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Anesthetic Management of Electroconvulsive Therapy

Anesthesia for ECT has been the subject of recent reviews.^{[159] [160]} Anesthesia and neuromuscular blockade are necessary during ECT to prevent psychological and physical trauma. Rapid recovery is desirable. Careful preoperative evaluation is necessary, with particular attention paid to coexisting neurologic and cardiac disease, osteoporosis and other causes of bone fragility, and medications that the patient may be receiving. The patient may be a poor historian because of the psychiatric condition, and accompanying caregivers may need to provide the necessary history and assurance of fasting status. Standard monitors are used. Pretreatment with glycopyrrolate (0.2 mg intravenously), which does not cross the blood-brain barrier, can reduce the occurrence of bradycardia and the amount of oral secretions associated with ECT, as discussed later. After preoxygenation, anesthesia is administered by peripheral intravenous catheter, and neuromuscular blockade is induced. When relaxation is adequate and satisfactory mask ventilation with oxygen is ensured, a bite block is placed and a stimulus is delivered to induce the seizure. If the patient has a hiatal hernia and gastroesophageal reflux, rapid-sequence induction and endotracheal intubation with cricoid pressure may be a reasonable approach. Adequate ventilation is ensured during the procedure because among other detrimental effects, hypoxia and hypercarbia decrease seizure duration and thus the efficacy of ECT.^{[161] [162]} The peripheral seizure is monitored by patient observation, as well as by electromyography, and the central seizure is monitored by electroencephalography. It must be remembered that the duration of the central seizure may outlast peripheral clonic manifestations. A blood pressure cuff inflated to isolate a limb before administration of a neuromuscular blocker can assist in monitoring peripheral seizure. In patients undergoing their initial ECT treatment, more than one stimulus may be necessary, and additional anesthetic or neuromuscular blocking drug (or both) may need to be administered. After the procedure, ventilation with oxygen by mask is continued until the patient awakens and is breathing adequately. During this time, tachycardia and hypertension, if persistent or of hazardous magnitude, may require treatment. The patient is monitored in a fully staffed and well-equipped recovery area after the procedure until routine discharge criteria are met. Some patients demonstrate significant oxygen desaturation after ECT, and we routinely administer oxygen by nasal cannula until the patient is fully awake.^[163]

Many intravenous anesthetics have been used to induce anesthesia for ECT, including methohexital, thiopental, propofol, and ketamine. Methohexital (0.75 to 1.0 mg/kg) is the most commonly used drug for ECT anesthesia and is considered the "gold standard."^[160] Propofol (0.75 mg/kg) was found to reduce seizure duration, which was believed to decrease the efficacy of ECT. However, more recent studies have demonstrated no difference in outcome with propofol versus methohexital.^{[164] [165] [166]} Administration of methohexital, as well as propofol, is associated with pain on injection, which may be poorly tolerated by psychiatrically fragile patients. The use of thiopental (1.5 to 2.5 mg/kg) avoids pain on injection, but it is associated with more hypertension and tachycardia than propofol is.^[167] Etomidate may prolong seizures and recovery, but prolongation of the seizure may be useful in patients in whom seizure duration is deemed too short with other agents.^[168] Benzodiazepines have anticonvulsant activity and should be avoided before ECT.^[160] Ketamine has been demonstrated to not increase seizure length or produce excessive postprocedural agitation.^[169] Given the hemodynamic response expected after ECT, ketamine would seem to be a less desirable agent.^[160]

Complete neuromuscular blockade is not necessary for ECT and may not be desirable because monitoring of peripheral seizure duration would be impeded. Partial neuromuscular blockade is necessary, however, to reduce the peripheral manifestations of the seizure and to prevent trauma to the patient. Succinylcholine has been used most frequently for neuromuscular blockade during ECT because of its short duration of action and low frequency of side effects. An initial dose of 0.5 mg/kg is administered and adjusted for subsequent treatments according to the patient's response. Mivacurium has been suggested as an alternative to succinylcholine, but it may not be as effective as succinylcholine in preventing tonicclonic muscle contractions, which could result in traumatic injury to the patient.^{[170] [171]} Mivacurium also necessitates prolonged postprocedural ventilatory support, thus increasing anesthetic requirements and costs.^[172] Both succinylcholine and mivacurium are metabolized by plasma cholinesterase, and alternative nondepolarizing muscle relaxants such as vecuronium or atracurium/cisatracurium may need to be used in patients with plasma cholinesterase deficiency. Relatively prolonged neuromuscular blockade may need to be accepted in such patients to avoid trauma from the seizure.

Prophylactic medications have been advocated to avoid various side effects of ECT. Transient asystole is rare during ECT, but it may be prevented with anticholinergic pretreatment. Glycopyrrolate is preferred over atropine because glycopyrrolate has no central anticholinergic side effects. In addition, glycopyrrolate is an effective antisialagogue. Both esmolol and labetalol have been successfully used to control hypertension and tachycardia after ECT.^[173] Some evidence has shown that esmolol reduces seizure duration.^{[174] [175]} Routine treatment with esmolol or labetalol is not recommended because the hypertension and tachycardia are usually self-limited, as are premature ventricular contractions. Should treatment be necessary, these drugs can be administered immediately after the stimulus.^[160]

The anesthetics and neuromuscular blocking drugs administered to each patient should, as in other anesthetic procedures, be accurately recorded. Such recording is especially important with ECT because the treatment is repeated over a period of several weeks to months and consistent patient conditions must be provided for a predictable response to the ECT stimulus. Moreover, patients' responses to previous treatment, such as the development of arrhythmias or agitation, and to the additional medications that were required, such as β-antagonists or benzodiazepines, should be noted so that extra precautions can be taken at subsequent treatments. Proper anesthetic

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