Anesthesiology

Electroconvulsive therapy

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What the Anesthesiologist Should Know before the Operative Procedure

Prior to the introduction of anesthesia for electroconvulsive therapy (ECT) in the 1970s, up to 50% of patients experienced fractures of the extremities, vertebrae, or teeth. Anesthetic care with the use of sedative/hypnotics, muscle relaxants, and ventilatory support has greatly decreased the risk of injury associated with ECT. ECT is now considered a low-risk procedure, thanks to anesthetic intervention, with death or injury occurring in 1 in 50,000 treatments. The safety of ECT now means that more high-risk patients are being considered for the procedure. It is common for elderly patients or patients with comorbidities such as coronary artery disease (CAD) and end-stage renal disease (ESRD) to receive ECT.

ECT causes generalized autonomic nervous system stimulation, with subsequent physiologic effects. Initially, there is parasympathetic outflow that can cause bradycardia or occasional asystole, hypotension, and salivation. The parasympathetic discharge is followed by immediate sympathetic discharge with a surge in endogenous catecholamines. This sympathetic stimulation is associated with hypertension, tachycardia, dysrhythmias (premature atrial or ventricular contractions, ventricular tachycardia), marked increase in cerebral blood flow (CBF), and possible increase in intracranial pressure (ICP).

Electrocardiogram (ECG) changes, such as ST-segment depression and T-wave inversion, without myocardial enzyme changes can be seen as well. This sympathetic discharge is usually self-limiting and terminates within a couple minutes, but can lead to significant morbidity in high-risk cardiac patients if not controlled appropriately.

1. What is the urgency of the surgery?

What is the risk of delay in order to obtain additional preoperative information?

In general, the urgency to perform ECT is low, except in manic or depressed patients who are at imminent risk of suicide.

Emergent:ECT is rarely performed emergently.

Urgent: High risk of suicide is an indication for urgent ECT, as the therapeutic effect is quicker than pharmacologic intervention.

Elective:The majority of ECT is performed electively.

2. Preoperative evaluation

Complete medical history and physical examination is prudent, with emphasis on:

  1. Cardiovascular disease: Patients with significant CAD, recent history of myocardial infarction (MI), cardiac conduction defects, uncontrolled hypertension (HTN), cardiac arrhythmias, pheochromocytoma, or aortic aneurysms.

  2. Intracranial pathology: Patients with recent cerebrovascular accident (CVA), cerebral aneurysms, or arteriovenous malformation (AVM) or elevated intracranial pressure (ICP) of any etiology are of grave concern.

Medically unstable conditions warranting further evaluation include:

  1. Unstable angina, uncontrolled HTN, new-onset arrhythmia, aneurysmal disease (aortic or cerebral), elevated ICP, cardiac conduction defects.

  2. Delaying procedure may be indicated if any of the above conditions are present.

  3. Relative contraindications: Aortic and intracranial aneurysmal disease, elevated ICP, recent CVA, subarachnoid hemorrhage, cardiac conduction defects, and high-risk pregnancy.

  4. Contraindications: Pheochromocytoma.

3. What are the implications of co-existing disease on perioperative care?

b. Cardiovascular system

Acute/unstable conditions

ECT is almost exclusively an elective procedure that can and should be postponed in light of acute or unstable cardiovascular disease. Essentially, only acute MI or unstable angina requires further preprocedure investigation via functional cardiac studies. New cardiac conduction system dysfunction should be evaluated further via electrophysiological studies.

Baseline coronary artery disease or cardiac dysfunction

Stable CAD/angina or compensated congestive heart failure (CHF) are not contraindications for ECT and require no prior work-up. Asymptomatic or treated cardiac dysrhythmias require no further intervention. Cardiac pacemakers (PPM) should be temporarily set to an asynchronous mode (i.e., DOO, AOO, VOO), and internal defibrillators (AICD) should be disabled (usually with magnet placement) during ECT.

The therapeutic goals for cardiac disease are hemodynamic control to avoid cardiac ischemia and malignant cardiac rhythms resulting from parasympathetic and sympathetic discharge associated with ECT. All cardiac medications should be continued preprocedure.

c. Pulmonary

Chronic obstructive pulmonary disease

Patients with chronic obstructive pulmonary disease (COPD), even severe disease, require no additional preprocedure work up for ECT. All medications for COPD (i.e., beta-agonists, inhaled corticosteroids) should be continued. If a patient has severe lung parenchymal disease or a resting oxygen requirement, be prepared for possible rapid desaturation if the patient is not adequately ventilated after induction of anesthesia.

Reactive airway disease (asthma)

No prior workup indicated. All medications for reactive airways disease (i.e., beta-agonists, inhaled corticosteroids) should be continued. Be aware of the possibility of severe bronchospasm with parasympathetic discharge associated with ECT, or with the use of beta-blockers to blunt sympathetic response. If preprocedure wheezing is noted, give inhaled/nebulized beta-agonists as needed.

d. Renal-GI:

  1. Patients with chronic renal insufficiency (CRI) or ESRD should have potassium levels checked prior to ECT. Succinylcholine is not contraindicated in CRI or ESRD provided the preprocedure potassium is normal (<5.5 mEq/dL). Patients on peritoneal dialysis should have an empty peritoneum prior to ECT. Medication doses should be adjusted for reduced renal clearance, and hypotension should be anticipated in patients who have just received dialysis with >2kg weight loss (aggressive ultrafiltration).

  2. Patients with severe gastroesophageal reflux (GERD) should be considered high risk for aspiration, and serious thought should be given to securing the airway with an endotracheal tube (ETT).

  3. Patients with liver dysfunction or a history of liver disease should have medication doses adjusted accordingly, but require no further preprocedure work-up.

e. Neurologic:

Acute disease

Acute issues that would require delay of ECT would include an elevated ICP with change in mental status, SAH, hemorrhagic CVA, and newly diagnosed intracranial aneurysmal disease. All of these patients should receive neurosurgical evaluation prior to consideration for ECT. New-onset seizure disorder should be evaluated to avoid status epilepticus after ECT. Cerebral aneurysmal disease is a relative contraindication for ECT.

Chronic disease

Patients with chronic, stable SAH, CVA or epilepsy require no further preprocedure work-up. Patients with known shunted hydrocephalus require no additional intervention if their shunt is functioning properly. The therapeutic goal for patients with intracranial pathology is to control systemic HTN in hopes of attenuating severe increases in CBF.

It is important to note that increase in cerebral oxygen demand plays an important role in increased CBF in ECT, so decreases in systemic HTN may not adequately control cerebral hyperemia seen in ECT. Anticonvulsants taken for seizure disorders should be continued to prevent uncontrolled or prolonged seizures. If anticonvulsants are taken for psychotropic effects or pain management, they should be discontinued as they can alter seizure threshold. Benzodiazepines can be continued, as flumazenil can be given to counteract their anticonvulsive properties.

f. Endocrine:

It is important to keep in mind that patients with longstanding diabetes mellitus (DM) may have autonomic dysfunction, and the expected autonomic nervous system (ANS) response to ECT may be attenuated. In any case, patients can experience hypoglycemia due to the sympathetic discharge associated with ECT. Check baseline blood sugar levels pre-procedure. Hold oral hypoglycemics, half the dose of long-acting basal insulin the night before, and hold or half the morning dose of short-acting insulin. Administer glucose solutions as needed.

g. Additional systems/conditions which may be of concern in a patient undergoing this procedure and are relevant for the anesthetic plan (eg. musculoskeletal in orthopedic procedures, hematologic in a cancer patient)

  1. Patients with severe, uncontrolled HTN, especially if associated with headache (HA), tachycardia, palpitations, or diaphoresis, should have plasma metanepherines and urinary vanillylmandelic acid levels checked to rule out pheochromocytoma (an absolute contraindication to ECT).

  2. Patients with known aortic aneurysmal disease should have the size and rate of change of their aneurysm evaluated before initiation of ECT. Large or unstable aortic aneurysms are a contraindication to ECT.

  3. Pregnant women should be evaluated for risk of premature labor or pregnancy-induced HTN. ECT is considered relatively contraindicated in high-risk obstetric patients (i.e., cervical incompetence, history of premature labor).

4. What are the patient's medications and how should they be managed in the perioperative period?

N/A

h. Are there medications commonly seen in patients undergoing this procedure and for which should there be greater concern?

Most patients for ECT will be on one or a combination of antidepressants (tricyclics, monoamine oxidase inhibitors, serotonin reuptake inhibitors, or lithium carbonate) or antipsychotic drugs (typical or atypical). In addition, many patients with cardiac disease may be on a variety of antihypertensive or antiarrhythmic drugs.

i. What should be recommended with regard to continuation of medications taken chronically?

Cardiac: Medications for blood pressure, congestive heart failure, angina, heart rate or rhythm control should be continued (i.e., beta-blockers, alpha2 agonists, digitalis, nitrates, diuretics, angiotensin converting enzyme inhibitors). The anesthesiologist must be aware of how sympatholytics or sympathomimetic drugs can attenuate or exaggerate the physiologic effects of ECT.

Pulmonary: Medications for COPD or reactive airways disease (i.e., beta-agonists, inhaled corticosteroids) should be continued.

Renal: All medications for ESRD should be continued (i.e., phosphate binders, erythropoietin).

Neurologic: Anticonvulsants taken for seizure disorder should be continued to prevent uncontrolled or prolonged seizures. If anticonvulsants are taken for psychotropic effects or pain, they should be discontinued as they can alter seizure threshold. Benzodiazepines can be continued, as flumazenil can be given to counteract their anticonvulsive properties.

Endocrine: Discontinue oral hypoglycemics and half the dose of long-acting basal insulin the night before, discontinue or half the morning dose of short-acting insulin (avoid hypoglycemia).

Antiplatelet: Should be continued, as should anticoagulation therapy for dysrhythmias (atrial fibrillation) and thromboembolic events (pulmonary embolus).

Psychiatric: Most patients will be on some antidepressant medications. Given the efficacy of selected serotonin reuptake inhibitors (SSRIs) and new generation serotonin/norepinephrine/dopamine reuptake inhibitor drugs, very few patients are currently taking tricyclic antidepressants (TCAs) or monoamine oxidase inhibitors (MAOIs).

Although the current recommendation is that antidepressants need not be stopped prior to ECT, it is important to understand the effects of these drugs as they can exacerbate some of the physiologic effects of ECT. TCAs and MAOIs block reuptake and metabolism of norepinepherine, serotonin, and dopamine respectively, and can exaggerate the effects of sympathetic discharge seen with ECT. TCAs have anticholinergic effects as well, and can exacerbate the effects of parasympathetic outflow or centrally acting anticholinergic dugs. It is recommended to discontinue lithium carbonate as it can prolong neuromuscular blocking drugs (NMBDs). Typical and atypical antipsychotics can be continued prior to ECT.

j. How To modify care for patients with known allergies -

As with any other anesthetic, drugs should be selected with consideration of specific patient drug allergies.

k. Latex allergy- If the patient has a sensitivity to latex (eg. rash from gloves, underwear, etc.) versus anaphylactic reaction, prepare the operating room with latex-free products.

N/A

l. Does the patient have any antibiotic allergies- - Common antibiotic allergies and alternative antibiotics]

Antibiotic prophylaxis is not indicated for ECT.

m. Does the patient have a history of allergy to anesthesia?

Malignant hyperthermia

Documented: Avoid all trigger drugs such as succinylcholine and inhalational agents:

  1. Proposed general anesthetic plan: Anesthesia for ECT consists of intravenous (IV) sedative/hypnotics which will not trigger malignant hyperthermia (MH). If there is a suspicion or known history of MH, short acting non-depolarizing NMBD (i.e., mivacurium) or reduced dose of rapid acting non-depolarizing NMBD (rocuronium) with a secure airway (endotracheal tube) should be used.

  2. Ensure that an MH cart is available: MH protocol.

  3. Family history or risk factors for MH or history of Neuroleptic Malignant Syndrome (NMS): As above.

Local anesthetics/ muscle relaxants

If succinylcholine is contraindicated (i.e., hyperkalemia, upper motor neuron disease), short-acting non-depolarizing NMBD (i.e., mivacurium) or rapid-acting non-depolarizing NMBD (rocuronium) with a secure airway (endotracheal tube) should be used.

5. What laboratory tests should be obtained and has everything been reviewed?

There are no required laboratory investigations or preoperative testing for a patient with benign history and physical examination. Preoperative testing should only be pursued based on known comorbidities that will affect treatment (i.e., chronic renal insufficiency (CRI)/ESRD, symptomatic CAD).

  • Hemoglobin levels:Not indicated for ECT.

  • Electrolytes:Check potassium levels and creatinine clearance in ESRD.

  • Coagulation panel:Not indicated for ECT.

  • Imaging: CT to assess aortic aneurysmal disease if routine surveillance scans not available. Computed tomography (CT)/magnetic resonance imaging (MRI)/angiogram of brain to assess known SAH or intracranial aneurysmal disease.

Other tests:LFT’s should be checked for known liver disease to assess drug metabolism and dosing. ECG is useful for known history of CAD, cardiac conduction disease, or dysrhythmia.

Intraoperative Management: What are the options for anesthetic management and how to determine the best technique?

The anesthetic goals during ECT include:

  • provide safe, fast-track anesthesia

  • minimize convulsive motor activity to prevent injury (i.e., fractures)

  • provide loss of consciousness with the least anticonvulsive effects

  • prevent hypoxia

  • manage physiologic effects of ECT itself

Regional anesthesia

Regional anesthesia is not typically used for ECT.

General anesthesia

Benefits: Patient comfort and safety (low likelihood of patient injury with use of paralytics, less emotional trauma from treatment), better control of patient hemodynamics.

Drawbacks:Many sedative/hypnotic drugs have anticonvulsive properties, need for airway control.

Other issues: Intravenous access and standard ASA monitors are absolutely necessary for anesthetic management of ECT.

Airway concerns:Usually mask ventilation is adequate to ventilate/oxygenate the patient. However, consider rapid sequence induction (RSI) with ETT to secure airway in patients with known severe GERD, pregnancy, or other conditions at high risk for pulmonary aspiration.

Monitored anesthesia care

Anesthesia care is not typically used for ECT.

6. What is the author's preferred method of anesthesia technique and why?

General

Anesthetic technique

  1. Monitoring: Standard American Society of Anesthesiologists (ASA) monitors (ECG, non-invasive blood pressure monitor [NIBP], end-tidal carbon dioxide concentration in the expired air [ETCO2], blood oxygen satuation [SPO2], peripheral nerve stimulation)

  2. Access: All patients require peripheral IV cannulation prior to procedure

  3. Airway/ventilation: Typically a mask is adequate for airway control, but secure airway device (LMA or ETT) should be considered when clinically appropriate

  4. Procedure: The goal of ECT is to produce a generalized seizure by introduction of an electrical stimulus to the head of the patient. After appropriate IV access and basic monitoring have been established, the anesthesiologist uses a short-acting IV anesthetic to establish general anesthesia. Once anesthesia and ventilation have been safely established, a tourniquet is quickly applied to an extremity (typically a lower extremity) and a short acting IV neuromuscular blocking drug (NMBD) is given. The NMBD will prevent patient injury from generalized tonic–clonic movements. Use of the tourniquet will allow the selected extremity to be spared paralysis, allowing the provider to observe tonic–clonic movement solely in that limb and, thus, seizure duration. Once paralysis is established, an electrical stimulus is applied to the patient's head and seizure activity is measured via EEG and observing the nonparalyzed extremity. During the treatment, the anesthesiologist administers appropriate IV agents to attenuate/control the ANS discharge common with ECT. Once seizure activity has ceased, the patient is allowed to emerge from general anesthesia with appropriate airway/ventilatory support. If an intermediate or long-acting non-depolarizing NMBD is used, reversal agents may be administered prior to emergence.

Anesthetic agents

Seizure threshold and duration are inversely related. ECT-evoked seizure may be shortened or aborted by an agent that increases seizure threshold. It is important to choose an anesthetic agent that will produce adequate anesthesia and optimal seizure duration.

The ideal anesthetic for ECT provides:

  • smooth and rapid induction of general anesthesia

  • minimal antagonistic effects on seizure activity

  • short duration and rapid recovery

  • hemodynamic stability and attenuation of physiologic ECT effects

  • minimal injection pain

  1. Methohexital: A barbiturate with short onset (seconds) and duration of action (2-8 minutes), with minimal effect on seizure threshold.Considered the first choice for ECT anesthesia if no contraindication to barbiturates exists (i.e., porphyria). Common dose is 0.75-1.0 mg/kg.

  2. Thiopental: A barbiturate with short onset and duration, but compared to methohexital significantly shortens seizure duration. Greater attenuation of sympathetic nervous system (SNS) discharge, incidence of bradycardia, and ventricular ectopy. Common dose is 3-5 mg/kg. Can cause histamine release.

  3. Propofol:Fast onset and short duration, but has significant anticonvulsant properties. In low doses (0.75 mg/kg) seizure duration comparable to methohexital, but in larger doses (1-1.5 mg/kg) significantly shortens seizure duration. SNS response is attenuated compare to methohexital, thiopental, and etomidate. Causes pain on injection.

  4. Etomidate:Generally associated with longer seizure duration (0.15-0.3 mg/kg) and minimal cardiodepressant effects. It is a good choice for patients where optimal seizure length has not been achieved with other agents. However, it can cause myoclonus, which may interfere with interpretation of seizure activity. It is also associated with post-operative nausea and vomiting (PONV) and causes pain on injection.

  5. Ketamine:Does not increase seizure activity/duration compared to methohexital, does not cause respiratory depression, and is seldom used for ECT due to the increase in ICP and sympathomimetic properties.

  6. Benzodiazepines: Profound increase in seizure threshold and decrease in seizure duration, so not suitable for ECT. Patients taking benzodiazepines prior to ECT can be given a dose of flumazenil immediately prior to treatment.

  7. Volatile gases: Only sevoflurane has been compared to intravenous barbiturates for ECT, with seizure duration and blunting of SNS response being comparable. However, use of volatile agents is time consuming and an uncommon practice in ECT.

  8. Opioids: Alfentanil (10-30 mcg/kg) or remifentanil (1 mcg/kg) can be used at induction so that less propofol or thiopental is needed. This can lengthen seizure duration.

Muscle relaxants

These drugs are used to prevent injury (fracture, dislocation) and postprocedure myalgias. Short-acting agents are ideal.

  1. Succinylcholine: Most commonly used; at common doses of 0.5 to 1.5 mg/kg. Rapid onset and short acting, but patients can still have myalgias from muscle fasciculation related to this depolarizing NMBD (a small dose of non-depolarizing drug can be used as a pretreatment). Be cautious of pronounced bradyarrhythmias. Cannot be used in patients who are susceptible to MH and hyperkalemia (i.e, upper motor neuron disease, muscular dystrophy, paraplegia, NMS), and with pseudocholinesterase deficiency.

  2. Non-depolarizing NMBD: Used only when succinylcholine is contraindicated. Short-acting agents are preferred, usually need anticholinesterase reversal drugs.

  • Mivacurium: Most often used when succinylcholine is contraindicated. Intubating doses (0.15-0.25 mg/kg) are required for effective ECT conditions. Onset (1-2 minutes) and duration (16-20 minutes) with this dose is reasonably short, but may cause significant histamine release and hypotension. Anticholinesterase reversal drugs should be considered.

  • Atracurium: Most commonly used if succinylcholine or mivacurium cannot be used. Intubation dose (0.5 mg/kg) has short onset (2 minutes) but duration (25-30 minutes) requires anticholinesterase reversal drugs.

Agents to control hemodynamic changes

  1. Glycopyrrolate or atropine can be given prior to or at induction to attenuate the initial parasympathetic discharge of ECT. Glycopyrrolate is preferred, as it causes less tachycardia and is a more potent antisialagogue.

  2. Hypertension and tachycardia associated with ECT can be successfully treated most commonly with esmolol or labetalol. In patients who cannot tolerate beta-blockade (asthma, COPD), alpha-agonists (clonidine, dexmedetomidine), calcium channel antagonists (diltiazem, nicardipine), and ganglionic blockers (trimethaphan) can be used as well. Nitroglycerin and nitroprusside are seldom used in ECT unless the patient has significant CAD. Unless tachycardia or HTN would be poorly tolerated (CAD, AS, severe AI), it is unnecessary to pre-treat with beta-blockade or antihypertensives as the SNS discharge following ECT (including dysrhythmias) are self-limiting. In addition, short-acting opioids (alfentanil, remifentanil) can also be used to blunt SNS stimulation. All of these agents have minimal effect on seizure duration.

Other considerations

  • In patients where adequate seizure activity/duration cannot be achieved, the anesthesiologist may assist by hyperventilating the patient, as elevated CO2 increases the seizure threshold.

  • Pretreatment with aminophylline, theophylline, and caffeine have all been reported to prolong seizure activity.

In general, complications during anesthesia for ECT are rare. The most common are listed below:

Cardiac:The most common complication or morbidity associated with ECT is myocardial ischemia. The sympathetic discharge following ECT is self-limiting, but if not controlled appropriately in patient at risk for myocardial ischemia it can cause morbidity. Death from asystole has been reported, but is exceedingly rare. Tachyarrhythmias are also common, but rarely cause morbidity in the absence of pre-existing conduction system disease.

Pulmonary:The most common pulmonary complication is pulmonary aspiration. Most airway management is via mask-ventilation, but in high-risk patients (pregnant, severe GERD) a secure airway with an ETT is advisable. Residual weakness from neuromuscular blockade may require prolonged ventilatory assistance.

Neurologic:In the absence of intracranial mass or aneurysmal disease, cerebrovascular complications are rare. The most common neurologic complication is status epilepticus, or prolonged seizure duration. This can be treated with IV administration of benzodiazepines (can be given IM if required), barbiturates, propofol, or anticonvulsants that can be administered as a rapid bolus (fosphenytoin, levetiracetam). If necessary, muscle relaxants should be given and the airway secured with an ETT.

a. Neurologic:

N/A

b. If the patient is intubated, are there any special criteria for extubation?

N/A

c. Postoperative management

What analgesic modalities can I implement?

The most common pain complaints after ECT are myalgias and headache, particularly in the younger patient population. The myalgias may be related to succinylcholine use. These can be treated by premedication with acetaminophen or ketorolac prior to ECT. Small doses of opioid can be used postprocedure as well.

What level bed acuity is appropriate?

Unless the patient is already an inpatient, the majority of ECT is done on an ambulatory basis.

What are common postoperative complications, and ways to prevent and treat them?

Postprocedure nausea can occur, especially if etomidate is used. In patients with a known history of PONV or where etomidate must be used, pretreatment with ondansetron or other serotonin antagonists is effective. Use sedating antiemetics (promethazine, diphenhydramine) cautiously as most patients will experience a post-ictal state. Use caution with butyrophenones (droperidol) in patients on antipsychotics or with a history of NMS.

What's the Evidence?

Hooten, WM, Rasmussen, KG. "Effects of general anesthetic agents in adults receiving electroconvulsive therapy: A systematic review". J ECT. vol. 24. 2008. pp. 208-23.

(An excellent review of the various pharmacologic agents used in anesthetic management of ECT. Focus on efficacy based on comparative studies.)

Saito, S. "Anesthesia management for electroconvulsive therapy: hemodynamic and respiratory management". J Anesth. vol. 19. 2005. pp. 142-9.

(A review that highlights hemodynamic management very well, with specific information on cardiovascular, cerebrovascular, and seizure effects of commonly used drugs in ECT.)

Wagner, KJ, Mollenberg, O, Rentrop, M, Werner, C, Kochs, EF. "Guide to anaesthetic selection for electroconvulsive therapy". CNS Drugs. vol. 19. 2005. pp. 745-58.

(A well-organized general review of ECT management that includes physiologic effects of ECT, preoperative discussion, and overview of anesthetic technique.)

Ding, Z, White, PF. "Anesthesia for electroconvulsive therapy". Anesth Analg.. vol. 94. 2002. pp. 1351-64.

(A succinct general overview of anesthetic technique for ECT that includes special considerations, special populations and post-procedure concerns.)
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