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Pain, 4 (1977) 49-57 @ Elsevier/North-Holland

Biomedical

Press

RESPONSE TO COLD PRESSOR PAIN AND TO ACUPUNCTURE ANALGESIA IN ORIENTAL AND OCCIDENTAL SUBJECTS

V. JANE

KNOX

Department (Accepted

*, KIT SHUM and DEBORAH

of Psychology, February

7th,

Queen’s

University,

M. MCLAUGHLIN Kingston,

Ont. (Canada)

1977)

SUMMARY

On a no treatment trial, a group of 24 oriental subjects rated cold pressor pain as significantly more painful and distressing than did a group of 24 occidental subjects. For half of the Orientals and half of the Occidentals, a second trial was conducted after acupuncture analgesia had been induced. The remaining 12 Orientals and 12 Occidentals served as no treatment controls on trial 2. Regardless of racial group, there was no difference between the pain of those experimental subjects who received acupuncture and the pain of those controls who did not. As they had on trial 1, Orientals reported significantly more pain and distress in response to ice water on trial 2. It is concluded that: (1) if acupuncture does work better for the Chinese than for other racial groups, the likely cause is a more refined patient selection procedure rather than an inherent difference in response to acupuncture; (2) evidence does not support the stereotyped view of Orientals as stoical in the face of physical pain.

INTRODUCTION

The phenomenon of acupuncture analgesia has attracted considerable attention in the recent literature on pain control. Reports of its use in China suggest that the technique is a promising one. When used to control the acute pain of surgery, observers have reported success rates rangmg from 67% [ 51 to as high as 98% [19] for some surgical procedures. Success has also been reported with experimentally induced pain in China; in a series of experiments, the Research Group of Acupuncture Anesthesia of Peking Medical College [24] found pain threshold increases with acupuncture which approached those associated with morphine. l Requests for reprints should be sent to V. Jane Queen’s University, Kingston, Ont., Canada.

Knox,

Department

of Psychology,

50

When used in the West, acupuncture appears to be less effective. For example, Frost et al. [12] administered acupuncture analgesia for two types of acute clinical pain, that of dental extractions and that experienced postoperatively. For 27% of their dental patients acupuncture was an effective analgesia and for 32% of their postoperative sample acupuncture provided at least some pain relief. For both patient groups, the success rates obtained by Frost et al. were no better than those which would be expected with a placebo treatment f3]. Reports of the effect of acupuncture on experimentally induced pain are more common in the Western literature. While some have found reductions in reported pain [1,2,4,7,8,10,17,22,25,26] the effect is typically a small one. Furthermore, a number of studies have found acupuncture to be either ineffective or no more effective than a placebo treatment [6,9,11,20,21,23]. The study reported here was designed to explore the apparent East vs. West discrepancy in the response to acupuncture by comparing its effect on experimentally induced pain in oriental and occidental subjects. Circulating ice water (cold pressor test) is used as a source of pain. Response to this pain stimulus is evaluated with an open-ended verbal report scale used extensively by Hilgard 113-151. Our specific purpose is to determine whether oriental subjects are more responsive to acupuncture analgesia than their occidental counterparts under equivalent laboratory conditions. An ancilliary purpose of the present study is to compare the response to cold pressor pain of Orientals and Occidentals. A number of authors [ 18,271 have suggested that as a group, Orientals are more stoical and hence are likely to show a lesser reaction to painful s~lrnu~ati(~n than their occidental counterparts. A study by Woodrow et al. [28] contradicts this view; Orientals were willing to tolerate significantly lower levels of pressure pain than either Negroes or Caucasians. Data from preacupuncture trials in the present investigation will permit a further comparison of the response to pain of Orientals and Occidentals. ME’IXODS

Subjects

Oriental subjects were selected from the student population of Queen’s University and from the surrounding community. The criteria for their participation in the experiment were being Chinese and having been raised in the Orient. Approximately 50 individuals who met these criteria were contacted by telephone and asked to participate in an experiment that would involve physical pain and might also involve acupuncture. Twenty-five agreed. Of these, one was subsequently excluded because of failure to withstand cold pressor pain, The final sample consisted of 24 subjects from Taiwan, Hong Kong and Malaysia with a mean age of 20.58 years (range: 17-25) and a mean length of time in the West of 27.63 months (range: 9-84). Occidental subjects were all students at Queen’s University. Approximately 35 individuals were telephoned and asked to participate in the experi-

51

ment. Of the 25 who agreed, one was unable to tolerate cold pressor pain. The remaining 24 subjects had a mean age of 22.5 years (range: 19-31) and had all been raised in North America. None was of oriental ancestry. Within each racial group 12 subjects were randomly assigned to the experimental condition and the remaining 12 to the control condition. Apparatus Cold pressor pain was produced by immersing the hand and forearm in a 42.3 liter tank of circulating ice water with a temperature which ranged from 0.5 to 1.5”C. Ice cubes were confined by wire mesh to a space 3.8 cm wide adjacent to each of the 4 walls of the tank. In order to avoid local warming of the water around the immersed limb, the water was circulated through the tank at a rate of approximately 1022 liters/h by a Tee1 Model lP681 pump. An arm rest, consisting of a metal frame slung with plastic webbing, was hinged to one end of the tank. The hand and arm were placed on the arm rest before immersion. To ensure that positioning of the experimental limb was constant, the subject loosely grasped a plastic crossbar on the arm rest. A pulley arrangement permitted the experimenter to drop the arm quickly into the water and to remove it at the end of the trial. However, the hand and arm were not strapped on to the apparatus, so the subject could remove them himself if the pain became unbearable. Acupuncture analgesia was induced via two 2%gauge stainless steel acupuncture needles, one inserted to a depth of approximately 3 cm between the thumb and forefinger of the experimental arm (Ho-ku), the other 3.84.5 cm into the experimental forearm (Hsi-shang). The needles were attached to a model 71.1 battery operated acupuncture anesthesia apparatus manufactured in the People’s Republic of China. Peak-to-peak trapezoidal wave pulses of approximately 15 V, 0.04 mA were delivered at a frequency of 4-5 pulses/set. Each pulse had a 50% voltage drop over the 0.37 msec duration, and each was followed by a reverse polarity inductive spike. Induction time was 20 min for all subjects. Proced we Each subject was seen for one session of approximately 60 min. During this period the subject experienced a total of three 60 set cold pressor trials, as described below. The same two female experimenters were used for all subjects. Experimenter 1 administered the pain trials; experimenter 2, a physician and acupuncturist from the People’s Republic of China, induced acupuncture analgesia and assisted experimenter 1 with the cold pressor equipment. The experimental session was divided into 3 parts: (1) and (2) were the same for all subjects, and part (3) differed between the experimental and control groups. The overall plan was as follows. (1) Training trial. When a subject arrived at the laboratory, a brief medical screening was conducted by experimenter 2. No subject was eliminated on the basis of this screening. The subject was then given a practice trial with

52

the cold pressor apparatus. Refore this trial was begun, the subject was read instructions which explained the apparatus, and the sensations one might expect. Hilgard’s pain report scale was also described. During the training trial, the right arm was immersed in the ice water, while the left arm was always used during the experiment proper. In all other respects, the practice dip was identical to subsequent dips. The subject sat in a straight backed chair beside the ice water tank with a blanket on his lap, and his arm on the arm rest. The 60 set trial began when experimenter 1 lowered the arm rest into the water. During the trial, the subject was asked to rate the pain intensity on Hilgard’s scale every 5 set (the cue word “report” was used), so that a maximum of 12 ratings was produced on each trial. If the subject had not wit.hdrawn his hand earlier in the trial, experimenter 1 raised the arm rest at 60 set and wrapped the subject’s arm in a warm towel. Each dip was followed by a brief questionnaire. (2) Experimental trial 1. ‘l’his trial marked the beginning of the experiment proper and was simply a repeat of the training trial procedure using the left arm. It was begun when the training trial had been completed and the experimenters were satisfied that the subject understood the use of the pain rating scale. For the majority of the Orientals, the latter required that instructions be translated into the subjects’ native tongue by experimenter 2. (3) Expenmental trial 2. For this trial, procedures for the two groups diverged as follows: Experimental group. Subjects were informed that they would receive acupuncture prior to this cold pressor trial. Until this point subjects were unaware of their group assignment. The acupuncture procedure was fully explained, and the subjects then lay on a hospital bed while the two needles were inserted into the experimental arm. Needle insertion was 5-7 min after the first experimental dip. The subject remained on the bed until the end of the 20 min induction, at which point the needles were immediately withdrawn and the subject moved to the cold pressor apparatus. The postacupuncture trial began immediately. The maximum time between needle removal and the end of the cold pressor trial was 90 sec. Control group, Subjects were told that, their second experimental dip would be identical to their first. To equate conditions across groups, these subjects also lay on the hospital bed for 20 min. They were given the rationale that this allowed the experimental limb to fully recover from the first trial. At the end of the 20 min, the procedure used in experimental trial 1 was repeated. RESULTS

Course of pain Ten subjects terminated an ice water trial before the 60 set mark by voluntarily withdrawing their hands. One of these was an occidental experimental and the remaining 9 were oriental subjects (5 controls and 4 experimentals). With one exception (an oriental control subject), this withdrawal occurred on both trials of the experiment. In order to avoid extensive prorating, course of pain data to 30 set, consisting of 6 verbal pain reports per

53

subject per trial were analyzed *. These data were examined with separate analyses of variance for each of the two experimental trials. The independent variables were pain rating periods, treatment groups and race. As may be seen in Fig. 1, on experimental trial 1, both the oriental experimental group and the oriental control group reported a higher course of pain than their occidental counterparts. Analysis of the data from this no treatment trial indicates that while subjects’ course of pain over 30 set did not differ significantly as a function of treatment group, F(1,44) = 0.14, there was a significant difference as a function of race, with Orientals reporting significantly higher pain overall, F(1,44) = 5.94, P< 0.025. Further, the pain of oriental subjects mounted significantly more rapidly than that of the occidental subjects, F(5,220) = 4.40, P < 0.0025. As is evident from Fig. 1, the pain ratings produced on experimental trial 2 are remarkably similar to those on experimental trial 1. Analysis of experimental trial 2 data indicates that on their second cold pressor dip, oriental subjects again reported pain that was significantly higher overall, F(1,44) = 6.22, P< 0.025, and more rapidly mounting, F(5,220) = 6.31, P< 0.001, than that of occidental subjects. It is apparent in Fig. 1 that acupuncture did not significantly affect the course of pain of either the oriental or the occidental subjects, F( 5,220) = 1.03. Distress ratings It has been shown previously that subjects can give separate ratings for experimental pain and the suffering or distress associated with it [ 161. In the present experiment subjects were asked after each cold pressor trial to recall the amount of distress they had experienced. Ratings were given on a numerical scale analogous to the pain rating scale. Subjects’ retrospective distress ratings paralleled their reports of pain intensity during the experiment. After experimental trial 1, oriental subjects rated the experience of cold pressor pain as significantly more distressing than did Occidentals, F(1,44) = 7.13, P-C 0.01. In a separate analysis of variance a similar significant difference was obtained for distress ratings after experimental trial 2, F(1,44) = 4.17, P < 0.05. Subjects who received acupuncture were no less distressed than those who did not, F(1,44) = 0.40, and the distress ratings of Orientals and Occidentals were not differentially affected by the treatment, F(1,44) = 1.52. Final inquiry When the experiment

was over, subjects were questioned

about their prior

* It was still necessary to prorate the data of 3 oriental subjects. Two of these were controls for whom two missing data points on experimental trial 1 and one on experimental trial 2 were added. The third was an experimental who had 3 missing data points on experimental trial 1 and one on experimental trial 2. On the bas:a of previous work with the pain rating scale [ 151 and from examination of course of pain data for all subjects in

the experiment,

it was concluded

that the most appropriate

extrapolation

was linear.

54

IO EXPERIMENTAL

9

EXPERIMENTAL ORIENTALS

--,

8

6

K’

EXPERIMENTAL OCCIDENTALS

OCCIDENTALS OCCIDEKTALS

OCCIDENTALS

I,, 5

IO

‘5

20

25

30

SELOr 0.25). Although the two racial groups had responded similarly to acupuncture analgesia, their postexperimental views of the technique differed significantly; 10 of the 12 Orientals

55

in contrast acupuncture

to only 3 of the 12 Occidentals, reported a positive opinion as a method of pain control (Fisher Exact Test, P < 0.02).

of

DISCUSSION

In the present experiment, acupuncture was found to have no effect on experimentally induced pain. In this respect our data support the null findings cited earlier and extend these to include not only occidental but oriental subjects as well. It should be noted that the group means presented here are not masking any individual cases either of pain elimination or of dramatic pain reduction after acupuncture analgesia; responses to the treatment were highly variable in both racial groups but all of our subjects reported considerable pain on the acupuncture trial. Indeed some subjects in each group reported worse pain after acupuncture than they had before acupuncture. It would appear that when subjects are selected at random to receive acupuncture analgesia, Orientals do not respond differently from Occidentals. If acupuncture does work better for the Chinese than it does for other racial groups, a likely cause is a more refined procedure for subject selection rather than an inherent difference in response to acupuncture. All of our oriental subjects were reared in their country of origin, and identified with Chinese rather than Western cultural traditions. Postexperimental questioning suggested that one distinction between their cultural milieu and that of our occidental subjects involved acupuncture; more Orientals had prior exposure to the technique, and as a group their attitudes toward acupuncture analgesia were more favorable, even in light of their own inability to become analgesic with acupuncture in the present experiment. However, the fact that none of these oriental subjects was drawn from the population of the People’s Republic of China clearly limits the conclusions that can be drawn from our findings. The possibility that the prevailing belief system in Mainland China is unique in favoring a positive response to acupuncture remains a subject for future investigations. An ancilliary purpose of our investigation was to compare Orientals and Occidentals in their response to cold pressor pain. Our data confirm those of Woodrow et al. [28]; Orientals in the present investigation were significantly less tolerant of pain than Occidentals. Not only did our oriental subjects report significantly higher pain and distress than our occidental subjects during the ice water trials, but 9 of the 24 Orientals (compared to only one Occidental) withdrew their hands before the 60 set end point. At least with experimentally induced pain, the stereotypic view of the stoical Oriental can not be maintained; in the present situation, Orientals reported more pain, found it more distressing, and terminated it more often than did Occidentals. Unless one is willing to postulate that this pattern is reversed with clinical pain, the suggestion that there is a “generalized stoicism” on the part of the Chinese [ 181 no longer appears a compelling one.

56 ACKNOWLEDGEMENTS

This investigation was supported try of Health. The assistance of William Gekoski acknowledged.

by Grant and

Carol

AC6

from

the

Handfield-Jones

Ontario

Minis-

is gratefully

REFERENCES 1 Anderson,

2 3 4

8

9 10 11 12 13 l-4 15

16

17 18 19 20

D.G., Jamieson, J.L. and Mann, S.C., Analgesic effects of acupuncture on the pain of ice water: a double-blind study, Canad. J. Psychol., 28 (1974) 239-244. Andersson, S.A. and Holmgren, E., On acupuncture analgesia and the mechanism of pain, Amer. J. chin. Med., 3 (1975) 311-334. Beecher, H.K., Measurement of Subjective Responses: Quantitative Effects of Drugs, Oxford University Press, New York, 1959. Berlin, F.S., Bartlett, R.L. and Black, J.D., Acupuncture and placebo: effects on delaying the terminating response to a painful stimulus, Anesthesiology, 42 (1975) 527531. Bonica, J.J., Acupuncture anesthesia in the People’s Republic of China, J. Amer. med. Ass., 229 (1974) 1317-1325. Brennan, R.W., Welduis, J. and Chu, R., Acupuncture anesthesia, Lancet, 2 (1973) 849. Chapman, C.R., Gehrig, J.D. and Wilson, M.E., Acupuncture compared with 33 per cent nitrous oxide for dental analgesia: a sensory decision theory evaluation, Anesthesiology, 42 (1975) 532-537. Chapman, C.R., Wilson, M.E. and Gehrig, J.D., Comparative effects of acupuncture and transcutaneous stimulation on the perception of painful dental stimuli, Pain, 2 (1976) 265-283. Clark, W.C. and Yang, J.C., Acupunctural analgesia? Evaluation by signal detection theory, Science, 184 (1974) 1096-1098. Croze, S., Antonietti, C. and Duclaux, R., Changes in burning pain threshold induced by acupuncture in man, Brain Res., 104 (1976) 335-340. Day, R.L., Kitahata, L.M., Kao, F.F., Motoyama, E.K. and Hardy, J.D., Acupuncture anesthesia: a psychophysical study, Anesthesiology, 43 (1975) 507-517. Frost, E.A.M., Hsu, C.Y. and Sadowsky, D., Acupuncture therapy: comparative values in acute and chronic pain, N.Y. St. J. Med., 76 (1976) 695-697. Hilgard, E.R., Pain as a puzzle for psychology and physiology, Amer. Psychol., 24 (1969) 103-113. Hilgard, E.R., The alleviation of pain by hypnosis, Pain, 1 (1975) 213-231. Hilgard, E.R., Ruth, J.C., Lange, A.F., Lenox, J.R., Morgan, A.H. and Sachs, LB., The psychophysics of cold pressor pain and its modification through hypnotic suggestion, Amer. J. Psychol., 87 (1974) 17-31. Knox, V.J., Morgan, A.H. and Hilgard, E.R., Pain and suffering in ischemia: the paradox of hypnotically suggested anesthesia as contradicted by reports from the “hidden observer”, Arch. gen. Psychiat., 30 (1974) 840-847. Knox, V.J. and Shum, K., Reduction of cold pressor pain with acupuncture analgesia in high and low hypnotic subjects, J. abnorm. Psychol., in press. Kroger, W.S., Acupunctural analgesia: its explanation by conditioning theory, autogenie training and hypnosis, Amer. J. Psychiat., 130 (1973) 855-860. Li, C.-L., Neurological basis of pain and its possible relationship to acupuncture-analgesia, Amer. J. chin. Med., 1 (1973) 61-72. Li, C.L., Ahlberg, D., Lansdell, H., Gravitz, M.A., Chen, T.C., Ting, C.Y., Bak, A.F. and Blessing, D., Acupuncture and hypnosis: effects on induced pain, Exp. Neurol., 49 (1975) 272-280.

57 21 Lynn, B. and Perl, E.R., Acupuncture analgesia of the skin in relation to the traditional meridian map, J. Physiol. (Lond.), 245 (1975) 83. 22 Mayer, D.J., Price, D.D., Barber, J. and Rafii, A., Acupuncture analgesia: evidence for activation of a pain inhibitory system as a mechanism of action. In: J.J. Bonica and D. Albe-Fessard (Eds.), Advances in Pain Research and Therapy, Vol. 1, Raven Press, New York, 1976, pp. 751-754. 23 Pauser, G., Reichmann, C., Baum, M., Benzer, H., Haider, W. and Thoma, H., The influence of acupuncture analgesia on the sensation and feeling of pain and the autonomic state of the organism, Wien. klin Wschr., 87 (1975) 25-28 (abstract). 24 Research Group of Acupuncture Anesthesia, Peking Medical College, Effect of acupuncture on pain threshold of human skin, Chin. med. J., 3 (1973) 151-157. 25 Smith, G.M., Chiang, H.T., Kitz, R.J. and Antoon, A., Acupuncture and experimentally induced ischemic pain. In: J.J. Bonica (Ed.), Advances in Neurology, Vol. 4, Raven Press, New York, 1974, pp. 827-832. 26 Stewart, D., Thomson, J. and Oswald, I., Acupuncture analgesia: an experimental investigation, Brit. med. J., 1 (1977) 67-70. 27 Wilson, W.P., Blazer, D.G. and Nashold, B.S., Observations on pain and suffering, Psychosomatics, 17 (1976) 73-76. 28 Woodrow, K.M., Friedman, G.D., Siegelaub, A.B. and Cohen, M.F., Pain tolerance: differences according to age, sex and race, Psychosom. Med., 34 (1972) 548-556.

Response to cold pressor pain and to acupuncture analgesia in Oriental and Occidental subjects.

49 Pain, 4 (1977) 49-57 @ Elsevier/North-Holland Biomedical Press RESPONSE TO COLD PRESSOR PAIN AND TO ACUPUNCTURE ANALGESIA IN ORIENTAL AND OCCID...
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