Effect of Anesthetic Dose in ECT: New Study from Sweden
Out on PubMed, from researchers in Sweden, is this study:
The effect of anaesthetic dose on response and remission in electroconvulsive therapy for major depressive disorder: nationwide register-based cohort study.
BJPsych Open. 2021 Mar 23;7(2):e71. doi: 10.1192/bjo.2021.31.PMID: 33752777
Aims: We aimed to examine the effect of different dose intervals of anaesthetics on response and remission after ECT for MDD.
Method: We conducted a nationwide cohort study, using data from Swedish registers. Low-, medium- and high-dose intervals, adjusted for age and gender, were constructed for each anaesthetic drug. Response and remission were measured with the Clinical Global Impression - Severity and Improvement scales (CGI-I and CGI-S), and a self-rated version of the Montgomery-Åsberg Depression Rating Scale (MADRS-S). Logistic regression models were used to calculate adjusted odds ratios for response and remission rates.
Results: The study included 7917 patients who received ECT for MDD during 2012-2018. Patients were given either thiopental (64.1%) or propofol (35.9%). Low-dose intervals of anaesthetics were associated with increased rates of response (CGI-I: odds ratio 1.22, 95% CI 1.07-1.40, P = 0.004; MADRS-S: odds ratio 1.31, 95% CI 1.09-1.56, P = 0.004) and remission (CGI-S: odds ratio 1.37, 95% CI 1.17-1.60, P ≤ 0.001; MADRS-S: odds ratio 1.31, 95% CI 1.10-1.54, P = 0.002).
Conclusions: We found improved treatment outcomes with low- compared with high-dose anaesthetic during ECT for MDD. To enhance treatment effect, deep anaesthesia during ECT for MDD should be avoided.
Keywords: Depressive disorders; antidepressants; electroconvulsive therapy; epidemiology; outcome studies.
The pdf is here.
and from the text:
In this study, patients with MDD who received low-dose anaesthetic
during ECT had higher response and remission rates compared
with patients who received high-dose anaesthetic. All of our outcomes pointed in the same direction, with superior MDD treatment
outcomes, measured with both clinical assessments and self-rated
scales, for low- compared with high-dose intervals. For one of our
secondary outcomes, distinct response, there was a dose-dependent
relationship. Furthermore, treatment series were shorter and seizure
durations were longer for patients who received low-dose intervals.
We found an increased risk of subjective memory worsening for
patients who received low-dose intervals compared with patients
who received high-dose intervals. The measurements of memory
disturbance are routinely done the day after the last ECT session.
With this in mind, it is more likely that the seizure activity itself
was associated with the greater effect on memory the day after treatment rather than a direct effect of the anaesthetics. Previous studies
have shown that objective negative effects on memory typically disappear within 15 days, and after this, the cognitive function
improves. The prolonged epileptic seizures in the low-dose interval group could explain the increased subjective memory worsening
the day after the last ECT.
This is yet another excellent data paper from Swedish colleagues, using their national health care registers. Although intuitively obvious, the conclusion that lighter anesthesia is associated with more effective seizures, and therefore better outcomes, is now supported by this good evidence. Again, we note the power of having thousands of patients in the cohorts.
As stated by the authors, it is a limitation that patient weights were not available, so the dose intervals are absolute, not in mg/kg.
I would emphasize that the risk of too light anesthesia is awareness of the effects of succinylcholine, very frightening for the patient, and a rare complication that is avoided by careful practice. Adequate anesthetic depth, but not excessive, is the aim of ECT anesthesia, and is the cogent, main message of these authors.
This paper is definitely worth a full read by all ECT providers, ~15 minutes.
Thank you for the comment. I completely agree, there is an optimum, not to light and not to deep anesthesia. To deep means inadequate seizures and slow improvement, to light means risk of awareness and postictal agitation. The optimum is an important part of the art of high quality ECT, which is developed in close collaboration between the psychiatrist and the anesthesiologist.
ReplyDeleteExcellent article and comments. I am fairly liberal in using midalozam after the seizure has ended to minimize emergence agitation and presumably blunt recollection of any unpleasant aspect of the procedure including patient being "too light." The point of this article dovetails nicely with work finding that extending the time after the anesthetic is injected until the stimulus is given may enhance the response to ECT.
ReplyDeleteThis is really again a great study from Sweden. Congratulations on that. I think it's really the first study that clearly shows that a higher dose of anticonvulsant anesthesia is not conducive to a good outcome.
ReplyDeleteHowever, the clinically relevant question of which dose should ultimately be selected for a patient so that he achieves a good outcome and on the other hand does not suffer from postictal agitation, should also take into account the timing. A large number of studies have now shown that not only the dose but also the timing plays a role in terms of effect and side effects.
"The lighter- the better?" was already said in 2006, even if it is not necessary to measure the depth of anesthesia, both, dose and timing of anticonvulsive anesthetic drugs should be considered.
Sascha Sartorius
This is really again a great study from Sweden. Congratulations on that. I think it's really the first study that clearly shows that a higher dose of anticonvulsant anesthesia is not conducive to a good outcome.
ReplyDeleteHowever, the clinically relevant question of which dose should ultimately be selected for a patient so that he achieves a good outcome and on the other hand does not suffer from postictal agitation, should also take into account the timing. A large number of studies have now shown that not only the dose but also the timing plays a role in terms of effect and side effects.
"The lighter- the better?" was already said in 2006, even if it is not necessary to measure the depth of anesthesia, both, dose and timing of anticonvulsive anesthetic drugs should be considered.
Sascha Sartorius