Electroconvulsive therapy (ECT) is used to treat severe depression, catatonia, treatment-resistant mania, and schizophrenia, and may be considered in patients who have not responded to medications, are debilitated by serious side effects, or are acutely suicidal. ECT involves unilateral or bilateral electrode placement followed by a brief electrical stimulus applied through the electrodes with a goal of eliciting a controlled seizure. Usually, a series of 6 to 12 treatments over 2 to 4 weeks is required for a clinical response, and maintenance ECT may be considered for patients with severe psychiatric disease.

1. Physiologic effects of ECT

   1. The electrical stimulus applied transcutaneously produces a generalized tonic–clonic seizure which will be detected on electroencephalogram (EEG) monitoring. Optimal duration of seizure is unknown, but a duration of longer than 20 seconds is typically desired, and seizures lasting longer than 120 seconds may need to be terminated pharmacologically.

   2. An initial vagal discharge may result in severe bradycardia and mild hypotension. Subsequent sympathetic nervous system activation produces hypertension and tachycardia, which can persist for 5 to 10 minutes. ECG changes are common and may include atrial or ventricular arrhythmias and ST segment and T wave changes. A second postictal parasympathetic surge may also occur and may lead to severe bradycardia and asystole, most commonly in young otherwise healthy men.

   3. Increased cerebral blood flow and metabolic rate lead to increased ICP. Increased intraocular and intragastric pressure may occur.

2. Anesthetic goals

   include amnesia for the duration of the seizure with a rapid return to consciousness, prevention of damage from tonic–clonic contractures (eg, long bone fractures and other musculoskeletal injuries), control of hemodynamic response to induced seizure, and avoidance of interference with initiation and duration of induced seizure.

3. Contraindications.

   The only absolute contraindication to ECT is known history of pheochromocytoma, however multiple relative contraindications

   should be considered. Among the most important relative contraindications to ECT are intracranial hypertension (particularly with a space-occupying lesion and mass effect), recent cerebrovascular accident or myocardial infarction, unprotected cerebral aneurysm, myocardial ischemia, major unstable fractures, uncontrolled glaucoma, retinal detachment, and untreated active venous thromboembolism. Patients on maintenance treatment with benzodiazepines or lithium may need to discontinue these medications before ECT; benzodiazepines are anticonvulsants that may abolish or attenuate the seizure; lithium is associated with worsened post-ECT cognitive dysfunction and delirium.

4. Anesthetic management

   1. Sedative premedication is not indicated and may prolong emergence. Anticholinergic drugs may be used to reduce secretions and to minimize bradycardia. Ondansetron may be useful in patients with a history of nausea and vomiting.

   2. A small-gauge IV cannula is placed for drug administration, and standard monitors are applied.

   3. The patient is preoxygenated with 100% oxygen; anesthesia may be induced with methohexital, etomidate, or propofol and succinylcholine. Patients are ventilated with 100% oxygen via mask and Ambu bag. Small doses of short-acting nondepolarizing muscle relaxant can be used in patients with contraindications to succinylcholine. Pretreatment with labetalol or esmolol blunts the hypertensive response and may be useful in patients with hypertension or coronary artery disease.

   4. Ketorolac may decrease muscle pains after ECT.

   5. Rolled gauze pads placed bilaterally as bite blocks protect gums and lips from biting from electrical stimulus and subsequent seizure.

   6. Nature and duration of induced seizures can be monitored by EEG or by “isolated arm” technique. With the latter, inflation of a blood pressure cuff interrupts blood supply to one arm before injecting muscle relaxant; seizure activity is apparent in the isolated arm.

   7. Patients are ventilated with oxygen by facemask until spontaneous ventilation resumes. They are then placed in a lateral decubitus position and monitored in a recovery area until awake and alert. Agitated delirium may occur after ECT and can be treated with small doses of propofol or benzodiazepine.

   8. Patients with underlying medical conditions may require special attention:

      1. Patients with gastroesophageal reflux may require aspiration prophylaxis and rapid sequence intubation.

      2. Patients with severe cardiac dysfunction may require invasive monitoring.

      3. Patients with intracranial mass lesions may require invasive blood pressure monitoring for tight hemodynamic control; hyperventilation before inducing a seizure may reduce the ICP response.

      4. Pregnant patients may require endotracheal intubation, fetal monitoring, and left uterine displacement.

   9. Rarely, an induced seizure will not spontaneously terminate. Ventilation with 100% oxygen is continued, and seizure is terminated within 3 minutes with propofol or benzodiazepines.

5. Psychiatric drug interactions.

   Patients requiring ECT may be treated with psychotropic drugs that have potent side effects and interactions with anesthetic drugs.

   1. Tricyclic antidepressants (eg, amitriptyline, nortriptyline, desipramine, imipramine, and doxepin) potentiate effects of norepinephrine and

      serotonin by preventing reuptake. Untoward effects include postural hypotension, sedation, dry mouth, urinary retention, and tachycardia.

   2. Monoamine oxidase inhibitors (MAOIs) (eg, phenelzine and isocarboxazid) increase availability of norepinephrine at postsynaptic receptors; orthostatic hypotension and severe hypertension may occur. Tyramine, present in certain foods, may produce a hypertensive crisis in patients taking MAOIs. Although it has been recommended previously that MAOI therapy be discontinued at least 10 days before elective surgery, the risk of severe depression outweighs the risks of discontinuing the drug. Important interactions between MAOIs and anesthetics include severe hypertension with indirectly acting vasopressors (ephedrine). Administration of meperidine (and meperidine derivatives) to patients receiving MAOIs has been associated with serotonin syndrome (SS) characterized by severe hemodynamic instability, respiratory depression, and malignant hyperpyrexia.

   3. Selective serotonin reuptake inhibitors (eg, fluoxetine, sertraline, fluvoxamine, and paroxetine) are associated with mild adverse effects with no known significant interactions with anesthetic drugs.