Pulse Waveform Characteristics Research Articles

Using the Characteristics of Pulse Waveform to Enhance the Accuracy of Blood Pressure Measurement by a Multi-Dimension Regression Model

With the advancement of wearable technology, many physiological monitoring instruments are gradually being converted into wearable devices. However, as a consumer product, the blood pressure monitor is still a cuff-type device, which does perform a beat-by-beat continuous blood pressure measurement. Consequently, the cuffless blood pressure measurement device was developed and it is based on the pulse transit time (PTT), although its accuracy remains inadequate. According to the cardiac hemodynamic theorem, blood pressure relates to the arterial characteristics and the contours of the pulse wave include some characteristics of the artery. Therefore, the purpose of this study was to use the contour characteristics of the pulses measured by photoplethysmography (PPG) to estimate the blood pressure using a linear multi-dimension regression model. Ten subjects participated in the experiment, and the blood pressure levels of the subjects were elevated by exercise. The results showed that the mean and standard deviation (mean ± SD) of the root mean square error of the estimated systolic and diastolic pressures within the best five parameters were 6.9 ± 2.81 mmHg and 4.0 ± 0.65 mmHg, respectively. Compared to the results that used one parameter, the PTT, for estimating the systolic and diastolic pressures, 8.2 ± 2.1 mmHg and 4.5 ± 0.79 mmHg, respectively, our results were better.

Effects of Bio-Impedance Sensor Placement Relative to the Arterial Sites for Capturing Hemodynamic Parameters.

Accurate measurement of the heart pulse waveform based on blood volume changes inside the arteries is crucial for reliable estimation of hemodynamic parameters such as blood pressure and cardiac output. Placement of blood volume sensors such as bio-impedance sensors close to the arterial sites is essential for the accurate measurement of the pulse waveform. The effect of sensor location relative to the wrist arteries on the pulse waveform had not been studied previously on human subjects. In this paper, we explore the effect of arterial and off-arterial placement of the bio-impedance sensor on important pulse waveform features such as pulse transit time (PTT), which is the travel time of the arterial pressure pulse between two sensors, and diastolic peak error (DPE), a measure of pulse signal sharpness. Placing the current injection and voltage sensing electrodes of a bio-impedance sensor on the radial artery provide greater accuracy for such features. We find that arterial PTT has a significantly lower standard deviation compared to off-arterial PTT indicating better signal quality. Similarly, we observe that DPE is much smaller for arterial bio-impedance which confirms our expectations. Based on these features, the location of the artery can be determined using an array of sensors placed around the artery.

A Non-Invasive Continuous Blood Pressure Estimation Approach Based on Machine Learning.

Considering the existing issues of traditional blood pressure (BP) measurement methods and non-invasive continuous BP measurement techniques, this study aims to establish the systolic BP and diastolic BP estimation models based on machine learning using pulse transit time and characteristics of pulse waveform. In the process of model construction, the mean impact value method was introduced to investigate the impact of each feature on the models and the genetic algorithm was introduced to implement parameter optimization. The experimental results showed that the proposed models could effectively describe the nonlinear relationship between the features and BP and had higher accuracy than the traditional methods with the error of 3.27 ± 5.52 mmHg for systolic BP and 1.16 ± 1.97 mmHg for diastolic BP. Moreover, the estimation errors met the requirements of the Advancement of Medical Instrumentation and British Hypertension Society criteria. In conclusion, this study was helpful in promoting the practical application of methods for non-invasive continuous BP estimation models.

Research on Arterial Stiffness Status in Type 2 Diabetic Patients Based on Pulse Waveform Characteristics

Research on Arterial Stiffness Status in Type 2 Diabetic Patients Based on Pulse Waveform Characteristics

Changes of Arterial Pulse Waveform Characteristics with Gestational Age during Normal Pregnancy

Arterial pulse waveform analysis has been widely used to reflect physiological changes in the cardiovascular system. This study aimed to comprehensively investigate the changes of waveform characteristics of both photoplethysmographic (PPG) and radial pulses with gestational age during normal pregnancy. PPG and radial pulses were simultaneously recorded from 130 healthy pregnant women at seven gestational time points. After normalizing the arterial pulse waveforms, the abscissa of notch point, the total pulse area and the reflection index were extracted and compared between different measurement points and between the PPG and radial pulses using post-hoc multiple comparisons with Bonferrioni correction. The results showed that the effect of gestational age on all the three waveform characteristics was significant (all p < 0.001) after adjusting for maternal age, heart rate and blood pressures. All the three waveform characteristics demonstrated similar changing trends with gestational age, and they were all significantly different between the measurements from gestational week 12–15 and the others (all p < 0.05, except for the PPG total pulse area between the first and second measurement points). In conclusion, this study has comprehensively quantified similar changes of both PPG and radial pulse waveform characteristics with gestational age.

Arterial Pulse Waveform Characteristics Difference between the Three Trimesters of Healthy Pregnant Women.

During pregnancy, the pregnant mother undergoes significant physiological changes in order to accommodate the developing fetus. In recent years, arterial pulse wave has been widely used to reflect these physiological changes. The aim of this study was to investigate the changes of radial pulse and photoplethysmography (PPG) pulse waveform characteristic with gestational age in normal pregnant women. 40 pregnant women volunteers were recruited from February 2016 to September 2016 from the Haidian Maternal & Child Health Hospital in Beijing. Both radial pulses and PPG pulses were recorded simultaneously using a PowerLab data collection system at a sampling rate of 1000Hz for offline analysis. Their pulses were measured from each pregnant woman at three trimesters (first trimester between week 11-13; second trimester between week 20-22 and the third trimester between week 3739). Three waveform characteristics (total pulse area; pulse area1: the area before the notch position; pulse area2: the area after the notch position) were derived. The results showed that the total pulse area and pulse area2 from both radial and PPG pulses decreased significantly between two paired consecutive trimesters (all P<0.01, except the comparisons between the second and third trimesters for PPG pulses). In summary, this study has quantified the pulse waveform characteristic differences in terms of pulse areas between the three trimesters, providing useful scientific evidence to better understand the cardiovascular physiological changes during normal pregnancy.

Real-Time Pulse Waveform Profiling Algorithm for Wearable Applications

A pulse waveform profiling algorithm is introduced for processing real-time photoplethysmography (PPG) data in mobile applications. The real PPG waveform is discriminated from artifacts based on rules of probability distribution and physiological significance. The swift background is removed through a two-step method to minimize its effect on the final waveform analysis: interpolating the midpoint of the amplitude of the PPG AC part and then interpolating the minimum of each pulse period. The pulse waveform features are extracted from the stratified PPG wave data. The implementation of the proposed algorithm in a real-time mobile application demonstrated its high efficiency and robustness with a sensitivity of around 96% and a positive specificity of 100%. The potential applications of these extracted features are discussed in terms of long-term trends in physiology such as circadian and arrhythmia real-time monitoring.

PP.03.12] SIGNIFICANT INTER-ARM DIFFERENCE IN BLOOD PRESSURE IS ASSOCIATED WITH INCREASED ARTERIAL STIFFNESS AND ABDOMINAL OBESITY IN VERY ELDERLY HYPERTENSIVES

Objective: Inter-arm difference in blood pressure (BP) and orthostatic BP response have important prognostic significance in hypertensive patients. However, data on prevalence, predictors and clinical associations of those phenomena are controversial. The aim was to investigate inter-arm difference, orthostatic response and to establish their clinical associations in very elderly hypertensives. Design and method: 67 hypertensive subjects older than 80 years (mean age 84,1 ± 3,1 years, 25,5% male, mean clinic brachial SBP 134,8 ± 23,2 mm Hg) were included in cross-sectional study. Simultaneous bilateral brachial BP measurements were performed using oscillometric validated cuff-based device in supine position and then after 2 minutes of standing. Central pulse waveform characteristics and arterial stiffness parameters were estimated by BPLab Vasotens system. Results: The median of inter-arm difference in SBP (IADSBP) was 4,00 (2,5; 9,0) mm Hg. 25,4% participants had IADSBP of 10 mm Hg and more. Compared to others, those with IADSBP of 10 mmHg and more had significantly higher body mass index (31,4 ± 5,7 vs 28,5 ± 4,1 kg/m2, p < 0,05), waist circumference (116,3 ± 13,6 vs 107,7 ± 11,2 cm, p < 0,05) and pulse wave velocity in aorta (11,7 ± 1,5 vs 10,8 ± 1,7 m/s, p < 0,05). Positive correlation between IADSBP and augmentation index was revealed (r = 0,277, p < 0,05). Patients with asymptomatic orthostatic hypotension (OH) (22,4% participants) had higher levels of brachial SBP and pulse pressure (PP) while central BPs and markers of arterial stiffness did not differ from those without OH. Conclusions: Significant IADSBP is associated with increased arterial stiffness and abdominal obesity in very elderly hypertensive patients, whereas there was no evidence of interrelation between orthostatic response and arterial stiffness in such patients

Quantification of radial arterial pulse characteristics change during exercise and recovery

It is physiologically important to understand the arterial pulse waveform characteristics change during exercise and recovery. However, there is a lack of a comprehensive investigation. This study aimed to provide scientific evidence on the arterial pulse characteristics change during exercise and recovery. Sixty-five healthy subjects were studied. The exercise loads were gradually increased from 0 to 125 W for female subjects and to 150 W for male subjects. Radial pulses were digitally recorded during exercise and 4-min recovery. Four parameters were extracted from the raw arterial pulse waveform, including the pulse amplitude, width, pulse peak and dicrotic notch time. Five parameters were extracted from the normalized radial pulse waveform, including the pulse peak and dicrotic notch position, pulse Area, Area1 and Area2 separated by notch point. With increasing loads during exercise, the raw pulse amplitude increased significantly with decreased pulse period, reduced peak and notch time. From the normalized pulses, the pulse Area, pulse Area1 and Area2 decreased, respectively, from 38 ± 4, 61 ± 5 and 23 ± 5 at rest to 34 ± 4, 52 ± 6 and 13 ± 5 at 150-W exercise load. During recovery, an opposite trend was observed. This study quantitatively demonstrated significant changes of radial pulse characteristics during different exercise loads and recovery phases.

Inter-arm difference and orthostatic changes of brachial blood pressure in the very elderly patients under antihypertensive treatment

Background. Inter-arm difference in blood pressure (BP) and orthostatic BP response are significant prognostic factors in hypertensive patients, especially in the elderly ones. However, data on their prevalence, predictors and clinical associations remain contradictory. The aim of our study was to investigate inter-arm difference and orthostatic response and to establish their clinical associations in the very elderly hypertensive patients. Design and methods. We enrolled 67 hypertensive subjects older than 80 years (mean age 84,1 ± 3,1 years, 25,5 % male, mean clinic brachial systolic BP (SBP) 134,8 ± 23,2 mm Hg) in a cross-sectional study. Simultaneous bilateral brachial BP measurements were performed using oscillometric validated cuffbased device in sitting position and then 2 minutes after standing up. Central pulse waveform characteristics and arterial stiffness parameters were estimated by BPLab Vasotens system (Petr Telegin, Russia). Results. The median of inter-arm difference in SBP (IADSBP) was 4,00 (2,50, 9,00) mm Hg. IADSBP was ≥ 10 mm Hg in 25,4 % participants. Compared to others, those with IADSBP ≥ 10 mmHg had significantly higher body mass index (31,39 ± 5,73 vs 28,48 ± 4,1 kg/m2 , p < 0,05), waist circumference (116,3 ± 13,6 vs 107,7 ± 11,2 cm, p < 0,05) and pulse wave velocity in aorta (11,65 ± 1,46 vs 10,75 ± 1,71 m/s, p < 0,05). A positive correlation between IADSBP and augmentation index was revealed (r = 0,277, p < 0,05). Patients with asymptomatic orthostatic hypotension (22,4 % participants) had higher levels of brachial SBP and pulse pressure while central BP and markers of arterial stiffness did not differ from those without orthostatic hypotension. Conclusions. Significant IADSBP is associated with increased arterial stiffness and abdominal obesity in the very elderly hypertensive patients, whereas there is no evidence of interrelation between orthostatic response and arterial stiffness in these patients.

Influential factors for pressure pulse waveform in healthy young adults.

The effects of gender and other contributory factors on pulse waveform are still under arguments. In view of different results caused by few considerations of possible influential factors and general agreement of gender relating to pulse waveform, this study aims to address the confounding factors interfering with the association between gender and pulse waveform characteristics. A novel method was proposed to noninvasively detect pressure pulse wave and assess the morphology of pulse wave. Forty healthy young subjects were included in the present research. Height, weight, systolic blood pressure (SBP), and diastolic blood pressure (DBP) were measured manually and body mass index (BMI), pulse blood pressure (PP) and heart rate (HR) were calculated automatically. Student's t test was used to analyze the gender difference and analysis of variance (ANOVA) to examine the effects of intrinsic factors. Univariate regression analysis was performed to assess the main factors on the waveform characteristics. Waveform features were found significantly different between genders. However this study indicates that the main factors for time-related and amplitude-related parameters are HR and SBP respectively. In conclusion, the impact of HR and SBP on pulse waveform features should not be underestimated, especially when analyzing the gender difference.

Central arterial pulse waveform acquisition with a portable pen-like optical fiber sensor.

Pulse waveform features related to cardiovascular pathologies and arterial stiffness have been extensively studied, and optical fiber sensors have been studied with an aim to simplify the pulse waveform acquisition in the carotid artery. In this paper, a novel optical fiber sensor to record pulse waveform in the carotid artery has been proposed. The pulse waveform optical fiber sensor design, based on fiber Bragg gratings, is presented. The probe was characterized, and its response to controlled waveforms was studied. Finally, tests were performed on human subjects. The developed sensor has a displacement sensitivity of 21.2 pm/μm, with ability to detect the carotid pulse wave in the neck surface, with a resolution of 1.3 mmHg. This study revealed a new technological approach for acquisition of the central pulse waveform.

Using the dynamics of mouth opening in echolocating bats to predict pulse parameters among individual Eptesicus fuscus

The big brown bat (Eptesicus fuscus) produces echolocation sounds in its larynx and emits them through its open mouth. Individual mouth-opening cycles last for about 50 ms, with the sound produced in the middle, when the mouth is approaching or reaching maximum gape angle. In previous work, the mouth gape-angle at pulse emission only weakly predicted pulse duration and the terminal frequency of the first-harmonic FM downsweep. In the present study, we investigated whether the dynamics of mouth opening around the time of pulse emission predict additional pulse waveform characteristics. Mouth angle openings for 24 ms before and 24 ms after pulse emission were compared to pulse waveform parameters for three big brown bats performing a target detection task. In general, coupling to the air through the mouth seems less important than laryngeal factors for determining acoustic parameters of the broadcasts. Differences in mouth opening dynamics and pulse parameters among individual bats highlight this relation. [Supported by NSF and ONR.]

Comparison of Subjective versus Objective Lower-Extremity Arterial Plethysmographic Waveform Analysis for the Identification of Hemodynamically Significant Inflow Disease

Objective Segmental pressures and subjective air plethysmography waveform (APW) analysis commonly are used in the noninvasive diagnosis of lower-extremity peripheral arterial disease (PAD) and have been used historically to define the extent of PAD. A recent investigation identified objective thigh arterial pulse waveform characteristics for defining hemodynamically significant (&gt;50% diameter) PAD above the level of the common femoral artery (INFLOW). The purpose of this study is to compare subjective and objective APW analysis methodologies for defining INFLOW. Methods Patients who underwent segmental APW analysis and arteriography within 30 days of their noninvasive procedure were studied. Objective APW characteristics obtained from the thigh cuff included acceleration time, maximum amplitude, waveform down-slope curvature, relative amplitude reduction, and gain compensation index. Arteriograms were the basis for comparisons of objective APW criteria versus subjective APW pattern recognition interpretations of INFLOW disease. Results A total of 107 extremities were analyzed. There were statistically significant differences in sensitivity, specificity, positive predictive and negative predictive values, and accuracy for identifying hemodynamically significant INFLOW disease using objective (85%, 93%, 85%, 93%, 91%) versus subjective (53%, 85%, 62%, 80%, 75%) APW analysis, p = 0.0110. Conclusions Objective APW analysis of thigh level waveform characteristics may improve the identification of INFLOW disease in patients undergoing physiologic testing for lower extremity PAD.

Onsite Detection Technology and its Application for Electric Cable Partial Discharge

This paper introduces the electric cable partial discharge detection technology and elaborates pulse waveform characteristics of cable partial discharge, PD signal’s detection theory and basic method of cable PD source localization. On this basis, application examples of substation cable-site detection are given.

Spironolactone to prevent cardiovascular events in early-stage chronic kidney disease (STOP-CKD): study protocol for a randomized controlled pilot trial.

BackgroundChronic kidney disease is associated with increased arterial stiffness even in the early stages and this is thought to be a key mediator in the pathophysiology of the increased cardiovascular risk associated with this condition. The use of low-dose spironolactone has previously been shown to improve arterial stiffness and reduce left ventricular mass safely in early-stage chronic kidney disease in the context of careful monitoring at a university hospital. However, the majority of patients with chronic kidney disease are managed by their general practitioners in the community. It is not known whether similar beneficial effects can be achieved safely using spironolactone in the primary care setting. The aim of this study is to determine whether low-dose spironolactone can safely lower arterial stiffness in patients with stage 3 chronic kidney disease in the primary care setting.Methods/designSTOP-CKD is a multicentre, prospective, randomized, double-blind, placebo-controlled pilot trial of 240 adult patients with stage 3 chronic kidney disease recruited from up to 20 general practices in South Birmingham, England. Participants will be randomly allocated using a secured web-based computer randomization system to receive either spironolactone 25 mg once daily or a matching inactive placebo for 40 weeks, followed by a wash-out period of 6 weeks. Investigators, outcome assessors, data analysts and participants will all be blinded to the treatment allocation. The primary endpoint is improved arterial stiffness, as measured by carotid-femoral pulse wave velocity between baseline and 40 weeks. The secondary endpoints are incidence of hyperkalaemia, change in estimated glomerular filtration rate, change in urine albumin:creatinine ratio, change in brachial blood pressure, change in pulse waveform characteristics and overall tolerability of spironolactone. An additional quality control study, aiming to compare the laboratory serum potassium results of samples processed via two methods (utilizing routine transport or centrifugation on site before rapid transport to the laboratory) for 100 participants and a qualitative research study exploring patients’ and general practitioners’ attitudes to research and the use of spironolactone in chronic kidney disease in the community setting will be embedded in this pilot study.Trial registrationCurrent Controlled Trials ISRCTN80658312.

Central pulse pressure amplification is associated with more extensive and severe coronary artery disease

Objectives. We investigate the association between noninvasively determined central pulse waveform characteristics and the extent and severity of coronary artery disease (CAD) in patients undergoing coronary angiography with the clinical diagnosis of CAD. Design. We included 145 consecutive patients with stable angina pectoris (SAP), unstable angina pectoris (USAP), or acute myocardial infarction (AMI) who were decided to undergo coronary angiography. Gensini and SYNTAX scores were calculated. Noninvasive PWA was performed with the SphygmoCor system. Results. Dividing the patients into tertiles according to augmentation index (AIx), more patients had significant CAD with higher Gensini and SYNTAX scores and lower myocardial blush grade (MBG) (p < 0.001 for all) in the third tertile. The AIx value to predict the presence of moderate to severe CAD as determined by SYNTAX score ≥ 23 was 24.45% (ROC analysis AUC: 0.96; sensitivity 88%, specificity: 93%, 95% CI: 0.93–0.99, p < 0.001). AIx was significantly correlated with Gensini and SYNTAX scores in SAP, USAP, and AMI patients after adjusting for age, gender, height, heart rate, hypertension, and diabetes. Conclusions. Increased AIx is associated with the presence and severity of CAD, and it may be used in selected patients during cardiovascular evaluation in outpatient settings for risk stratification prior to coronary angiography.

The effects of the shape of localized defect in ball bearings on the vibration waveform

Ball bearings, one of the most widely used components in rotating machinery, play a critical role in system performance. Localized defects such as pit and spall may develop in ball bearings during service. The vibration waveform of the impulse generated by a ball passing over a defect on the races is determined by the shape and size of the localized defect. Hence, it is important to study the relationship between the localized defect shape and its pulse waveform characteristics in order to diagnose the types of defect in bearings. This study examines the effects of the defect shape, radial load and shaft speed on the pulse waveform characteristics generated by localized defects using the method of explicit dynamic finite element analysis. To validate the proposed model, the results obtained from the experiments have also been provided, and the waveform and the duration of the pulse generated by the defect on the outer race are in good agreement with the simulation results, which shows validation of the proposed model. Both the experimental results and the simulation results have confirmed that the impulse shape generated by the defect on the raceway will be influenced by the contact deformations at the edges of the defect. The results obtained also demonstrate that the explicit dynamic finite element analysis approach can be used to analyze the pulse waveform characteristic generated by localized defects in ball bearings.

Brachial pulse waveform characteristics predict development of organ failure in septic patients

Pulse waveform characteristics (pulse wave transit time and augmentation index) are measures of arterial stiffness. Previous studies have found an association between severity of acute inflammatory states and increased arterial stiffness but it is not known whether non-invasive pulse waveform analysis could predict development of multiple organ failure in septic patients. The purpose of this study was to evaluate the photoplethysmographic brachial artery pulse wave transit time and augmentation index and their changes in response to induced forearm ischemia in septic ICU patients and correlate these indices to the development of subsequent end organ damage.

Reflections on determinants of augmentation index

Reflections on determinants of augmentation index