Complementary Therapies in Medicine (2007) 15, 190—198

Developing classification indices for Chinesepulse diagnosis

Jian-Jun Shu ∗, Yuguang Sun

School of Mechanical & Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue,Singapore 639798, Singapore

Available online 21 August 2006

KEYWORDSChinese pulse diagnosis;Classification indices

SummaryAim: To develop classification criteria for Chinese pulse diagnosis and to objectifythe ancient diagnostic technique.Methods: Chinese pulse curves are treated as wave signals. Multidimensional variableanalysis is performed to provide the best curve fit between the recorded Chinesepulse waveforms and the collective Gamma density functions.Results: Chinese pulses can be recognized quantitatively by the newly-developedfour classification indices, that is, the wave length, the relative phase difference,the rate parameter, and the peak ratio. The new quantitative classification not onlyreduces the dependency of pulse diagnosis on Chinese physician’s experience, butalso is able to interpret pathological wrist-pulse waveforms more precisely.Conclusions: Traditionally, Chinese physicians use fingertips to feel the wrist-pulsesof patients in order to determine their health conditions. The qualitative theory

of the Chinese pulse diagnosis is based on the experience of Chinese physiciansfor thousands of years. However, there are no quantitative theories to relate thesedifferent wrist-pulse waveforms to the health conditions of patients. In this paper,new quantified classification indices have been introduced to interpret the Chinese

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Introduction

Chinese pulse diagnosis in traditional Chinese

medicine (TCM) has been practiced for more than2000 years.1,2 Chinese physicians use fingertipsto feel the wrist-pulses of patients in order todetermine their health conditions. The wrist-pulse

∗ Corresponding author. Tel.: +65 6790 4459;fax: +65 6791 1859.

E-mail address: mjjshu@ntu.edu.sg (J.-J. Shu).

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0965-2299/$ — see front matter © 2006 Elsevier Ltd. All rights reservdoi:10.1016/j.ctim.2006.06.004

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as been recognized as the most fundamentalignal of life, containing vital information of healthctivities.

Pathologic changes of a person’s body conditionre reflected in the wrist-pulse pictures. Clinicaltudies demonstrate that patients with hyper-ension, hypercholesterolemia, cardiovascular

isease, and diabetes, exhibit premature loss ofrterial elasticity and endothelial function, whichventually resulted in decreased flexibility of vas-ulature, and heightened stress to the circulatory

ed.

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eveloping classification indices for Chinese pulse d

ystem. The wrist-pulse shape, amplitude, andhythm are also altered in correspondence withhe hemodynamic characteristics of blood flow.

The growing recognition of the importance ofeveloping effective preventive medical system toontemporary healthcare has placed Chinese pulseiagnosis an important position.3 However, wrist-ulse assessment is a matter of technical skillnd subjective experience. The intuitional accu-acy depends upon the individual’s persistent prac-ice and quality of sensitive awareness. Differenthinese physicians might not always give identi-

al wrist-pulse waveform pattern recognition forome given patient. The classifications of wrist-ulse waveform patterns identified and named byifferent Chinese physicians in their medical lit-

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Figure 1 The 13 Chinese pulse wav

osis 191

ratures are not always the same. In history, Chi-ese physicians clearly appreciated the significancef the wrist-pulses and association of changes inhe wrist-pulses with diseases, but they did notrogress beyond the stage of manual palpations,hereby remaining largely uninfluenced by quanti-ative measurements. Solid quantified descriptionf Chinese pulse diagnosis would pave a way in itsodernizing advancements.This paper aims to extract characteristics of Chi-

ese pulses from their waveforms by introducinguantified classification indices. These classifica-

ion indices can be served for wrist-pulse waveformattern recognition and classification in Chineseulse diagnosis. This is a subject dealing with auto-ated Chinese pulse diagnosis. The fact that an

eforms and their descriptions.

192 J.-J. Shu, Y. Sun

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electronic device is interfaced with a personal com-puter holds open the possibility that an automatedsystem of interpreting Chinese pulse waveform pat-terns could be developed.

Methods

Chinese pulse waveforms

Chinese pulse waveforms are recorded non-

invasively with a pressure sensor. A wrist-watch-like structure is mounted to keep the sensor posi-tion well over radial artery. A sphygmomanometercuff is wrapped around a wrist-watch-like struc-

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ure to provide hold-down pressure. The Chineseulse waveforms are captured and digitized by annalog-to-digital converter and recorded onto aersonal computer. Thirteen Chinese pulse wave-orms in TCM are recorded and their descriptions2

re shown below in Fig. 1. The 13 Chinese pulseaveforms appear more likely to help practitioneretermine imbalances that relate to the selectionf traditional style therapeutics, i.e. acupunctureoints and individual herbs.

hinese pulse waveform analysis

beating heart generates pressure and flow waveshich propagate throughout the arterial system.

Developing classification indices for Chinese pulse diagn

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igure 2 Forward wave is higher in amplitude, and back-ard wave is lower in amplitude, with a phase shift.

he shapes of wrist-pulse waveforms are altered byheir continuous interaction with the non-uniformrterial system.4—6 The pressure waves expand therterial walls as traveling, and the expansions arealpable as the wrist-pulses.

Each discontinuity reflects the incident waves inhe mechanical and geometrical properties of therterial tree, e.g. at bifurcations and stenoses. Thealpable wrist-pulses can thus be studied in termsf one forward traveling wave component, the col-ective waves running from heart to periphery andontaining information of the heart itself; and oneackward traveling wave component, the collectiveaves containing information of the reflection sitesnd the periphery of the arterial system. Moreover,he reflected pressure waves tend to increase theoad to the heart and play a major role in deter-ining the wrist-pulse waveform patterns. Hence,rist-pulse waveforms can be expressed in terms of

ts forward and backward running components withphase shift in time as illustrated in Fig. 2.A normal wrist-pulse waveform has a smooth,

airly sharp upstroke, a momentarily sustainedeak, a quick downstroke and decay. The reflectedave also has similar shape to the initial wave but

maller in amplitude.7 Such wrist-pulse curve looks

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Table 1 Classification indices

Pulses ˛ ˇ � A

Hurried 3.1 5.8 15 1600Rapid 4 4.3 20 2000Soggy 5 5.7 20 2700Wiry 4 3.4 19 1000Surging 3.5 3.4 6 2500Intermittent 3.6 3.8 16 1500Fine 3.8 5.6 10 3600Normal 2.4 2.9 17 600Wiry and slippery 5.5 5.9 19 5800Choppy 3 4.9 7 1200Knotted 1.7 1.6 5 100Slippery 3.9 4.9 20 5700Slow 7 3.5 23 280

L is the length of wave, 10Lˇ/˛ gives the point where the wave rearelative phase difference between forward and backward waves, re

osis 193

ike the shape of Gamma density function. Withoutoss of generality, the wrist-pulse waveforms can beiewed as the summation of forward and backwardaves by using the following function:

(t|˛, ˇ, �, A, B) = Af(t|˛, ˇ, 0) + Bf(t|˛, ˇ, �)

= At˛ e−ˇt/10 + Bt˛ e−ˇ(t−�)/10,

here the base function is Gamma density function,ormed by the product of one power function andne exponential function:

(t|˛, ˇ, �) = t˛ e−ˇ(t−�)/10, t ≥ �

or describing forward wave f(t|˛, ˇ, 0) and back-ard wave f(t|˛, ˇ, �). ˛ and ˇ are the shape and

ate parameters, respectively. A and B are ampli-udes of forward and backward waves, respectively.

is the phase shift or time delay between forwardave and backward wave. These parameters arestimated to provide the best curve fit between the3 recorded Chinese pulse waveforms and the col-ective Gamma density functions.

esults

hinese pulse waveform pattern recognition

n order to study the characteristic of each Chineseulse waveform quantitatively, single period ofecorded Chinese pulse has been carefully selectedrom each pulse wave-train. The selection is to pro-

ide typical and representative single-period Chi-ese pulse waveforms out of the entire wave-trainor the characteristic analysis. The parameters (˛,, �, A, B) for each Chinese pulse are deter-

B L 10Lˇ/˛ A/B �/L

350 31 0.60 4.57 0.48300 42 0.26 6.67 0.48

1850 47 0.24 1.46 0.43150 49 0.17 6.67 0.39450 50 0.19 5.56 0.12450 53 0.20 3.33 0.30

1200 53 0.28 3.00 0.19200 55 0.22 3.00 0.31

3000 55 0.20 1.93 0.35900 56 0.29 1.33 0.13250 59 0.16 0.40 0.08

2200 68 0.18 2.59 0.2990 82 0.06 3.11 0.28

ches its peak value, A/B and �/L are the peak ratio and thespectively.

194

mined based on minimizing the difference betweenactual recorded waveform and the proposed func-tion F(t|˛, ˇ, �, A, B). In Fig. 3, bubble and solidlines represent the actual recorded waveform and

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Figure 3 Thirteen Chinese pulses (pa

J.-J. Shu, Y. Sun

ts corresponding fitted function F(t|˛, ˇ, �, A, B)or each Chinese pulse.

The values of parameters (˛, ˇ, �, A, B) in theodel for each Chinese pulse are summarized and

rameters and their waveforms).

Developing classification indices for Chinese pulse diagnosis 195

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isted in Table 1 below. The parameters in Table 1ave been arranged according to the wave lengthL). The parameters L, 10Lˇ/˛, A/B and �/L arelso shown in Table 1.

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lassification of Chinese pulses

he values of the parameters describe character-stic of Chinese pulses in recognizing their wave-

196 J.-J. Shu, Y. Sun

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Figure 3

form patterns:

I. Whether Chinese pulse is rapid or slow is animportant quality to be determined in Chinesepulse diagnosis. The length (L) of the Chinesepulse wave, which reflects its period or fre-quency, can firstly be considered to classify the

13 Chinese pulse waveforms. As shown in theresults, hurried pulse is very small in length(L), while slow pulse is large. These two Chi-nese pulses stand out of the other 11 Chinese

Table 2 Chinese wrist-pulse distinguishing and grouping

ntinued ).

pulses in their length (L) and can be recognizedby the length easily. The rest 11 Chinese pulsesare undistinguishable purely by examining theirlengths at this stage and should be groupedtogether.

II. Next, �/L should be used to classify the rest11 Chinese pulses. The value �/L shows the

relative phase difference between the for-ward and backward waves in each Chinesepulse waveform. The 11 Chinese pulses can beclassified into four groups by �/L. They are

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197

Table 3 Chinese pulse pattern recognition process

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{knotted, surging, choppy}, {fine}, {slippery,intermittent, normal, wiry and slippery, wiry}and {soggy, rapid}. At this stage, fine pulseis obviously recognizable, while other Chinesepulses are undistinguishable in their respectivegroups.

III. ˇ should be used to classify the rest. At thisstage, knotted, surging, choppy, normal, slip-pery, wiry and slippery, rapid and soggy pulseare recognizable by examining ˇ. Only intermit-tent pulse and wiry pulse are left undistinguish-able, remaining in group.

IV. Finally these two Chinese pulses are recogniz-able by examining A/B.

The procedure of Chinese pulse grouping andclassification is illustrated in Table 2 shown below.

According to the grouping and classificationabove, the ranges of parameters to group and clas-sify the Chinese pulses in each stage are set inTable 3.

Discussion

Chinese pulse diagnosis plays an important role inpatient evaluation in traditional Chinese medicine.Pathologic changes of a person’s body condition arereflected in wrist-pulse waveforms. Chinese physi-cians use fingertips to diagnose the wrist-pulses ofpatients in order to determine their health con-ditions. Hence different Chinese physicians mayinterpret a pathological wrist-pulse waveform ina totally different way. The fact that an elec-tronic device is interfaced with a personal com-puter holds open the possibility that an automatedsystem of interpreting Chinese pulse waveform pat-terns relating to the health conditions of patients

could be developed. In order to perform the auto-mated Chinese pulse diagnosis, the following newclassification indices have been introduced in thispaper to extract characteristics of Chinese pulses

J.-J. Shu, Y. Sun

rom their waveforms:

Rate parameter ˇ—–governing the shape of wave-form and the property of the waveform decay.Phase difference �—–phase difference betweenforward wave and backward wave.Relative phase difference �/L—–phase differencerelative to the entire period.Wave length L—–period of wave.Peak ratio A/B—–ratio of forward wave peak tobackward wave peak.

Chinese pulses can be recognized quantitativelyy the newly-developed classification indices (L,/L, ˇ, A/B). The new quantitative classificationot only reduces the dependency of pulse diag-osis on Chinese physician’s experience, but alsos able to interpret pathological wrist-pulse wave-orms more precisely. The quantitative informationill help us better to characterize or differenti-te the wrist-pulse waveforms, independently toonfirm the health states of patients, and therebyo develop means for non-invasively diagnosing ayriad of diseases associated with malfunctioning

rgan systems.

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