Reliability of the Prognos Electrodermal Device for Measurements of Electrical Skin Resistance at Acupuncture Points

Connecting the dots: alterations in bioelectric activity at acupuncture Ting (Jing-Well) points following CV4 cranial manipulation

CONTEXT

The mechanisms by which osteopathic cranial manipulative medicine (OCMM) promotes health and healing have yet to be fully elucidated. One commonly utilized OCMM technique, compression of the fourth ventricle (CV4), has been theorized to balance autonomic nervous system (ANS) activity. There is growing evidence that the ANS also plays a significant mechanistic role in acupuncture. Potential connections between OCMM and acupuncture meridian theory largely remain unknown.

OBJECTIVES

By measuring specific electrical parameters at acupuncture points that have been shown to correlate with ANS activity, the objectives of this study were to: 1) determine if CV4 has any influence on the bioelectric properties of the acupuncture meridian system; and 2) determine if CV4 affects the ANS.

METHODS

A total of 77 males and females ages 18-78 years, all volunteers recruited by local flyers and personal or phone contact, were randomized into CV4 (n=40) and Sham (n=37) groups. All CV4 participants were treated by the same physician utilizing standard CV4 protocol. The Sham treatment, performed by a different physician, consisted of the supine participant's occiput resting passively on the physician's finger pads for a similar duration as those in the CV4 group. Among several devices developed to assess ANS activity at acupuncture points, evidence suggests that the Apparatus for Meridian Identification (AMI) is the most accurate and valid. Utilizing the AMI, bioelectric skin parameters were measured immediately before and after CV4 or Sham treatments. Student's or Welch's t tests and Wilcoxon tests were utilized for analysis of normally and non-normally distributed data, respectively.

RESULTS

Statistical significance was determined with a p value less than 0.05. Sham treatments showed insignificant (p=0.754) before vs. after differences in ANS activity measured at acupuncture points, whereas CV4 treatment significantly (p=0.00015) affected ANS activity.

CONCLUSIONS

This research suggests that CV4 has demonstrable biophysical effects on the acupuncture meridian system occurring via the ANS, and that the underlying mechanisms of OCMM and acupuncture may be related. Further studies are needed to clarify this.

Characterisation of Human Skin Impedance at Acupuncture Point Pc4 Ximen and pericardium meridian using the four-electrode method

Introduction

Traditional Chinese medicine offers several theories to explain the mechanism of acupuncture. One of these theories proposes that acupuncture points and meridians have unique electrical properties and their electrical skin impedance is lower than surrounding areas. The aim of this study was to evaluate the differences in electrical skin impedance between PC4 and the pericardium meridian compared with the surrounding areas.

Methods

Eighteen healthy subjects (10 women) were recruited to participate in the study. An impedance meter based on the four-electrode technique was designed specifically for the study. Twenty-five points were marked on the skin: one on the point PC4, four others on the pericardium meridian and 20 points around it. The electrical impedance of each point was measured with the four-electrode device.

Results

The mean electrical skin impedance at PC4 was significantly different from the 20 of the surrounding points but not significantly different from the four adjacent points. The mean skin impedance of the five points over the pericardium meridian was significantly different from that of parallel rows of points using repeated measures analysis of variance (p<0.001)

Conclusion

Within the possible limits of this measurement technique, skin impedance along the pericardium meridian is lower than surrounding areas, supporting the idea of different properties of the pericardium meridian compared with the control areas. Evidence on skin impedance at PC4 is inconclusive and further studies are needed.

Acute Physiological and Psychological Effects of Qigong Exercise in Older Practitioners

Qigong is a gentle exercise that promotes health and well-being. This study evaluated the acute physiological and psychological effects of one session of qigong exercise in older practitioners. A total of 45 participants (mean age, 65.14 years) were recruited. Meridian electrical conductance, State-Trait Anxiety Inventory (STAI), heart rate variability (HRV), and Short Form 36 (SF-36) were evaluated and compared before and after one session of qigong exercise. The results revealed that the electrical conductance of all meridians, except spleen and bladder meridians, increased significantly (p < 0.05). Compared with baseline values, upper to lower body ratio and sympathetic/vagal index were significantly improved and closer to 1 (p = 0.011 and p = 0.007, resp.). STAI-S and STAI-T scores decreased significantly (p < 0.001 and p = 0.001, resp.). The RR interval of HRV decreased significantly (p = 0.035), a significant positive correlation was observed between kidney meridian electrical conductance and SF-36 physical scores (r = 0.74, p = 0.018), and a positive correlation was observed between pericardium meridian electrical conductance and SF-36 mental scores (r = 0.50, p = 0.06). In conclusion, one session of qigong exercise increased meridian electrical conductance, reduced anxiety, and improved body and autonomic nervous system balance. These findings provide scientific evidence for acute physiological and psychological effects of qigong exercise in older practitioners.

Acupuncture Meridian Energies in Patients Who Are Mentally Disturbed

BACKGROUND AND OBJECTIVE

Acupuncture medicine states that different pathologies exhibit different patterns of excitation in the 24 main acupuncture meridians. Previous exploratory work has shown that groups of patients with the same pathology exhibit such characteristic patterns when limited numbers of acupuncture points are measured with the AcuGraph meridian energy measuring device. This study reports patterns of meridian energies observed in an exploratory assessment of different classes of patient with mental disturbance.

METHODS

This study was a three-group cross-sectional design. Participants were patients who had been diagnosed by their GP with anxiety (n = 21) and depression (n = 26) and who were entering a treatment program, along with age- and sex-matched controls (n = 44). Patients diagnosed with mild mental disturbance who were aged 20-50 years were eligible to take part. Patients with any cut, wart, or mole on their fingertips or with excess sweating, which would interfere with conductance measurements, were excluded. The assessment comprised conductance values at Jing-Well acupuncture points by AcuGraph4 on entry into the treatment program.

RESULTS

Patients with anxiety had higher meridian energy levels (81.84 ± 38.63) and significant Upper-Lower imbalances (p < 0.05) favoring the upper meridians. Patients with depression had lower energy levels and lower standard deviations (53.36 ± 33.48) as a group. Controls exhibited intermediate energy levels but recorded the lowest scoring variances (62.61 ± 27.05) of the three groups. Kidney meridians had the lowest energy for both of the pathology groups. For the group suffering with anxiety, bladder meridians were also low.

CONCLUSION

Higher variances in AcuGraph4 measurements were observed in patients with either anxiety or depression compared with controls whose variances were the lowest. These results are in accordance with previous observations of greater variance in conductance values in pathology groups. With regard to meridian energies, the lowest were in those with depression, while those with anxiety were the highest. Controls exhibited intermediate energy levels.

Electrodermal Screening of Asthmatics with AcuGraph 4

Traditional Chinese Medicine holds that acupuncture meridian activity is correlated with quality of function of specific organs. This study sets out to determine acupuncture meridian characteristics of subjects with moderate asthma distinguishing them from healthy subjects. Fifty asthma patients (age 35.36 ± 8.68 years) and fifty similarly aged (34.11 ± 7.29 years) healthy volunteers were enrolled in the study. Electrodermal conductances at Jing Well points were measured with Acugraph 4 and also Peak Expiratory Flow Rate (PEFR) for the asthma group. All mean meridian conductances were lower for the asthma group, significance differences were in Lung and right Bladder meridians. In contrast, all but two of the standard deviations of group meridian conductances for the Asthma group were higher than those for the Healthy group. Difference in mean PEFR values between Asthma and Healthy groups was significant. These suggest that group measures of electrical conductance at Jing Well points can distinguish asthma from healthy individuals. The study provides support for the usefulness of meridian energy measurements to assess organ related dysfunction and for the idea that pathology groups exhibit higher standard deviations i.e. lower quality of regulation.

Altered Impedance of Ear Acupuncture Point MT2 in Breast Cancer Patients: A Preliminary Observation

Skin impedance at acupuncture points (APs) has been used as a diagnostic aid for more than 50 years. In this study, we have a diagnostic tool (JXT-2008) to measure the skin impedance of ear APs of 30 breast cancer patients and the corresponding skin impedance of ear APs of 30 healthy humans, and then we compared these changes in ear AP impedance in breast cancer patients and healthy individuals.

The Study of Dynamic Characteristic of Acupoints Based on the Primary Dysmenorrhea Patients with the Tenderness Reflection on Diji (SP 8)

In TCM theory, acupoint is not a fixed point but a portal with dynamic characteristics where the channel qi enters and flows out. The dynamic characteristics have been verified primarily by detecting the tenderness reaction on Diji (SP 8) in primary dysmenorrhea patients. In this study, finger pressing and algometer were applied in Diji (SP 8) area of participants in menstrual period and nonmenstrual period, respectively, to detect the tenderness occurrence rate, the VAS score of the tenderest point, the tenderness threshold of the tenderest point, and the location of the tenderest point. The result suggests that the acupoint may not be a fixed location but a point in a dynamic state within a certain range in time and space varying with different physiological and pathological status.

Investigation of the electrical impedance of acupuncture points and non-acupuncture points before and after acupuncture, using a four-electrode device

AIM

To evaluate the effect of acupuncture on skin electrical impedance of selected points, before and after acupuncture on one acupuncture point (PC6), using a four-electrode device.

METHODS

Six acupuncture and non-acupuncture points on both sides of the body were selected to evaluate the effects of acupuncture on electrical properties of these points.

RESULTS

There were no results significant differences of electrical impedance before and after acupuncture in the selected points.

CONCLUSIONS

According to our experimental set-up, acupuncture at one point without stimulation does not alter skin electrical impedance in healthy volunteers and there is no difference between acupuncture points and non-acupuncture points.

Electrodermal Screening of Biologically Active Points for Upper Gastrointestinal Bleeding

The purpose of this case-control study was to investigate the relationship between the electrical resistance of the skin at biologically active points (BAPs) on the main meridians and upper gastrointestinal bleeding (UGIB). Electrical resistance to direct current at 20 BAPs on the fingers and toes of 100 patients with (38 men, 12 women; mean age [range], 58.20 ± 19.62 [18–83] years) and without (27 men, 23 women; 49.54 ± 12.12 [22–74] years) UGIB was measured through electrodermal screening (EDS), based on the theory of electroacupuncture according to Voll (EAV). Data were compared through analysis of variance (ANOVA), receiver operating characteristic (ROC) curve analysis, and logistic regression. The initial readings were lower in the UGIB group, indicating blood and energy deficiency due to UGIB. Significant differences in indicator drop values were observed at nine BAPs (p < 0.05) on the bilateral small intestine, bilateral stomach, bilateral circulation, bilateral fibroid degeneration, and right lymph meridians. The area under the ROC curve values of the BAPs on the bilateral small intestine and stomach meridians were larger than 0.5, suggesting the diagnostic accuracy of EDS for UGIB on the basis of the indicator drop of these BAPs. Logistic regression revealed that when the indicator drop of the BAP on the left stomach meridian increased by one score, the risk of UGIB increased by about 1.545–3.523 times. In conclusion, the change in the electrical resistance of the skin measured by EDS at the BAPs on the bilateral small intestine and stomach meridians provides specific information on UGIB.

Imaging-guided hyperstimulation analgesia in low back pain

Low back pain in patients with myofascial pain syndrome is characterized by painful active myofascial trigger points (ATPs) in muscles. This article reviews a novel, noninvasive modality that combines simultaneous imaging and treatment, thus taking advantage of the electrodermal information available from imaged ATPs to deliver localized neurostimulation, to stimulate peripheral nerve endings (Aδ fibers) and in turn, to release endogenous endorphins. "Hyperstimulation analgesia" with localized, intense, low-rate electrical pulses applied to painful ATPs was found to be effective in 95% patients with chronic nonspecific low back pain, in a clinical validation study.

Development and evaluation of a novel four-electrode device system for monitoring skin impedance

Qi, meridians, and acupoints are important issues in Chinese medicine. One of the theories claims that acupuncture points and meridians have unique electrical properties. The associations between acupuncture points or meridians and special electrical properties are still under debate. In the current study, we introduced and explained a device for this kind of research and evaluated the reliability of this device as well as effects of pressure, cleaning the skin by alcohol and exfoliation on electrical skin measurements. Fifteen subjects (10 female, 5 male) were recruited to participate in the study. An impedance meter based on the four-electrode technique was designed and fabricated specifically for this study. The effects of pressure, cleaning of the skin by alcohol, and exfoliation on electrical skin impedance were evaluated separately. The device repeatability was also evaluated 30 times in a 30 minutes period. Scale weight up to 200 grams, cleaning the skin with alcohol, and exfoliation didn't affect the performance of this device. The device performance didn't change significantly during the 30 minutes measurement either. The new system we evaluated can be a reliable tool for researches on electrical skin impedance in acupuncture, as its performance is fairly stable even in the presence of various confounding factors such as various pressures on the probe, cleaning the skin with alcohol and exfoliation.

Reliability of AcuGraph system for measuring skin conductance at acupoints

OBJECTIVE

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

A multichannel system for continuous measurements of skin resistance and capacitance at acupuncture points

Electrodermal screening (EDS) is based on three commonly held assumptions: acupuncture points (APs) have lower electrical resistance than non-APs; resistance at APs varies with health and disease; and effective acupuncture treatments are associated with normalization of resistance at APs. Although evidence confirming these assumptions is limited, EDS is frequently practiced worldwide. Researchers are also beginning to assess EDS' utility as an outcome measure in acupuncture trials. Fundamental in developing EDS as a research tool is the need for an accurate and reliable measurement. We developed an automated multichannel prototype system, the Octopus, and recorded electrical resistance and capacitance at eight skin sites in 33 healthy participants over 2 hours. The Octopus accurately measured against known resistors (within 2.5% of the mean value) and capacitors (within 10% of the mean value), and yielded repeatable readings at all eight skin sites: LR 1 (r=0.79), SP 1 (r=0.79), toe non-AP (r=0.77), LU 9 (r=0.97), PC 6 (r=0.96), wrist non-APs (r=0.97), SP 6 (r=0.96), and leg non-APs (r=0.97). Resistance at APs was significantly lower than the nearby non-APs in one out of three comparisons.

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.

Measurement reliability for acupoint activity determined with the prognos ohmmeter

The concepts of meridians and acupoints are critical to traditional Chinese medicine but are met with skepticism in Western medicine. Empirical validation of these concepts is in its beginning stages and still hampered by problems with measurement. A promising avenue and foundation for validity testing is the demonstration that acupoint activity can be reliably measured via determination of electrical resistance at well-defined body surface points. In this article, efforts are described to maximize measurement reliability; we tested a variety of protocols to determine which method of data aggregation is associated with maximal reliability. Twenty-one healthy individuals were subjected to 5 repeated measurement cycles to test the predicted increase in reliability with increasing number of aggregated measurements. Reliability, defined as internal consistency, was indeed highest for 5 measurements (mean alpha = .88). Even the aggregate of only three measures was quite reliable (alpha = .84). Reliability for measuring acupoints on the left side of the body was roughly .05 higher than on the right side. Consistent with previous literature, we conclude that with repeated measures the reliability of electrical resistance measurements at acupoints is high and that a strong foundation for validation research is now laid.

Attitudes and interests toward research among students at two colleges of acupuncture and Oriental medicine

BACKGROUND

Collaborative input from clinicians of acupuncture and Oriental medicine (AOM) is required for sound AOM research, and AOM training institutions have begun to include research education into their curriculum. However, few attempts have been made to systematically evaluate AOM practitioners' perspectives on the value of research to their profession.

METHODS

We conducted surveys of AOM students at two institutions that have begun to integrate research training into their curriculum, the New England School of Acupuncture and the Oregon College of Oriental Medicine. Surveys were conducted to assess current attitudes regarding the value of research and to serve as a reference point for documenting the impact of ongoing research training programs on these attitudes. Surveys at both institutions were independently developed and administered but shared seven questions that were phrased very similarly. This paper summarizes responses to these questions.

RESULTS

Surveys at both institutions suggest interest in research among AOM students is high in first-year students; students in later years showed a lower level of interest, but the cross-sectional design of this survey does not allow any temporal effects to be inferred. Results also indicate that AOM students believe research is highly relevant to how both the public and the health insurance industry view their system of healthcare but not highly relevant to their own clinical practice of AOM. The belief that research is of limited relevance to clinical practice was associated with widespread belief that scientific methods may not be consistent with the principles of AOM.

CONCLUSIONS

Results of these surveys provide important preliminary information about attitudes of AOM students toward research, and thus the value and future specific needs of research training programs targeting this population. Repeated implementation of validated versions of our surveys are needed to confirm the trends we report and to evaluate the impact of research training programs already in place on AOM students' attitudes toward research.

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.

Evaluation of Applied Kinesiology meridian techniques by means of surface electromyography (sEMG): demonstration of the regulatory influence of antique acupuncture points

Background

The use of Applied Kinesiology techniques based on manual muscle tests relies on the relationship between muscles and acupuncture meridians. Applied Kinesiology detects body dysfunctions based on changes in muscle tone. Muscle tonification or inhibition within the test setting can be achieved with selected acupoints. These acupoints belong to either the same meridian or related meridians. The aim of this study is to analyze muscle sedation and tonification by means of surface electromyography.

Methods

Manual muscle tests were carried out using standard Applied Kinesiology (AK) techniques. The investigation included basic AK procedures such as sedation and tonification with specific acupoints. The sedation and tonification acupoints were selected from related meridians according to the Five Elements. The tonification effect of these acupoints was also tested while interfering effects were induced by manual stimulation of scars. The effects of selective neural therapy, i.e. individually tested and selected anesthetic agent, for the treatment of scars were also studied. The characteristics of muscle action were documented by surface electromyographys (sEMG).

Results

The sEMG data showed a diminution of signal intensity when sedation was used. Graded sedation resulted in a graded diminution of signal amplitude. Graded increase in signal amplitude was observed when antique acupuncture points were used for tonification. The tactile stretch stimulus of scars localized in meridian-independent places produced diminution of signal intensity on a reference muscle, similar to sedation. These changes, however, were not corrected by tonification acupoints. Correction of these interferences was achieved by lesion specific neural therapy with local anesthetics.

Conclusion

We demonstrated the central working principles, i.e. sedation and tonification, of Applied Kinesiology through the use of specific acupoints that have an influence on manual muscle tests. Sedation decreases RMS signal in sEMG, whereas tonification increases it. Interfering stimuli from scars were corrected by selective neural therapy.

Electrical characterization of acupuncture points: technical issues and challenges

Acupuncture points are frequently described as having distinct electrical properties. These properties include increased conductance, reduced impedance and resistance, increased capacitance, and elevated electrical potential compared to adjacent nonacupuncture points. Commercial electrodiagnostic devices have used this assertion as a means to localize and analyze acupuncture points for diagnostic purposes. Yet, the electrical characterization of acupuncture points is associated with important technical issues that are often overlooked. Electrode polarizability, stratum corneum impedance, presence of sweat glands, choice of contact medium, electrode geometry, and other factors contribute to the final electrodermal reading and may cause doubts about the validity of available electrodiagnostic devices. The goal of this review is to help researchers and clinicians understand these factors affecting electrodermal readings, to make apparent the difficulties and challenges confronting electrodermal readings, and to increase understanding about how these possible associations can be interpreted and understood from the perspective of biology.

Electrical skin impedance at acupuncture points

OBJECTIVES

To test whether electrical skin impedance at each of three acupuncture points (APs) is significantly lower than at nearby sites on the meridian (MP) and off the meridian (NP).

DESIGN

Two instruments - Prognos (MedPrevent GmbH, Waldershof, Germany), a constant-current (DC) device, and PT Probe (designed for this study), a 100-Hz sinusoidal-current (AC) device-were used to record electrical impedance at three APs (right Gallbladder 14, right Pericardium 8, and left Triple Energizer 1), and two control sites for each AP. Each AP, MP, and NP was measured four times in random order with each device.

SETTING

The study was conducted over a period of 4 days at the Oregon College of Oriental Medicine (OCOM).

SUBJECTS

Twenty (20) healthy adults (14 women and 6 men), all recruited from the OCOM student body and faculty, participated in the study.

RESULTS

The Prognos measurements had an intraclass correlation (ICC) = 0.84 and coefficient of variation (CV) = 0.43. The PT Probe had ICC = 0.81 and CV = 0.31. Impedance values at APs were not significantly less than at MPs or NPs. Impedance values at MPs were also not significantly less than NPs, although their individual p values were <0.05 in 4 of 6 cases. There was a significant trend of increasing impedance with repeated measurements with both the Prognos (p =0.003) and the PT Probe (p= 0.003).

CONCLUSIONS

Within the reliability limits of our study methods, none of the three APs tested has lower skin impedance than at either of the nearby control points. These results are not consistent with previous studies that detected lower skin impedance at APs than nearby sites. Further study is necessary to determine whether MPs have lower skin impedance than nearby NPs. Our study suggests caution is warranted when developing, using, and interpreting results from electrodermal screening devices. Further studies are needed to clarify the clinically important and controversial hypothesis that APs are sites of lower impedance.

Skin impedance measurements for acupuncture research: development of a continuous recording system

Skin impedance at acupuncture points (APs) has been used as a diagnostic/therapeutic aid for more than 50 years. Currently, researchers are evaluating the electrophysiologic properties of APs as a possible means of understanding acupuncture's mechanism. To comprehensively assess the diagnostic, therapeutic and mechanistic implications of acupuncture point skin impedance, a device capable of reliably recording impedances from 100 kΩ to 50 MΩ at multiple APs over extended time periods is needed. This article describes design considerations, development and testing of a single channel skin impedance system (hardware, control software and customized electrodes). The system was tested for accuracy against known resistors and capacitors. Two electrodes (the AMI and the ORI) were compared for reliability of recording over 30 min. Two APs (LU 9 and PC 6) and a nearby non-AP site were measured simultaneously in four individuals for 60 min. Our measurement system performed accurately (within 5%) against known resistors (580 kΩ–10 MΩ) and capacitors (10 nF–150 nF). Both the AMI electrode and the modified ORI electrode recorded skin impedance reliably on the volar surface of the forearm (r = 0.87 and r = 0.79, respectively). In four of four volunteers tested, skin impedance at LU 9 was less than at the nearby non-AP site. In three of four volunteers skin impedance was less at PC 6 than at the nearby non-AP site. We conclude that our system is a suitable device upon which we can develop a fully automated multi-channel device capable of recording skin impedance at multiple APs simultaneously over 24 h.

Prognos®in the Diagnosis of Amalgam Hypersensitivity – a Diagnostic Case-Control Study

OBJECTIVE

We aimed to investigate whether the Prognos device might be a useful tool in the diagnosis of disorders suspected to be due to dental amalgam fillings.

PARTICIPANTS AND METHODS

A diagnostic case-control study was performed in 27 patients who complained about health problems attributed to amalgam (cases), 27 healthy volunteers with amalgam fillings (controls I), and 27 healthy amalgamfree volunteers (controls II). All participants were tested before and after application of 300 mg DMPS (2.3-dimercapto- 1-propanesulfonic acid) with Prognos, a diagnostic device for the energetic measurement of Traditional Chinese Medicine meridians. In addition, mercury was measured in blood, urine, and saliva, and a lymphocyte transformation test (LTT) was performed.

RESULTS

Diagnoses derived from the first and second Prognos testing did not agree above chance (Cohen's Kappa = -0.11, 95% confidence interval -0.33 to 0.10; p = 0.30). Agreement for secondary outcome measures was poor, too. Prognos measurements did not differ between cases and controls. Correlations with measurements in urine, blood and saliva were low.

CONCLUSION

In this study Prognos could not be shown to be a useful tool in the diagnosis of disorders suspected to be due to dental amalgam fillings.

[A new sensor technique for measurements of electrical potential profiles of human skin at acupuncture points]

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.