Biomedical Engineering Reference
In-Depth Information
• Cardiac demand pacemakers that detect a user's heart rate and turn on a pacemaker
when the heart rate falls below a predetermined level can in certain circumstances be
a
ected by stimulation. This is because the pulses from the stimulator may be con-
fused with the heart's intrinsic signals and fool the pacemaker into thinking that the
heart is beating faster than it is. A pacemaker or implantable de
ff
brillator should be
considered to be an absolute contraindication to upper limb and shoulder stimulation.
Electrical stimulators can sometimes be used with caution for lower limb applications
in these patients as long as the action of the pacemaker/de
fi
fi
brillator and heart is
checked by a cardiologist while the stimulator is in use.
• Electrical stimulation should be used with extreme care in patients with any other
type of active implantable medical device, such as a spinal cord stimulator or intrathe-
cal pump. This is because electrical stimulation currents can interfere with the oper-
ation or even damage the circuitry of an implanted device. In addition, electrical
stimulators should not be used over metal implants, whether active (pacemakers,
spinal cord stimulators, etc.) or passive (orthopedic nails, metal plates, prosthetic
joints, etc.) because these will distort the
flow of current through the body and may
cause internal hot spots with high current density that can destroy adjacent tissues.
• Electrical stimulation should not be applied over the eyes or the carotid sinuses (side
of neck), due to the risk of acute hypotension through a vasovagal re
fl
ex.
• Electrical stimulation electrodes should not be placed over the anterior neck because
of possible laryngospasm due to laryngeal muscle contraction.
• Electronic equipment such as ECG monitors, ECG alarms, sleep apnea monitors, and
so on, may not operate properly when electrical stimulators are in use.
• Electrical stimulation should not be used during pregnancy because it may induce
premature labor.
• With the exception of electrical stimulation that is speci
fl
cally intended for the stim-
ulation of the brain, electrodes should never be placed to cause current to
fi
ow tran-
scerebrally (through the head), as this may induce seizures and have other undesirable
neurological consequences.
• With the exception of electrical stimulation that is speci
fl
cally intended for stimula-
tion of the heart, electrodes should never be placed to cause current to
fi
ow across the
chest (e.g., both arms simultaneously) because electrical stimulation currents may
cause or lead to arrhythmic events. For the same reason, patients should be warned
never to handle the electrodes while a stimulator is on since a current path through
the heart could be created by accident.
• There are rare anecdotal reports that people who have poorly controlled epilepsy have
had symptoms increased after using electrical stimulation. There is no known mech-
anism for this e
fl
ect, but our advice is that electrical stimulators should not be used
in patients with epilepsy that is not well controlled by drugs.
• Because electrical stimulation (especially EMS and IFC) will increase local blood
circulation, it is possible that stimulation in the area of a malignant tumor might
increase the rate of metastasizing and therefore the spread of the cancer. Electrodes
should never be placed over the area of a known tumor.
• Long-term stimulation at the same electrode site may cause skin irritation through
possible allergic reaction to tape or gel. Poor skin condition can be a problem when
self-adhesive skin electrodes are used. This is because there is a greater chance of
skin irritation. Electrodes should never be placed over broken skin or over rashes,
blisters, spots, and so on.
• Electrical currents used in some modes of electrical stimulation (e.g., IFC) are large
enough that they may cause skin burns under the electrodes. For this reason, the
electrodes should not be placed in an area of sensory impairment (e.g., in cases of
ff
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