Skin bioimpedance (SBI) measurements at acupuncture points (APs), although widely used by acupuncturists, have yet to be formally tested for within and between subject variability and reproducibility over time. Work of early researching acupuncturists in the 1970s and 1980s suggest a potential for developing these measurements into clinically useful biomarkers. The process of doing so, however, involves several preliminary steps including: determining the accuracy of the test instrument, documenting inter-observer variability, assessing within and between subject variability in healthy individuals, and determining sensitivity and specificity of the measurements for specific disease states.
A study evaluating within and between subject variability took place at the General Clinical Research Center (GCRC) at Oregon Health & Science University (OHSU). Skin bioimpedance at the 24 jing well APs on twenty-four participants was measured every 20 minutes over a 24-hour period. SBI measurements were correlated with salivary cortisol and heart rate variability. In addition to documenting physiological variability we also describe any inherent rhythmic patterns in these SBI measurements.