What is TENS?
T.E.N.S is a form of pain relief used in labour. It stands for Transcutaneous (which means through the skin) Electrical Nerve Stimulation.
It is a battery operated, electrical unit, that gives a tingling sensation (via electrodes) by stimulating the nerves through the skin, to help give relief from pain.
The TENS machine for use in labour has a base unit with various settings (which will be pre-programmed) and two intensity dials, as well as a lead with a booster button. It operates using a nine volt square battery (which will be supplied).
There are two wires that attach to the unit and a pair of electrodes (sticky pads) that attach to each wire. When used in labour, these pads are placed on the mother’s back.
How does it work?
It works by increasing the body’s natural form of painkillers – endorphins, as well as helping the brain ‘tune out’ the messages of pain it receives.
The brain registers ‘pain’ when signals are sent from the nerves in the painful region.
In labour, the brain receives pain signals, via nerves, from the cervix, uterus, lower back and coccyx region.
When the TENS machine is applied, it sends electrical stimulation to the nerve roots, which sends a different (tingling) signal to the brain, and thus the brain starts to concentrate on the new sensation and less so on the pain.
(A simple example is when a child falls on their knee, receiving pain signals from the nerves in the knee, a parent will instinctively rub the painful area, which now sends a different signal to the brain and thus lessens the pain felt).
Can it be used with other forms of pain relief?
Yes. It can be used with entonox (gas and air); meptid or pethidine. It may even be used during the insertion of an epidural, simply remove the lower set of pads or electrodes, but keep the top set in place.
Once the epidural takes effect, TENS may be removed as it becomes ineffective.
Is it safe?
Remove during a bath or in the birthing pool (which will continue endorphin production anyway) and then re-apply TENS pads when skin is dry.
As it interferes with brain signals and uses an electrical current:
- Do not use if you have Epilepsy
- Do not use if you have a cardiac pacemaker
- Do not use on broken/numb areas of skin
- Do not use when driving
- Do not use if you have been diagnosed with cancer
TENS in labour?
An obstetric TENS machine used in labour is different to an ordinary TENS machine, in that it has a unique booster button that changes the intensity from low to high (when experiencing a contraction) and changes the frequency from a pulsating sensation to a continuous one.
During the low, pulsating setting, when not experiencing a contraction, it is stimulating endorphins, similar to massage therapy. When a contraction is felt, the booster button pressed, it changes to the high intensity, continuous setting and this is when it interferes with the pain signals (Pain Gate Control Theory).
The positioning of the electrodes on the back, is therefore very important, to target the appropriate nerve roots, during labour pain.
- Ensure the skin on your back is dry and oil-free
- Place a new nine volt square battery into the machine (ensuring the rubber stopper is removed)
- Connect the white ends of the four electrode pads to the black and red ends of the leads. Each pair of electrodes should be attached to one lead, with one red end and one black end. Whether the red or black end is applied to the left or right is irrelevant.
- Apply the sticky electrode pads to the back:
– One pair of electrodes is placed at bra strap level, an
inch either side of the spine (with leads hanging down).
– The other pair of electrodes is placed over the sacral dimples, an inch either side of
the spine (with leads going upwards).
- Make sure machine is off and intensity dials are switched to off, then connect the two leads to the two terminals at the side of the machine.
- Check booster button is in the raised position to begin with, for a low frequency burst or pulsating setting.
- Check both channels are working by slowly turning one dial on and slowly increasing the strength until a mild tingling sensation is felt, then turn it off and repeat with the other dial.
- When assured both channels are working, switch on both intensity dials and slowly increase the intensity until a strong tingling sensation is felt in both sets of pads and the pulsating/burst function is clearly felt, then turn the dial down a little to a comfortable level.
- When a contraction starts, press the booster button down to change to a high frequency, continuous setting.
- When the contraction has stopped, press the button again to the raised position, to return to the low frequency, burst or pulsating setting.
- As the brain becomes used to the sensation and pain levels increase over time, the intensity dial will need to be turned up to increase the tingling sensation felt.
- When TENS is no longer needed, turn both intensity dials to ‘off’ before removing the pads.
- Dispose of the pads only but keep all leads and wires and return the whole TENS unit and pack to the rehabilitation centre at The James Cook University Hospital to re-claim your deposit.
For advice or further information please contact the physiotherapy department.
Telephone: 01642 854453
Email: [email protected]
Kitchmen S., (2001) Electrotherapy:
Evidence Based Practice, Churchill Livingstone. Clutte E., (1994) Analgesia in labour;
A review of the TENS method Professional Care of Mother and Child Vol 4(2): 50-2 Crothers E., (1998) TENS for Labour Pain Journal of Chartered Physiotherapists in Women’s Health 83: 6-10.
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