Prognosis of Diabetic Peripheral Neuropathy via Decomposed Digital Volume Pulse from the Fingertip.

Diabetic peripheral neuropathy (DPN) is a very common neurological disorder in diabetic patients. This study presents a new percussion-based index for predicting DPN by decomposing digital volume pulse (DVP) signals from the fingertip. In this study, 130 subjects (50 individuals 44 to 89 years of age without diabetes and 80 patients 37 to 86 years of age with type 2 diabetes) were enrolled. After baseline measurement and blood tests, 25 diabetic patients developed DPN within the following five years. After removing high-frequency noise in the original DVP signals, the decomposed DVP signals were used for percussion entropy index (PEIDVP) computation. Effects of risk factors on the incidence of DPN in diabetic patients within five years of follow-up were tested using binary logistic regression analysis, controlling for age, waist circumference, low-density lipoprotein cholesterol, and the new index. Multivariate analysis showed that patients who did not develop DPN in the five-year period had higher PEIDVP values than those with DPN, as determined by logistic regression model (PEIDVP: odds ratio 0.913, 95% CI 0.850 to 0.980). This study shows that PEIDVP can be a major protective factor in relation to the studied binary outcome (i.e., DPN or not in diabetic patients five years after baseline measurement).

Assessment of Subtle Changes in Diabetes-Associated Arteriosclerosis using Photoplethysmographic Pulse Wave from Index Finger.

Distortions in macro- and microcirculation are principal contributors to diabetes-associated complications. This study aimed at investigating the validity of applying non-invasive photoplethysmographic (PPG) waveform parameters in detecting diabetes-induced subtitle changes in arterial stiffness. Between July 2009 and October 2010, totally 94 middle-aged and elderly subjects were recruited including 48 without diabetes (Group 1) and 46 with the disease (Group 2). Demographic (i.e., age, gender), anthropometric (body-mass index), biochemical (i.e., glycated hemoglobin concentration), and hemodynamic (i.e., systolic blood pressure, heart rate) parameters were obtained. Crest time (CT) and crest time ratio (CTR) computed from PPG signals acquired from left index finger were compared with left index finger pulse wave velocity (PWVfinger) obtained from six-channel ECG-PWV system to investigate the differences between the two groups and the associations of these indices with the parameters of testing subjects. Significant difference was only noted in CTR between the two groups (P < 0.005). Despite correlation of both CT and CTR with age, only CTR demonstrated significant associations with hemodynamic parameters. CTR could differentiate diabetic patients from healthy individuals despite absence of difference in arterial stiffness assessed by conventional PWV, highlighting its superior sensitivity to subtle changes in diabetes-associated arteriosclerosis.

Combination of R-R Interval and Crest Time in Assessing Complexity Using Multiscale Cross-Approximate Entropy in Normal and Diabetic Subjects.

The present study aimed at testing the hypothesis that application of multiscale cross-approximate entropy (MCAE) analysis in the study of nonlinear coupling behavior of two synchronized time series of different natures [i.e., R-R interval (RRI) and crest time (CT, the time interval from foot to peakof a pulse wave)] could yield information on complexity related to diabetes-associated vascular changes. Signals of a single waveform parameter (i.e., CT) from photoplethysmography and RRI from electrocardiogram were simultaneously acquired within a period of one thousand cardiac cycles for the computation of different multiscale entropy indices from healthy young adults (n = 22) (Group 1), upper-middle aged non-diabetic subjects (n = 34) (Group 2) and diabetic patients (n = 34) (Group 3). The demographic (i.e., age), anthropometric (i.e., body height, body weight, waist circumference, body-mass index), hemodynamic (i.e., systolic and diastolic blood pressures), and serum biochemical (i.e., high- and low-density lipoprotein cholesterol, total cholesterol, and triglyceride) parameters were compared with different multiscale entropy indices including small- and large-scale multiscale entropy indices for CT and RRI [MEISS(CT), MEILS(CT), MEISS(RRI), MEILS(RRI), respectively] as well as small- and large-scale multiscale cross-approximate entropy indices [MCEISS, MCEILS, respectively]. The results demonstrated that both MEILS(RRI) and MCEILS significantly differentiated between Group 2 and Group 3 (all p < 0.017). Multivariate linear regression analysis showed significant associations of MEILS(RRI) and MCEILS(RRI,CT) with age and glycated hemoglobin level (all p < 0.017). The findings highlight the successful application of a novel multiscale cross-approximate entropy index in non-invasively identifying diabetes-associated subtle changes in vascular functional integrity, which is of clinical importance in preventive medicine.

Assessment of autonomic dysfunction in patients with type 2 diabetes using reactive hyperemia.

It is known that aging and type 2 diabetes mellitus contribute to atherosclerosis and autonomic dysfunction. By using the air pressure sensing system (APSS), peak-peak intervals (PPIs) of wrist arterial waveforms from baseline and reactive hyperemia (RH) were obtained. Through frequency domain analysis of heart rate variability (HRV) and nonlinear Poincaré method, the HRV of healthy young individuals (Group 1, n=25), healthy upper middle-aged individuals (Group 2, n=22), and patients with type 2 diabetes (Group 3, n=28) were assessed. By using the standard deviation (SD) of the instantaneous PPI variability (SD1)/the SD of the long PPI variability (SD2) ratio (SSR), PPIs of the same individuals before and after RH induction were compared. Reduced SSR1₋10 was noted only in patients with diabetes. Moreover, a significient correlation between SSR1₋10 and endothelial function was observed in all subjects (r=0.290, p=0.033) after RH. However, no correlation with low-frequency to high-frequency power ratio (LHR) was noted before and after RH. In conclusion, according to our results, campared to the baseline, there were more significant changes of SSR1₋10 after RH in patients with diabetes; and, a significient correlation between SSR1₋10 and endothelial function at the moment of RH was noted.

Heart rate variability behavior in young men after short-term carotenoid-containing supplementation.

Background: Heart rate variability can reflect the risk of developing cardiovascular disease (CVD), while carotenoids are good for CVD prevention. However, the acute effect of short-term carotenoid-containing supplementation on heart rate variability in young men is unclear. Methods: Thirty young men between 20 and 29 years of age without personal or family history of cardiovascular diseases were randomly divided into control and experimental groups. The anthropometric data, physiological parameters, and serum biochemical data were acquired, which were without significant difference between the two groups, at the beginning of trial. The participants in the experimental group consumed one pack of compound nutritional supplements in the morning (e.g., 10 AM) and another pack at night (e.g., 7 PM) each day. Heart rate variability was measured again once a month. Repeated measures analysis of variance with Roy's largest root test and Bonferroni post hoc test were applied for primary outcomes. Results: Repeated measures analysis of variance indicated a significant time interaction effect for the estimated marginal means of percussion entropy index scale (T1 versus T3, T1 versus T4, and T2 versus T4 with p = 0.009, 0.005, and 0.032, respectively). Roy's largest root test indicates there were significant differences between the means of the index after the intervention between two groups only on T3 and T4 (p = 0.007, η 2 = 0.232 and p = 0.028, η 2 = 0.162, respectively). Conclusion: Short-term carotenoid-containing supplementation could help young men by increasing heart rate variability capacity compared to controls over three months.

Penile arterial waveform analyzing system for early identification of young adults with high risk of erectile dysfunction.

INTRODUCTION: High prevalence of erectile dysfunction in young adults has raised much concern regarding early identification of risk factors for timely intervention. AIM: This study aimed at identifying young males at risk through a novel penile arterial waveform analyzing system. METHODS: Between July 2009 and December 2010, 30 young adult volunteers of age 18 to 29 without known history of vascular diseases or erectile dysfunction were recruited. MAIN OUTCOME MEASURES: Basic demographic and anthropometric characteristics (i.e., age, body weight, body height, body mass index, waist circumference) were recorded. Blood samples were obtained for determining levels of testosterone, glycosylated hemoglobin, triglyceride, fasting sugar, low- and high-density lipoproteins (HDL). Data obtained from visual sexual stimulation (VSS) RigiScan and the penile arterial waveform amplitude (PAWA) ratios were compared in terms of their correlations with anthropometric and serum biochemical parameters using Pearson's correlation analysis. RESULTS: PAWA ratios were found to correlate with Rigidity (tip and base) (r = 0.425, P = 0.019 and r = 0.664, P < 0.001, respectively). Significant associations of PAWA ratios were noted not only with serum testosterone level but also with risk factors for metabolic and cardiovascular diseases including total triglyceride, HDL, age, waist circumference, body mass index, and diastolic blood pressure. However, VSS RigiScan failed in identifying significant correlations with HDL, age, and diastolic blood pressure. CONCLUSIONS: Not only could the penile waveform analyzing system assess penile endothelial function in young adults, but the results also showed significant associations with their serum testosterone levels and metabolic parameters. The findings suggest that PAWA ratio may serve as an indicator for early identification and treatment of young adults at risk of erectile dysfunction.

Six-channel ECG-based pulse wave velocity for assessing whole-body arterial stiffness.

BACKGROUND: Despite the proposal of different means of non-invasive arterial stiffness assessment, none offers simultaneous information on whole-body peripheral arterial condition. We investigated the validity of applying a six-channel electrocardiogram-based pulse wave velocity (ECG-PWV) measurement system for this purpose. METHODS: The study consisted of two parts. Part One enrolled hypertensive (Group 1, n = 32) and normal (Group 2, n = 32) subjects, whereas Part Two recruited diabetic (Group 3, n = 50) and normal (Group 4, n = 50) subjects. To validate the application of ECG-PWV in assessing peripheral arterial stiffness in different parts of body, ECG-PWV data were compared with three other parameters including the cardio-ankle vascular index (CAVI), pulse wave velocity-digital volume pulse (PWV-DVP) and intima-media thickness (IMT). RESULTS: ECG-PWV in healthy subjects in Part One correlated significantly with CAVI and PWV-DVP (p < 0.05), whereas ECG-PWV and CAVI were significantly different between the hypertensive and normal subjects. Moreover, comparison of IMT and ECG-PWV from different sites showed significant correlation only between IMT and ECG-PWV from earlobe (r = 0.495, p = 0.004). No significant association, however, was noted between IMT and CAVI. For Part Two, significant differences existed between diabetic and normal subjects in body weight, waist circumference, level of HbA1c, fasting blood sugar, serum creatinine and ECG-PWV from the foot. However, no significant difference was noted in PWV-DVP between two groups. CONCLUSIONS: Six-channel ECG-PWV measurement system showed remarkable correlation with IMT in hypertensive subjects and with key anthropometric and biochemical parameters in diabetic patients, suggesting its validity in assessing whole-body arterial stiffness in subjects with peripheral arterial diseases within 10 min.

Calculation of an Improved Stiffness Index Using Decomposed Radial Pulse and Digital Volume Pulse Signals.

The stiffness index (SI) is used to estimate cardiovascular risk in humans. In this study, we developed a refined SI for determining arterial stiffness based on the decomposed radial pulse and digital volume pulse (DVP) waveforms. In total, 40 mature asymptomatic subjects (20 male and 20 female, 42 to 76 years of age) and 40 subjects with type 2 diabetes mellitus (T2DM) (23 male and 17 female, 35 to 78 years of age) were enrolled in this study. We measured subjects' radial pulse at the wrist and their DVP at the fingertip, and then implemented ensemble empirical mode decomposition (EEMD) to derive the orthogonal intrinsic mode functions (IMFs). An improved SI (SInew) was calculated by dividing the body height by the mean transit time between the first IMF5 peak and the IMF6 trough. Another traditional index, pulse wave velocity (PWVfinger), was also included for comparison. For the PWVfinger index, the subjects with T2DM presented significantly higher SInew values measured according to the radial pulse (SInew-RP) and DVP signals (SInew-DVP). Using a one-way analysis of variance, we found no statistically significant difference between SInew-RP and PWVfinger when applied to the same test subjects. Binary logistic regression analysis showed that a high SInew-RP value was the most significant risk factor for developing T2DM (SInew-RP odds ratio 3.17, 95% CI 1.53-6.57; SInew-DVP odds ratio 2.85, 95% CI 1.27-6.40). Our refined stiffness index could provide significant information regarding the decomposed radial pulse and digital volume pulse signals in assessments of arterial stiffness.

A First Step towards a Comprehensive Approach to Harmonic Analysis of Synchronous Peripheral Volume Pulses: A Proof-of-Concept Study.

The harmonic analysis (HA) of arterial radial pulses in humans has been widely investigated in recent years for clinical applications of traditional Chinese medicine. This study aimed at establishing the validity of carrying out HA on synchronous peripheral volume pulses for predicting diabetes-induced subtle changes in heart energy. In this study, 141 subjects (Group 1: 63 healthy elderly subjects; Group 2: 78 diabetic subjects) were enrolled at the same hospital. After routine blood sampling, all synchronous electrocardiogram (ECG) and photoplethysmography (PPG) measurements (i.e., at the six locations) were acquired in the morning. HA of synchronous peripheral volume pulses and radial pulse waves was performed and analyzed after a short period of an ensemble averaging process based on the R-wave peak location. This study utilized HA for the peripheral volume pulses and found that the averaged total pulse energy (i.e., the C0 of the DTFS) was identical in the same subject. A logistic regression model with C0 and a waist circumference variable showed a graded association with the risk of developing type 2 diabetes. The adjusted odds ratio for C0 and the waist circumference were 0.986 (95% confidence interval: 0.977, 0.994) and 1.130 (95% confidence interval: 1.045, 1.222), respectively. C0 also showed significant negative correlations with risk factors for type 2 diabetes mellitus, including glycosylated hemoglobin and fasting plasma glucose (r = -0.438, p < 0.001; r = -0.358, p < 0.001, respectively). This study established a new application of harmonic analysis in synchronous peripheral volume pulses for clinical applications. The findings showed that the C0 could be used as a prognostic indicator of a protective factor for predicting type 2 diabetes.

Reactive Hyperemia-Triggered Wrist Pulse Analysis for Early Monitoring of Young Men with High Atherosclerotic Risk.

The high prevalence of cardiovascular disease in young adults has raised significant concern regarding the early identification of risk factors to allow for timely intervention. This study aimed to identify young males at risk of atherosclerosis using a noninvasive instrument and an initial application percussion entropy analysis of the wrist pressure pulse (WPP). In total, 49 young males aged 18 to 28, without any known history of vascular disease, were recruited. Blood samples were obtained whereby a TC/HDL cutoff value of 4 was used to divide the young men into low-risk (Group 1, TC/HDL < 4, N = 32) and high-risk (Group 2, TC/HDL ≥ 4, N = 17) groups regarding atherosclerosis. The reactive hyperemia-triggered WPPs were measured using a modified air-pressure-sensing system (MAPSS). The dilation index (DI) of the endothelial function and percussion entropy index (PEI) of the heart rate variability (HRV) assessments, calculated using pragmatic signal-processing techniques, were compared between the two groups. The nonparametric Mann-Whitney U test showed that the DI and PEI of the two groups showed statistical differences (both p < 0.05). Not only could the MAPSS assess endothelial function and HRV in young males, but the results also showed that waist circumference and PEI may serve as indicators for the early identification of young males at risk of atherosclerosis.

Compatibility of pulse-pulse intervals with R-R intervals in assessing cardiac autonomic function and its relation to risks of atherosclerosis.

OBJECTIVE: Heart rate variability (HRV) analysis using electrocardiographic R-R intervals (RRIs) in either a time or a frequency domain is a useful tool for assessing cardiac autonomic dysfunction in clinical research. For convenience, pulse-pulse intervals (PPIs) acquired by photoplethysmography have been used to assess HRV. However, the compatibility of PPI with RRI is controversial. MATERIALS AND METHODS: In this study, we investigated the compatibility of PPI with RRI in five groups of participants, including nonoverweight young individuals with a body mass index (BMI) <24 kg/m2 (Group 1, n = 20, aged 18-40 years), overweight young individuals with a BMI ≥24 kg/m2 (Group 2, n = 13, aged 21-38 years), nonoverweight upper middle-aged individuals with a BMI <24 kg/m2 (Group 3, n = 21, aged 45-89 years), overweight upper middle-aged individuals with a BMI ≥24 kg/m2 (Group 4, n = 14, aged 43-74 years), and diabetic patients with a BMI ≥24 kg/m2 (Group 5, n = 19, aged 35-74 years). We then used cross-approximate entropy (CAE) to assess the compatibility between RRI and PPI and analyzed HRV in the time and frequency domains derived from PPR and RRI with traditional methods. RESULTS: The CAE values in Group 1 were significantly lower than those in Group 2 (1.68 ± 0.16 vs. 1.78 ± 0.15, P = 0.041), Group 3 (1.68 ± 0.16 vs. 2.05 ± 0.27, P < 0.001), Group 4 (1.68 ± 0.16 vs. 1.87 ± 0.23, P = 0.023), and Group 5 (1.68 ± 0.16 vs. 2.09 ± 0.23, P < 0.001). There were no significant differences in HRV acquired by PPI and RRI, except for proportion of pairs of adjacent NN intervals differing by more than 50 ms in the entire recording in Group 1. All HRVs derived from PPI were different from those acquired from RRI in the other groups. CONCLUSION: PPI may be an alternative parameter for effectively assessing cardiac autonomic function in nonoverweight healthy individuals. It should be used carefully in overweight, elderly, or diabetic individuals.

Percussion Entropy Analysis of Synchronized ECG and PPG Signals as a Prognostic Indicator for Future Peripheral Neuropathy in Type 2 Diabetic Subjects.

Diabetic peripheral neuropathy (DPN) is one of the most common chronic complications of diabetes. It has become an essential public health crisis, especially for care in the home. Synchronized electrocardiogram (ECG) and photoplethysmography (PPG) signals were obtained from healthy non-diabetic (n = 37) and diabetic (n = 85) subjects without peripheral neuropathy, recruited from the diabetic outpatient clinic. The conventional parameters, including low-/high-frequency power ratio (LHR), small-scale multiscale entropy index (MEISS), large-scale multiscale entropy index (MEILS), electrocardiogram-based pulse wave velocity (PWVmean), and percussion entropy index (PEI), were computed as baseline and were then followed for six years after the initial PEI measurement. Three new diabetic subgroups with different PEI values were identified for the goodness-of-fit test and Cox proportional Hazards model for relative risks analysis. Finally, Cox regression analysis showed that the PEI value was significantly and independently associated with the risk of developing DPN after adjustment for some traditional risk factors for diabetes (relative risks = 4.77, 95% confidence interval = 1.87 to 6.31, p = 0.015). These findings suggest that the PEI is an important risk parameter for new-onset DPN as a result of a chronic complication of diabetes and, thus, a smaller PEI value can provide valid information that may help identify type 2 diabetic patients at a greater risk of future DPN.

In vivo assessment of endothelial function in small animals using an infrared pulse detector.

OBJECTIVE: Endothelial dysfunction is the earliest change in atherosclerosis. Flow-mediated dilatation (FMD) is used to assess endothelial function in humans. However, this assessment is not easy in small animals. This study demonstrated the reliability and reproducibility of a proposed instrument for in vivo assessment of FMD in a rodent model using infrared pulse sensors. MATERIALS AND METHODS: We used 24 adult male Wistar Kyoto rats randomly divided into three groups. FMD was measured under continuous infusion of normal saline followed by intra-arterial infusion of acetylcholine (Ach; n = 8), sodium nitroprusside (SNP; n = 8), or Nω-nitro-L-arginine methyl ester (L-NAME; n = 8). RESULTS: The dilatation indices (DIs) of all three groups were similar before application of the vasoactive agents (1.82 ± 0.46, 1.81 ± 0.44, and 1.93 ± 0.40, P = 0.877, by one-way analysis of variance). The DI was significantly increased during infusion of Ach (2.97 ± 1.03 vs. 1.82 ± 0.46, P = 0.015), unchanged during infusion of SNP (1.81 ± 0.44 vs. 1.98 ± 0.40, P = 0.574), and attenuated during infusion of L-NAME (1.91 ± 0.40 vs. 1.42 ± 0.35; P = 0.028). CONCLUSION: The results of this study correlated well with those of human studies, suggesting that this method can be used for in vivo evaluation of endothelial function in small animals.

Instantaneous frequency from Hilbert-Huang transformation of digital volume pulse as indicator of diabetes and arterial stiffness in upper-middle-aged subjects.

To investigate the value of decomposed short-time digital volume pulse (DVP) signals in discerning systemic vascular anomaly in diabetic patients, demographic and anthropometric parameters, serum lipid profile, fasting blood glucose and glycated hemoglobin (HbA1c) levels were obtained from 29 healthy adults (Group 1) and 29 age-matched type 2 diabetes mellitus patients (Group 2). Six-second DVP signals from right index finger acquired through photoplethysmography were decomposed using ensemble empirical mode decomposition. Using one intrinsic mode function (IMF5), stiffness index (SI) and instantaneous energy of maximal energy (fEmax) were obtained. Other indicators of arterial stiffness, including electrocardiogram-pulse wave velocity of foot (ECG-PWVfoot), crest time (CT) and crest time ratio (CTR), were obtained from the testing subjects for comparison. The mean body weight, body mass index, waist circumference, HbA1c and fasting blood sugar levels were higher in Group 2 than those in Group 1, whereas values of systolic and diastolic blood pressure were lower in Group 2 than those in Group 1. SI and fEmax were significantly higher in Group 2 than those in Group 1. Moreover, fEmax was positively associated with HbA1c concentration, CT and SI in Group 2 (p < 0.05) but not in Group 1. When all subjects were considered, fEmax was highly significantly associated with HbA1c and fasting blood sugar levels, and SI (all p < 0.001). After Hilbert-Huang transformation, short-time DVP signals could give significant information on arterial stiffness and vascular anomaly in diabetic patients.

Application of multiscale Poincaré short-time computation versus multiscale entropy in analyzing fingertip photoplethysmogram amplitudes to differentiate diabetic from non-diabetic subjects.

BACKGROUND AND OBJECTIVES: Multiscale Poincaré (MSP) plots have recently been introduced to facilitate the visualization of time series of physiological signals. This study aimed at investigating the feasibility of MSP application in distinguishing subjects with and without diabetes. METHODS: Using photoplethysmogram (PPG) waveform amplitudes acquired from unilateral fingertip of non-diabetic (n = 34) and diabetic (n = 30) subjects, MSP indices (MSPI) of the two groups were compared using 1000, 500, 250, 100 data points. Data from Poincaré index (short-term variability/long-term variability [i.e. SD1/SD2] ratio, SSR) and multiscale entropy (MSE) were also obtained with the four corresponding data points for comparison. RESULTS: SSR and MSPI were both negatively related to glycated hemoglobin (HbA1c) and fasting blood sugar levels. Significant negative correlation was also noted between MSPI and pulse pressure. When only 500 and 250 data points were included, significant elevations in the non-diabetic group were only noted in MSPI (both p < 0.01). Furthermore, MSPI was significantly higher in non-diabetic than that in diabetic subjects on all scales (i.e., 1-10) but not using MSE when utilizing 1000 data points. CONCLUSIONS: The results demonstrated enhanced sensitivity of MSP in differentiating between non-diabetic and diabetic subjects compared to SSR and MSE, highlighting the feasibility of MSP application in biomedical data analysis to reduce computational time and enhance sensitivity.

Novel Compliance Index derived from digital volume pulse associated with risk factors and exercise capacity in patients undergoing treadmill exercise tests.

OBJECTIVE: Although large-artery stiffness is a well-known independent factor for cardiovascular risk, the importance of small-artery stiffness is not well elucidated. We have developed a novel Compliance Index as a marker of small-artery stiffness. This study aimed to determine the clinical significance of this index by evaluating 140 patients without left ventricular dysfunction referred for treadmill exercise tests. METHODS: Immediately after a 10-min rest period before the test, the pulse wave velocity and Compliance Index were measured. The patients were then given a symptom-limited treadmill test using Bruce's protocol. Our dual-channel photoplethysmography system automatically measured the area under the curve of each digital volume pulse, which represented the volume change in the finger with each heart beat. The Compliance Index was calculated by dividing the area under the curve of finger digital volume pulse by pulse pressure. RESULTS: The Compliance Index was significantly correlated with pulse wave velocity (r=-0.254, P=0.002), systolic blood pressure (r=-0.606, P<0.001), and diastolic blood pressure (r=-0.323, P<0.001). It was lower in males (3.3+/-1.4 versus 4.8+/-2.4 units, P<0.001), in hypertensive patients (3.2+/-1.5 versus 4.4+/-2.2 units, P<0.001), and in smokers (3.0+/-1.5 versus 4.1+/-2.1 units, P=0.006). CONCLUSIONS: The Compliance Index was lower in patients with risk factors and was associated with poor exercise capacity. This index may be clinically useful for evaluating arterial stiffness.

Assessment of Vascular Health With Photoplethysmographic Waveforms From the Fingertip.

Although the flow-mediated dilation (FMD) index is considered the most reliable indicator of vascular endothelial function, previous studies have proved that the dilatation index (DI) measured by the highly reproducible air pressure sensing system (APSS) is just as accurate in effectively determining endothelial function. Besides, not only is APSS cheaper than the instrument for FMD ratio measurement, but operation of the former is also simple to facilitate its domestic use. However, APSS had the pitfall of being time consuming because of the large amount of computation involved. This paper attempted to validate a new self-developed endothelial function screening (EFS) device that utilized the photoplethysmography (PPG) system for acquiring PPG waveform signals from the index finger through an infrared sensor and a pressure cuff for applying pressure on ipsilateral upper arm for eliciting reactive hyperemic response to assess vascular health. The mean peak amplitude of the signals during the hyperemic phase was divided by that of the baseline to produce an EFS ratio. About 52 volunteers of age 34.76 ± 15.23 years without history of cardiovascular diseases were recruited for vascular endothelial function evaluation using the EFS device and the APSS. Bland-Altman analysis showed good consistency between the EFS ratio and DI. Besides, linear regression analysis demonstrated highly significant correlation between the two sets of data (p < 0.001, r2 = 0.6261) In conclusion, this paper, which attempted to validate a self-developed, economical, and time-efficient device that can be operated in a domestic setting, demonstrated that the EFS device yielded consistent results on vascular endothelial function comparable to those acquired through APSS.

Difference in bilateral digital volume pulse as a novel non-invasive approach to assessing arteriosclerosis in aged and diabetic subjects: A preliminary study.

OBJECTIVE: This study aimed at validating photoplethysmography for assessing bilateral blood pressure differences through investigating the correlations of digital volume pulse with arteriosclerosis risk. METHODS: Totally, 111 subjects (70 healthy and 41 diabetic) were recruited. Demographic, blood pressure and anthropometric data were recorded. Blood was collected for determining serum cholesterol, total triglyceride, total cholesterol, high-/low-density lipoprotein cholesterol, fasting blood sugar and glycated haemoglobin concentrations. Arterial stiffness was assessed with electrocardiogram-based pulse wave velocity, crest time and inter-digital volume pulse differences. RESULTS: Receiver operating characteristic curve demonstrated high inter-digital volume pulse difference sensitivity to glycated haemoglobin level over 6.5%. Linear regression analysis demonstrated significant correlation between inter-digital volume pulse difference and electrocardiogram-based pulse wave velocity ( r = 0.692, p < 0.001). Compared with electrocardiogram-based pulse wave velocity, inter-digital volume pulse difference exhibited highly significant correlations with age, glycated haemoglobin level, pulse pressure, total cholesterol/high-density lipoprotein ratio, crest time, high-density lipoprotein and systolic blood pressure (all ps < 0.001). CONCLUSION: In conclusion, the results not only demonstrated successful application of a novel non-invasive waveform contour index, inter-digital volume pulse difference, in differentiating young from aged subjects and patients with good diabetic control from those with poor diabetic control but also validated its use in identifying arteriosclerosis risks. The results, therefore, endorse its domestic application as non-invasive tool for arteriosclerosis risk screening.

Effects of Combined Far-Infrared Radiation and Acupuncture at ST36 on Peripheral Blood Perfusion and Autonomic Activities.

Using four-channel photoplethysmography (PPG) for acquiring peripheral arterial waveforms, this study investigated vascular and autonomic impacts of combined acupuncture-far infrared radiation (FIR) in improving peripheral circulation. Twenty healthy young adults aged 25.5 ± 4.6 were enrolled for 30-minute measurement. Each subject underwent four treatment strategies, including acupuncture at ST36 (Zusanli), pseudoacupuncture, FIR, and combined acupuncture-FIR at different time points. Response was assessed at 5-minute intervals. Area under arterial waveform at baseline was defined as AreaBaseline, whereas AreaStim referred to area at each 5-minute substage during and after treatment. AreaStim/AreaBaseline was compared at different stages and among different strategies. Autonomic activity at different stages was assessed using low-to-high frequency power ratio (LHR). The results demonstrated increased perfusion for each therapeutic strategy from stage 1 to stage 2 (all p < 0.02). Elevated perfusion was noted for all treatment strategies at stage 3 compared to stage 1 except pseudoacupuncture. Increased LHR was noted only in subjects undergoing pseudoacupuncture at stage 3 compared to stage 1 (p = 0.045). Reduced LHR at stage 2 compared to stage 1 was found only in combined treatment group (p = 0.041). In conclusion, the results support clinical benefits of combined acupuncture-FIR treatment in enhancing peripheral perfusion and parasympathetic activity.

A comparison of Cornell and Sokolow-Lyon electrocardiographic criteria for left ventricular hypertrophy in a military male population in Taiwan: the Cardiorespiratory fitness and HospItalization Events in armed Forces study.

BACKGROUND: The Cornell and Sokolow-Lyon electrocardiography (ECG) criteria have been widely used for diagnosing left ventricular hypertrophy (LVH) in patients with hypertension. However, the correlations of these ECG criteria with LVH were rarely compared in military members who received rigorous training, particularly of the Asian male population. METHODS: We compared the Cornell voltage and product criteria with the Sokolow-Lyon criteria for the echocardiographic LVH in 539 military male members, ages 18-50 years and free of hypertension in the Cardiorespiratory fitness and HospItalization Events in armed Forces (CHIEF) study in Taiwan. Pearson's correlation coefficient was used to determine the association of each ECG criterion with the index of left ventricular mass (LVM, g)/height (m)2.7. The sensitivities and specificities were estimated using a receiver-operating characteristics (ROC) curve in relation to the echocardiographic LVH which was defined as LVM index ≥49 g/m2.7. RESULTS: The correlations of the Cornell voltage and product criteria (r=0.24 and 0.26 respectively, both P<0.0001) were stronger than that of the Sokolow-Lyon criteria (r=0.049 and 0.095, and P=0.26 and 0.03 respectively) with the LVM index. Similarly the performances of the Cornell voltage and product criteria for the echocardiographic LVH [area under curve (AUC): 0.66 and 0.68, both P<0.0001] were superior to that of the Sokolow-Lyon criteria (AUC: 0.54 and 0.53, both P>0.1) in the area under the ROC curve analysis. CONCLUSIONS: The Cornell ECG criteria for the echocardiographic LVH had better performance than the Sokolow-Lyon criteria in a young military male cohort in Taiwan.