The Antalgic Effect of Pulse Frequency and Pad Size of TENS on Blunt Pressure Pain

Study Overview
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Brief Summary
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The purpose of this study is to determine the antalgic of surface electrical stimulation with pulse frequencies and pad sizes on blunting pressure pain on healthy human due to various temporal and spatial summations of the stimulation.

Detailed Description
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Potential participants expressing interest in the study will be given to read the contraindications for the pain tests and the stimulation intervention, which has been documented on the consent form. All participants meeting entry requirements will be invited to participate in the experiments which take place on a separate occasion. Each participant will sign the consent form and will be told again that they can withdraw from the study at any time and without explanation. Each participant will be required to experience a 10-minute pre-stimulation period, a 30 minute TENS intervention, a 30 minute follow-up period. Participants will be seated on a chair with arm support provided by a side table. The investigator will be then informed the stimulation intervention and used pad size on the stimulation periods in written form contained in a sealed envelope. After the participant's verbal permission is obtained, the investigator will apply the pads on the dorsal forearm area. Either the large size pad, 5cm x 10cm, or the small size,2.5cm x 2.5cm, will be choose to place on the dorsal side of the forearm to straddle the site for blunt pressure pain. The muscle bellies of the forearm are mainly located on the proximal half part. The proximal pad will be attached to the lateral epi-condyle of the elbow, and the distal electrode will be placed 3cm distal to the proximal one along the line between the lateral part of elbow and the mid-point of the wrist. The pads will be then connected to the intervention stimulator. The investigator will relay instructions to the participants using cue cards displayed 30 seconds before any required action. Before each blunting pressure pain test, the participant will sit comfortably and place their right upper extremity on a side table with the shoulder abduction, elbow flexion, the forearm pronation. The test will be induced using a pressure algometer with a flat circular probe, measuring 1.1cm in diameter (1cm2 on skin surface). Force will be displayed digitally in increments of 0.1 Newton. The algometer will be applied to the mid-point between the intervention pads. The rate of the pressure algometer application will be around 6 Newtons per second on average. The participants will be asked to concentrate on the sensations in the forearm. When the pressure becomes definitely painful, the participant will state Pain! and the force will be stopped. The pain threshold will be taken twice in a minute for one test and each measurement will take no more than 30 seconds. There will be seven 1-minute tests performed in this experiment. The first test in pre-stimulation period. The second and third tests were administered and started at 9, 19, 29 minute time points in the stimulation-on period. A 30 minute post stimulation period will be then followed. Another 3 tests will be performed in this period in ten-minute intervals at 39, 49, 59 minute time points after the stimulation start.

Official Title
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The Effect of Pulse Frequency and Pad Size of Transcutaneous Electrical Nerve Stimulation (TENS) on Experimental Blunt Pressure Pain in Healthy Participants

Conditions
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Transcutaneous Electrical Nerve Stimulation, Blunt Pressure Pain, Pad Size, Pulse Frequency, Analgesia

Intervention / Treatment
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* Device: Control TENS
* Device: Sham TENS
* Device: High frequency TENS with large pads
* Device: Low frequency TENS with large pads
* Device: High frequency TENS with small pads
* Device: Low frequency TENS with small pads


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Healthy and aged 18 years or over Exclusion Criteria: Any open wound around the arm or hand area, including edema or inflammation; Cardiac or vascular problems (such as coronary artery disease, coronary thrombosis, or angina pain, high blood pressures, phlebitis, and pacemaker implantation); Any dermatological problems or infections around the hand, forearm, or arm area (such as dermatitis or eczema, bacterial or fungal infections); Any history of neoplasm or malignancy; Bleeding diseases on the arm or hand (such as haemorrhage); Menstruation or pregnancy; Abnormal neurological signs in the upper limbs (such as altered skin sensations); Hypersensitivity or phobia to electrical application; Any current medication regime.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 26 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Interventional Model Description: One hundred eighty participants (equal number of females and males, Fig. 1) were randomly assigned into six groups with the following TENS characteristics. (1) Group 1: control group, (2) group 2: sham group, (3) group 3: high frequency (80 pps)/large pad (5 cm x 10 cm) group, (4) group 4: low frequency (3 pps)/large pad (5 cm x 10 cm) group, (5) group 5: high frequency (80 pps)/small pad (5 cm x 2.5 cm) group, and (6) group 6: low frequency (3 pps)/small pad (5 cm x 2.5 cm) group.
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: High frequency TENS with large pads<br>TENS=transcutaneous electrical nerve stimulation High frequency TENS was a 80 Hz TENS delivered via a pair of electrodes with the size of 5 cm x 10 cm Dosage: same as electrical density using a standardized pad size (5cm x 5cm) with comfortable intensity | Device: High frequency TENS with large pads<br>* High frequency TENS was delivered on large electrodes<br>|
| Experimental: Low frequency TENS with large pads<br>TENS=transcutaneous electrical nerve stimulation Low frequency TENS was a 3 Hz TENS delivered via a pair of electrodes with the size of 5 cm x 10 cm Dosage: same as electrical density using a standardized pad size (5cm x 5cm) with comfortable intensity | Device: Low frequency TENS with large pads<br>* Low frequency TENS was delivered on large electrodes<br>|
| Experimental: High frequency TENS with small pads<br>TENS=transcutaneous electrical nerve stimulation High frequency TENS was a 80 Hz TENS delivered via a pair of electrodes with the size of 5 cm x 2.5 cm Dosage: same as electrical density using a standardized pad size (5cm x 5cm) with comfortable intensity | Device: High frequency TENS with small pads<br>* High frequency TENS was delivered on small electrodes<br>|
| Experimental: Low frequency TENS with small pads<br>TENS=transcutaneous electrical nerve stimulation Low frequency TENS was a 3 Hz TENS delivered via a pair of electrodes with the size of 5 cm x 2.5 cm Dosage: same as electrical density using a standardized pad size (5cm x 5cm) with comfortable intensity | Device: Low frequency TENS with small pads<br>* Low frequency TENS was delivered on small electrodes<br>|
| Placebo Comparator: Control TENS<br>TENS=transcutaneous electrical nerve stimulation Control TENS was the application of electrical stimulation via skin with no current | Device: Control TENS<br>* Control TENS was the application of electrical stimulation via skin with no current<br>|
| Sham Comparator: Sham TENS<br>TENS=transcutaneous electrical nerve stimulation Sham TENS was the application of electrical stimulation via skin with no current on the participant, who was told that the TENS was turn-on whether you feel it or not | Device: Sham TENS<br>* Sham TENS was the application of electrical stimulation via skin with no current on the participant, who was told TENS is at a turn-on level whether or not you feel it<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| blunting pressure pain threshold | The test will be induced using a pressure algometer with a flat circular probe, measuring 1.1cm in diameter (1cm2 on skin surface). Force will be displayed digitally in increments of 0.1 Newton. The algometer will be applied to the mid-point between the electrodes. The rate of the pressure algometer application will be around 6 Newtons per second on average. The participants will be asked to concentrate on the sensations in the forearm. When the pressure becomes definitely painful, the participant will state Pain! to stop the pressure force. | 6 months | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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transcutaneous electrical nerve stimulation, pad size, pulse frequency, blunt pressure pain, healthy humans.