Transcutaneous electrical stim (TENS) Flashcards
what is TENS
is a method of electrical stimulation whereby low frequency electrical currents are applied to the skin via leads, and surface electrodes, stimulating sensory nerves, principally for the symptomatic relief of pain
clinical use of TENS- success not guaranteed
acute pain joint pains, LBP, neurogenic pain, post-op pain, obstetric pain- during labour, chronic pain, arthritic condition- RhA
advantages and disadvantage of TENS for pain control
advantages- non-invasive, few side effects, patient controlled, battery operated and portable
disadvantages- allergic skin condition (electrode material, conductive gel, tape to hold electors in place), short lived relief, same as control
what does the biphasic nature mean
the biphasic nature of the pulse means that there is no electrolyte built up under the electrodies, thus minimising skin reactions
TENS labelled
intensity, pulse with, pulse rate, different modes- burst, Normal, modulated- in between, stronger sensation=more stimulus= reduces pain
dual channel machines (4 pads)
2 pairs of electrodes, applied simultaneously,useful for widespread and diffuse pain, intensity is set separately for each channel, other parameters selected cover both channel
parameters of TENS
current intensity (strength)- 0-80mA, pulse frequency (rate- 2-250Hz), pulse width (duration- 50-250us), intensity controls- sufficient to depolarize sensory nerves.
different modes of TENS
burst mode- pulses are produced in bursts or trains usually at a rate of 2-3 bursts per sec- stimulates both nerve types (AB and AD, good for opioid mechanisms), modulation- less regular pulse outputs, minimising accommodation
pathological effects of TENS
aims to excite sensory nerves thereby activating specific natural pain relief mechanism, can influence pain gate mechanisms- stimulates AB fibres- produces reduction in transmission of nociceptive fibres (80-120Hz) and endogenous opioid system
mechanisms of action- endogenous opioid system
release of endogenous opiates, stimulation of AD fibres causes release of encephalin in the interneurons of the posterior horn of the spinal cord and in the midbrain. encephalin inhibits the C fibres system and reduces the activation of noxious sensory pathways. AD fibres respond to 2.5Hx
Conventional/ normal TENS
high frequency- 80-130Hz, narrow pulse width, 30 mins minimum effective time, as long as needed, pain relief during stimulation
AB fibres- pain gate activation- 90-130Hz
acupuncture/ low TENS
low frequency 2-5Hz, wider (longer pulse width), strong intensity- not at patient threshold, 30 mins treatment is minimally effective dose, apply at intervals throughout the day, carry over several hours
Burst TENS
high frequency- 90-130Hz, narrow pulse width, relatively high intensity, a series of pulses repeated 2-3 times per sec, stimulates both pain gate and opioid mechanism
modulated TENS
delivers irregular bursts of stimulation, reducing accommodation,
brief intense TENS
for rapid pain relief, pulse frequency high (80-130Hz), pulse width is high, intensity is close to tolerance level, energy delivered high, 15-30 mins
frequency selection
no single frequency works for everyone, patient and therapist need to identify the most effective frequency for pain relief, manipulare stimulation frequency dial or button to achieve this
electrode placement
machines may be single or dual channel, position electrodes to stimulate the sensory nerves which enter the spinal cord at the same level- dermatomes, myotomes, sclerotomes, motor points, nerve root, peripheral nerve/trunk, trigger point
contraindications
patients who do not comprescence the physio instructions or who are unable to cooperate, patient with pacemakers, skin allergies to electrodes, gel or tape, dermatological donations- dermatitis, broken skin, eczema, area of tumor or suspected malignancy, abnormal sensation, current/ recurrent bleeding, compromised circulation, area of active TB, devitalised skin, epilepsy
where not to place electrodes
over trunk/pelvis in first 12 weeks of pregnancy, over pregnant uterus at any stage in pregnancy, over the eyes, epiphyseal regions in children, over anterior neck
precautions
abnormal skin sensation- reposition, epilepsy- seek with medical practitioner, abnormal electrodes used in labour may interfere with foetal monitoring
hazards
drop in BP, skin irritations, skin burns, electric shocks
mandatory
explanation of treatment- ensure understanding, colloquial terminology, informed consent- verbal or written, tests- sharp blunt sensation, questions- contraindications and precautions, warnings- if the patient experiences anything other than the expected sensation, they should inform the physio ASAP
prior to each application
visual checks of the electrodes, functional output of the unit, leads and electrodes is tested, the patient is positioned comfortably, with adequate support, the area to be treated is exposed, the skin is cleaned
application
if using aqueous gel, the gel is applied to the skin uniformly, once the electrodes are applied the current is switched on and increasing slowly, the unit is switched off prior to removal of the electrodes, patients are advised never to use TENS whilst driving or operating machinery
