SEN 008
Issue 9.3
23 May 2019 Page 6of 29
Patients with an implanted electronic device such as a cardiac pacemaker must not be subjected to electrical stimulation until
specialist medical opinion has been obtained.
Patients with cerebrovascular accidents (CVAs or Stroke) may have unexpected electromyographic responses.
TetraGraph is not for use near shortwave or microwave therapy equipment as this can cause unwanted stimulation in the
electrodes and incorrect operation.
When applying the TetraSens Electrodes, make sure that the contacts of the connector do not touch other conductive parts
including any connected to earth.
To avoid micro and macro-shock keep all indwelling wires and catheters clear of stimulating electrodes.
Do not touch electrodes during stimulation, as it may affect the neuromuscular response.
If high frequency (HF) electrocautery is being conducted on an arm, place the TetraSens electrodes on the opposite arm.
HF electrocautery creates interference which can cause TetraGraph to stop updating its display; it will resume after the HF
electrocautery has ceased. This behaviour is by design so that electrocautery does not interfere with NMT measurement and
result in spurious results.
If the electrosurgical grounding fails, skin burns may occur at the site of the electrodes.
High frequency stimulation (tetanus) will lead to a 2 to 3-minute period of post-tetanic potentiation in which subsequent evoked
responses are potentiated. The TetraGraph has this 3-minute delay built in.
Hypothermia of monitored muscle will significantly affect neuromuscular transmission and give erroneous information. Best
practice is to maintain the peripheral muscle normothermic.
The use of electrodes other than TetraSens, the reuse of electrodes or poor application of electrodes may result in burns due to
the current density of the stimulation electrode.
Only apply electrodes to clean, dry skin without signs of damage such as burns, tattoos or inflammation.
The TetraGraph must not be modified as this may cause a hazard to the patient.
Only use the charger and cable provided when connecting to the TetraGraph unit.
Before use, ensure the monitor is intact and the battery is fully charged. Also visually inspect the device and the TetraCord
cable for any loose or damaged parts.
If the performance of the device changes from that specified, required or expected, take the device out of service immediately.
Maintenance work must be conducted by trained personnel following the manufacturer’s guidelines.
Do not expose the device to excessive heat.
Do not use abrasive cleaners on the display. See chapter 18 for recommended cleaning procedures.
The side effects that can occur from use of TetraGraph and its TetraSens Electrodes are the following:
Allergic reaction to clinical adhesive or hydrogel.
Localised irritation if stimulation electrodes are not securely fitted or are reused.
Neurostimulation using maximal currents may induce pain in un-anaesthetised patients.
NOTE: TetraSens electrodes are for single use only.
11. Symbols and Icons
The following symbols are used on the TetraGraph device and its display, and on the
TetraSens electrode.
