1. ECT Stimulus Dosing Protocol
Establishing Seizure Thresholds (ST) & Treatment Sessions
Introduction
Seizure Threshold (ST) is the lowest stimulus dose that produces an adequate
seizure.
Adequate seizure: generalised cerebral seizure activity associated with a tonic
convulsion demonstrated by either
•
•
EEG evidence of 3 per second spike and wave activity
or
Generalised, bilateral tonic-clonic motor activity
The length of the seizure is not critical in determining the presence of an adequate
seizure.
The choice of laterality of treatment is the responsibility of the prescribing
clinician. There is no “default setting” by the ECT team.
The laterality of treatment also forms part of the consent process as patients need to
be consented for unilateral or bilateral.
Prescribing clinicians need to be aware of differences between unilateral and bilateral
ECT. Unilateral ECT is less likely to cause cognitive side effects but higher
suprathreshold doses are needed. Bilateral ECT is probably more effective in severe
depression than unilateral.
If a prescribing clinician has concerns as to choice of laterality then advice can be
obtained from the lead consultant for ECT.
Dose Titration
The patient is given increasing doses of electrical stimulus until an adequate seizure
is obtained. Once the seizure threshold is established, the treatment dose can be
calculated from the appropriate chart and used in subsequent treatment stimulations
(see appropriate Titration Schedule) .
Most patients are expected to have a seizure threshold below 100mc (20%)
and will be successfully titrated within two sessions.
The purpose of stimulus dosing is to ensure that patients subsequently receive
treatment doses, which are sufficiently in excess of the patient’s seizure threshold to
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2. be therapeutic whilst minimising cognitive side effects. In general this means that for
bilateral ECT the treatment dose should be 1½ to 2 times the seizure threshold and
for unilateral ECT at least 4 times the seizure threshold.
First Treatment Session
Decide on which level to proceed. Start at the following dose levels according to sex
and electrode placement.
Female unilateral
Female bilateral
Male unilateral
Male bilateral
level
level
level
level
1
2
2
2
In addition to above:
1. Increase by one level if patient is over 50, by 2 levels if over 70
2. Under the age of 70 Increase by a further one level if the patient is on
Benzodiazepines or anticonvulsants, is dehydrated, has had ECT within the previous
month, or other predictors of raised seizure threshold are present. (This does not
apply if over 70 years)
THYMATRON DOSAGE LEVELS
Level
mC
Settings %
1
5
25
2
10
50
3
15
75
4
25
125
5
35
175
6
50
250
7
70
350
8
100
500
2

3. 9
150 (75x2)
750
10
200
1000
First Treatment
Having decided at which level to begin, please consult appropriate titration schedule.
If no seizure after first stimulation, wait 20-30 seconds before proceeding to second
stimulation. If partial seizure or seizure of inadequate duration wait 30 seconds
before proceeding to second stimulation. If still inadequate seizure, consider a third
stimulation after 30 seconds.
Do not proceed to a third stimulation without prior discussion with ECT Lead
Consultant and Anaesthetist.
Second Treatment Session
Continue as per appropriate flowchart. If no seizure after first stimulation wait 30
seconds before proceeding to second stimulation. If partial seizure or seizure of
inadequate duration wait 30 seconds before proceeding to second stimulation.
However, do not proceed to a third stimulation without prior discussion with ECT
Lead Consultant and Anaesthetist.
Third and Subsequent Treatment Sessions
Continue with calculated treatment dose but remember that seizure threshold may
increase by up to 80% over a course of treatment.
Because the patient’s clinical progress overrides all theoretical considerations, the
above instructions can only be a guide, based on our present knowledge of ECT. If
the patient is not responding to treatment it may be necessary to increase the dose
by a greater percentage or to consider switching from unilateral to bilateral ECT. If
the patient is experiencing marked cognitive side effects it may be necessary to
switch to unilateral ECT, or space treatment sessions more widely, or reduce the
treatment dose.
The aim is to deliver effective treatment for each patient on each occasion.
1.
For Unilateral ECT:
ECT is given to the non-dominant hemisphere, usually the right, even in lefthanded patients. For left handed people, first measure seizure threshold with
right unilateral ECT and in confusion occurs switch to left unilateral ECT next
time. Do not increase dose until sure of laterality.
• The seizure threshold is less than for bilateral ECT.
• The effective dose of electricity is between 5-8 times seizure threshold.
• Even at high doses the cognitive side effects are negligible so this is presently
the treatment of choice for young people, patients where speed of response is
not paramount or those suffering from dementia.
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4. •
•
•
Because of reduced cognitive side effects, measurement of the seizure
threshold may be less critical than for bilateral ECT.
It may be necessary to change to bilateral ECT if there has been no beneficial
effect after 4 unilateral ECT treatments.
For unilateral ECT (when maintaining a wide difference between threshold
and treatment doses is critical for efficacy), in the absence of significant
cognitive side effects, increase treatment dose (in mC) by 5 – 10% at each
subsequent treatment session
2. For Bilateral ECT:
•
•
•
•
•
This involves giving a dose of electricity approximately 1.5-2 times above
seizure threshold using a bi-temporal electrode position.
Most patients (75%) will have a seizure threshold (ST) below 100mC but
there may be considerable variation between individuals so it is best to
measure the ST.
If there has been no clinical improvement after 4 apparently ‘adequate’ ECT
treatments then increase the dose next time by 75-100mC, provided there
have been no cognitive side effects.
It is vital to record any post treatment confusion because this is an indication
that the dose of electricity has been too high for that particular patient, who
may therefore be at increased risk of cognitive side effects.
If cognitive side-effects are troublesome:
i)
ii)
reduce dose by 50mC OR
consider high dose unilateral ECT
For bilateral ECT (which has some effect even at the slightly supra-threshold doses)
it is usually sufficient to increase the dose only if there is poor clinical progress or if
there is a marked deterioration in the quality of the EEG seizure or motor fit.
For all treatments:
•
•
•
•
•
•
•
Both efficacy and side effects increase with the dose above seizure threshold
for any given individual.
The seizure length is idiosyncratic and is not itself an indicator of efficacy.
However as the course of treatment proceeds it may be necessary to
increase the dose of electricity given to take account of the anticonvulsant
action of ECT. A progressive shortening of the seizure may give some
indication of this.
The timing of the visible seizure is taken from the end of stimulation to the
end of bilateral seizure activity.
The seizure length as determined by the EEG will usually be 10-40% longer
than the visible seizure; the relationship between these also tends to be
idiosyncratic.
There is good correlation between short EEG seizures and short visible
seizures but the converse is not true; up to 6% of patients with a short visible
seizure may be experiencing prolonged cerebral EEG activity. Such seizure
activity should be terminated after 120 seconds.
ECT machines are not directly comparable in terms of effect for a given total
charge.
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5. Switching between unilateral and bilateral ECT
A switch from unilateral ECT to bilateral may be indicated if there is poor clinical
response. A switch from bilateral to unilateral ECT may be indicated if there is
significant cognitive impairment. In both cases the seizure threshold should be retitrated using the appropriate charts and the treatment dose calculated. If no seizure
results or is inadequate in duration, the anaesthetist will further ventilate the patient.
The patient may be re-stimulated after the anaesthetist has given approval. Restimulation should only occur in accordance with the Stimulus Dosing Protocol.
•
•
•
The treating doctor should also check their technique — in particular did they
apply the electrodes firmly enough?
In the event that the patient still does not fit after further stimulation in
accordance with the Stimulus Dosing Protocol, then an entry should be made
in the patient’s case-notes to bring the attention to the patient’s own
psychiatric team.
The psychiatric team may then wish to consider matters such as doses of
drugs with anti-convulsant effects. At the next treatment it will be desirable to:
-
Pay special attention to stimulation technique
Adjust the stimulus strength in accordance with the Stimulus Dosing
Protocol
The anesthetist may wish to alter the dosages of anesthetic drugs
What if the patient does not have an adequate seizure
If no seizure results or is inadequate in duration, the anesthetist will further
ventilate the patient. The patient may be re-stimulated after the anesthetist has
given approval. Re-stimulation should only occur in accordance with the Stimulus
Dosing Protocol.
The treating doctor should also check their technique — in particular did they
apply the electrodes firmly enough?
In the event that the patient still does not fit after further stimulation in accordance
with the Stimulus Dosing Protocol, then an entry should be made in the patient’s
case-notes to bring the attention to the patient’s own psychiatric team.
The psychiatric team may then wish to consider matters such as doses of drugs
with anti-convulsant effects. At the next treatment it will be desirable to: -
Pay special attention to stimulation technique
Adjust the stimulus strength in accordance with the Stimulus Dosing
Protocol
The anesthetist may wish to alter the dosages of anesthetics drug.
Poor Clinical Response to ECT
The clinical team should review patients who fail to respond within 4 to 6 treatment
sessions. Consideration should be given to increasing the treatment stimulus to the
higher dose (for bilateral ECT this is approximately 2.5 x ST, for unilateral ECT this is
6 x ST) or switching from unilateral to bilateral ECT.
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6. Bilateral treatment and increasing the stimulus dose has shown to be more effective
but produces more cognitive side effects. In some circumstances consideration may
need to be given to changing the anaesthetic agent from Propofol to Etomidate
(Propofol raises seizure threshold). This should be discussed with the clinical team
involved (including RMO, ECT Lead Consultant and Anaesthetist) and clearly
documented in the medical file/ECT care pathway.
Procedure for Discontinuation of ECT
The prescribing and discontinuation of ECT are the decision of the patients
Consultants/RMO. However, the decision to discontinue ECT may also take place in
the context of discussion with the ECT Consultant and/or Anaesthetist in the light of
adverse reactions to ECT such as cognitive problems or anaesthetic problems.
Discontinuation may also take place because of poor efficacy or, most importantly,
because the patient has withdrawn consent.
The clinical status of a patient should always be assessed between each ECT
session and treatment should be stopped when response has been achieved.
A patient should not receive more treatments than is required to achieve an adequate
response, even if more have been prescribed, hence the patient must be reviewed
after each treatment during the treatment course.
Recommendations from ECT Handbook:
A set course of treatments should not be prescribed – the need for further treatments
should be assessed after each individual treatment.
Bilateral ECT
If no clinical improvement at all is seen after six properly-given-bilateral treatments,
then the course should be abandoned.
It may be worth continuing up to twelve bilateral treatments before abandoning ECT
in patients who have shown definite but slight or temporary improvement with early
treatments.
Unilateral ECT
For patients who do not respond to unilateral ECT, consideration should be given to
switching to bilateral treatment. It will be necessary to re-titrate seizure threshold in
this case
Procedure for Prolonged Convulsion – Tardive seizures
To be discussed with the Anaesthetist
Seizures lasting longer than 120 seconds (EEG) should be terminated using
intravenous Diazepam, 5 – 20mgs given over a period of 10 – 20 seconds.
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7. Missed Seizures during Treatment
This is less likely to occur with unilateral ECT where the treatment dose is at least 4x
the seizure threshold. When bilateral ECT is used the treatment dose is 1.5x the
seizure threshold and it is possible that seizures may be missed due to increasing
seizure threshold occurring during the course of ECT.
If the patient fails to have a seizure, wait 30 seconds and re-instate and re-stimulate
at the next available treatment dose. A further treatment (of one incremental step)
may be indicated after discussion with the Anaesthetist, if again there is no seizure.
At the next session revert back to the previously calculated treatment dose. If there
is another missed seizure wait 30 seconds and repeat the procedure described
above. Following two consecutive treatment sessions where there has been missed
seizure, the treatment dose should be increased by one level. Clinical progress
should be monitored and consideration given to switching to high dose ECT
(calculated from the original seizure threshold) if there is insufficient improvement.
Procedure for Emergence Delerium
To be discussed with the Anaesthetist
During recovery, patients suffering from states of agitation associated with rhythmic
or aimless repetitive movements or other evidence of gross confusion should be
given intravenous Midazolam, 1 – 5 mgs slowly.
In the case of recurring emergence delirium consideration should be given to
routinely administering intravenous Midazolam 1 – 5mgs as soon as EEG seizure
has terminated.
In both situations patients will need extra oxygenation until they have fully regained
consciousness. Need to discuss with Anaesthetist.
The above procedures will be reviewed in light of clinical research
Refs:The ECT Handbook, second edition, 2005. Royal College of Psychiatrists.
McColl & Sackeim, Archives Gen Psychiatry May 2000. vol 57, 438-444.
Mayur PM et al 1999 Brit J Psych. 174:270-2
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8. Appendix A
UNILATERAL ECT TREATMENT TABLE
Level
Titration Dose
Seizure Threshold
% (mC)
Treatment Dose
% Max (mC)
High dose for use
in non responders
% (mC)
1
5% (25)
20% (100)
30% (150)
2
10% (50)
40% (200)
60% (300)
3
15% (75)
60% (300)
90% (450)
4
25% (125)
100% (500)
150% (750)
5
35% (175)
140% (700)
200 % (1000)
6
50% (250)
200% (1000)
200% (1000)
70% (350)
200% (1000)
200% (1000)
100% (500)
200% (1000)
200% (1000)
9
150% (750)
200% (1000)
200% (1000)
10
200% (1000)
200% (1000)
200% (1000)
7
8
8

9. Appendix B
BILATERAL ECT TREATMENT TABLE
Titration Dose
(Seizure
Threshold)
% (mC)
Treatment
Dose
High Dose (For
use in nonresponders)
1
5% (25)
10% (50)
15% (75)
2
10% (50)
15% (75)
25% (125)
3
15% (75)
25% (125)
40% (200)
4
25% (125)
40% (200)
65% (325)
5
35% (175)
55% (275)
75% (375)
6
50% (250)
75% (375)
130% (650)
7
70% (350)
110% (550)
190% (950)
8
100% (500)
150% (750)
200% (1000)
9
150 (750)
(75x2)
200% (1000)
200% (1000)
10
200% (1000)
(100x2)
200% (1000)
200% (1000)
Level
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10. TITRATION SCHEDULE FOR PATIENT COMMENCING AT 5% BILATERAL
1ST Session
Fit
ST=5% Treat next session 10% B/L
5%
No Fit
Increase 3 Levels
25%
No fit
Increase 1 level
35%
Fit
D/W Lead Consultant prior to
2nd session.
No Fit
Fit
Second Session
nc
Increase 1 Level
Reduce 2 levels
10%
ST= 35%
Treat next session 55% B/L
Fit
ST= 10%
Treat at next session
15% B/L
50%
No Fit
Increase 1 Level
15%
Fit
ST=50%
Treat Next session
75% B/L
No fit Increase to 70%
( or change anaesthetic
agent as previously
discussed.)
70%
Fit
No Fit
ST=15%
ST=25%
Treat at next session Treat at This session
25% B/L
40% B/L
Fit
ST=70%
Treat at Next
Session 110%
10
No fit
D/W Lead
Consultant
? 100%
ST = SEISURE THRESHOLD

11. eco
TITRATION SCHEDULE FOR PATIENT COMMENCING AT 5% Unilateral
1ST Session
Fit
ST=5%
Treat at Next Session 20%
5%
No Fit
Increase 3 Levels
25%
No Fit
Increase 1 level
35%
Fit
Fit
No Fit
2ND Session
Reduce 2 levels
10%
Fit
ST=35%
Treat 140% UNI.
This session
ST= 35%
Assume ST= > 35% 2nd & subsequent
Session 200%
No Fit
ST= 10%
Treat at next session
40% Uni.
Increase up 1 level
15%
Fit
ST=15%
Treat as next session.
60% UNI.
No Fit
ST=25%
Treat at This session
100% UNI.
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ST=SEIZURE THRESHOLD

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13. 13

14. 14

15. 15

16. 16

17. 17