How PainTrace™ Works

The PainTrace™ device works much like biofeedback devices in order to measure skin potential (SP), the natural electric charge of the skin. Our unit emits no electricity, not even a volt. It measures passively, as in an electrocardiogram. A stick-on disposable electrode similar to that used for an ECG is placed appropriately on the animal being tested. On humans, the leads are placed in the center of each palm. Lead wires are snapped onto the electrodes and these lead wires are themselves connected across a resistor box. Thousands of measurements have shown that the voltage on the left and right sides of the body on the vast majority of animals is never identical except while unconscious (sleep or general anesthesia). The normal inequality means that the skin on one side has higher voltage than the other. The readout displays this difference.

Readings on an unconscious subject will produce a flat line trace right down the middle of the recorder’s graph. A healthy subject without pain will normally produce a trace that makes a line above the midline, if the graph is turned so that the arrow of time runs to the right as on normal graphs. When a painful injury occurs, the adrenaline-producing sympathetic nervous system (SNS), the excitable part of the autonomic nervous system (ANS), increases its activity and the subject’s trace will rise further above the neutral baseline. If the pain is above 3 on the 1-10 scale, this begins to raise pulse and blood pressure and the baroreceptors are activated. These are pressure sensors in two key arteries that act much like traffic cops for blood pressure. Once triggered, the baroreceptors activate the parasympathetic nervous system (PNS) which is the relaxing part of the ANS. It works to lower blood pressure and pulse to restore normality. PNS and SNS work every moment of every day to keep our cardiac activity on a more or less even keel.

It is well established by researchers that pain lasting more than 20-30 minutes activates an increase in PNS through the vagal nerves. This activity actually triggers the release of natural opiates or endorphins in our bodies and partially counters the pain. It is a natural pain-relieving process. This is done primarily through the right cardiac vagal nerve. In addition to slowing the heart it slows the physiology of other tissue through which it passes, and this lowered physiological activity lowers skin potential (SP) as well, primarily on the right side. When the electric charge of the skin on the right side drops, the PainTrace™ reading runs below the neutral baseline. This is the signal that the subject is in pain. After successful treatment of that pain, the subject’s trace will rise.