Thymatron
®
System IV Instructions for Use
38
The static impedance test checks the quality of the skin-to-electrode contact. With the Thymatron® System IV,
the static impedance should be greater than 100 ohms and less than 3000 ohms before the treatment stimulus
dose is administered. A static impedance reading of less than 100 ohms suggests a short circuit, probably in the
stimulus cable. An impedance reading of 3000 ohms or more appears as the flashing number 3000; if this occurs
the impedance should be reduced by the following steps:
Try pressing firmly on each Thymapad™ again while testing the impedance. This is especially important for the
vertex electrode with unilateral ECT, which should be pressed vigorously in place with the foam handle
applicator provided. Also, for unilateral ECT, make sure that the hair and scalp under the vertex stimulus
electrode are thoroughly moistened with a saline-soaked pad.
If necessary, remove the Thymapad™, pass it under running water, shake off the excess water, wait a few
minutes and then reapply the Thymapad™ by pressing it firmly into place.
Check to make sure the electrodes have not slipped or twisted.
Reposition the stimulus electrodes to minimize the amount of hair underneath.
Increase pressure on the stimulus electrode by pressing harder with the foam handle applicator.
Gently rub the skin under the stimulus electrodes with a fine emery board or Skin Prep tape (3-M) to remove the
top layer of dead cells and sebum. Reapply the stimulus electrodes exactly as before.
A common reason for high impedance is that one or more steps were omitted from skin site preparation. Please
be sure to follow each instruction step when using Thymapad™ stimulus electrodes. During cold weather skin
thickens and hardens, causing the static impedance to rise. Also, some patients have high readings despite all
procedures. Try applying skin lotion to the electrode sites between treatments and shortly after waking on ECT
days.
If the static impedance reading remains >3000 ohms after trying the above procedures, try replacing each
Thymapad™, the lead-wires or the stimulus cable, in that order.
MOUTH PROTECTION
During the ECT stimulus and seizure the jaw muscles commonly clench tightly. This poses risks of tooth
fracture or displacement and biting of tongue and cheeks. These can cause mouth bleeding with pulmonary
aspiration of blood. These risks are mitigated by inserting a mouth protector prior to the electrical stimulus.
Somatics' mouth protectors have channels for ventilation and are available in reusable (sterilizable) and single-
use types. They are accompanied by instructions for insertion.
BASELINE EEG COLLECTION
Prior to collecting a baseline EEG, be sure the automatic EEG endpoint detection feature of the Thymatron®
System IV is enabled; the EEG monitoring electrodes are properly applied to the patient; the monitoring cable
