Transcutaneous electrical nerve stimulation (TENS or TNS) is the use of electric current produced by a device to stimulate the nerves for therapeutic purposes. TENS, by definition, covers the complete range of transcutaneously applied currents used for nerve excitation although the term is often used with a more restrictive intent, namely to describe the kind of pulses produced by portable stimulators used to treat pain. The unit is usually connected to the skin using two or more electrodes.
A typical battery-operated TENS unit is able to modulate pulse width, frequency and intensity. Generally TENS is applied at high frequency (>50 Hz) with an intensity below motor contraction (sensory intensity) or low frequency (<10 Hz) with an intensity that produces motor contraction.
Basic scientific evidence suggests that there are peripheral and central nervous system mechanisms underlying the analgesic action of TENS. Studies also show that tolerance to repeated application of TENS can be prevented by multiple strategies, both pharmacologic and nonpharmacologic. Experimental pain studies and clinical trials are beginning to refine parameters of stimulation to obtain the best pain relief. It seems that stimulation intensity is a critical factor for the effectiveness of TENS.
One meta-analysis was able to show the positive treatment effects of electrical stimulation for relief of chronic musculoskeletal pain, and randomized controlled trials consistently demonstrate the effectiveness of TENS for acute, emergent, and postoperative pain conditions. However, the effectiveness of TENS on individual pain conditions, such as low back pain, is still controversial, likely because of poor study designs and small sample size. Thus, continued research of TENS mechanisms and stimulation parameters in adequately characterized patient populations is critical.
MH8000 TENS and EMS Combo device
Dual Power source: DC 9V battery or mains power adapter.
The Combo unit integrates EMS and TENS functions with 7 treatment modes. This unit is a hybrid stimulator which can be used for muscle stimulation and pain relief.
- Dual Channel, isolated between channels.
- Timer setting from 5-90 Minutes, 5min./step, or continue.
- Time count down monitored on LCD screen.
- Automatic switch off after 30 seconds if unit is not in use.
- CE 0434, FDA 510k
- Waveform: Asymmetrical rectangular biphasic pulse.
- Amplitude: 0 – 80 mA into 500 ohm load.
- Selectable pulse width: Adjustable, from 50us – 300us, 10us/step.
- Pulse Rate: Adjustable, from 2 Hz – 150 Hz, 2Hz~20 Hz in 1 Hz/step and 20~ 150 Hz in 5 Hz/step.
- Modes for EMS:
S (Synchronous) Mode, A (Alternative) Mode
- Modes for TENS:
N (Normal) Mode, M (Rate and Width Modulation) Mode, B (Burst) Mode, SD (Width Modulation) Mode, MR (Rate Modulation) Mode
- Open Electrode Detect: If an open circuit is detected at the output of channel 1 or 2 the output current will be reset at zero. This is an option function and only active in Pulse Width between from 100uS and 300uS.
- Contraction Time: Adjustable, from 2-90 seconds, 1sec./step, (EMS only).
- Relaxation Time: Adjustable, from 2-90 seconds, 1sec./step, (EMS only).
- Ramp Time: Adjustable, from 1-8 seconds, 1sec./step, (EMS only).
- Patient compliance meter: The patient compliance timer can memorize 100 sets of therapy session records; the total record time is 400 hours; 240 minutes for a single therapy session.