Derivation and validation of gray-box models to estimate noninvasive in-vivo percentage glycated hemoglobin using digital volume pulse waveform

Glycated hemoglobin and blood oxygenation are the two most important factors for monitoring a patient’s average blood glucose and blood oxygen levels. Digital volume pulse acquisition is a convenient method, even for a person with no previous training or experience, can be utilized to estimate the two abovementioned physiological parameters. The physiological basis assumptions are utilized to develop two-finger models for estimating the percent glycated hemoglobin and blood oxygenation levels. The first model consists of a blood-vessel-only hypothesis, whereas the second model is based on a whole-finger model system. The two gray-box systems were validated on diabetic and nondiabetic patients. The mean absolute errors for the percent glycated hemoglobin (%HbA1c) and percent oxygen saturation (%SpO2) were 0.375 and 1.676 for the blood-vessel model and 0.271 and 1.395 for the whole-finger model, respectively. The repeatability analysis indicated that these models resulted in a mean percent coefficient of variation (%CV) of 2.08% and 1.74% for %HbA1c and 0.54% and 0.49% for %SpO2 in the respective models. Herein, both models exhibited similar performances (HbA1c estimation Pearson’s R values were 0.92 and 0.96, respectively), despite the model assumptions differing greatly. The bias values in the Bland–Altman analysis for both models were – 0.03 ± 0.458 and – 0.063 ± 0.326 for HbA1c estimation, and 0.178 ± 2.002 and – 0.246 ± 1.69 for SpO2 estimation, respectively. Both models have a very high potential for use in real-world scenarios. The whole-finger model with a lower standard deviation in bias and higher Pearson’s R value performs better in terms of higher precision and accuracy than the blood-vessel model.

Derivation and Validation of Gray-Box Models to Estimate Non-Invasive In-vivo Percentage Glycated Hemoglobin Using Digital Volume Pulse Waveform

Glycated hemoglobin and blood oxygenation are the two most important factors for monitoring a patient’s oxygen levels in the blood and the amount of average blood glucose levels. Digital Volume Pulse acquisition is a convenient method, even for a person with no previous training or experience, can be utilized to estimate the two abovementioned physiological parameters. The physiological basis assumptions are utilized to develop two-finger models for estimating the percent glycated hemoglobin and blood oxygenation levels. The first model consists of a blood vessel only hypothesis, while the second model is based on a whole-finger model system. We validated our two gray-box systems on diabetic and non-diabetic patients and obtained the mean absolute errors for the percent glycated hemoglobin (%HbA1c) and percent oxygen saturation (%SpO2) of 0.375 and 1.676, respectively, for the blood vessel model and 0.271 and 1.395, respectively, for the whole-finger model. The precision analysis indicated that these models resulted in 2.08% and 1.74% mean %CV for %HbA1c and 0.54% and 0.49% mean %CV for %SpO2 in the respective models. Herein, both models exhibit close performances to each other (HbA1c estimation Pearson R values are 0.92 and 0.96, respectively), even though the model assumptions greatly differed between them. Both of the models have a very high potential to be used in real-world scenarios. The whole-finger model performs better in terms of higher precision and accuracy compared to the blood vessel model.

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).

EFFECT OF ACUPUNCTURE IN HEART AURICULAR POINT IN TWO INDEXES OF DIGITAL VOLUME PULSE IN HEALTHY SUBJECTS

Objective: The aim of the study was to determine the changes in two indices derived from the digital volume pulse (DVP) elicited by acupuncture in auricular heart acupoint in healthy subjects. Methods: Eighteen healthy subjects aged 26.22±2.98 years (mean±standard deviation) were assigned to receive auricular acupuncture in auricular heart acupoint in the right ear. The DVP was recorded by photoplethysmography. RIDVP was determined by the relative amplitudes of systolic and diastolic components of the DVP and SIDVP, by the relative timing of these components. Auricular acupoint heart was stimulated by manual acupuncture. The RIDVP and SIDVP indices were calculated for basal and post-acupuncture conditions. Results: Both RIDVP (p=0.0375) and SIDVP (p=0.0063) were significantly decreased by acupuncture of the right auricular acupoint heart when comparing the pre- and post-acupuncture values. Conclusions: These results indicate that manual acupuncture of auricular acupoint heart produces acute effects on vascular physiology. RIDVP and SIDVP indices can be used to assess and demonstrate a vasodilatory activity of auricular acupoint heart.

Digital Volume Pulse Measured at the Fingertip as an Indicator of Diabetic Peripheral Neuropathy in the Aged and Diabetic

This study investigated the application of a modified percussion entropy index (PEIPPI) in assessing the complexity of baroreflex sensitivity (BRS) for diabetic peripheral neuropathy prognosis. The index was acquired by comparing the obedience of the fluctuation tendency in the change between the amplitudes of continuous digital volume pulse (DVP) and variations in the peak-to-peak interval (PPI) from a decomposed intrinsic mode function (i.e., IMF6) through ensemble empirical mode decomposition (EEMD). In total, 100 middle-aged subjects were split into 3 groups: healthy subjects (group 1, 48–89 years, n = 34), subjects with type 2 diabetes without peripheral neuropathy within 5 years (group 2, 42–86 years, n = 42, HbA1c ≥ 6.5%), and type 2 diabetic patients with peripheral neuropathy within 5 years (group 3, 37–75 years, n = 24). The results were also found to be very successful at discriminating between PEIPPI values among the three groups (p < 0.017), and indicated significant associations with the anthropometric (i.e., body weight and waist circumference) and serum biochemical (i.e., triglycerides, glycated hemoglobin, and fasting blood glucose) parameters in all subjects (p < 0.05). The present study, which utilized the DVP signals of aged, overweight subjects and diabetic patients, successfully determined the PPI intervals from IMF6 through EEMD. The PEIPPI can provide a prognosis of peripheral neuropathy from diabetic patients within 5 years after photoplethysmography (PPG) measurement.

Impact of the Apolipoprotein E (epsilon) Genotype on Cardiometabolic Risk Markers and Responsiveness to Acute and Chronic Dietary Fat Manipulation

Apolipoprotein (APO) E (ε) genotype is considered to play an important role in lipid responses to dietary fat manipulation but the impact on novel cardiometabolic risk markers is unclear. To address this knowledge gap, we investigated the relationship between the APOE genotype and cardiometabolic risk markers in response to acute and chronic dietary fat intakes. Associations with fasting (baseline) outcome measures (n = 218) were determined using data from the chronic DIVAS (n = 191/195 adults at moderate cardiovascular disease risk) and acute DIVAS-2 (n = 27/32 postmenopausal women) studies examining the effects of diets/meals varying in saturated, polyunsaturated and monounsaturated (MUFA) fatty acid composition. Participants were retrospectively genotyped for APOE (rs429358, rs7412). For baseline cardiometabolic outcomes, E4 carriers had higher fasting total and low-density lipoprotein-cholesterol (LDL-C), total cholesterol: high-density lipoprotein-cholesterol (HDL-C) and LDL-C: HDL-C ratios, but lower C-reactive protein (CRP) than E3/E3 and E2 carriers (p ≤ 0.003). Digital volume pulse stiffness index was higher in E2 carriers than the E3/E3 group (p = 0.011). Following chronic dietary fat intake, the significant diet × genotype interaction was found for fasting triacylglycerol (p = 0.010), with indication of a differential responsiveness to MUFA intake between the E3/E3 and E4 carriers (p = 0.006). Test fat × genotype interactions were observed for the incremental area under the curve for the postprandial apolipoprotein B (apoB; p = 0.022) and digital volume pulse reflection index (DVP-RI; p = 0.030) responses after the MUFA-rich meals, with a reduction in E4 carriers and increase in the E3/E3 group for the apoB response, but an increase in E4 carriers and decrease in the E3/E3 group for the DVP-RI response. In conclusion, baseline associations between the APOE genotype and fasting lipids and CRP confirm previous findings, although a novel interaction with digital volume pulse arterial stiffness was observed in the fasted state and differential postprandial apoB and DVP-RI responses after the MUFA-rich meals. The reported differential impact of the APOE genotype on cardiometabolic markers in the acute and chronic state requires confirmation.

Comparison of beta2-adrenergic and hyperemia-induced arterial vasodilation assessed by digital pulse contour analysis

Introduction. The Reflection Index (RIDVP) derived from digital volume pulse (DVP) analysis has proved to be useful in the assessment of endothelium‑dependent vasodilation induced by albuterol. Little is known of the effect of shear‑stress‑induced vasorelaxation on RIDVP.Material and Methods. Thirty three healthy volunteers (22 females, 11 males, mean age 57 yrs) were recruited. Assessment of endothelium‑dependent vasorelaxation was performed by the analysis of digital volume pulse after albuterol challenge or locally‑induced hyperemia. Results. he hyperemia‑induced vasodilation led to a significant decrease of RIDVP in comparison with the values obtained at rest (∆RIHyper 69 ± 2 % vs 64 ± 2, p < 0.0001). Similarly albuterol administration resulted in a significant drop in RIDVP (∆RIAlb 71 ± 2 % vs 67 ± 2 %, p < 0.0001). There was no significant difference between ∆RIHyper and ∆RIAlb (5.2 ± 0.8 % vs 4.6 ± 1.0 %, p = 0.61). We observed a significant correlation between the small vessel reaction in response to albuterol or hyperemia (r = 0.52, p = 0.01).Conclusions. Our study demonstrated that hyperemia‑induced changes in the Reflexion Index derived from the digital volume pulse are similar to those observed after albuterol‑challenge and both are correlated.

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.