A clinical study of the pulse wave characteristics at the three pulse diagnosis positions of chon, gwan and cheok

An FBG-based optical pressure sensor for the measurement of radial artery pulse pressure

One of the diagnostic tool for clinical evaluation and disease diagnosis is a pulse waveform analysis. High fidelity radial artery pulse waveforms have been investigated in clinical research to compute central aortic pressure, which has been demonstrated to be predictive of cardiovascular diseases. The radial artery must be inspected from several angles in order to obtain the best pulse waveform for estimate and diagnosis. In this study, we present the design and experimental testing of an optical sensor based on Fiber Bragg Gratings (FBG). A 3D printed device along with the FBG is used to measure the radial artery pulses. The proposed sensor is used for the purpose of quantifying the radial artery pulse waveform across major pulse position point. The suggested optical sensing system can measure the pulse signal with good accuracy. The main characteristic parameters of the pulse can then be retrieved from the processed signal for their use in clinical applications. By conducting experiments under the direction of medical experts, the pulse signals are measured. In order to experimentally validate the sensor, we used it to detect the pulse waveforms at Guan position of the wrist's radial artery in accordance with the diagnostic standards. The findings show that combining optical technologies for physiological monitoring and radial artery pulse waveform monitoring using FBG in clinical applications are highly feasible.

Method for Inkjet-printing PEDOT:PSS polymer electrode arrays on piezoelectric PVDF-TrFE fibers

We present a method for printing conductive polymers onto P(VDF-TrFE) nanofibers to create all-polymer piezoelectric devices. Inkjet printing is an attractive fabrication approach for rapid prototyping of flexible electronics, but until now with limited applications in developing P(VDF-TrFE) nanofiber-based devices. We have demonstrated an approach to infill the void space within a piezoelectric nanofibrous matrix to allow for the inkjet printing of aqueous inks while avoiding leakage that typically leads to electrical shorting and without significant loss of voltage output. This was done using a diluted PDMS solution and a commercially available conductive ink. The 1 cm² devices showed a 254 mV/N sensitivity to impact as well as a sensitivity to bending. The device was shown to be able to detect breathing and pulse rate when placed superficially to the carotid and radial arteries. Using these techniques, flexible piezoelectric sensing can be done in an array format, shown with applications in foot movement sensing.

The use of time-domain analysis on the choice of measurement location for pulse diagnosis research: A pilot study

BACKGROUND

Pulse diagnosis researches acquiring pulse waves from the wrist radial artery has not yet addressed the issue of whether this information is affected by differences in the hemodynamic characteristics of pressure waves derived from different locations. This study aimed to clarify whether the blood dynamic states are identical with regard to the "three positions and nine indicators" ((Equation is included in full-text article.)) listed in traditional Chinese medicine (TCM).

METHODS

A total of 37 participants of CAD group and 20 participants of healthy group were recruited, and pressure pulse waves were measured at 18 locations on both hands. A multivariate analysis (MANOVA) was performed with a "randomized block design" using SPSS 22.0 and R 3.4.1 to examine the time-domain parameters that represented certain hemodynamic characteristics.

RESULTS

In CAD group, the results showed significant differences (p < 0.05) among the h1, h2, h3, h1/t, and h3/h1 measurements of the pulse waves using different indicators at the same position; the h1, h2, h3, and h1/t measurements of the pulse waves at different positions using the indicator "Superficial"; and the h1, h2, h3, h1/t, and h3/h1 measurements of the pulse waves at different positions using the indicator "Medium". In healthy group, the results showed significant differences (p < 0.05) among the h1, h2, h3, and h1/t measurements of the pulse waves using different indicators at the same position; the h1, h2, and h1/t measurements of the pulse waves at different positions using the same indicator.

CONCLUSION

Because of the differences in the hemodynamic characteristics among the different positions and indicators, the article might provide a new opinion for future pulse diagnosis investigations to carefully consider the measurement location to ensure the completeness of the information.

Pulse wave response characteristics for thickness and hardness of the cover layer in pulse sensors to measure radial artery pulse

Background

Piezo-resistive pressure sensors are widely used for measuring pulse waves of the radial artery. Pulse sensors are generally fabricated with a cover layer because pressure sensors without a cover layer are fragile when they come into direct contact with the skin near the radial artery. However, no study has evaluated the dynamic pulse wave response of pulse sensors depending on the thickness and hardness of the cover layer. This study analyzed the dynamic pulse wave response according to the thickness and hardness of the cover layer and suggests an appropriate thickness and hardness for the design of pulse sensors with semiconductor device-based pressure sensors.

Methods

Pulse sensors with 6 different cover layers with various thicknesses (0.8 mm, 1 mm, 2 mm) and hardnesses (Shore type A; 30, 43, 49, 71) were fabricated. Experiments for evaluating the dynamic pulse responses of the fabricated sensors were performed using a pulse simulator to transmit the same pulse wave to each of the sensors. To evaluate the dynamic responses of the fabricated pulse sensors, experiments with the pulse sensors were conducted using a simulator that artificially generated a constant pulse wave. The pulse wave simulator consisted of a motorized cam device that generated the artificial radial pulse waveform by adjusting the stroke of the cylindrical air pump and an air tube that conveyed the pulse to the artificial wrist.

Results

The amplitude of the measured pulse pressure decreased with increasing thickness and hardness of the cover layer. Normalized waveform analysis showed that the thickness rather than the hardness of the cover layer contributed more to waveform distortion. Analysis of the channel distribution of the pulse sensor with respect to the applied constant dynamic pressure showed that the material of the cover layer had a large effect.

Conclusions

In this study, in-line array pulse sensors with various cover layers were fabricated, the dynamic pulse wave responses according to the thickness and the hardness of the cover layer were analyzed, and an appropriate thickness and hardness for the cover layer were suggested. The dynamic pulse wave responses of pulse sensors revealed in this study will contribute to the fabrication of improved pulse sensors and pulse wave analyses.

Precise Detection of Wrist Pulse Using Digital Speckle Pattern Interferometry

Pulse diagnosis is one of the four diagnostic methods of traditional Chinese medicine. However it suffers from the lack of objective and efficient detection method. We propose a noncontact optical method to detect human wrist pulse, aiming at the precise determination of the temporal and spatial distributions of pulse. The method uses the spatial-carrier digital speckle pattern interferometry (DSPI) to measure the micro/nanoscale skin displacement dynamically. Significant improvements in DSPI measurement have been made to allow the DSPI to detect the comprehensive information of the arterial pulsation at locations of Cun, Guan, and Chi. The experimental results prove that the spatiotemporal distributions of pulse can be obtained by the proposed method. The obtained data can be further used to describe most of the pulse parameters such as rate, rhythm, depth, length, width, and contour.

Gaussian modelling characteristics changes derived from finger photoplethysmographic pulses during exercise and recovery

Gaussian modelling method has been reported as a useful method to analyze arterial pulse waveform changes. This study aimed to provide scientific evidence on Gaussian modelling characteristics changes derived from the finger photoplethysmographic (PPG) pulses during exercise and recovery. 65 healthy subjects (18 female and 47 male) were recruited. Finger PPG pulses were digitally recorded with 5 different exercise loads (0, 50, 75, 100, 125W) as well as during each of 4minute (min) recovery period. The PPG pulses were normalized in both width and amplitude for each recording, which were decomposed into three independent Gaussian waves with nine parameters determined, including the peak amplitude (H₁, H₂, H₃), peak time position (N₁, N₂, N₃) and half-width (W₁, W₂, W₃) from each Gaussian wave, and four extended parameters determined, including the peak time interval (T_1,2, T_1,3) and amplitude ratio (R_1,2, R_1,3) between 1st Gaussian wave and 2nd, 3rd Gaussian waves. These derived parameters were finally compared between different exercise loads and recovery phases. With gradually increased exercise loads, the peak amplitude H₂, peak time position N₁, N₂, N₃, and half-width W₁, W₂ increased, peak amplitude H₃ decreased significantly (all P<0.05). The peak time interval T_1,2 and T_1,3 increased significantly from 10.6±1.2 and 36.0±4.4 at rest to 14.4±2.3 and 45.1±6.5 at 100W exercise load, respectively (both P<0.05). The amplitude ratio R_{1,2 also} increased from 1.07±0.2 at rest to 1.22±0.2 at 100W, and the amplitude ratio R_1,3 decreased from 1.10±0.3 at rest to 0.42±0.2 at 125W (all P<0.05). An opposite changing trend of these parameters was observed during recovery phases. In conclusion, this study has quantitatively demonstrated significant changes of Gaussian modelling characteristics derived from finger PPG pulse with exercise and during recovery, providing scientific evidence for the physiological mechanism that exercise increases cardiac ejection and vasodilation, and reduces the total peripheral vascular resistance.

Traditional Chinese medicine wrist pulse-taking is associated with pulse waveform analysis and hemodynamics in hypertension

BACKGROUND

Pulse wave analysis (PWA) quantifies the phenomenon of pulse waveform propagation in patients with cardiovascular diseases, whereas pulse image analysis (PIA) is a subjective examination in traditional Chinese medicine.

OBJECTIVE

This study evaluated the association of PIA with PWA and hemodynamics in patients with hypertension.

DESIGN, SETTING, PARTICIPANTS AND INTERVENTIONS

This observational, cross-sectional study enrolled 45 patients (26 men, (55.2 ± 10.3) years, systolic blood pressure (155 ± 28) mmHg, diastolic blood pressure (93 ± 17) mmHg) for assessment of clinical and laboratorial data.

MAIN OUTCOME MEASURES

Primary outcomes comprised: pattern differentiation based on an automated method; PIA at the radial artery using the 'simultaneous pressing' method for identification of factors such as strength (strong/weak), depth (superficial/deep), and speed (fast/moderate/slow); and PWA at the same artery using a noninvasive system.

RESULTS

Significant multivariate main effects were observed for depth (λ=0.648, F5,29 =3.149, P=0.022, η(2) =0.352), strength (λ=0.608, F5,29 =3.736, P=0.010, η(2) =0.392), and speed (λ=0.535, F5,29 =5.302, P=0.002, η(2) =0.465). General effects comprised high values of PWA and blood pressure for superficial, strong, and fast pulse images. A strong pulse was found for pulse pressure ≥ 62.5 mmHg and systolic blood pressure ≥ 149.5 mmHg, whereas a superficial pulse was found for heart rate ≥ 58.25 beats/min; a fast pulse was found for heart rate ≥ 69.6 beats/min and pulse wave velocity ≥ 9.185 m/s.

CONCLUSION

Associations were explained by LaPlace's law, arterial remodeling in hypertension, alongside the traditional criterion for classifying speed in pulse images. PIA is associated with PWA and hemodynamics in patients with hypertension. Systolic and pulse pressures, heart rate, and pulse wave velocity are quantitative variables that have information to describe the qualitative pulse images such as strength, depth and speed.

Modeling the Pulse Signal by Wave-Shape Function and Analyzing by Synchrosqueezing Transform

We apply the recently developed adaptive non-harmonic model based on the wave-shape function, as well as the time-frequency analysis tool called synchrosqueezing transform (SST) to model and analyze oscillatory physiological signals. To demonstrate how the model and algorithm work, we apply them to study the pulse wave signal. By extracting features called the spectral pulse signature, and based on functional regression, we characterize the hemodynamics from the radial pulse wave signals recorded by the sphygmomanometer. Analysis results suggest the potential of the proposed signal processing approach to extract health-related hemodynamics features.

Development of a Tonometric Sensor with a Decoupled Circular Array for Precisely Measuring Radial Artery Pulse

The radial artery pulse is one of the major diagnostic indices used clinically in both Eastern and Western medicine. One of the prominent methods for measuring the radial artery pulse is the piezoresistive sensor array. Independence among channels and an appropriate sensor arrangement are important for effectively assessing the spatial-temporal information of the pulse. This study developed a circular-type seven-channel piezoresistive sensor array using face-down bonding (FDB) as one of the sensor combination methods. The three-layered housing structure that included independent pressure sensor units using the FDB method not only enabled elimination of the crosstalk among channels, but also allowed various array patterns to be created for effective pulse measurement. The sensors were arranged in a circular-type arrangement such that they could estimate the direction of the radial artery and precisely measure the pulse wave. The performance of the fabricated sensor array was validated by evaluating the sensor sensitivity per channel, and the possibility of estimating the blood vessel direction was demonstrated through a radial artery pulse simulator. We expect the proposed sensor to allow accurate extraction of the pulse indices for pulse diagnosis.

Association of hypertension with physical factors of wrist pulse waves using a computational approach: a pilot study

BACKGROUND

The objectives of this pilot study were to examine the association between hypertension and physical factors of wrist pulse waves to avoid subjective diagnoses in Traditional Chinese Medicine (TCM) and Traditional Korean Medicine (TKM). An additional objective was to assess the predictive power of individual and combined physical factors in order to identify the degree of agreement between diagnosis accuracies using physical factors and using a sphygmomanometer in the prediction of hypertension.

METHODS

In total, 393 women aged 46 to 73 years participated in this study. Logistic regression (LR) and a naïve Bayes algorithm (NB) were used to assess statistically significant differences and the predictive power of hypertension, and a wrapper-based machine learning method was used to evaluate the predictive power of combinations of physical factors.

RESULTS

In both wrists, L-PPI and R-PPI (maximum pulse amplitudes in the left Gwan and right Gwan) were the factors most strongly associated with hypertension after adjusting for age and body mass index (p = <0.001, odds ratio (OR) = 2.006 on the left and p = <0.001, OR = 2.504 on the right), and the best predictors (NB-AUC = 0.692, LR-AUC = 0.7 on the left and NB-AUC = 0.759, LR-AUC = 0.763 on the right). Analyses of both individual and combined physical factors revealed that the predictive power of the physical factors in the right wrist was higher than for the left wrist. The predictive powers of the combined physical factors were higher than those of the best single predictors in both the left and right wrists.

CONCLUSION

We suggested new physical factors related to the sum of the area on the particular region of pulse waves in both wrists. L-PPI and R-PPI among all variables used in this study were good indicators of hypertension. Our findings support the quantification and objectification of pulse patterns and disease in TCM and TKM for complementary and alternative medicine.

Differences in the Properties of the Radial Artery between Cun, Guan, Chi, and Nearby Segments Using Ultrasonographic Imaging: A Pilot Study on Arterial Depth, Diameter, and Blood Flow

Aim of the Study. The three conventional pulse-diagnostic palpation locations (PLs) on both wrists are Cun, Guan, and Chi, and each location reveals different clinical information. To identify anatomical or hemodynamic specificity, we used ultrasonographic imaging to determine the arterial diameter, radial artery depth, and arterial blood flow velocity at the three PLs and at nearby non-PL segments. Methods. We applied an ultrasound scanner to 44 subjects and studied the changes in the arterial diameter and depth as well as in the average/maximum blood flow velocities along the radial artery at three PLs and three non-PLs located more proximally than Chi. Results. All of the measurements at all of the PLs were significantly different (P < 0.01). Artery depth was significantly different among the non-PLs; however, this difference became insignificant after normalization to the arm circumference. Conclusions. Substantial changes in the hemodynamic and anatomical properties of the radial artery around the three PLs were insignificant at the nearby non-PLs segments. This finding may provide a partial explanation for the diagnostic use of “Cun, Guan, and Chi.”

New assessment model of pulse depth based on sensor displacement in pulse diagnostic devices

An accurate assessment of the pulse depth in pulse diagnosis is vital to determine the floating and sunken pulse qualities (PQs), which are two of the four most basic PQs. In this work, we proposed a novel model of assessing the pulse depth based on sensor displacement (SD) normal to the skin surface and compared this model with two previous models which assessed the pulse depth using contact pressure (CP). In contrast to conventional stepwise CP variation tonometry, we applied a continuously evolving tonometric mechanism at a constant velocity and defined the pulse depth index as the optimal SD where the largest pulse amplitude was observed. By calculating the pulse depth index for 18 volunteers, we showed that the pulse was deepest at Cheok (significance level: P < 0.01), while no significant difference was found between Chon and Gwan. In contrast, the two CP-based models estimated that the pulse was shallowest at Gwan (P < 0.05). For the repeated measures, the new SD-based model showed a smaller coefficient of variation (CV ≈ 7.6%) than the two CP-based models (CV ≈ 13.5% and 12.3%, resp.). The SD-based pulse depth assessment is not sensitive to the complex geometry around the palpation locations and temperature variation of contact sensors, which allows cost-effective sensor technology.

Intrarater and interrater reliability of pulse examination in traditional Indian Ayurvedic medicine

Background

In Ayurveda, pulse examination (nadipariksha) is an important tool to assess the status of three doshas: vata, pitta, and kapha. Long historical use has been seen as a documentation of its efficacy; however, there is a lack of a quantitative measure of the reliability of the pulse examination method. The objective of this study was to test the intrarater and interrater reliability of pulse examination in Ayurveda.

Methods

Fifteen registered Ayurvedic doctors with 3–15 years of experience examined the pulse of 20 healthy volunteers twice, for a total of 600 examinations. The examinations were performed blind and in a random order. Only the current status of dosha-specific methods of pulse examination were considered. Cohen's weighted κ statistic was used as a measure of intrarater and interrater reliability, and a hypothesis of homogeneous diagnosis (random rating) was tested. Following this, we tested whether proportions of ratings were equal between doctors.

Results

According to the Landis and Koch scale, the level of reliability ranged from poor to moderate. It was observed that the doctors more frequently diagnosed a combination of two doshas than a single dosha. The κ values were generally larger for experienced doctors (p = 0.04).

Conclusion

Experience and proper training have important roles in pulse examination.

Three-dimensional motion of the radial artery and the spatiality, rhythmicity, formability and intensity of TCM pulse diagnosis

Traditional Chinese medicine (TCM) pulse diagnosis can reflect the condition of human bodies. 44 young healthy human beings were involved in the investigation of the relationship between the three dimensional motion of the radial artery and the spatiality, rhythmicity, formability and intensity of TCM pulse diagnosis in TCM pulse diagnostics. The color Doppler vascular imaging, the self-designed cardioelectric phasic marking and non-pressure arm bath-tube were used in the study. Both the radial artery and other arm superficial arteries had three forms of motion, namely diametrical motion, axial motion and the displacement of the axial center. The three forms of motion changed periodically, which was identical with that found in pulsation. The displacement of the vascular axial center was a three-dimensional message of the overall vascular revolving motion observed on a two-e level. Systematically studying the rules of vascular motion and the relationship between the rules of vascular motion and the spatiality, rhythmicity, formability and intensity of TCM pulse patterns has great significance in revealing the specificity of the vascular motion and explaining the mechanisms in the formation of TCM pulse diagnosis. This research could make TCM pulse diagnosis more understandable.

Pulse waveform analysis as a bridge between pulse examination in Chinese medicine and cardiology

Pulse examination was probably the earliest attempt to distinguish between health and illnesses. Starting at the pre-Hippocratic era, Chinese medicine practitioners developed techniques for pulse examination and defined pulse images based on their perceptions of pulse waveforms at the radial artery. Pulse images were described using basic variables (frequency, rhythm, wideness, length, deepness, and qualities) developed under philosophical trends such as Taoism and Confucianism. Recent advances in biomedical instrumentation applied to cardiology opened possibilities to research on pulse examination based on ancient Chinese medical theories: the pulse wave analysis. Although strongly influenced by philosophy, some characteristics used to describe a pulse image are interpretable as parameters obtained by pulse waveform analysis such as pulse wave velocity and augmentation index. Those clinical parameters reflect concepts unique to Chinese medicine - such as yinyang - while are based on wave reflection and resonance theories of fluids mechanics. Major limitations for integration of Chinese and Western pulse examination are related to quantitative description of pulse images and pattern differentiation based on pulse examination. Recent evidence suggests that wave reflection and resonance phenomena may bridge Chinese medicine and cardiology to provide a more evidence-based medical practice.

Development of pulse diagnostic devices in Korea

In Korean medicine, pulse diagnosis is one of the important methods for determining the health status of a patient. For over 40 years, electromechanical pulse diagnostic devices have been developed to objectify and quantify pulse diagnoses. In this paper, we review previous research and development for pulse diagnostic devices according to various fields of study: demand analysis and current phase, literature studies, sensors, actuators, systems, physical quantity studies, clinical studies, and the U-health system. We point out some confusing issues that have been naively accepted without strict verification: original pressure pulse waveform and derivative pressure pulse waveform, pressure signals and other signal types, and minutely controlled pressure exertion issues. We then consider some technical and clinical issues to achieve the development of a pulse diagnostic device that is appropriate both technically and in terms of Korean medicine. We hope to show the history of pulse diagnostic device research in Korea and propose a proper method to research and develop these devices.

Development of a radial pulse tonometric (RPT) sensor with a temperature compensation mechanism

Several RPT sensors have been developed to acquire objective and quantitative pulse waves. These sensors offer improved performance with respect to pressure calibration, size and sensor deployment, but not temperature. Since most pressure sensors are sensitive to temperature, various temperature compensation techniques have been developed, but these techniques are largely inapplicable to RPT sensors due to the size restrictions of the sensor, and incompatibility between the compensation techniques and the RPT sensor. Consequently, in this paper a new RPT sensor comprising six piezoresistive pressure sensors and one thermistor has been developed through finite element analysis and then a suitable temperature compensation technique has been proposed. This technique compensates for temperature variations by using the thermistor and simple compensation equations. As verification of the proposed compensation technique, pulse waves of all types were successfully compensated for temperature changes.

Novel diagnostic model for the deficient and excess pulse qualities

The deficient and excess pulse qualities (DEPs) are the two representatives of the deficiency and excess syndromes, respectively. Despite its importance in the objectification of pulse diagnosis, a reliable classification model for the DEPs has not been reported to date. In this work, we propose a classification method for the DEPs based on a clinical study. First, through factor analysis and Fisher's discriminant analysis, we show that all the pulse amplitudes obtained at various applied pressures at Chon, Gwan, and Cheok contribute on equal orders of magnitude in the determination of the DEPs. Then, we discuss that the pulse pressure or the average pulse amplitude is appropriate for describing the collective behaviors of the pulse amplitudes and a simple and reliable classification can be constructed from either quantity. Finally, we propose an enhanced classification model that combines the two complementary variables sequentially.

Temporal and spatial properties of arterial pulsation measurement using pressure sensor array

Conventionally, a pulse taking platform is based on a single sensor, which initiates a feasible method of quantitative pulse diagnosis. The aim of this paper is to implement a pulse taking platform with a tactile array sensor. Three-dimensional wrist pulse signals are constructed, and the length, width, ascending slope, and descending slope are defined following the surface of the wrist pulse. And the pressure waveform of the wrist pulse obtained through proposed pulse-taking platform has the same performance as the single sensor. Finally, the results of a paired samples t-test reveal that the repeatability of the proposal platform is consistent with clinical experience. On the other hand, the results of ANOVA indicate that differences exist among different pulse taking depths, and this result is consistent with clinical experience in traditional Chinese medicine pulse diagnosis (TCMPD). Hence, the proposed pulse taking platform with an array sensor is feasible for quantification in TCMPD.

Novel diagnostic algorithm for the floating and sunken pulse qualities and its clinical test

We propose a novel classification algorithm for the floating pulse and the sunken pulse using a newly defined coefficient (C_fs). To examine the validity of the proposed algorithm, we carried out a clinical test in which 12 oriental medical doctors made pairwise diagnoses on the pulses of volunteering subjects. 169 subjects were simultaneously diagnosed by paired doctors, and the diagnoses in 121 subjects were concordant, yielding an accuracy of 72% and a Matthews correlation coefficient of 0.42, which indicates reasonable agreement between doctors. Two sample T-tests showed that subjects in the sunken pulse group had significantly higher BMI and C_fs (P < .05) than those in the floating pulse group. The pulse classification by the algorithm converged with the diagnoses of paired doctors with an accuracy up to 69%. With these results, we confirm the validity of the novel classification algorithm for the floating and sunken pulses.

Developing the effective method of spectral harmonic energy ratio to analyze the arterial pulse spectrum

In this article, we analyze the arterial pulse in the spectral domain. A parameter, the spectral harmonic energy ratio (SHER), is developed to assess the features of the overly decreased spectral energy in the fourth to sixth harmonic for palpitation patients. Compared with normal subjects, the statistical results reveal that the mean value of SHER in the patient group (57.7 ± 27.9) is significantly higher than that of the normal group (39.7 ± 20.9) (P-value = .0066 < .01). This means that the total energy in the fourth to sixth harmonic of palpitation patients is significantly less than it is in normal subjects. In other words, the spectral distribution of the arterial pulse gradually decreases for normal subjects while it decreases abruptly in higher-order harmonics (the fourth, fifth and sixth harmonics) for palpitation patients. Hence, SHER is an effective method to distinguish the two groups in the spectral domain. Also, we can thus know that a "gradual decrease" might mean a "balanced" state, whereas an "abrupt decrease" might mean an "unbalanced" state in blood circulation and pulse diagnosis. By SHER, we can determine the ratio of energy distribution in different harmonic bands, and this method gives us a novel viewpoint from which to comprehend and quantify the spectral harmonic distribution of circulation information conveyed by the arterial pulse. These concepts can be further applied to improve the clinical diagnosis not only in Western medicine but also in traditional Chinese medicine (TCM).

Radial pressure pulse and heart rate variability in heat- and cold-stressed humans

This study aims to explore the effects of heat and cold stress on the radial pressure pulse (RPP) and heart rate variability (HRV). The subjects immersed their left hand into 45°C and 7°C water for 2 minutes. Sixty healthy subjects (age 25 ± 4 yr; 29 men and 31 women) were enrolled in this study. All subjects underwent the supine temperature measurements of the bilateral forearms, brachial arterial blood pressure, HRV and RPP with a pulse analyzer in normothermic conditions, and thermal stresses. The power spectral low-frequency (LF) and high-frequency (HF) components of HRV decreased in the heat test and increased in the cold test. The heat stress significantly reduced radial augmentation index (AIr) (P < .05), but the cold stress significantly increased AIr (P < .01). The spectral energy of RPP did not show any statistical difference in 0 ~ 10 Hz region under both conditions, but in the region of 10 ~ 50 Hz, there was a significant increase (P < .01) in the heat test and a significant decrease in the cold test (P < .01). The changes in AIr induced by heat and cold stress were significantly negatively correlated with the spectral energy in the region of 10 ~ 50 Hz (SE_10−50 Hz) but not in the region of 0 ~ 10 Hz (SE_0−10 Hz). The results demonstrated that the SE_10−50 Hz, which only possessed a small percentage in total pulse energy, presented more physiological characteristics than the SE_0−10 Hz under the thermal stresses.