Thymatron
®
System IV Instructions for Use
42
above for bilateral ECT.
NOTE: Once a patient obtains a satisfactory seizure with a given PERCENT ENERGY stimulus dose with
unilateral ECT, we do not recommend administering subsequent treatments with progressively lower settings in
an attempt to deliver the smallest stimulus that will still induce a seizure. This is because minimum stimulus
dosing has been associated with inadequate therapeutic efficacy for right unilateral ECT.
STIMULUS TITRATION PROCEDURE
For those who prefer to set the initial stimulus dose relative to the seizure threshold, a simple and practical
stimulus titration schedule for unilateral ECT starts with an initial setting of between 1% and 5% ENERGY,
followed by re-stimulations at between 5% and 10% ENERGY. Increase increments until a seizure occurs, to a
maximum of 4 stimulations in a treatment session (on average, fewer than three stimuli are required). Once the
seizure threshold is determined for a specific PERCENT ENERGY setting, the recommended dosing level for
unilateral ECT is 4-6 times that threshold value (e.g., 60% to 90% ENERGY for a threshold value of 15%
ENERGY).
Because seizure thresholds for bitemporal and bifrontal ECT are higher than those for right unilateral ECT, the
initial dose for stimulus titration with bitemporal ECT should be between 5% and 10% Energy, with 5%
ENERGY increments as described above. The subsequent treatments should be administered at doses
approximately 2 times this threshold (e.g., 40% ENERGY for a patient with 20% ENERGY seizure threshold).
“BENCHMARK” METHOD FOR SETTING AND ADJUSTING STIMULUS
Because neither seizure duration nor seizure threshold are systematically related to the clinical efficacy of an
ECT treatment, you may wish to consider regulating the stimulus dose according to a physiological measurement
that has been reported to correlate with treatment response (the "target measurement"). Possible target
measurements include Postictal Suppression Index (PSI), Maximum Sustained Power (MSP), or peak heart rate
(PEAK HR).
Unlike stimulus threshold titration, the benchmark method does not require administering consecutively
increasing sub-threshold stimulus doses until a seizure is obtained. Rather, at the first ECT treatment a high
enough stimulus dose is given to induce an expected vigorous and effective seizure in virtually all patients. The
value for the benchmark measurement reported in the end-of-treatment report for this first ECT treatment is then
used as a target for all subsequent treatments.
Selection of the initial stimulus dose for the benchmark method can be made by the fixed-dose method or an
age-based method. A fixed dose of 75-90% ENERGY should be high enough for most patients, regardless of
treatment electrode placement. Alternatively, the PERCENT ENERGY dial can be set to the patient’s age for
unilateral ECT, or to 50-75% ENERGY of the patient’s age for the various bilateral placements: bitemporal,
bifrontal, or LART.
Dosage should be adjusted for subsequent treatments to maintain the selected variable (PSI, MSP, peak HR)
