Features to look at when comparing
Maternity TENS units
Contraction Timer
Only MamaTENs MyTime has a timer to tell you how long and how far apart
your contractions are
Intensity Controls
These should be very easy to use, without delicate manipulation.
Older analogue units have two rotary knobs. This means that you have to make two
adjustments. A small error can give painfully high stimulus. Not ideal for someone in
labour.
Digital push-button units will increase one step at a time. However, this can seem a
little slow when things get painful. The Ramp feature on MamaTENS gives rapid,
easily controllable, change.
MamaTENS MyTime has very small steps and “Comfort Strength Control” to avoid
discomfort.
Intensity
A further mechanism – Brief Intense TENS – is useful in childbirth. Very high levels of
stimulation can give enhanced pain relief, but the effect only lasts a few minutes.
Using conventional intensity controls would need continuous adjustment.
The MamaTENS Ramp control is a simple and effective solution.
Anything above 100mA is painful (activates Pain Nerves, creating pain). In the USA,
FDA places limits on maximum charge per pulse, which would be exceeded at about
120mA
1/2 Channels
Two channels (four pads) are essential, together with specially designed large pads.
The electrode pads need to cover the nerves entering the spine at six different
vertebrae.
Splitting a single channel unit into two is not ideal – if resistance is higher in one set of
pads, the current will flow through the other set. If one set of pads becomes detached,
the output in the other set will almost double.
Programme Settings
Older analogue units have dials for adjusting Frequency and Pulse Width. These
have a very limited value, since you will not be able to make adjustments while in
labour.
Programmes must use clinically proven settings: Pain Gate 80-150 Hz, Endorphin
Release 2-10 Hz. Burst Mode in Obi TENS does not seem to access Pain Gate.
Waveform
A balanced, bipolar waveform is less likely to cause irritation under the electrodes,
and is more comfortable.
The waveform also affects the perceived strength of the signal. In some units, with
limited output circuits, the waveform deteriorates as the intensity setting is increased.
The perceived strength depends on peak intensity, waveform, and pulse width.
Pulse Width
The higher the pulse width, the stronger the feeling, and the more likely to stimulate
muscle contractions.
Battery Life
Labour can last 60 hours. The two sets of batteries provided need to last this long.
AAA batteries hold less than half the energy of AA batteries.
A PP3 battery holds slightly more than half.
Neck Cord/Belt clip
Most mums prefer to hold the unit in their hands, or to have a neck cord.
Boost Button
Having a separate cord can be a nuisance when there are other things going on
Hygiene
It is difficult to clean leads effectively. Leads should not be re-used between patients.
Maternity TENS Comparison Sheet
Mode
Number of
Channels
Controls
Contraction
Timer
Programmes
MyTime
MamaTENS
Femme TENS
Obi TENS
Elle TENS
Digital
2, With single
intensity control
Digital
2, With single
intensity control
Analogue
2, with two separate controls
Digital
2. Single output/split into 4
pads
Digital
7
YES
7
No
5
No
4
No
9
No
3 Preset
programmes,
clinically
approved.
Burst and Boost
modes in two,
Ramp in third.
3 Preset
programmes,
clinically
approved.
Burst and Boost
modes in two,
Ramp in third.
Two Modes: Continuous and
Burst
Two modes
Burst 1 16 Hz, Boost 1
80Hz
Burst 2 32 Hz
Burst 2 .100 Hz
Optimax
This is an adjustable
pulse width. Default is
150. Choices are
50,100,150,200,250
Integrated within the
unit
2x 1.5V AA
Adjustable frequency and pulse
width controls
Frequency: 1-120 Hz
Pulse Width: 50-250 uS
Battery
Integrated within
the unit
2x 1.5V AA
Integrated within
the unit
2x 1.5V AA
Burst Mode: 2 bursts per second
Remote button connected to unit
via a leadwire
9V PP3 battery
Specified output
70mA
75mA
0-70 mA (500 ohms load)
Booster Button
Burst Mode: (pulse
frequency 32Hz, pulse width
200us, 2 burst/ sec and 8
pulse/ burst)
Boost Mode: (pulse
frequency 80Hz, pulse width
100us, constant pulse)
Integrated within the unit
2 X1.5V AAA Battery (Type
LR03)
0- 100V zero to peak at
500ohm load adjustable in
10 steps
200mA into 500 ohm load.*
14 steps
44V/88mA in 15 steps
Waveform degrades at
higher settings.(110mA
in spec)
15 steps
15 steps
Continuous
140 steps
CSC
No
No
Overload cutout
Overload cut-out
YES
Pad Alarm
Biphasic
Square, biphasic Asymmetrical bi-phasic rectangular Symmetrical Monophasic
Asymmetrical bi-phasic
Waveform
balanced,
balanced,
Rectangular
rectangular
* If true, this would be a dangerously high output (according to USA FDA definition). We think it is probably an error in published specification
** Elle TENS “Optimax” is a pulse width adjustment. However, at high intensities, the output circuit is unable to deliver more power, and increasing the pulse
width merely gives a rapidly decaying waveform.
Intensity control
MamaTENS vs Elle TENS
Optimax
Lock
Intensity 2
Boost
ON/OFF
Prog
Intensity
Key Feature Differences
1) RAMP
MamaTENS Ramp mode using Brief Intense TENS
2) CONTROLS
Elle TENS has two additional controls: Two intensity controls, and “Optimax” Pulse Width
adjustment which makes only a small difference since maximum pulse energy is limited by
the circuit component.
Mama “Lock” button is seldom used.
3) SETTINGS
Burst settings in Elle TENS are 16 and 32 Hz. These are well below the optimum range for
Pain Gate. Burst is supposed to activate both Pain Gate and Endorphin release
mechanisms