Page 47 of 56
EN109-1498740-40 IFU
Securing electrodes
•
Non-adhesive electrodes should be secured firmly with tape or straps.
•
It is important that electrodes remain in complete contact without edges lifting throughout the
treatment.
•
Securing electrodes is very important when applying NMES as the skin moves when the muscle
contracts.
•
Unsecured electrodes can lead to electrical burns and very uncomfortable stimulation.
Electrode sponges
•
Sponges should be appropriately moistened (not too wet or too dry) with tap water and should
be replaced when they become dirty, as this decreases their conductivity.
•
It is recommended that a sufficient number of sponges be available to enable complete drying
before re-use
–
this will limit growth of water-borne bacteria.
Current density
In the particular standard for Electrical Nerve and Muscle Stimulators, IEC 60601-2-10, it is
recommended not to exceed a current density of 2 mA r.m.s. / cm², otherwise skin irritations or
etching can occur.
For all current waveforms, the stimulator output current can never exceed 50 mA r.m.s. This implies
that with an electrode surface of 25 cm² the current density can never exceed 2 mA r.m.s. / cm². As
a rule of thumb for smaller electrodes, such as the 3.2 mm self-adhesives, the maximum current
setting available on the stimulator for a given current waveform should proportionally be reduced.
For a precise calculation of the r.m.s. value of a pulsed current waveform the following formula can
be used:
𝐼
𝑅𝑀𝑆
= 𝐼
𝑝𝑒𝑎𝑘
√𝑝ℎ𝑎𝑠𝑒 𝑑𝑢𝑟𝑎𝑡𝑖𝑜𝑛 [
µ𝑠
] ∗ 𝑝𝑢𝑙𝑠𝑒 𝑓𝑟𝑒𝑞𝑢𝑒𝑛𝑐𝑦 [𝐻𝑧] ∗ 10
6
For symmetrical TENS currents, the phase duration should be multiplied by 2. The value of the peak
current
𝐼
𝑝𝑒𝑎𝑘
can be taken from the current display.
Electrodes should be placed with care, ensuring good electrical contact over the entire electrode
surface.
Connection and disconnection reactions
Constant Current (CC) output characteristics may cause unpleasant connection and disconnection
reactions if the electrodes are not securely placed or lose contact with the skin. Make sure the
current amplitude is set to 0 mA when you apply or remove the electrodes.
