times a week until there is no further improvement. Most patients remit with a total of 6–12 treatments, but some patients require considerably more treatments. To prevent a relapse of the mood or psychotic episode that prompted the acute course of ECT, therapy may be continued with single ECT at an interval of 1–8 weeks during the first 6 months after remission. Thereafter, maintenance ECT may be a treatment option for patients who recovered from the acute episode and need prevention of a new episode.

Contraindications

There are no absolute medical contraindications to ECT in adults. Relative contraindications include untreated cerebral aneurysms, recent intracerebral hemorrhage, space-occupying cerebral lesions, cardiac failure, recent myocardial infarction, pheochromocytoma, retinal detachment, or glaucoma. In these situations, the risk–benefit ratio for the patients and their specific compromised clinical situation has to be calculated. If after this decision ECT remains the treatment of choice, appropriate precautions have to be performed to minimize the patient’s risk.

Preprocedure Management

Prior to elective ECT, written informed consent for anesthesia must be obtained from the patient or his responsible legal representative as for every anesthesia for diagnostic or surgical procedures. In cases of a life-threatening situation in which there is no possibility to obtain informed consent from the patient, ECT can also be administered after legal authorization and obtaining the informed consent of the patients’ legal representatives.

Pre-ECT medical evaluation is identical to the approach of a patient undergoing any procedure requiring general anesthesia. The evaluation should identify coexisting medical illnesses and evaluate their potential interaction with and impact on ECT treatment. In this respect, a thorough history and focused physical examination is required. Further investigations like electrocardiograms, chest radiographs, and blood tests should be performed as clinically indicated.

The majority of patients scheduled for ECT receive a variety of psychiatric drugs such as antidepressants, anticonvulsants, mood stabilizers, antipsychotics, anxiolytic drugs, or central nervous system stimulants with possible side effects. ^, Between these drugs and drugs used for anesthesia, pharmacodynamic or pharmacokinetic interactions may occur, and their characteristics may vary between subtle and significant. ^, For example, lithium may be associated with postprocedural delirium and may prolong the effects of succinylcholine. In close cooperation between anesthetists and psychiatrists it has to be clarified if the psychiatric medication should be modified or withhold prior to ECT. In most cases, patients should take their regular medications without tapering until the morning of the procedure. Although life-threatening drug interactions are rare, awareness of detection and adequate treatment is highly required.

Usually, patients will receive no premedication since most of the drugs used for this purpose interfere with seizure generation and may delay emergence.

Current fasting [nil per os (NPO)] guidelines for the procedure are 6 h for a meal and 2 h for clear liquids. Since patients often do not comprehend the need for withholding food and drink, NPO status must be checked prior to the procedure.