TENs Flashcards
TENS vs interferential therapy
TENS Pulsed current Transcutaneous Electrical Nerve Stimulation Low frequency current Newer current Non invasive Portable User Friendly Low initial outlay and low running costs Few contraindications Minimal side effects Non- addictive Can be used by patient at home-empowers patient interferential therapy
Alternating Current (Sinusoidal) Uses two medium frequency currents to create a low frequency current ‘Interference’ Predecessor of TENS Non invasive Few contraindications Minimal side effects Non- addictive Used in clinic rather than at home More bulky and expensive Fewer current options
physiological effects
Sympathetic nerve 1-5Hz Parasympathetic nerve 10-15Hz Motor nerve 10-50Hz Sensory Nerve (Non-pain) 90-130Hz Nociceptive fibres 2-10 Hz Smooth muscle 0-10Hz nerve stimulation Motor nerve 10-50Hz What effect will this have? Sensory Nerve (Non-pain) 90-130Hz What effect will this have? Nociceptive fibres 2-10 Hz What effect will this have?
pain relief - pain gait theory
descending pain inhibtion
Pain Gate Theory
Use of high frequencies (90-130Hz) stimulates the large diameter sensory fibres (Aβ)
Activation of Aβ nerve fibres can inhibit transmission of noxious stimuli (from Aδ & C fibres) from the spinal cord to the brain
Descending Pain Inhibition
Use of lower frequencies (2-5Hz) stimulates Aδ & C fibres
Stimulation of Aδ & C fibres activates the opioid mechanisms…
…leading to descending inhibition of pain
pain gait theory
AB fibres are
activated and block
the AD and C fibres-
Conventional TENS
Interferential
descending pain inhibition
Has been shown to activate the descending pain inhibitory systems
Growing evidence – role of endorphins
Acupuncture-like TENS
waveforms TENS interferential
TENS - rectangular biphasic
interferential - sinusoidal
TENS parameters
Variables on modern TENS machines output intensity (A) 0-80mA (1-50mA) pulse frequency 2-150pps (Hz) pulse width duration 50-250 microseconds
Amplitude
‘strong but comfortable sensation’
Should be based on patient’s subjective report rather than the machine settings
Influenced by size of electrode, placement of electrode, the patient’s tolerance, area etc.
Does require periodic adjustment to allow for any adaptation
modulation in TENS
Can vary the
pulse duration
frequency
amplitude
Some machine allow all 3 parameters to be changed, others only allow 1 or 2.
Cyclical variation is believed to prevent adaptation of the nerves to the current
Appropriate if used for long periods
treatment duration TENS
Depends on type used
Conventional –up to one hour at a time, intermittently during day.
Acupuncture –no more than 30 minutes
Types of TENS
Conventional TENS
Acupuncture-like TENS
Intense TENS
Burst TENS
Conventional TENS
Aim:
to selectively activate the large diameter sensory fibres (A fibres without activating the pain fibres) or motor fibres
High frequency: 90 - 130 Hz or pps
Low amplitude: ‘subjectively comfortable’
Short Pulse Duration: 50-80s
Time: maximum tx time of 1 hour as often as required but with 30 min breaks between
Rapid onset but short acting pain relief
Accupuncture like TENS
Aim to selectively activate the small diameter A and C fibres Activates the opioid system Release of endogenous opiates Low Frequency: 2-5 Hz Wider Pulse Durations: 200-250 s Higher Intensity/Amplitude strong, uncomfortable sensation, may also stimulate slow twitch motor fibres Time: once a day for 20-30 minutes
Brief intense TENS
Burst TENS
Aim: to produce rapid pain relief by activating the A fibres at an intensity that is just tolerable to the patient Can be poorly tolerated Shown to produce peripheral blockade of nociceptive activity and segmental and extrasegmental activity High pulse frequency: 90-130 Hz/pps High Pulse duration (width): 200s Intensity: highest patient can tolerate Time: no more that 15 minutes
Conventional TENS, interrupted by bursts of 2-5 burst/second
Burst mode switch on machine
Frequency 40-150 Hz
Pulse Duration: 100 s
Intensity: higher than for Conventional
Thought to combine both conventional and Acupuncture-like
Which TENS to use
Conventional is commonly tried first
Acupuncture-like used frequently for chronic pain
Based on descending pain inhibition effect
Brief Intense and Burst TENS used less frequently
Most of research is based Conventional or Acupuncture-like TENS
CIs to TENS
Undiagnosed pain Lack of normal sensation – risk of burn Pacemakers/Cardiac arrythmias Malignant tumours Over the carotid sinuses Pregnancy Allergic reactions to electrodes Epilepsy Drive/operate machinery (TENS)
TENS Precautions
Cardiac disease Electrodes over the anterior chest wall (C/I) some consider this a Contra-indication Impaired sensation Impaired cognition/comprehension Skin irritation Open Wounds/Fragile skin
Adverse effects
Contact Allergies- use hypoallergenic self-adhesive electrodes
Headache
Hypotension-if electrodes placed over C/spine
Electrical Burn
Check sensation
Avoid prolonged treatment duration
Avoid excessive intensities
Electrode placement
Over or around the painful area
Along the nerve root
Place along acupuncture points
Contra-lateral to site of pain
Application - Electrode Types
TENS
Hypoallergenic, Self-adhesive
Single use, disposable
Caution with attaching/removing- do not pull from wire.
Sharp-blunt test
Must be done prior to first treatment
Use specialised instrument with a sharp end and a blunt end
Explain test to patient
Demonstrate on a separate area to area being tested
Ask patient to close eyes
Apply sharp and blunt ends to the area to be tested, randomly
If patient cannot tell difference between sharp & blunt sensation impaired: TENS not appropriate
Method of application
TENS application
TENS
2 pole
(one or two channels)
Introduction to patient and Explanation of procedure
Check contra-indications
Remove jewellery/clothing etc
Check blunt/sharp skin sensation
Ensure patient is comfortable and area to be treated is fully supported
Switch machine on /Set parameters –ensure amplitude at 0
This may vary by machine. For some you can set parameters with machine off and others have to be set with machine on
Position electrodes securely on patient’s skin
Connect electrodes to machine lead
Advise patient that you are going to turn up amplitude and they should feel a ‘strong, comfortable sensation’
Gradually turn up intensity until patient feels ‘strong, comfortable sensation’
Electrode placement
Contra planar
Co-planar
Termination of treatment
Slowly decrease intensity Switch machine off Disconnect electrodes from lead Remove electrodes from patient’s skin Check patient’s skin Reassess any relevant outcomes Record treatment
TENS for home use
All new TENS users should have supervised trial in clinic before home use
Show patient how to use machine
Check usual precautions/contraindications
Establish effect ( relevant outcome)
Need minimum of 30-60 minutes trial
Home trial for 1- 2 weeks and re-evaluate
Try Conventional TENS first
Indications for TENS/ IFT
Acute pain e.g. post injury, post -op
Chronic Pain e.g. CLBP, OA, RA etc.
Labour Pain (specifically TENS)
TENS post-op
Reduce need for analgesia and improves respiratory function
Conflicting results!
Review of 17 RCTs reported that TENS had no significant benefit over a placebo- no benefit (Carroll et al, 1996)
Meta-analysis of 21 studies in 1350 patients found it reduced need for analgesics, but needs to be administered near the wound at a strong intensity (Bjordal et a, 2003)
Labour pain TENS
Used in first and second stage of labour
Specially designed ‘obstetric TENS’ has a ‘boost’ control for contractions
Systematic review by Carroll (1997) of 10 RCTs found no significant benefit for TENS
High levels of patient satisfaction (Johnson, 1997)
TENS produces a significant decrease in pain during labour and postpones the need for pharmacological analgesia for pain relief.
Pedro 8/10
Chronic pain
Arthritis, Pain following amputation, nerve pains, low back pain, cancer pain
Lack of good quality studies
Comparison of AL-TENS and conventional TENS in Chronic LBP (Flowerdew and Gadsby, 1997)- AL TENS more effective than conventional or placebo
More effective than placebo for chronic LBP. TENS 1.6 times and AL-TENS 7 times more effective (Fargas-Babjak, 2001)
OA
In knee OA compared with NSAIDS (Lone et al, 2003)-TENS more effective than NSAIDS, placebo meds or placebo TENS.
Recommended for use in knee OA by Philadelphia Panel (2001).
Not recommended in 2014 NICE guidelines for care and management of OA
http://guidance.nice.org.uk/CG177/NICEGuidance/pdf/English
Dose - response
TENS effectiveness is affected by four important factors: Type of application Site of application Treatment duration of TENS Optimal frequencies and intensities.
Important to consider these when
interpreting results from research studies
(Claydon and Chesterton, 2008)
Placebo effect
‘A substance with no medicinal properties which causes a patient to improve because of his belief in its efficacy’.
evidence for effectiveness
Knee OA
Systematic Review
18 studies (11 = TENS, 4 = IFT; 1 = TENS & IFT; 2 = pulsed electrostimulation)
difference in pain scores between electrostimulation and control of 0.2 cm on a 10 cm visual analogue scale
‘not confirm that transcutaneous electrostimulation is effective for pain relief…inconclusive…inclusion of only small trials of questionable quality…appropriately designed trials of adequate power are warranted’
(
TENS cancer pain
In one RCT, there were no significant differences betweenTENSand placebo in women with chronic pain secondary to breast cancer treatment. In the other RCT, there were no significant differences between acupuncture ‐typeTENSand sham in palliative care patients; this study was underpowered
Fibromyalgia
8 RCTs
TENS only or TENS combined with Exercise
Insufficient high‐quality studies to allow us to come to any conclusions about the effectiveness of TENS for fibromyalgia pain
Findings for measures of pain were inconsistently reported
Classification of nerve fibre types
diameter.(microns). myelin speed m/sec
A alpha - 10 - 20. yes v fast 70-110
A beta. 5-10. yes. fast 30-60
A gamma 3-6. yes Fast 20-30
A delta. 2-5 yes. Fast 20-30
B <3 inter-med. medium 5-15
C <1.3. no. slow .5-2
