Transcutaneous electrical nerve stimulation (TENS) is a therapy that uses low-voltage electrical current for pain relief. You do TENS with a small, battery-powered machine about the size of a pocket radio. Usually, you connect two electrodes (wires that conduct electrical current) from the machine to your skin.
1. This picture appears to be showing the performance of CPR. There are two people positioned over the head and side of the person on the ground. This may be one person performing compressions and the other performing artificial ventilation.