Please make sure that you are well aware of the precautions and contraindications while doing any form of electrical stimulation. These are as under:

1- TENS or NMES (Neuromuscular electrical stimulation) over the thoracic region because current may interfere with the function of vital organs including heart.

2- TENS or NMES in the thoracic region of the patients with demand type of cardiac pace makers because the current may interfere with pace maker activity and may lead to asystole or ventricular fibrillation.

3- TENS or NMES in the region of phrenic nerve or urinary bladder stimulator because current may interfere with the normal operation of these devices.

4- TENS or NMES over the carotid sinus because current may interfere with the normal regulation of the blood pressure and cardiac contractility and may produce cardiac arrhythmia or bradycardia.

5- TENS or NMES in hypertensive or hypotensive patients because autonomic responses may adversely affect control of blood pressure.

6- TENS or NMES in the area of peripheral vascular disorders such as venous thrombosis or thrombophilibitis because of the risk of releasing emboli.

7- TENS or NMES in the region of neoplasm or infections because muscular and circulatory effects may aggravates these conditions.

8- TENS or NMES on the trunk of pregnant females because of the risk of inducing uterine contractions which may influence the developing fetus.

9- TENS or NMES in close proximity to diathermy devices because of the potential for loss of control of stimulation parameters.

10- TENS or NMES in areas of excessive adipose tissue as in obese patients because level of stimulation required activating muscle in such patients may produce adverse autonomic reactions.

11- TENS or NMES in patients who are unable to provide clear feedback regarding the level of stimulation such as infants, senile subjects, or individuals with mental disorders.

Please also have a look over this article

Transcutaneous electrical nerve stimulation (TENS)

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