Counselling and medication are often thought of as the only interventions for psychiatric disorders, but electroconvulsive therapy (ECT) has also been applied in clinical practice for over 80 years. ECT refers to the application of an electric stimulus through the patient’s scalp to treat psychiatric disorders such as treatment-resistant depression, catatonia, and schizophrenia. It is a safe, effective, and evidence-based therapy performed under general anesthesia with muscle relaxation. An appropriate level of anesthesia is essential for safe and successful ECT; however, little is known about this because of the limited interest from anesthesiologists. As the incidence of ECT increases, more anesthesiologists will be required to better understand the physiological changes, complications, and pharmacological actions of anesthetics and adjuvant drugs. Therefore, this review focuses on the fundamental physiological changes, management, and pharmacological actions associated with various drugs, such as anesthetics and neuromuscular blocking agents, as well as the comorbidities, indications, contraindications, and complications of using these agents as part of an ECT procedure through a literature review and our own experiences.
Electroconvulsive therapy (ECT), also known as electroshock therapy, is a unique treatment in patients with major depression, affective disorders, catatonia, schizophrenia, and other psychotic disorders for which pharmacological treatments do not produce adequate responses [
Recently, ECT has been reported to produce symptom relief effects in 70–90% of cases, which is a superior outcome to the use of antidepressants and has a recurrence rate of approximately 20% [
The worldwide frequency of ECT interventions is approximately 4.9 (0.4–81.2) out of 10,000 people. In Asian countries, particularly China, Taiwan, and India, there has been a significant increase in the number of reported cases [
ECT involves the transmission of an electric current through the brain, causing generalized tonic-clonic seizures. During this procedure, the position of the electrode and the physical properties of the electrical stimulation affect the seizure threshold, which is related to the therapeutic effect and cognitive impairment. Three electrode positions (bitemporal, bifrontal, and right unilateral) are commonly adopted. Among these, the bitemporal position is the most widely used. In addition to the electrode positioning and physical properties of electrical stimulation, various factors can also affect the seizure threshold (
The antidepressant effects of ECT are related to seizure duration, as measured using electroencephalography (EEG), electromyography, or muscle movement. Seizure duration assessment by muscle movement during general anesthesia is performed by placing a tourniquet on the arm or leg and blocking the blood flow to exclude the effect of muscle relaxants. The seizure duration on an EEG is approximately 5 s longer than the muscle movement [
In the acute phase, the number of ECT treatments is not defined but must be performed until the symptoms are relieved or stabilized. Most patients who undergo ECT receive 6–12 treatments per course. However, patients with depression may require fewer patients, while patients with schizophrenia may require more treatment per course [
Maintenance ECT (M-ECT) has been used for ongoing procedures to prevent the recurrence of a new episode of depression and can last for years, possibly indefinitely. In most cases, M-ECT has a schedule of 3–8 weeks, but some patients may require longer periods of weekly treatment [
Most guidelines recommend ECT as the first-line treatment for severe depressive episodes, such as the presence of psychotic features, catatonia, high suicide risk, and/or food or fluid refusal. A history of previous positive response and patient preference are also important considerations [
According to the 2001 consensus statement of the American Psychiatric Association (APA), there are no absolute contraindications for ECT [
The preoperative evaluation of ECT was comparable to that used in other general surgeries. Medical histories relevant to these assessments and important for a successful ECT include psychiatric history; drug history, including the type, dose, response, compliance, and side effects of any psychiatric drugs; and physical and laboratory examination results such as electrocardiography, chest radiography, serum creatine, and electrolytes [
Although ECT is a low-risk procedure, certain hemodynamic abnormalities may increase the risk of complications in patients with cardiovascular disease. Abrupt hemodynamic changes during ECT typically spontaneously recover a few minutes after a seizure. However, these changes can cause serious complications in patients with cardiovascular disease, and careful monitoring and preparation, including cardiopulmonary resuscitation, are needed in these patients [
As in adult patients, appropriate preoperative evaluations should be performed prior to ECT in pediatric patients. If a child has comorbidities, additional examinations and an increased planning time for anesthesia are required. In children with central nervous system malignancies, hydrocephalus, or cardiopulmonary diseases, the anesthesiologist should prepare for the interaction of anesthetics and any immediate negative effects of the procedure [
Pregnancy testing should be performed in all women of reproductive age. Although pregnancy is not a contraindication for ECT, fetal exposure to anesthetics must be minimized [
The physiology of the patient changes dramatically during the ECT. Between the electrical stimulation and the onset of seizure, conditions such as hypotension, bradycardia, and asystole can occur because the parasympathetic nervous system becomes dominant during this period. Tachycardia and hypertension occur during seizures because of rebound sympathetic activity [
Cerebral blood flow, intracranial pressure, cerebral metabolic rate, and cerebral oxygen consumption increase during seizures because of transient cerebral ischemia and cerebral hemorrhage [
Prior to ECT, patients should fast from solid food for more than 8 h. Clear liquids are permissible during this time to enable oral medications such as antihypertensive drugs to be taken up to 2 h before the procedure. To prevent post-ECT myalgia, patients can be pre-medicated with enteric-coated aspirin, acetaminophen, or intravenous ketorolac. Ventilation during ECT is assisted by a face mask with a standard simple bag-valve-mask system. Tracheal intubation is not recommended, except in very specific situations (e.g., late pregnancy or emergency treatments in which the patient has a full stomach), because ECT is typically performed frequently (two or three times a week for 3–4 weeks), and each procedure lasts only a few minutes. In obese patients with sleep apnea syndrome, an oral airway can be helpful in maintaining ventilation during the procedure.
Non-invasive blood pressure, pulse oximetry, electrocardiography, and capnography are recommended during an ECT procedure. A tourniquet technique or electromyographic monitoring should be employed to quantify the duration of the motor seizure activity. The tourniquet technique is used to isolate the distal circulation using a pressure of 160–200 mmHg before administering the muscle relaxant. Although sufficient muscle relaxation is necessary during ECT, forceful jaw clenching is still inevitable with this intervention because of the direct stimulation of the masticatory muscles, particularly the temporalis and masseter muscles, by electrical current. Hence, a bite block should be carefully placed before the application of the electrical stimulus to protect the patient’s teeth and minimize the risk of lacerating the tongue. Standard noninvasive hemodynamic variables and oxygen saturation should be monitored for 15–30 min after ECT [
Although ECT is known to be safe in adults, it is not commonly used in children and adolescents because of the risk of damage to the nervous system at the early stages. However, the indications for ECT in the pediatric population have increased steadily over the past 20 years [
ECT has been reported to be an effective and safe treatment for pregnancy-induced depression, unipolar depression, bipolar disorder, schizophrenia, and other psychiatric illnesses [
When it is difficult to maintain the patient's airway, or if fasting is insufficient, laryngeal mask airway or cricoid compression and endotracheal intubation can be helpful [
ECT units have faced certain challenges during the COVID-19 pandemic. These issues include screening, personal protective equipment, airway management, and maintenance of recovery rooms and facilities to prevent the spread and transmission of COVID-19 [
The ideal characteristics of an anesthetic to be used for ECT include rapid onset, attenuation of ECT-induced physiological changes, minimal anticonvulsant effects, and rapid recovery. Although most of the currently available anesthetic agents can be used for ECT, seizure duration, hemodynamic stability, recovery time, antidepressant effect, and cognitive side effects must be considered when selecting this drug. Most anesthetics have a dose-dependent anticonvulsant effect; therefore, the minimum effective dose should be used during ECT [
Methohexital is the gold standard drug among the established anesthetics [
Thiopental sodium (1.5–2.5 mg/kg) and thiamylal (1.5–2.5 mg/kg) reduce the seizure duration and have a slower recovery compared to methohexital (0.5–1.0 mg/kg). Both of these agents also increase the incidence of arrhythmias such as sinus bradycardia and premature ventricular contraction, as well as increase the blood flow in the middle cerebral artery after ECT compared with propofol [
Etomidate (0.15–0.3 mg/kg) is effective in patients with a short seizure duration (i.e., < 20 s) even under maximum stimulation because it prolongs this duration compared to methohexital, thiopental, or propofol [
Propofol is the most commonly used intravenous anesthetic owing to its rapid recovery and antiemetic mode of action. However, the seizure duration after ECT is shorter with this drug because it has stronger anticonvulsant effects than other intravenous anesthetics [
Ketamine is an intravenous anesthetic with both hypnotic and analgesic effects. The recommended dose of ketamine (1–2 mg/kg) can help achieve the desired ECT effects, but a low dose of this drug (0.4–0.8 mg/kg) leads to a shorter seizure duration on an EEG compared to methohexital. Because ketamine can also increase blood pressure, heart rate, and intracranial pressure, it is not generally preferred over methohexital or propofol for use in ECT procedures [
Benzodiazepines, such as midazolam and lorazepam, can alter the threshold and duration of seizures after ECT. In patients who have been taking benzodiazepine over the long term, seizures may not occur owing to its anticonvulsant effects [
Dexmedetomidine is rarely used alone; in combination with other intravenous anesthetics, it can reduce the acute hemodynamic changes that are possible after ECT. Moreover, if dexmedetomidine at a 1 µg/kg dose is administered 10 min prior to ECT, it can reduce the extent of post-ECT agitation without affecting seizure duration or patient recovery time [
Most ECT procedures are performed outside the operating theatre, and intravenous anesthesia is generally preferred over inhalational anesthesia. However, as possible inhalation anesthetics, sevoflurane (1.7%) and nitrous oxide (50%) can more potently reduce acute hemodynamic changes following ECT than thiopental [
Neuromuscular blocking agents are necessary to prevent possible musculoskeletal complications of ECT, such as myalgia, dislocation, and fracture, and are effective because they typically have a fast onset and a short duration of action [
Succinylcholine is the oldest and most commonly used neuromuscular blocking agent in ECT protocols [
In patients receiving intravenous atracurium, a 0.3 mg/kg pretreatment leads to significantly more ECT-induced moderate and vigorous convulsions (86 vs. 16%) and a shorter recovery time (4.2 ± 0.4 min vs. 9.2 ± 0.8 min) when compared with patients receiving 0.3 mg/kg [
Vecuronium and rocuronium are non-depolarizing neuromuscular blocking agents with an aminosteroid structure that can also be used as part of the ECT protocol. Although the long duration of action has been a problem with these treatments, the development of sugammadex could make them useful in ECT. Sugammadex is a cyclodextrin-based compound with an antagonistic mode of action against aminosteroid nondepolarizing neuromuscular blockers. If sugammadex was used in conjunction with rocuronium during ECT, rapid onset of action and recovery could be expected. Hence, this potential drug combination has attracted attention as a possible alternative to succinylcholine [
As acute cardiovascular reactions following ECT can cause serious complications, cardiovascular drugs are used to relieve acute parasympathetic and sympathetic reactions [
Pretreatment with anticholinergics as part of the ECT protocol has been reported to reduce the incidence of premature atrial contracture, bradycardia, and asystole, as well as decrease secretion and salivation [
β-blockers, such as esmolol and labetalol, attenuate the sympathetic and cardiovascular responses following ECT. Pretreatments of ECT patients with esmolol (1.0 mg/kg) or labetalol (0.3 mg/kg) are more effective than those with fentanyl (1.5 mg/kg) or lidocaine (1.0 mg/kg) [
Nicardipine (1.25–5 mg, i.v.) has a rapid hemodynamic control effect without impact on the cardiovascular inhibitory action of methohexital due to its rapid onset. Moreover, small doses of nicardipine have little effect on the duration of seizures [
Nitroglycerin (NTG, 3 μg/kg, i.v.) can reduce hemodynamic changes after ECT compared to esmolol (2 mg/kg, i.v.) [
Although trimethaphan is not currently the preferred drug in clinical practice, its bolus administration at 5–15 mg can control hemodynamic changes after ECT without affecting the duration of the seizure [
Lidocaine can also attenuate the onset of hemodynamic changes after ECT, but it also decreases seizure duration in a dose-dependent manner [
Opioids can act as a “seizure enhancers” by reducing the required hypnotic dose. Hence, short-acting opioids are effective in patients with an insufficient duration of seizures following ECT [
Magnesium sulfates can reduce ECT-related hypertension and have no effect on seizure duration. The combined use of these compounds with remifentanil may delay the recovery of spontaneous respiration but can also prevent tachycardia and hypertension in elderly patients with ischemic heart disease [
ECT is a safe procedure in patients with minimal comorbidities. However, cardiovascular changes and psychiatric complications may occur following treatment. Pulmonary aspiration, respiratory failure, and residual neuromuscular blockade must be considered as possible complications of ECT interventions because neuromuscular blocking agents are used [
ECT is a safe and effective treatment for various psychiatric disorders, and accepted indications for its use has steadily increased over time. Anesthesia during ECT should ideally provide deep hypnosis, ensure muscle relaxation to reduce injury, have minimal effects on seizure duration, and allow for rapid recovery to a baseline neurological and cardiopulmonary status. Multiple anesthetic agents are acceptable for use during ECT, and the choice of this drug should be considered for any underlying comorbidities that the patient has.
None.
No potential conflict of interest relevant to this article was reported.
Data sharing not applicable to this article as no datasets were generated or analyzed during the current study.
Conceptualization: Hong-Seuk Yang. Data curation: Dong Ho Park, Chang Young Jung. Project administration: Kyoung-Woon Joung, Hong-Seuk Yang. Visualization: Kyoung-Woon Joung. Writing - original draft: Kyoung-Woon Joung. Writing - review & editing: Kyoung-Woon Joung, Dong Ho Park, Chang Young Jung. Investigation: Kyoung-Woon Joung. Resources: Dong Ho Park, Chang Young Jung. Supervision: Hong-Seuk Yang.
Factors Affecting Seizure Thresholds
Factors that increase the seizure threshold |
Age |
Skull thickness |
Bilateral stimulation |
Repeated stimulation |
Drugs |
Use of barbiturates, benzodiazepines, or anticonvulsants |
Factors that decrease the seizure threshold |
Genuine seizure |
Hyperventilation/hypocapnia |
Female sex |
Hyperoxia |
Drugs |
Use of caffeine, antidepressants, or clozapines |
Currently Used Indications for Electroconvulsive Therapy
Major depression, single, or recurrent episodes |
Bipolar major depression, depressed, or mixed type |
Schizophrenia |
Catatonia |
Schizophreniform or schizoaffective disorder |
Atypical psychosis |
Other psychiatric conditions |
Obsessive compulsive disorder |
Pregnancy depression, severe postpartum depression, or psychosis |
Miscellaneous conditions |
Parkinson's disease |
Neuroleptic malignant syndrome |
Status epilepticus |
Delirium |
Dementia with behavioral disturbances |
Secondary catatonia |
Dopa-responsive dystonia (Segawa syndrome) |
Self-injurious behavior in autism |
Effects of Commonly Used Anesthetics in Electroconvulsive Therapy Protocols and Comparisons of the Physiologic Changes Before and After Electrical Stimulation (Before/After)
Heart rate | Blood pressure | Cerebral blood flow | Seizure duration | Others | |
---|---|---|---|---|---|
Methohexital | → / ↑ | ↓ / ↑↑ | NE | → | Standard anesthetics for ECT |
Thiopental | ↑ / ↑ | ↓ / ↑↑ | ↓ / ↑↑ | ↓ | Histamine release |
Etomidate | → / ↑ | → / ↑↑ | NE | ↑ | Injection pain, slow recovery |
Propofol | ↓ / ↑→ | ↓ / ↑ | ↓ / ↑ | ↓ | Injection pain |
Ketamine | ↑ / ↑ | ↓ / ↑↑ | ↓ / ↑↑ | ↑↓ | Psychotic action |
Benzodiazepine | → / ↑ | ↓ / ↑ | NE | ↓↓ | Long acting |
Sevoflurane | ↑ / ↑ | ↓ / ↑ | ↓ / ↑↑ | ↓↓ | Slow induction |
ECT: electroconvulsive therapy, NE: not evaluated.
Physiologic Changes and Adverse Events Associated with Electroconvulsive Therapy
Central nervous system | Increases in the cerebral blood flow, intracranial pressure, and cerebral metabolic rate |
Dizziness, headache, amnesia, agitation, cognitive impairment, delirium, cerebral hemorrhage | |
Cardiovascular system | Increases in blood pressure, heart rate, and cardiac output |
Arrhythmia, hypertension, myocardial infarction, stress-induced cardiomyopathy | |
Musculoskeletal system | Tonic - clonic seizure |
Myalgia, dislocation, fracture | |
Others | Increased salivation |
Nausea, vomiting, dental fractures, lacerations of the gum, gingiva, and tongue |