Effects of hot and cold foods on signals of heart rate variability and nail fold microcirculation of healthy young humans: a pilot study.

In traditional Chinese medicine, hot- and cold-attribute of food ingredients are a major part of dietary therapy. The aim of this study was to establish a suitable scientific methodology to define the attributes of food ingredients by investigating the relationship between food attributes and the physiological signals produced in healthy young subjects with different constitutions. Thirty subjects were grouped into hot and cold constitutions by Chinese medical doctors. Every subject took water, aged ginger tea and coconut water, which are well recognized as having neutral-, hot- and cold-attribute, respectively, on different visits. The different physiological signals induced by the samples were observed using skin and axillary temperature sensors, a heart rate variability analyzer and a laser Doppler anemometer. We found that the capillary red blood cell (RBC) velocity in nail fold microcirculation (NFM) of the subjects with hot constitution accelerated significantly after taking the hot-attribute aged ginger tea, which might be the result of elevated vagal activity leading to arteriole dilation in these subjects. In contrast, in subjects with cold constitution, capillary RBC velocity decelerated significantly and skin temperature decreased markedly after taking the cold-attribute coconut water, which might have been induced by sympathetic nerve activation causing the arteriole to be constricted. Accordingly, the use of capillary RBC velocity of NFM measured by laser Doppler anemometer may be a promising way to classify attributes of food ingredients commonly used in Chinese medicine dietary therapy in accordance with different personal constitutions.

Effect of hot-attribute aged ginger tea on chinese medical pulse condition of healthy young humans.

Young individuals typically have a dry-heat ( zào rè) constitution and feel overly stimulated. This study observes specialties on the right-bar ( yòu guan) section of the radial-arterial pulse of healthy young subjects, and investigates pulse variations induced by different attribute foods. Chinese medical doctors grouped thirty subjects into heat and non-heat constitutions. Each subject took water, aged ginger tea, and coconut water, well recognized as neutral, hot, and cold drinks, on different visits. The current study observed physiological signals induced by the samples using novel noninvasive sphygmography and a blood pressure monitor. As the baseline bigger percussion wave, dicrotic wave, and area in the sphygmogram of the non-heat constitution subjects, this work suggests that blood vessels of these subjects may be more relaxed than that of the heat constitution ones. Stroke volume increased and pulse pressure decreased in the non-heat constitution subjects after taking aged ginger tea, which may elevate arterial compliance corresponding to maintaining an estimated radial-arterial diameter in our study. However, the percussion wave widened and the valley increased in the heat constitution subjects after taking aged ginger tea. This corresponds to the markedly reduced radial-arterial diameter, indicating tighter blood vessels than the baseline status. Accordingly, this study confirms that selecting foods with attributes opposite to personal constitutions is important for reestablishing a healthy cold-heat balance within the human body. Moreover, novel noninvasive sphygmography may be a useful instrument to classify scientifically the heat personal constitution and the responses to different attribute foods.

Quantitative analysis of sensor for pressure waveform measurement.

BACKGROUND: Arterial pressure waveforms contain important diagnostic and physiological information since their contour depends on a healthy cardiovascular system 1. A sensor was placed at the measured artery and some contact pressure was used to measure the pressure waveform. However, where is the location of the sensor just about enough to detect a complete pressure waveform for the diagnosis? How much contact pressure is needed over the pulse point? These two problems still remain unresolved. METHOD: In this study, we propose a quantitative analysis to evaluate the pressure waveform for locating the position and applying the appropriate force between the sensor and the radial artery. The two-axis mechanism and the modified sensor have been designed to estimate the radial arterial width and detect the contact pressure. The template matching method was used to analyze the pressure waveform. In the X-axis scan, we found that the arterial diameter changed waveform (ADCW) and the pressure waveform would change from small to large and then back to small again when the sensor was moved across the radial artery. In the Z-axis scan, we also found that the ADCW and the pressure waveform would change from small to large and then back to small again when the applied contact pressure continuously increased. RESULTS: In the X-axis scan, the template correlation coefficients of the left and right boundaries of the radial arterial width were 0.987 +/- 0.016 and 0.978 +/- 0.028, respectively. In the Z-axis scan, when the excessive contact pressure was more than 100 mm Hg, the template correlation was below 0.983. In applying force, when using the maximum amplitude as the criteria level, the lower contact pressure (r = 0.988 +/- 0.004) was better than the higher contact pressure (r = 0.976 +/- 0.012). CONCLUSIONS: Although, the optimal detective position has to be close to the middle of the radial arterial, the pressure waveform also has a good completeness with a template correlation coefficient of above 0.99 when the position was within +/- 1 mm of the middle of the radial arterial range. In applying force, using the maximum amplitude as the criteria level, the lower contact pressure was better than the higher contact pressure.

A novel compliance measurement in radial arteries using strain-gauge plethysmography.

We propose a novel method for assessing the compliance of the radial artery by using a two-axis mechanism and a standard positioning procedure for detecting the optimal measuring site. A modified sensor was designed to simultaneously measure the arterial diameter change waveform (ADCW) and pressure pulse waveform with a strain gauge and piezoresistor. In the x-axis scanning, the sensor could be placed close to the middle of the radial artery when the ADCW reached the maximum amplitude. In the Z-axis scanning, the contact pressure was continuously increased for data measurement. Upon the deformation of the strain gauge following the change in the vascular cross-section, the ADCW was transferred to the change of the vascular radius. The loaded strain compliance of the radial artery (C(strain)) can be determined by dividing the dynamic changed radius by the pulse pressure. Twenty-three untreated, mild or moderate hypertensive patients aged 29-85 were compared with 14 normotensive patients aged 25-62. The maximum strain compliance between the two groups was significantly different (p < 0.005). Of the hypertensive patients, 14 were at risk of developing hyperlipidemia. There was a significant difference between this and the normotension group (p < 0.005).

A novel noninvasive measurement technique for analyzing the pressure pulse waveform of the radial artery.

Previous noninvasive measurements of the pulse waveform of the radial artery have not employed standard positioning procedures. Here, we propose a new noninvasive measuring apparatus that has a two-axis mechanism and employs a standard positioning procedure for detecting the optimal site for accurately measuring the pressure pulse waveform (PPW). A modified sensor was designed to simultaneously measure the arterial diameter changed waveform (ADCW) and PPW. Considering the artery as a cylinder, the measured waveform would be distorted if the sensor were not at the middle of arterial width. Moreover, a blood vessel is elastic, and its compliance changes with the transmural pressure, being maximal when the transmural pressure is equal to zero. The sensor should detect the PPW with the lowest possible distortion and, hence, an analysis of the vascular geometry and an arterial model were used to design a standard positioning procedure based on the ADCW for the X and Z axes. In order to verify the resolution of the X axis scanning procedure, the echo method was used to measure the radial artery outer diameter in ten healthy subjects. The difference between the scanning width and the actual arterial diameter was 0.36 +/- 0.23 mm (mean +/- SD). Finally, the PPW as measured at the optimal position was used to diagnose myocardial ischemia symptoms in 60 elderly subjects whose chief complaint was chest pain, with the exercise electrocardiogram being used as a reference to compare between individuals with and without myocardial ischemia. The PPW analysis used the harmonic components in the frequency domain. We found that the fourth harmonic of the Fourier series differed significantly between the groups (p = 0.0039), which is consistent with previous studies. The results indicate that our noninvasive measurement apparatus is very suitable for analyzing the PPW of the radial artery.

How to standardize 3 finger positions of examiner for palpating radial pulses at wrist in traditional Chinese medicine.

This study was to provide a standardized definition of the positioning method of finger placement on the radial artery for pulse diagnosis in traditional Chinese medicine (TCM); that is, to define the locations of Cun, Guan and Chi in TCM. A total of 200 subjects (100 males and 100 females, 18-40 years of age) were recruited from the general population. According to ancient TCM records, the "6% of the elbow length" (ELx6%) is used as the standard method of establishing the length of Cun. We hypothesized that the highest point of "prominent bone" (PB) is the lower limit of Cun, so "the distance between the distal wrist crease and the highest point of the PB" (DWP) is considered the length of Cun. If this hypothesis holds, then we can define the locations of Cun, Guan and Chi by using the ratio 6:6:7 from the ancient TCM records. The distribution of relative bias and paired t-test were used to verify the findings. The mean value of relative bias of DWP compared with ELx6% was close to 0% (males = 2.1%, SD = 12.2%; females = 0.2%, SD = 12.6%). The paired t-test confirmed that there was no significant difference (p > 0.05) between the mean values of the DWP and ELx6%. Therefore, it is reasonable to assume that the length of the Cun is equal to the length of the DWP. Our findings confirm that the location of Cun is from the distal wrist crease to the highest point of PB.