Strategies for Optimizing ECT Anesthesia

Bruce Jancin

October 20, 2020

General anesthesia for ECT gets short shrift in the psychiatric literature, yet it's an indispensable part of the procedure, with a major impact on its safety and outcomes, Alexander Sartorius, MD, asserted at the virtual congress of the European College of Neuropsychopharmacology.

Just how neglected is the topic?

"The two bibles of ECT – the American Psychiatric Association's 'The Practice of Electroconvulsive Therapy' and Richard Abrams's 'Electroconvulsive Therapy,' contain only three pages on anesthesia out of several hundred pages," noted Sartorius, a psychiatrist at the Central Institute of Mental Health in Mannheim, Germany.

Sartorius, who has published extensively on the management of general anesthesia in ECT, offered fresh insights into its optimization. He also shared how to swiftly identify and deal with its main side effects.

General anesthesia is an essential part of ECT for only one reason: Not to spare the patient from pain or trauma, as is widely supposed, but simply to avoid awareness of the muscle relaxant that's given to prevent bone fractures and other injuries caused by motor seizure, the psychiatrist explained.

Four anesthetic agents traditionally used for ECT have fallen by the wayside. The two barbiturates, thiopental and methohexital, have problematic anticonvulsant properties that complicate their use in a procedure whose whole purpose is to induce a seizure. Plus, they have black-box warnings in some countries. Etomidate, in contrast, has no anticonvulsant effect; however, anesthesiologists are increasingly leery of the drug. A single dose completely suppresses the hypothalamic-pituitary-adrenal axis for more than 24 hours, and mounting evidence suggests that etomidate may be associated with increased mortality.

Sartorius is a fan of ketofol, a combination of two anesthetic agents – ketamine and propofol – that provide rapid onset and cessation of action, pharmacokinetic predictability, synergistic efficacy, and minimal adverse effects when the two drugs are given in doses lower than standard as monotherapy.

Propofol has attractive qualities as an anesthetic, but it is a very potent anticonvulsant with an adverse effect on seizure quality and duration. When used alone for general anesthesia in ECT, a higher stimulation dose is often necessary to achieve adequate seizure quality, which in turn may produce worse cognitive side effects. In contrast, ketamine, which is listed as an essential drug by the World Health Organization, has no anticonvulsive effects.

"My conclusion about ketamine alone is it has less side effects than feared, and it's probably not more but definitely not less effective than the grand old four anesthetic agents," Sartorius said.

Plus, ketamine shows promise as an antidepressant agent in and of itself. Moreover, the fact that patients require a lower ECT stimulation dose while under the influence of ketamine could result in fewer cognitive side effects, although that's conjecture at this point, he added.

Ketofol is often administered in a 1:1 ratio of propofol to ketamine. That's not optimum for each individual patient undergoing ECT, as in many cases it results in so much propofol that seizure quality is diminished, in Sartorius's experience. He, therefore, recently published a retrospective study of 52 patients who received 919 ECT sessions with empirically determined doses of S-ketamine plus propofol for anesthesia. The endpoints were time in the recovery room and seizure duration and quality. Seizure quality was assessed as a composite of the ratio of duration of motor response to EEG seizure duration, peak heart rate, midictal amplitude, maximal interhemispheric coherence, and postictal suppression index.

The optimal S-ketamine/propofol ratio in terms of seizure quality was 1.52:1, with a mean relative dose of 0.72 mg/kg of S-ketamine and 0.54 mg/kg of propofol.

His team uses only the S-enantiomer of ketamine, not the racemic mixture known as ketamine, but his study results would translate to a 3:1 ratio of racemic ketamine to propofol, Sartorius said.

Time in the recovery room was dependent upon return of cardiorespiratory function and orientation status to baseline pre-ECT levels. Longer recovery room time proved to be significantly related to older age. The S-ketamine dose wasn't a significant factor.

Propofol was injected prior to S-ketamine in all patients. This was followed 1-2 minutes later by administration of succinylcholine as a muscle relaxant. It's important to then wait for at least another 2-3 minutes before delivering the ECT stimulation. Sartorius and others have demonstrated that waiting at least 4 minutes between anesthesia induction and delivery of the ECT charge results in a better-quality seizure.

"We have a timer running so we can be sure to wait longer than 4 minutes. That's a large advantage if you want to reduce the anticonvulsant property of propofol," he explained.

Anesthesia-Related Side Effects

Sartorius addressed postictal agitation syndrome, postanesthetic shivering, cardiac arrhythmias, and hypersalivation.

Postictal agitation syndrome: The deeper the level of sedation, the less likely this complication. Historically, in ECT without anesthesia, the incidence of postictal agitation was as high as 50%. At the center where Sartorius works, it's 2%-3%. The use of intraprocedural bispectral index monitoring of the achieved deepest level of sedation allows highly accurate prediction of postictal agitation.

"Do not restrain," he advised. "Patients are aware of this problematic situation. You have to keep everything calm and use the least possible amount of physical limitation. The good thing is that it's self-limited within 20 minutes in most cases. But in severe cases you have to escalate staff immediately, and you may want to use 10 mg of IV diazepam. The most important message is you have to increase the dose of your anesthetic with the next ECT; a lower dose of anesthetic is not the solution."

It is also important to watch for these possible complications:

  • Postanesthetic shivering: This is a rare but potentially fatal complication. It's important to be familiar with the grading system, and to recognize that grade 3 or 4 post-anesthetic shivering requires treatment. "The treatment of choice is clonidine. That should always be with you when you do ECT," Sartorius observed.

  • Cardiac arrhythmias: "ECT is a proarrhythmic intervention; don't forget that," he said.

  • Poststimulation asystole: This occurs in more than half of treated patients. It's caused by the current, not the seizure, and it stops within a few seconds after the current halts. If the asystoles bother the patient, try switching to bifrontal electrode placement. Right unilateral stimulation has been shown to increase the likelihood of asystole by 207-fold, compared with bifrontal stimulation.

  • Tachycardia: This is another common complication of ECT. It responds well to a short-acting beta-blocker.

  • Hypersalivation: The treatment of choice is glycopyrrolate, a muscarinic receptor antagonist that doesn't cross the blood-brain barrier.

Sartorius reported having no financial conflicts regarding his presentation.

SOURCE: Sartorius A et al. ECNP 2020, Session EDU03.02.

This article originally appeared on MDedge.com, part of the Medscape Professional Network.

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