Physiologic Responses to Acupuncture Point Stimulation A Pilot Study to Evaluate Methods an

Physiologic Responses to Acupuncture Point Stimulation:A Pilot Study to Evaluate Methods andInstrumentationD.Tsunami1,A.Colbert2,3,Z.Lu2,S.Pearson1,J.McNames1,R.Hammerschlag21Biomedical Signal Processing Laboratory,Electrical and Computer Engineering,Portland State University,Portland OR,USA2Oregon College of Oriental Medicine,Portland OR,USA3Kaiser-Permanente Center for Health ResearchAbstract—The physiological responses to needle stimulation of an acupuncture point and a nearby control point were compared in six healthy participants.The electrocardiogram(ECG),respi-ration,and electrodermal response(EDR)were measured along with the times of needle insertion,interim needle stimulation and needle removal.In addition to the aforementioned,any relevant events such as movement of the subject,unexpected noise,etc were annotated.Keywords—Acupuncture stimulation,physiologic response to acupuncture,electrodermal response,electrocardiogramI.I NTRODUCTIONR ESEARCH on the mechanism(s)of acupuncture has generated recent interest in characterizing physiological responses to individual acupuncture point(AP)stimulation. Studies focusing on acupuncture’s regulatory effects on the autonomic nervous system have demonstrated changes in heart rate variability,heart rate,arterial blood pressure,skin temper-ature and electrodermal responses(EDR)[1]–[12].The results of these individual studies,in which commonly used APs such as LI4,ST36,and MH6were stimulated,are varied and sometimes contradictory.Backer et al.[11]found a long-term lowering of blood pressure when LI4was stimulated while Lin et al.[4]observed only a temporary decrease in blood pressure with a return to baseline within3minutes.Young and McCarthy[6]determined that activation of an auricular AP decreased a stimulus-induced EDR while Wang and Cain [13]demonstrated a decrease in anxiety level but no significant change in EDR as a result of stimulating auricular APs.One group of researchers assessing acupuncture’s effect on heart rate variability(HRV)discovered a significant increase in the high frequency(HF)components with no change in the low frequency(LF)components on power spectrum analysis[9], while others[7],[14],[15]found either a trend toward or a significant increase in HF and decrease in LF components. Since the changes induced by acupuncture are usually small it is thought that HRV is especially suitable to detecting potentially subtle effects on autonomic nervous function. Our long term research goal is to determine if needle stimulation of specific APs can elicit measurable,repeatable short-term physiologic responses under rigorously controlled conditions.To this end we have developed a data acquisition This study was funded by the National Center for Complementary and Alternative Medicine/National Institutes of Health(AT00076)through the Oregon Center for Complementary and Alternative Medicine system that will simultaneously record ECG,EDR,respiration and skin temperature and allow for annotation of extraneous, possibly confounding events that might occur during the measurements.The purpose of this pilot study was to validate the methods to be used and to test the custom designed instrumentation on six healthy subjects in preparation for a future study involving150subjects.II.M ETHODOLOGYA.Experimental ProtocolSix healthy volunteers(3males and3females,aged21-63years)underwent two sequential measurement sessions lasting a total of2hours.Monitoring leads were attached to the subject20minutes prior to the onset of baseline recording.The ECG electrodes were configured in a three lead driven right leg topology.The electrodes used for the ECG and EDR were standard Ag/AgCl gel ECG electrodes. The EDR electrodes were placed on the palm and dorsum of the right hand.A respiratory impedance band was placed on the upper chest and a thermistor in the left axilla.An AP (left ST36located3cun below the lower border of patella, 1cun lateral to the anterior ridge of tibia)or a control point (located1.5cm lateral and inferior to ST36)was randomly selected for initial stimulation with a0.25mm stainless steel single use disposable acupuncture needle.The subjects were unaware of whether the point being stimulated during each session was the AP or the control and were out of the line of sight of the monitors recording the physiological signals. When the needle was inserted at either the real AP or the control point the deqi sensation(experienced as a dull ache, distended feeling,heaviness or tingling)was intentionally elicited.The exact measurement protocol followed is described in Table I.Any observable events that might be expected to impact the subject’s physiological state,such as environmental disturbances or movements on the part of the subject were annotated.B.InstrumentationThe instrumentation for recording the physiologic signals was custom developed for this study.A high level diagram of the EDR measurement instrumentation is shown in Fig.1.A frequency of100Hz was selected for the skin impedance measurements.The ECG circuit is shown in Fig2and isProceedings of the 26th Annual International Conference of the IEEE EMBS San Francisco, CA, USA • September 1-5, 2004TABLE IT HE SCHEDULE FOR DATA RECORDING BELOW USES THE FOLLOWINGABBREVIATIONS:ACUPUNCTURE POINT(AP),TREATING ACUPUNCTURIST (TA),STUDY COORDINATOR(SC),AND HEALTHY PARTICIPANT(HP).(hrs)(min)Phase1Prep8:00AM0.210.0Instrument HP8:10AM0.2 1.0Begin recordingPhase2Point18:11AM0.410.0HP rests8:21AM0.510.0Record baseline8:31AM0.6 2.0TA locates AP,inserts needle&stimulates for deqi8:33AM0.710.0Record response8:43AM0.70.5TA manipulates needlefor deqi8:43AM0.910.0Record response8:53AM0.90.5TA removes needle8:54AM0.910.0Record responsePhase3Point29:04AM 1.210.0HP rests9:14AM 1.410.0Record baseline9:24AM 1.4 2.0TA locates AP,inserts needle&stimulates for deqi9:26AM 1.610.0Record response9:36AM 1.60.5TA manipulates needlefor deqi9:36AM 1.810.0Record response9:46AM 1.80.5TA removes needle9:47AM 2.010.0Record response9:57AM 2.2 5.0SC interviews HPa standard driven right leg topology[16].The respiration was measured using a Pneumotrace II piezoelectric respiration band.The signals were recorded with a National Instruments DAQCard-6062E and custom software written in the LabWin-dows environment.III.R ESULTSThe ECG and the EDR signals exhibited the greatest de-gree of response to the acupuncture stimulation.There were changes in the low frequency power of the ECG signal during needle insertion and stimulation for both the acupuncture and control points.Fig.3.The primary frequency range in which the changes in power occurred was0−0.05Hz.The response was not sensitive or specific enough to allow the identification of a general trend in the responses to stimulation between the control and acupuncture points.The small number of subjects is perhaps the greatest impediment to any such determination.97697624.9 k3300 k2.2 F0.1 F150 k4.7 kvFig.2.The ECG detection circuit.50Frequency(Hz)0.20.4Time (min)NISTPMV ST STP MV NO05101520253035404550Fig.3.Example of a typical response in the low frequency power of the ECG signal.The annotations are shown as vertical red lines and labeled as follows:NI=needle in,NO=needle out,ST=stimulation start,STP= stimulation stop,and MV=movement.The EDR signal exhibited a far more definitive response to the acupuncture events.A qualitative description of the responses of the EDR impedance magnitude response to the events for all subjects and sessions is given in Table II.A small drop was defined as a drop of greater than100Ωbut less than 1kΩand a large drop was defined as a drop of greater then1 kΩ.The transient response of the skin impedance magnitude is usually a sharp decrease and this is most likely due to sweat ductfilling in the palm although this hypothesis has not been verified.The most striking feature of the EDR recordings is that out of the10recordings that were uncorrupted8exhibited large drops in impedance magnitude0.5−2.0minutes before the acupuncture point was stimulated.The conclusion drawn is that the subjects were anticipating the insertion procedure. An example of a typical response,subject1session2,is shown in Fig. 4.Another observation made was that the mean value of the impedance magnitude dropped in several cases after the anticipatory response and stayed lower during24.9 kMagnitude & Phase Detection Fig.1.A high level diagram of the EDR circuitry.the entire treatment.In these cases the impedance magnitudealso displayed a greater variability perhaps indicating contin-uing physiological or psychological responses that extended through the entire treatment.Of the12recordings7displayed a lower mean and greater variability after the initial treatment. Whether or not this effect endures and the extent of its duration require further study.An extreme example of the increase in variability and decrease in mean after stimulation is shown in Fig.6and a contrasting example of a subject that did not have this type of response is shown in Fig.5.Another fact to note is that both examples represent stimulation of a control rather than an acupuncture point.A statistical analysis of the differences between the responses to stimulation of the control and acupuncture points was not performed but a qualitative visual inspection of the recordings did not suggest a consistent difference in the responses between the two. The instrumentation performed well throughout most of the recordings although the ECG signal to noise ratio was large enough that for one recording the QRS complexes were undetectable.The thermistor also failed after thefirst subject due to a lead wire breaking.The EDR circuitry performed well and without error.The data corruption was caused by failures of the electrode wiring apparatus rather than the EDR circuitry itself.IV.D ISCUSSIONThe results of this study indicate that the physiologic re-sponse to acupuncture treatments indeed requires more study. The shortcomings of this present study are the small number of subjects and the fact that the main physiologic signal which was found to be responsive to the acupuncture stimulation is known to be extremely sensitive to psychological stress levels.The observation that the dermal impedance magnitude almost always drops before the needle insertion indicates the likelihood that the subjects are anticipating the event.There may be purely a psychological response and the changes in physiologic state observed may not be due to the acupuncture treatments.More carefully designed subsequent studies may reveal that acupuncture stimulation does indeed elicit a dis-cernable change in dermal impedance phase and magnitude and dynamic physiologic state of which they are indicative. The fact that the differences between control and acupuncture4|Z|(Ω)∠Z°Time (s)Fig.4.Example plot of EDR.The annotations are shown as vertical red lines and labeled as follows:NI=needle in,NO=needle out,ST=stimulation start,STP=stimulation stop,and MV=movement.4|Z|(Ω)∠Z°Time (s)Fig.5.Example of subject that did not exhibit a decreased mean or increased degree of variability after acupuncture stimulation.4|Z | (Ω)∠ Z °Time (s)Fig.6.Example of increased variability and decreased mean after acupunc-ture stimulation.TABLE IIA QUALITATIVE SUMMARY OF EDR MAGNITUDE RESULTS .LSDIS ALARGE SIMULTANEOUS DROP ,LDB IS A LARGE DROP BEFORE ,SSD IS ASMALL SIMULTANEOUS DROP ,SDB IS A SMALL DROP BEFORE ,NR IS NORESPONSE AND DC IS DATA CORRUPTED .11LDB 1.5min LSD SSD No 12LDB 0.5min LSD LSD Yes and LSD 21DCDC DC Yes 22LDB 1.5SSD SSD No 31LDB 1min SDB SSD Yes and SSD 32NRSSDNR No 41LDB 1.5min LDB 1.5min NR Yes 42LDB 1.5min LSD SSD No and SSD 51LDB 2min NR SSD No 52NRNRNR Yes 61LDB 1min LDB 1min NR No 62DCDCDCYespoints were indiscernible may be due to the individual varia-tion of subjects and the small number of subjects included in this study.Another factor to consider is the size and location of the ST 36point are not precisely defined and the control point selected was close enough to the point to enable subject blinding but may have also been close enough to also elicit a response.R EFERENCES[1]T.Harada H.Ueda N.Tsuda H.Tayama F.Ballegaard,S.Muteki andK.Ohishi,“Modulatory effect of acupuncture on the cardiovascular system:a cross-over study,”Acupunct Electrother Res ,vol.18,pp.103–115,1993.[2] C.Ionescu-Tirgoviste and S.Pruna,“The pattern of the electrodermalactivity as indicator of stress related reaction,”Rom J Physiol ,vol.30,pp.207–218,1993.[3]Y .X.Sugiyama,Y .Xue and T.Mano,“Transient increase in humanmuscle sympathetic nerve activity during manual acupuncture,”The Japanese Journal of Physiology ,vol.45,pp.337–345,1995.[4]J.M.Tsai S.J.Chiang P.Y .Ting H.Tang C.Y .Lou K.L.Hsieh L.C.Wang D.W.Lin,C.F.Liao and T.B.Lin,“Depressor effect on blood pressure and flow elicited by electroacupuncture in normal subjects,”Autonomic Neuroscience ,vol.107,pp.60–74,2003.[5]H.Yosikawa K.Nishijo,K.Mori and K.Yazawa,“Decreased heart rateby acupuncture stimulation in humans via facilitation of cardiac vagal activity and suppression of cardiac sympathetic nerve,”Neuroscience Letters ,vol.227,pp.165–168,1997.[6]M.F.Young and P.W.McCarthy,“Effect of acupuncture stimulationof the auricular sympathetic point on sudomotor response,”Journal of Alternative &Complementary Medicine ,vol.4,pp.29–38,1998.[7]T.B.J.Wang,J.D.Kuo and C.C.H.Yang,“An alternative method toenhance vagal activities and suppress sympathetic activities in humans,”Autonomic Neuroscience ,vol.100,pp.90–95,2002.[8]J.C.Xiong J.Yang C.F.Pan H.B.Chen Y .C.Tsai G.Rosen B.R.Wu,M.T.Hsieh and K.K.Kwong,“Central nervous pathway for acupuncture stimulation:localization of processing with functional mr imaging of the brain-preliminary experience,”Radiology ,vol.212,pp.133–141,1999.[9]H.Haker,E.Egekvist and P.Bjerring,“Effect of sensory stimulation(acupuncture)on sympathetic and parasympathetic activities in healthy subjects,”Journal of the Autonomic Nervous System ,vol.79,pp.52–59,2000.[10]J.L.Middlekauff,H.R.Yu and K.Hui,“Acupuncture effects on reflexresponses to mental stress in humans,”American Journal of Physiology -Regulative,Integrative and Comparative Physiology ,vol.280,pp.R1462–R1468,2001.[11]M.G.Valet M.Deppe M.Conrad B.Tolle T.R.Backer,M.Hammes andG.Dobos,“Different modes of manual acupuncture stimulation differ-entially modulate cerebral blood flow velocity,arterial blood pressure and heart rate in human subjects,”Neuroscience Letters ,vol.29,pp.203–206,2002.[12]T.Lindberg L.G.Sandberg,M.Lundeberg and B.Gerdle,“Effectsof acupuncture on skin and muscle blood flow in healthy subjects,”European Journal of Applied Physiology ,vol.90,pp.114–119,2003.[13]S.M.Wang and Z.N.Kain,“Auricular acupuncture:a potential treatmentfor anxiety,”Anesthesia &Analgesia ,vol.92,pp.548–553,2001.[14]K.Chen M.Li,Z.Jiao and C.Wang,“Effect of magnitopunctureon sympathetic and parasympathetic nerve activities in healthy drivers-assessment by power spectrum analysis of heart rate variability,”Euro-pean Journal of Applied Physiology ,vol.88,pp.404–410,2003.[15] D.Eich H.Pach J.Bertling R.Lemmer W.Klieser E.Agelink,M.W.Sanner and E.Lehmann,“Does acupuncture influence the cardiac autonomic nervous system in patients with minor depression or anxiety disorders?,”Fortschr Neurol Psychiat ,vol.71,pp.141–149,2003.[16]J.Webster,Medical Instrumentation ,John Wiley and Sons,Inc.,thirdedition,1998.。