76: Electroconvulsive Therapy

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CHAPTER 76 Electroconvulsive Therapy

Philip R. Levin, MD, Alma N. Juels, MD

1 What are the major indications for electroconvulsive therapy treatment?

Electroconvulsive therapy (ECT) treatment plays an important role in treating severe and medication-resistant depression with psychotic features, manic delirium, and catatonia. ECT has been noted to result in a prompt improvement in symptoms of depression. Some studies have shown ECT to be more effective than antidepressant medications alone in treating the psychotic subtype of depression. ECT also remains a treatment option for patients with schizophrenia who do not respond to pharmacologic treatment.

2 What are the downsides of antidepressant medication?

Although antidepressant medications are effective for many patients, the rate of response to the first agent administered can be as low as 50%. The elderly may not be able to tolerate depressant medications because of the inability to tolerate the many side effects associated with antidepressant medications. In addition, certain neuronal changes in the elderly can decrease the response to medications.

3 What are the proposed mechanisms by which electroconvulsive therapy is effective?

Although its mechanism of action remains unclear, ECT increases cortical γ-aminobutyric acid concentration and enhances serotonergic function.

4 Has electroconvulsive therapy always been considered a good treatment for depression?

ECT was first used as a treatment for psychiatric disorders in the 1930s. However, complications such as fractures and cognitive impairment raised serious concerns. If not dangerous (use of insulin to cause a hypoglycemic seizure), it was barbaric (no anesthetic agents or muscle relaxants were used). Its use declined when antidepressant medications were introduced. In recent decades further research and technical advances have led to a renewed interest in the role of ECT.

5 How safe is electroconvulsive therapy?

It is estimated that death associated with ECT occurs in one of 10,000 patients. Interestingly, ECT appears to have less morbidity and mortality compared to many antidepressant medications. Because of this strong safety record, patients with significant comorbidities are often candidates for ECT.

6 What is the physiologic response to electroconvulsive therapy?

During ECT a generalized seizure is induced, leading to an acute increase in cerebral blood flow and an associated increase in intracranial pressure (ICP). Immediately following the ECT stimulus, there is a marked transient parasympathetic response that may induce sinus bradycardia, other bradyarrhythmias, asystole, premature atrial or ventricular contractions. This is rapidly followed by a more prominent sympathetic response, resulting in an increase in heart rate of 20% or more and increases in blood pressure of 30% to 40% or more. Ventricular arrhythmias and ST-segment changes may be noted and tend to be self-limited. The duration of the tachycardia tends to correlate with the seizure duration as measured by electroencephalography (EEG), although hypertension often persists and requires therapy. Increases in adrenocorticotropic hormone, cortisol, epinephrine, vasopressin, prolactin, and growth hormone are noted. Intraocular pressure and intragastric pressure also transiently increase.

7 What patients are at increased risk for complications after electroconvulsive therapy?

ECT should be used cautiously if at all when the effects on cerebral blood flow, ICP, heart rate, and blood pressure may prove problematic to the patient because of coexisting disease. Thus patients with cerebral space-occupying lesions or cerebrovascular disease are at increased risk. Similarly patients with unstable cardiac disease, including patients with uncompensated congestive heart failure, severe valvular disease, unstable angina, recent myocardial infarction, and uncontrolled hypertension are all at increased risk of complications. Patients with pheochromocytoma should not receive ECT because massive amounts of epinephrine or norepinephrine may be released into the circulation. ECT has been used safely in persons with cardiac pacemaker or implantable cardiodefibrillators and during pregnancy.

8 What type of preoperative evaluation is necessary before electroconvulsive therapy treatment?

A standard preoperative anesthetic history must be taken, including identifying medications, allergies, and prior adverse anesthetic events. Presumably the patient has failed a course of antidepressant medications. The significant comorbidities discussed in Question 7 should be identified, and the stability of these conditions assessed. A prior history of response to ECT (both symptomatically and physiologically) is valuable. A physical examination is also considered extremely important. Remember to include an assessment of the patient’s teeth and mouth, since the ECT stimulus will result in brief yet intense masseter contraction. There are no absolute requirements for laboratory testing. A decision to order laboratory tests should be based on the stability of the patient’s comorbidities and medications. A pregnancy test in women of childbearing age is also reasonable. Optimal medical therapy in preparation for ECT is advised to minimize risk during and after treatment, although the patient’s psychiatric condition may not allow this. In general, the patient’s medications should be continued.

9 Describe the technique of electroconvulsive therapy, including appropriate monitors and medications

Commonly a psychiatrist, anesthesiologist, and nurse attend the patient. An intravenous line is established, and routine monitors, including electrocardiogram, intermittent blood pressure, and pulse oximetry are placed. On rare occasions, predicated on the patient’s comorbidities, arterial cannulation and continuous monitoring may be required. The psychiatrist places EEG leads to measure the cortical seizure. An additional blood pressure cuff is placed on a leg. This cuff will be inflated before administering muscle relaxants so the muscles are isolated from the circulation and after the ECT stimulus the duration of the motor seizure can be measured. Before inducing anesthesia, the patient is preoxygenated for a number of minutes with 100% oxygen.

Anticholinergic medications may be administered to lessen the effects of the initial parasympathetic discharge. In addition, they have antisialagogue properties. The medication most commonly used is glycopyrrolate, 0.2 to 0.4 mg intravenously.

Methohexital is the most common anesthetic induction agent used because it has a rapid, short duration of action, low cardiac toxicity, and, most important, minimal anticonvulsant properties. Side effects include hypotension, myoclonus, and pain on injection. A typical dose of methohexital is 0.75 to 1 mg/kg. In patients with left ventricular dysfunction, etomidate is an effective induction agent since it has minimal effects on myocardial contractility and cardiac output. Etomidate may also enhance seizure duration in patients who had prior ECT but whose seizure durations were thought inadequate to achieve a therapeutic effect. Side effects include pain on injection, nausea and vomiting, and delays in return of cognitive function. A typical dose of etomidate is 0.15 to 0.3 mg/kg.

Propofol has a rapid onset and a short duration of action and allows cognitive function to return soon. Although propofol use is associated with shorter seizure durations, recent investigations suggest that there is no difference in outcome when compared to methohexital. A typical dose of propofol is 0.75 to 1 mg/kg.

Although ketamine has also been used in ECT, compared with methohexital the EEG seizure duration is decreased; ketamine has the additional effects of increasing ICP and myocardial oxygen consumption. It does not seem to be an agent of choice.

The short-acting opioid remifentanil has been used for its anesthetic-sparing effects, providing a stable anesthetic when swings in heart rate and blood pressure are undesirable while having no effect on seizure duration. Potent volatile anesthetic agents offer no advantage over intravenous agents, with the possible exception of late in pregnancy, during which time ECT has been noted on occasion to produce titanic uterine contractions.

After anesthetic induction, the blood pressure cuff on the leg is inflated and acts as a tourniquet. The patient is hyperventilated by Ambu bag to lower seizure threshold. Typically the short-acting muscle relaxant succinylcholine (0.5 to 1.5 mg/kg) is administered. Before administering the electroconvulsive stimulus, a compressible mouth oral guard protector is inserted to protect the patient’s teeth, lips, and tongue from injury during the associated severe masseter contraction. Only rarely, based on patient circumstances, is the patient intubated. During the seizure itself the patient receives positive-pressure ventilation with 100% oxygen until spontaneous ventilation returns and the patient awakens. When stable, monitoring continues in the postanesthetic care unit until the patient is oriented and meets discharge criteria. Often the patient is confused or complains of a headache; benzodiazepines or opioids are appropriate treatments for these problems. However, benzodiazepines should be avoided before ECT because they increase seizure threshold.

Finally, it is common over a course of therapy that anesthetic medications require modification in their dosing; usually more medication is required. These adjustments must be made based on review of prior records and whether the patient experienced a seizure of therapeutic duration.

10 What additional medications are used to address hypertension and tachycardia?

The cardioselective β-adrenergic blocker esmolol is sometimes given by either bolus or infusion to blunt the sympathetic response of ECT. The mixed α- and β-adrenergic blocker labetalol is frequently administered for persistent hypertension.

Nitroglycerin (3 mcg kg) IV can be given 2 minutes before ECT, or 2% nitroglycerin ointment applied 45 minutes before ECT to attenuate the increase in blood pressure and provide coronary vasodilation.

11 What is an optimal seizure duration?

ECT-induced seizure activity lasting from 25 to 50 seconds is alleged to produce the best response. Patients experiencing an initial seizure lasting less than 15 seconds or greater than 180 seconds have been found to achieve a less favorable response to ECT.

12 What can be done to prolong a seizure of inadequate duration or terminate a prolonged seizure?

Etomidate is the induction drug of choice in patients experiencing inadequate seizure activity. The proconvulsant caffeine (500 mg) is often administered in situations in which the seizure duration during prior electroconvulsive treatments has been suboptimal. Aminophylline has also been used for this purpose. Prolonged ECT-induced seizures can be terminated with a benzodiazepine or bolus of propofol, 40 to 80 mg.

13 How many electroconvulsive therapy treatments are usually necessary?

ECT is given as a course of treatments. The total number needed to successfully treat psychiatric disturbance varies from patient to patient. For depression the typical range is from six to twelve treatments. Typically ECT is performed three times a week. In successful cases initial clinical improvement is usually evident after three to five treatments.

14 What are some of the adverse effects of electroconvulsive therapy?

An induced seizure lasting longer than 2 or 3 minutes is considered prolonged and can result in increased cognitive deficits. Prolonged apnea is said to occur if it takes longer than 5 minutes to regain spontaneous ventilations after ECT treatment and may be caused by a pseudocholinesterase deficiency, resulting in prolonged succinylcholine activity. Emergence delirium is characterized by restless agitation, aimless repetitive movements, grasping objects in view, or restless attempts to remove the monitors and intravenous line. It usually lasts from 10 to 45 minutes or more after the seizure and responds to benzodiazepines. Anterograde amnesia may occur immediately after an ECT treatment but tends to resolve usually within an hour. Retrograde amnesia is the most common persistent adverse effect of ECT. It is more commonly seen in elderly patients and those with preexisting cognitive impairment. Memory loss of events several months or years in the past can occur. Usually retrograde amnesia improves during the first few months after ECT, although many patients have incomplete recovery. Other adverse effects include headache, muscle aches, nausea, and fatigue.

KEY POINTS: Electroconvulsive Therapy image

1. ECT treatment is recommended for patients with depression with psychotic features, manic delirium, and catatonia and patients who cannot tolerate the side effects of antidepressant medications.
2. Typical physiologic responses to ECT include transient parasympathetic discharge resulting in bradyarrhythmias, followed by a sympathetic stimulus resulting in hypertension and tachycardia. Increases in cerebral blood flow and ICP are also noted.
3. Methohexital is the most common induction agent used during ECT because it has minimal anticonvulsant properties, a rapid onset, short duration of action, and low cardiac toxicity.
4. Succinylcholine is the most common muscle relaxant used during ECT because of its short duration of action.

15 Is electroconvulsive therapy curative?

ECT is an extremely effective acute treatment for major depressive episodes. However, a permanent cure is extremely rare. Maintenance therapy with occasional (weekly or monthly) ECT treatments in combination with antidepressant pharmacotherapy decreases the relapse rate, but more effective strategies for relapse prevention in mood disorders are urgently needed.

SUGGESTED READINGS

1. Alexopoulos G.S. Depression in the elderly. Lancet. 2005;365:1961-1970.

2. Lisanby S.H. Electroconvulsive therapy for depression. N Engl J Med. 2008;358:645-646.

3. Narayan V.B., Kumar J.M. Review of anaesthetic management for electroconvulsive therapy. Anaesth Clin Pharmacol. 2008;24:259-276.

4. Rush A.J., Trivedi M.H., Wisniewski S.R., et al. Acute and longer-term outcomes in depressed outpatients requiring one or several treatment steps: a STAR*D report. Am J Psychiatry. 2006;163:1905-1917.

5. Tharyan P., Adams C.E. Electroconvulsive therapy for schizophrenia. Cochrane Database Syst Rev. 2, 2005. CD000076

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