Digital Volume Pulse Waveform Research Articles

A digital volume pulse device-finger photo pulse plethysmography to trace the vascular integrity amongst the low back pain subjects with lumbar disc degenerative diseases diagnosed by MRI analysis.

Finger photo pulse plethysmography is a simple, inexpensive and non-invasive method for measurement of arterial stiffness. The objective is to assess the correlation of arterial stiffness in low back pain subjects with lumbar disc degeneration. Thirty-four back pain patients of both sexes in age group of 30-65 were included. Anthropometric measures like height, body weight, body mass index (BMI) were included. Stiffness index (SI) and reflection index (RI) were measured from the digital volume pulse waveform. There was a negative correlation between SI/RI and no correlation between SI and RI with BMI in both sexes. A significant correlation found between weight and BMI in both sexes. Arterial stiffness may not have any influence on disc degeneration. BMI showed some influence on disc degeneration and back pain.

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.

Digital Volume Pulse Analysis to Differentiate Diabetic From Non-Diabetic Subjects

This paper aims to examine the validity of digital volume pulse waveform index namely the diastolic pulse peak (Dpp) in the evaluation of type II diabetics. In total, 153 participants (115 healthy participants and 48 diabetics type II patients) are recruited during the study. A customized algorithm for DVP waveform analysis is developed in MATLAB to analyze and calculate Dpp and b/a indices. The b/a index is found to be negatively correlated with both age and HbA1C test (\(r=-83.8\) and \(r=-66.7\), respectively), while Dpp index is found to be positively correlated with age and HbA1C test (\(r=65.7\) and \(r= 63.3\), respectively). The DVP's Dpp index showed strong association with age and HbA1C test since it remains statistically significant based on the analysis of multi-linear regression. The model revealed that b/a, age, and Dpp contribute by 71.9\% of the variance in HbA1C test. The findings showed that age, b/a, and Dpp indices are promising factors in diabetes type II assessment. These findings expand the potential utility of DVP signal in clinical settings.

Classification of morphologic changes in photoplethysmographic waveforms

Abstract An ever increasing number of research is examining the question to what extent physiological information beyond the blood oxygen saturation could be drawn from the photoplethysmogram. One important approach to elicit that information from the photoplethysmogram is the analysis of its waveform. One prominent example for the value of photoplethysmographic waveform analysis in cardiovascular monitoring that has emerged is hemodynamic compensation assessment in the peri-operative setting or trauma situations, as digital pulse waveform dynamically changes with alterations in vascular tone or pulse wave velocity. In this work, we present an algorithm based on modern machine learning techniques that automatically finds individual digital volume pulses in photoplethysmographic signals and sorts them into one of the pulse classes defined by Dawber et al. We evaluate our approach based on two major datasets – a measurement study that we conducted ourselves as well as data from the PhysioNet MIMIC II database. As the results are satisfying we could demonstrate the capabilities of classification algorithms in the automated assessment of the digital volume pulse waveform measured by photoplethysmographic devices.

Assessment of relationship between measures of obesity and arterial stiffness in young healthy adults

Background: Obesity increases the risk of cardiovascular diseases. Overweight and obese individuals have significantly stiffer arteries than normal weight individuals, which might lead on to various cardiovascular complications. Aim: This study was undertaken to assess the effect of body fat on arterial stiffness in young adults. Arterial stiffness was analyzed by stiffness index (SI) and reflection index (RI) derived from digital volume pulse (DVP) waveform. Settings and Design: A cross-sectional study was conducted among healthy adults in the age group of 17-25 years from private medical, nursing, and dental colleges in Tamil Nadu. Materials and Methods: Ninety-seven young healthy adults of both sexes in the age group of 17-25 years were included in the study. Anthropometric measures like height, total body weight, body mass index (BMI), and waist circumference (WC) were measured. SI and RI derived from the finger photoplethysmographic DVP waveform. Statistical Analysis: Associations between SI and RI, and BMI and WC were assessed with Pearson correlation coefficient. Results: There was a strong correlation between SI/RI and BMI and WC in males and females ( r > 0.9). Conclusion: Obesity is associated with arterial stiffness in the young Indian population the association between SI/RI and BMI, the age at which it appears, and the prevalence of obesity among the young adults warn us about the increase in incidence of cardiovascular diseases.

ICA-Based Improved DTCWT Technique for MA Reduction in PPG Signals With Restored Respiratory Information

In addition to estimation of arterial blood oxygen saturation (SpO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ), pulse oximeter's photoplethysmographic (PPG) signals can be well utilized for extracting the vital respiratory information. The motion artifacts (MA) in PPGs not only make SpO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> estimations unreliable and inaccurate but also make it difficult to extract respiratory information. Addressing this issue, for the first time, we propose a novel approach called “ICA-based improved dual-tree complex wavelet transform (I <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> DTCWT)” technique, for efficient reduction of MAs leaving the respiratory information undisturbed. The method makes use of source separation ability of independent component analysis (ICA) along with computationally efficient modified DTCWT processing. A prototype pulse oximeter was developed and performance analysis of DTCWT, modified DTCWT and I <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> DTCWT processing methods was carried out using PPG data recorded with intentionally created MAs (horizontal MA, vertical MA, and bending MA). Experimental results demonstrated the efficiency of DTCWT processing methods in restoring PPG morphology and proved that there is a significant improvement guaranteed in reducing MAs with the presented methods. Statistical performance is evaluated in terms of measures like signal-to-noise ratio, normalized root mean square error, and correlation analysis with correlation co-efficient measure. The I <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> DTCWT outperformed other DTCWT processing methods in respect of MA reduction and the computed spectra revealed that safe extraction of respiratory information is guaranteed from these MA reduced PPGs. The proposed method is also validated by comparing with the well established signal extraction technology of MASIMO pulse oximeters, for which the discrete saturation transform (DST) is the key element. The %SpO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> estimations from processed PPGs by the proposed method closely followed the estimations based on DST and were very close to that of clean sections of PPG. In addition, the proposed method resulted in less computation cost compared to the MASIMO SET. Digital volume pulse waveform contour analysis is also performed on MA reduced PPGs to validate PPG morphology and the conventional parameters are calculated for assessing the arterial stiffness.

Patterns of digital volume pulse waveform and pulse transit time in young and older individuals

Introduction: Arterial wall changes underlie many disorders of aging and the complications of diseases like hypertension and diabetes mellitus. Analyzing the pulse wave is an easy, noninvasive method used to assess vessel wall stiffness and pulse changes. In this study the digital volume pulse wave and the pulse transit time of the thumb and big toe were analyzed in young and older subjects some of whom were hypertensive. We aimed to study the components and patterns of the pulse waveform and the pulse transit time and how they might change. Material and Methods: Seventy volunteers were drawn from the students and employees of the University of Khartoum. A Powerlab system, ECG leads and a Pulse Mechanotranducer were used. SPSS programme was used for analysis. Results:Young subjects had two main patterns of digital volume pulse waveform in the thumb and two patterns in big toe. The older subjects showed significant decrease in prominence of the diastolic pulse flow waves in both thumb and toe. There was a significant decrease in pulse transit time with advancing age. Discussion: The prominence of systolic deflections combined with decrease in diastolic deflections in the digital waveform in older subjects indicated shift in blood flow towards systole. Changes of pulse waveforms are more prominent in the feet than in the hands. The decreased pulse transit time could explain some, but not all of the observed changes especially in the feet. Digital volume waveform analysis can be developed into a bedside test . Keywords: arterial stiffness, digital volume pulse, pulse transit time, hypertensionSudan Journal of Medical Sciences Vol. 2 (4) 2007: pp. 231-236

Predicting Arterial Stiffness From the Digital Volume Pulse Waveform

Cardiovascular disease (CVD) is currently the biggest single cause of mortality in the developed world, hence, the early detection of its onset is vital for effective prevention therapies. Aortic stiffness as measured by aortic pulse wave velocity (PWV) has been shown to be an independent predictor of CVD, however, the measurement of PWV is complex and time consuming. Recent studies have shown that pulse contour characteristics depend on arterial properties such as arterial stiffness. This paper presents a method for estimating PWV from the digital volume pulse (DVP), a waveform that can be rapidly and simply acquired by measuring the transmission of infra-red light through the finger pulp. PWV and DVP were measured on 461 subjects attending a clinic in South East London. Techniques for extracting features from the DVP contour based on physiology and information theory were compared. Low and high stiffness were defined according to a threshold level of PWV chosen to be 10 m/s. Using a support vector machine-based classifier, it is possible to achieve high overall classification rates on unseen data. Further, the use of support vector regression techniques lead to a direct real-valued estimate of PWV which outperforms previous methods based on multilinear regression. We, therefore, conclude that support vector machine-based classification and regression techniques provide effective prediction of arterial stiffness from the simple measurement of the digital volume pulse. This technique could be usefully employed as a cheap and effective CVD screening technique for use in general practice clinics.

Assessment of the Vascular Effects of PC6 (Neiguan) Using the Second Derivative of the Finger Photoplethysmogram in Healthy and Hypertensive Subjects

Indices obtained from the second derivative of the digital volume pulse waveform have been proposed to characterize vascular aging, arterial rigidity, and the effects of vasoactive drugs. The purpose of this study was to assess the effects of manual needling of PC6 on SD(DVP) indices in healthy and untreated hypertensive subjects. AI, B:A, and D:A indices, based on the height of the wave components of SD(DVP), in 40 healthy subjects and 25 untreated hypertensive subjects were compared. DVP was obtained by measuring infrared light transmission through the finger. For each subject, 20-min-long DVP registration was obtained. PC6 was stimulated unilaterally by manual needling for 5 min (1-6 min). In each subject, pre-acupuncture DVP indices were compared to those of during acupuncture (1 vs. 4 min) and post-acupuncture (1 vs. 18 min). In healthy subjects, AI was significantly improved when comparing the pre- to the post-acupuncture values. In hypertensive subjects, the SD(DVP) indices improved significantly as follows: the AI index when the value of pre-acupuncture comparing to that of during acupuncture and post-acupuncture values; B:A and D:A indices when the pre-comparing to post-acupuncture values. There were significant differences between healthy and hypertensive subjects in AI, B:A, and D:A at baseline and in B:A in the during acupuncture period; there were no significant differences at post-acupuncture. These results indicate that manual needling of PC6 produced acute effects on vascular pathophysiology. Moreover, PC6 needling produced changes in SD(DVP) indices related to both large artery stiffness and the reflected wave originating in small arteries.