Reliability of AcuGraph system for measuring skin conductance at acupoints

There are many commercially available instruments for measuring electrical conductance, but there is little information about their reliability. The aim of this study was to quantify measurement variability and assess reliability of the AcuGraph system-a commonly used electrodermal screening device.

Four experiments were conducted to measure variability in electrical conductance readings obtained by the AcuGraph system. The first involved measuring known resistors. The second measured non-human organic matter. The third was a test-retest assessment of the Yuan-Source and Jing-Well points in 30 healthy volunteers who were measured by a single operator. The fourth was an interoperator reliability evaluation of seven acupuncturists at the Yuan-Source and Jing-Well acupoints on four individuals at two time points.

Against known resistors, the AcuGraph had an average coefficient of variability (CV) of 1.8% between operators and test-retests. On non-human organic material the AcuGraph had an average CV of 0.9% and 2.8%. When a single operator tested 30 participants, the average reliability for the Yuan-Source points was 0.86 and 0.76 for Jing-Well points with a CV of 23.2% and 25.9% respectively. The average CV for the seven acupuncturists was 24.5% on Yuan-Source points and 23.7% on Jing-Well points.

The AcuGraph measures known resistors and organic matter accurately and reliably. Skin conductance at acupoints recorded by one operator was also reliable. There was less consistency in electrodermal recordings obtained by seven different operators. Operator training and technical improvements to the AcuGraph may improve consistency among operators.