Impact of surgical intervention and postoperative pain on electrical skin resistance at acupuncture points: an exploratory study.

OBJECTIVES: One theory about acupuncture suggests that pathological processes can cause measurable changes in electrical skin resistance (ESR) at acupuncture points (APs). Although the theory has yet to be proven, ESR measurements (ESRMs) form a frequently used part of contemporary acupuncture. The aim of this study was to test the so-called 'electrical responsiveness' of APs in the setting of a defined operative trauma. METHODS: ESRMs (n=424) were performed at the APs and surrounding skin of GB34 and ST38 in 163 participants using an impedance meter array developed for the purpose of ESRMs. For each group the percentage of measurements with a significantly different ESR between the APs and the surrounding skin was calculated and compared with each other. Measurements of four groups were compared: healthy control subjects (n=30) and patients after ophthalmic (n=29), hip (n=42) and shoulder (n=30) surgery. The influence of postoperative pain intensity was also assessed. RESULTS: Group comparison showed no significant differences for ST38. The ESRMs at GB34 had a significantly higher percentage of measurements with an increased ESR after ophthalmic (23.2%) and hip (22.2%) surgery, but not after shoulder surgery (7.5%). Subgroup analysis showed that an increase in pain intensity tended to lead to a decrease in the number of APs with ESR changes. CONCLUSION: These results suggest that reactive changes in ESR at APs might exist. Pain and alertness seem to have an impact on ESR at APs. However, the current data do not allow for conclusions to be drawn concerning the clinical use of ESRMs.

Characteristics of electrical skin resistance at acupuncture points in healthy humans.

OBJECTIVES: The aim of this study was to evaluate the phenomenon of electrical skin resistance (ESR) changes at different acupuncture points (APs). SETTING: This single-blinded study was performed at the hospital of the University of Munich. DESIGN: Six common APs were measured (TE5, PC6, LU6, ST36, SP6, GB39) in 53 subjects. Subgroups were formed with varying time intervals for follow-ups (1 minute, 1 hour, 1 week) and a varying grade of reduction of the stratum corneum. METHODS: Electrical skin resistance measurements (ESRMs) were taken from a skin area of 6 x 6 cm using an array consisting of 64 (8 x 8) electrodes. The electrodes corresponding to the AP were located and the ESRM results were compared to those of the surrounding electrodes. The methodological setting made it possible to minimize major influence factors on electrical skin impedance measurements. RESULTS: A total of 631 ESRMs was evaluated: In 62.8% of the measured APs, no significant ESR difference was found. In 234 (37.2%) of the ESRMs, the ESR at the AP was significantly different from the surrounding skin area, with 163 (25.9%) points showing a lower and 71 (11.3%) points showing a higher ESR. Reproducibility was extremely high after 1 minute but was low after 1 hour and 1 week. CONCLUSIONS: This study shows that electrical skin resistance at APs can either be lower or higher compared to the surrounding area. The phenomenon is characterized by high short-term and low long-term reproducibility. Therefore, we conclude that APs might possess specific transient electrical properties. However, as the majority of the measured APs did not show a changed ESR, it cannot be concluded from our data that electrical skin resistance measurements can be used for acupuncture point localization or diagnostic/therapeutic purposes.

Changes in electrical skin resistance at gallbladder 34 (GB34).

OBJECTIVE: Electrodermal screening is widely used in the acupuncture community for point location, diagnosis and therapy. However the underlying theory that electrical skin resistance (ESR) of an area corresponding to an acupuncture point (AP) is lower than ESR of the surrounding areas is yet to be proven. The objective of this study was to evaluate and quantify the phenomenon of ESR changes at the Gallbladder 34 (GB34) Acupuncture Point (AP). MATERIALS AND METHODS: In this single-blinded study GB34 was measured bilaterally in 43 healthy volunteers. Electrical skin resistance measurements (ESRMs) were performed with a specially designed array consisting of 64 (8 x 8) electrodes on an area of 6 x 6 cm. Then the electrodes corresponding to the AP were identified and compared with those of the surrounding electrodes with Wilcoxon rank sum test. Values for p of less than 0.05 were considered statistically significant. RESULTS: Eighty-one ESRMs were evaluated. ESR was significantly different from the surrounding skin area in 27 (33.3%) cases with 15 (18.5%) points showing a lower and 12 (14.1%) points showing a higher ESR. CONCLUSION: This shows that ESR changes at APs exist in one third of the measured points, a very low rate for a postulation that forms the basis of various diagnosis and therapy systems.

[A new sensor technique for measurements of electrical potential profiles of human skin at acupuncture points]. / Eine neue Sensortechnik zur Messung von elektrischen Potentialprofilen der menschlichen Haut an Akupunkturpunkten.

UNLABELLED: From an electro-physiological point of view human skin shows an inhomogeneous pattern regarding its electrical resistance: in certain areas a decreased electrical resistance can be observed. It has been postulated that these areas correspond to acupuncture points. Subsequently, devices have been developed as detectors for acupuncture points which are used for diagnosis and treatment in acupuncture. However, most of these devices are inconsistent: they show a remarkable inaccuracy in their measurements and are poorly evaluated. Further analyses have shown that the measuring pens often used are subject to various disturbances such as pressure, angle of measurement, humidity of the skin, different thickness of stratum corneum of the skin and external disturbances such as temperature and humidity in the measuring room. MATERIAL AND METHODS: We present a new device for standardized measuring of electrical skin resistance. It consists of a field of 64 electrodes (measuring array) on a surface of 60 x 60 mm(2) and a distance of 8 mm between electrodes. For a more precise spatial resolution a field of 32 electrodes on a surface of 3.5 x 3.5 mm(2) with a distance of 0.65 mm is available. A high, precise, temporal resolution of electric potentials in human skin is realized by fast scanning of the electrodes. Technical details are described. CONCLUSIONS: First analyses of collected data show that reliable and valid measurements are possible. Using this device in a controlled and blinded study design will help elucidate the issue of altered skin resistance at acupuncture points and clarify if this phenomenon is unique at acupuncture points.