natus XLTEK Protektor32, Instructions For Use Manual

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XLTEK Protektor32 Instructions for Use
29
TcMEP Warnings and Cautions
Stimulating electrodes must be large enough so that the current density is always less
than 2 mA r.m.s./cm
2
. Current densities exceeding 2 mA r.m.s./cm
2
may require special
attention of the operator. For example, if the stimulus is stimulating at 100 mA at 10 Hz,
with a duration of 1 ms, then the stimulus electrode must be at least 0.5 cm 2 .
When an electrode with a small surface area is used (such as a needle electrode), the
current density rises.
Current density in TcMEP mode is dependent on the stimulation strength (voltage) and
number of pulses. If the stimulation parameters are different from those detailed in the
table and the voltage is greater than these thresholds, it may cause skin burns.
For a detailed description and calculations of the stimulation parameters needed to
achieve less than 2 mA rms / cm
2
refer to the Table 4 appearing below.
Patient movement may occur during stimulation, leading to inadvertent neural injury. Take
adequate steps to avoid stimulation when patient movement could cause injury.
Due to the high current density and risk of patient burns, corkscrew and needle electrodes
with low surface areas, such as those 13 mm long and 0.4 mm in diameter should not be
used for stimulation with the TcMEP stimulator.
Cortical stimulation may not be appropriate for use on patients with a history of skull
fracture or neurosurgical procedures to the head. Skull defects could provide high local
current densities.
Cortical stimulation may induce seizures and memory problems in those with a history of
epilepsy and other disorders with predisposition to seizures (e.g. alcoholism). Ensure that
necessary medical precautions are taken in case of such an episode.
Otherwise unexplained intra-operative seizures and possible arrhythmias are indications
of cease use of the TcMEP stimulator.
The TcMEP stimulator outputs must be connected to the stimulating electrodes only.
Unintentional misconnection of the outputs to ground electrodes could result in current
being dangerously applied to organs other than the cerebral cortex.
Studies by Calancie et al. relied upon to demonstrate safety and effectiveness of the
device employed threshold level monitoring to increase patient safety by minimizing
energy delivered.
When using the electrical stimulator many times over a long period, check the moisture
and the paste on the stimulation electrodes periodically. When electrical stimulation is
conducted over an extended period of time, the moisture and the paste on the stimulation
electrodes dry out; as a result, if the electrical stimulation continues with it dried out, the
point that is being stimulated with high current density will get hot and may cause a burn.