Limited value of pulse wave analysis in assessing arterial wave reflection and stiffness in the pulmonary artery.

We explored the use of the augmentation index (AI) based on pulse wave analysis (PWA) in the pulmonary circulation as a measure of wave reflection and arterial stiffness in individuals with and without pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH). Right heart catheterization was performed using a pressure and Doppler flow sensor-tipped catheter to obtain simultaneous pressure and flow velocity measurements in the pulmonary artery in 10 controls, 11 PAH patients, and 11 CTEPH patients. PWA was applied to the measured pressure, while wave intensity analysis (WIA) and wave separation analysis (WSA) were performed using both the pressure and velocity to determine the magnitudes and timings of reflected waves. Type C (AI < 0) pressure waveform dominated in controls and type A (AI > 12%) waveform dominated in PAH patients, while there was a mixture of types A, B, and C among CTEPH patients. AI was greater and the inflection time shorter in CTEPH compared to PAH patients. There was a poor correlation between AI and arterial wave speed as well as measures of wave reflection derived from WIA and WSA. The infection point did not match the timing of the backward compression wave in ~50% of the cases. In patients with type C waveforms, the inflection time correlated well to the timing of the late systolic forward decompression wave caused by ventricular relaxation. In conclusion quantifying pulmonary arterial wave reflection and stiffness using AI based on PWA may be inaccurate and should therefore be discouraged.

Establishing normal reference value of carotid ultrafast pulse wave velocity and evaluating changes on coronary slow flow.

Pulse wave velocity (PWV) measured by ultrafast ultrasound imaging can early evaluate arteriosclerosis. The study aimed to establish normal reference range for ufPWV in healthy adults and explore its influencing factors, and evaluate the ufPWV changes on coronary slow flow (CSF). ufPWV at the beginning and end of systole (ufPWV-BS and ufPWV-ES, respectively) was measured in healthy adults (201 cases). CSF was diagnosed based on thrombolysis in myocardial infarction (TIMI) frame count during coronary angiography. ufPWV-BS and ufPWV-ES were compared between CSF (50 cases) and control groups (50 healthy age-, body mass index-, and blood pressure-matched adults). In healthy adults, average ufPWV-BS and ufPWV-ES was 5.36 ± 1.27 m/s and 6.99 ± 1.93 m/s, respectively. ufPWV-BS and ufPWV-ES positively correlated with age, body mass index, and blood pressure. ufPWV-BS and ufPWV-ES in the CSF group were higher than in the control group (ufPWV-BS, 6.05 ± 1.07 vs. 5.26 ± 0.89 m/s, P < 0.001; ufPWV-ES, 9.07 ± 1.84 vs. 6.84 ± 1.08 m/s, P < 0.001). Receiver operating characteristic curves showed that ufPWV-ES was more sensitive than ufPWV-BS. The normal reference range of ufPWV for healthy adults was established. Age, body mass index, and blood pressure were the main influencing factors. ufPWV was increased in the patients with CSF. The findings indicated that, in addition to reflecting atherosclerosis, ufPWV might also provide a basis for the noninvasive evaluation of microvascular impairment in the patients with CSF.

Repeatability and reproducibility of pulse wave velocity in relation to hemodynamics and sodium excretion in stable patients with hypertension.

OBJECTIVE: Pulse wave velocity (PWV) is a useful marker for determining subclinical vascular damage and patient risk stratification. Repeatability and reproducibility of PWV in relation to influencing factors have not yet been determined. This study examined the repeatability and reproducibility of PWV, and whether hemodynamics and sodium excretion impact on PWV in hypertensive patients remaining on stable medication. METHODS: Office blood pressure (BP), heart rate (HR), carotid--femoral PWV and central BP (SphygmoCor device), impedance cardiography (HOTMAN device) and 24-h urinary sodium excretion (UNa) were measured at baseline and after 4 weeks in 74 hypertensive patients (age 56.8 ±â€Š11.5 years, mean ±â€ŠSD). Two PWV measurements were performed at each visit. RESULTS: Intraclass correlation coefficient (ICC) and 95% confidence interval (95% CI) between the two PWV measurements were 0.981 (0.970--0.988) at baseline, 0.975 (0.960--0.984) after 4 weeks and 0.851 (0.773--0.903) between both visits. There were no significant changes in BP, HR, thoracic fluid content, stroke volume and UNa between visits. Despite excellent ICC, reproducibility of PWV was related to BP (P < 0.001) and HR (P = 0.07) changes between visits. Nineteen out of 74 patients had a difference in PWV greater than ±1 m/s between both visits. CONCLUSION: In the medium-term observation, changes in BP and HR seem to affect PWV values. Our findings suggest that the assessment of PWV should be performed under stabilized BP and HR values, particularly in patients with newly diagnosed hypertension and/or low--moderate cardiovascular risk in whom the detection of asymptomatic hypertension-mediated organ damage impact on patient risk stratification.

Reference pulse wave velocity values in a healthy, normotensive Turkish population.

OBJECTIVE: Pulse wave velocity (PWV) is the primary determiner of arterial stiffness. In daily practice, the normal range of arterial stiffness is based on large multi-center studies conducted in the USA, Europe, Asia, and Australia. The goal of this study was to identify the reference values of brachial PWV in a healthy, normotensive Turkish population with no cardiovascular risk factors. METHODS: This retrospective study involved healthy, adult Turkish participants from Ankara. A total of 353 consecutive, normotensive individuals were enrolled in the study between September 2017 and January 2018 according to strict inclusion criteria, Normal PWV and 95% confidence interval values were acquired for 353 patients (mean age: 55.03±15.38 years; range: 20-95 years) who were divided into 6 age groups. RESULTS: The mean PWV was 7.75±1.89 m/s (range: 4.25- 15.90 m/s). The PWV had a positive linear correlation with age (r2=0.94; p=0.00). The PWV increased gradually by an average of 5% to 9% with each decade of life until the age of 50 years, after which the average PWV increased by 16%. CONCLUSION: To the best of our knowledge, this study is the first to define PWV reference values via brachial measurement in a healthy, normotensive Turkish population. These data provide important information for daily clinical practice in Turkey.

Artifacts in pulse transit time measurements using standard patient monitoring equipment.

OBJECTIVE: Pulse transit time (PTT) refers to the time it takes a pulse wave to travel between two arterial sites. PTT can be estimated, amongst others, using the electrocardiogram (ECG) and photoplethysmogram (PPG). Because we observed a sawtooth artifact in the PTT while using standard patient monitoring equipment for ECG and PPG, we explored the reasons for this artifact. METHODS: PPG and ECG were simulated at a heartrate of both 100 and 160 beats per minute while using a Masimo PPG post-processing module and a Philips patient monitor setup at the neonatal intensive care unit. Two different post-processing modules were used. PTT was defined as the difference between the R-peak in the ECG and the point of 50% increase in the PPG. RESULTS: A sawtooth artifact was seen in all simulations. Both length (59.2 to 72.4 s) and amplitude (30.8 to 36.0 ms) of the sawtooth were dependent on the post-processing module used. Furthermore, the absolute PTT value differed up to 250 ms depending on post-processing module and heart rate. The sawtooth occurred because the PPG wave continuously showed a minimal prolongation during the length of the sawtooth, followed by a sudden shortening. Both artifacts were generated in the post-processing module containing Masimo algorithms. CONCLUSION: Post-processing of the PPG signal in the Masimo module of the Philips patient monitor introduces a sawtooth in PPG and derived PTT. This sawtooth, together with a large module-dependent absolute difference in PTT, renders the thus-derived PTT insufficient for clinical purposes.

A Noninvasive, Economical, and Instant-Result Method to Diagnose and Monitor Type 2 Diabetes Using Pulse Wave: Case-Control Study.

BACKGROUND: We should pay more attention to the long-term monitoring and early warning of type 2 diabetes and its complications. The traditional blood glucose tests are traumatic and cannot effectively monitor the development of diabetic complications. The development of mobile health is changing rapidly. Therefore, we are interested in developing a new noninvasive, economical, and instant-result method to accurately diagnose and monitor type 2 diabetes and its complications. OBJECTIVE: We aimed to determine whether type 2 diabetes and its complications, including hypertension and hyperlipidemia, could be diagnosed and monitored by using pulse wave. METHODS: We collected the pulse wave parameters from 50 healthy people, 139 diabetic patients without hypertension and hyperlipidemia, 133 diabetic patients with hypertension, 70 diabetic patients with hyperlipidemia, and 75 diabetic patients with hypertension and hyperlipidemia. The pulse wave parameters showing significant differences among these groups were identified. Various machine learning models such as linear discriminant analysis, support vector machines (SVMs), and random forests were applied to classify the control group, diabetic patients, and diabetic patients with complications. RESULTS: There were significant differences in several pulse wave parameters among the 5 groups. The parameters height of tidal wave (h3), time distance between the start point of pulse wave and dominant wave (t1), and width of percussion wave in its one-third height position (W) increase and the height of dicrotic wave (h5) decreases when people develop diabetes. The parameters height of dominant wave (h1), h3, and height of dicrotic notch (h4) are found to be higher in diabetic patients with hypertension, whereas h5 is lower in diabetic patients with hyperlipidemia. For detecting diabetes, the method with the highest out-of-sample prediction accuracy is SVM with polynomial kernel. The algorithm can detect diabetes with 96.35% accuracy. However, all the algorithms have a low accuracy when predicting diabetic patients with hypertension and hyperlipidemia (below 70%). CONCLUSIONS: The results demonstrated that the noninvasive and convenient pulse-taking diagnosis described in this paper has the potential to become a low-cost and accurate method to monitor the development of diabetes. We are collecting more data to improve the accuracy for detecting hypertension and hyperlipidemia among diabetic patients. Mobile devices such as sport bands, smart watches, and other diagnostic tools are being developed based on the pulse wave method to improve the diagnosis and monitoring of diabetes, hypertension, and hyperlipidemia.

Comparison of arterial stiffness indices measured by pulse wave velocity and pulse wave analysis.

OBJECTIVE: Arterial stiffness indices measured by pulse wave velocity and pulse wave analysis have been widely studied in different populations. Only a few small studies have been reported regarding these two measurement methods. Therefore, the aim of our study was to compare the arterial stiffness indices measured by pulse wave velocity and pulse wave analysis in a randomly selected Chinese population. METHODS: A total of 4285 subjects were recruited from Gaoyou County, Jiangsu Province, China. There were 2017 (47.1%) participants with hypertension. Pulse wave velocity was assessed by using a VP-1000 Automatic Arteriosclerosis Measurement System. Large artery elasticity and small artery elasticity were measured by pulse wave analysis with an HDI/PulseWave CR-2000 Research CardioVascular Profiling System using the modified Windkessel model. RESULTS: Brachial-ankle pulse wave velocity, large artery elasticity and small artery elasticity were all significantly associated with the Framingham risk score (r = 0.588, -0.387, -0.448; p < .001). Brachial-ankle pulse wave velocity was correlated with both large artery elasticity (r = -0.486, p < .001) and small artery elasticity (r = -0.455, p < .001). In the receiver operating characteristic analysis, brachial-ankle pulse wave velocity [0.834, 95% confidence interval (0.821-0.845)] had a significantly larger area under the curve than both large artery elasticity [0.701, (0.684-0.715)] and small artery elasticity [0.696, (0.678-0.709)]. CONCLUSION: Brachial-ankle pulse wave velocity is significantly correlated with both large artery elasticity and small artery elasticity. The brachial-ankle pulse wave velocity measurement has a better predictive value for hypertension than the large artery elasticity and small artery elasticity measurements. What is new? We investigated the associations between brachial-ankle pulse wave velocity, large artery elasticity and small artery elasticity and compared the values of these indices for predicting hypertension for the first time in a randomly selected large population. What is relevant? Brachial-ankle pulse wave velocity was closely associated with large artery elasticity and small artery elasticity. The brachial-ankle pulse wave velocity measurement was a sensitive test for predicting hypertension in the study population when compared to large artery elasticity and small artery elasticity readings. SUMMARY: The present study confirms that brachial-ankle pulse wave velocity is significantly correlated with small and large arterial compliance and is a superior method of diagnosing hypertension compared to large artery elasticity and small artery elasticity.

Current assessment of pulse wave velocity: comprehensive review of validation studies.

OBJECTIVE: Carotid-femoral pulse wave velocity (PWV) is considered the gold standard for arterial stiffness assessment in clinical practice. A large number of devices to measure PWV have been developed and validated. We reviewed different validation studies of PWV estimation techniques and assessed their conformity to the Artery Society Guidelines and the American Heart Association recommendations. METHODS: Pubmed and Medline (1995-2017) were searched to identify PWV validation studies. Of the 96 article retrieved, 26 met the inclusion criteria. RESULTS: Several devices had been developed and validated to noninvasively measure arterial stiffness, using applanation tonometry (SphygmoCor, PulsePen), piezoelectric mechanotransducers (Complior), cuff-based oscillometry (Arteriograph, Vicorder and Mobil-O-Graph), photodiode sensors (pOpmètre) and devices assessing brachial-ankle pulse wave velocity and cardiac-ankle PWV. Ultrasound technique and MRI remain confined to clinical research. Good agreement was found with the Artery Society Guidelines. Two studies (Complior, SphygmoCor Xcel) showed best adherence with the guidelines. In Arteriograph, MRI, ultrasound and SphygmoCor Xcel validation studies sample size was smaller than the minimum suggested by the guidelines. High discrepancies between devices were shown in distance estimation: in two studies (Arteriograph, Complior) path length was estimated in conformity to the guidelines. Transit time was calculated using the intersecting tangent method, but in two studies (Vicorder, pOpmètre) best agreement was found using the maximum of the second derivative. Six studies reached the accuracy level 'excellent' defined in the Artery guidelines. CONCLUSION: Method to assess transit time and path length need validation in larger populations. Further studies are required in different risk population to implement clinical applicability of every device.

Pulse wave analysis using the Mobil-O-Graph, Arteriograph and Complior device: a comparative study.

PURPOSE: Pulse wave velocity (PWV) is a marker of arterial stiffness with major prognostic value. We compared Arteriograph and Complior devices with the Mobil-O-Graph for assessment of PWV and central systolic blood pressure (cSBP). MATERIALS AND METHODS: We studied 316 consecutive subjects (age: 55 ± 14 years). For each individual, we measured PWV and cSBP with Arteriograph, Complior and Mobil-O-Graph and compared the readings. Differences in values among three devices were calculated for each measurement. We used Bland-Altman analysis, intraclass correlation coefficient (ICC) and coefficient of variation (CV). RESULTS: Bland-Altman analysis indicated a mean difference for PWV: i.0.5 m/s (limits of agreement -1.4-2.4) between Complior and Mobil-O-Graph, ii.0.6 m/s (limits of agreement -1.4-2.6) between Arteriograph and Mobil-O-Graph. cSBP mean difference was 3.8 mmHg between Complior and Mobil-O-Graph (limits of agreement -12.5-20.1) and 9.2 mmHg between Arteriograph and Mobil-O-Graph (limits of agreement -7.6-26). ICC for PWV was 0.86 between Arteriograph and Mobil-O-Graph, 0.87 between Complior and Mobil-O-Graph and for cSBP 0.92 and 0.91 respectively. CV for PWV was 9.5% between Arteriograph and Mobil-O-Graph, 8.8% between Complior and Mobil-O-Graph. Respective values for cSBP were 6.8% and 5.1%. CONCLUSION: Our study shows acceptable agreement among the three devices regarding pulse wave analysis markers though Mobil-O-Graph appears to underestimate the values of these markers. Further studies are needed to explore the agreement between the 3 devices in various clinical settings and patient populations.

Obesity, High Blood Pressure, and Physical Activity Determine Vascular Phenotype in Young Children.

Cardiovascular disease often develops during childhood, but the determinants of vascular health and disease in young children remain unclear. The study aimed to investigate the association of obesity and hypertension, as well as physical fitness with retinal microvascular health and large artery stiffness, in children. In this cross-sectional study, 1171 primary school children (aged 7.2±0.4 years) were screened for central retinal arteriolar equivalent (CRAE) and central retinal venular equivalent (CRVE) diameters, pulse wave velocity (PWV), body mass index, blood pressure (BP), and cardiorespiratory fitness by standardized procedures for children. BP was categorized according to the reference values of the population-based German KiGGS study (Kinder- und Jugendgesundheitssurvey [Children- and Adolescents Health Survey]) and the American Academy of Pediatrics guidelines. Overweight (mean [95% CI]: CRAE, 200.5 [197.9-203.2] µm; CRVE, 231.4 [228.6-234.2] µm; PWV, 4.46 [4.41-4.52] m/s) and obese children (CRAE, 200.5 [196.4-204.7] µm; CRVE, 233.3 [229.0-237.7] µm; PWV, 4.51 [4.43-4.60] m/s) had narrower CRAE, wider CRVE, and higher PWV compared with normal-weight children (CRAE: 203.3 [202.5-204.1] µm, P<0.001; CRVE: 230.1 [229.1-230.9] µm, P=0.07; PWV: 4.33 [4.31-4.35] m/s, P<0.001). Children with high-normal BP (CRAE, 202.5 [200.0-205.0] µm; PWV, 4.44 [4.39-4.49] m/s) and BP in the hypertensive range (CRAE, 198.8 [196.7-201.0] µm; PWV, 4.56 [4.51-4.60] m/s) showed narrower CRAE, as well as higher PWV, compared with normotensive peers (CRAE: 203.7 [202.9-204.6] µm, P<0.001; PWV: 4.30 [4.28-4.32] m/s, P<0.001). With each unit increase of body mass index and systolic BP, CRAE decreased and PWV increased significantly. Children with the highest cardiorespiratory fitness had wider CRAE, narrower CRVE, and lower PWV compared with least fit children. Childhood obesity and hypertension, even at preclinical stages, are associated with microvascular and macrovascular impairments in young children. Primary prevention programs targeting physical activity behavior may have the potential to counteract development of small and large vessel disease early in life. Clinical Trial Registration- URL: http://www.clinicaltrials.gov . Unique identifier: NCT02853747.

Clinical Implications of the Revised AAP Pediatric Hypertension Guidelines.

BACKGROUND AND OBJECTIVES: New pediatric hypertension definitions were recently published in a clinical practice guideline (CPG). We evaluated the impact of the CPG, compared with the previous guideline ("Fourth Report on the Diagnosis, Evaluation, and Treatment of High Blood Pressure in Children and Adolescents"), on the prevalence of hypertension and associations with target organ damage (TOD) in high-risk youth. METHODS: Participants (10-18 years old) undergoing an evaluation of the cardiovascular effects of obesity and type 2 diabetes mellitus in youth were studied. Blood pressure was categorized according to the 2 guidelines as normal, elevated, and hypertension (stages 1 and 2). Measures of TOD (carotid artery intima-media thickness, pulse wave velocity, left ventricular mass, and diastolic function) were obtained. Associations between blood pressure categories and TOD and the sensitivity of hypertension classification in identifying TOD were evaluated. RESULTS: Data were available for 364 participants (65% female sex; 15.1 ± 2.1 years of age). Hypertension was identified in 8% and 13% as defined in the Fourth Report and CPG, respectively (P = .007). The 2 guidelines revealed similar associations with TOD; however, the CPG demonstrated improved sensitivity of TOD detection in hypertensive participants. For example, the proportion of participants with an abnormal left ventricular mass categorized as hypertensive increased from 20% to 31% as defined in the Fourth Report and CPG, respectively (P < .001). CONCLUSIONS: Incorporation of the CPG increased the prevalence of pediatric hypertension in a population of high-risk youth and improved the sensitivity of TOD identification in hypertensive participants.

Estimation of Cardiovascular Risk Predictors from Non-Invasively Measured Diametric Pulse Volume Waveforms via Multiple Measurement Information Fusion.

This paper presents a novel multiple measurement information fusion approach to the estimation of cardiovascular risk predictors from non-invasive pulse volume waveforms measured at the body's diametric (arm and ankle) locations. Leveraging the fact that diametric pulse volume waveforms originate from the common central pulse waveform, the approach estimates cardiovascular risk predictors in three steps by: (1) deriving lumped-parameter models of the central-diametric arterial lines from diametric pulse volume waveforms, (2) estimating central blood pressure waveform by analyzing the diametric pulse volume waveforms using the derived arterial line models, and (3) estimating cardiovascular risk predictors (including central systolic and pulse pressures, pulse pressure amplification, and pulse transit time) from the arterial line models and central blood pressure waveform in conjunction with the diametric pulse volume waveforms. Experimental results obtained from 164 human subjects with a wide blood pressure range (systolic 144 mmHg and diastolic 103 mmHg) showed that the approach could estimate cardiovascular risk predictors accurately (r ≥ 0.78). Further analysis showed that the approach outperformed a generalized transfer function regardless of the degree of pulse pressure amplification. The approach may be integrated with already available medical devices to enable convenient out-of-clinic cardiovascular risk prediction.

Pulse wave analysis reproducibility with the Complior Analyse device: a methodological study.

INTRODUCTION: The aim of this study was to assess the interobserver and intraobserver reproducibility, as well as the temporal variability of the new Complior Analyse assessing central arterial hemodynamic parameters through carotid pulse wave analysis (PWA). PATIENTS AND METHODS: Eighty-seven (60% men) participants, with a mean age of 34.26±16.58 years, were enrolled in a cross-sectional study. All patients were subjected to sequential measures of carotid PWA by two experienced operators. In a group of 27 patients, PWA was also determined 1 month after the first evaluation to address the temporal stability of the PWA estimations with the device. RESULTS: The analysis of concordance revealed a very good agreement for paired PWA values, regarding both intraobserver variability and interobserver variability and also the temporal variability. Intraclass correlation coefficients above 0.9 were calculated for central systolic blood pressure, central pulse pressure, and the augmentation index, in all three conditions. Small mean differences for intraobserver, interobserver, and temporal reproducibility were also observed for the three major parameters: -0.5 mmHg [limits of agreement (LOA): 9.1;8.1], 0.1 mmHg (LOA: 6.6;6.8), and -0.3 mmHg (LOA: 10.2;9.6), respectively, for central systolic blood pressure; 0.4 mmHg (LOA: 6.2;6.9), 1.0 mmHg (LOA: 6.0;8.1), and -0.4 mmHg (LOA: 6.7;6.1), respectively, for central pulse pressure; and 0.8% (LOA: 14.0;15.5), 0.1% (LOA: 15.6;15.9), and -0.1% (LOA: 16.2;16.1), respectively, for the augmentation index. The observed correlations were independent of sex, age, arterial pressure, heart rate, and BMI. CONCLUSION: The data demonstrated an excellent reproducibility of the Complior Analyse for the assessment of central hemodynamic parameters, when used in ideal conditions and by experienced observers. The results demonstrates that this device is suitable for the inclusion in integrated clinical follow-up programs, particularly regarding central arterial pressure estimations.

Reference intervals and percentiles for carotid-femoral pulse wave velocity in a healthy population aged between 9 and 87 years.

There is little information regarding age-related reference intervals (RIs) of carotid-femoral pulse wave velocity (cfPWV) for large healthy populations in South America. The aims of this study were to determine cfPWV RIs and percentiles in a cohort of healthy children, adolescents, and adults and to generate year-to-year percentile curves and body-height percentile curves for children and adolescents. cfPWV was measured in 1722 healthy participants with no cardiovascular risk factors (9-87 years, 60% men). First, RIs were evaluated for males and females through correlation and covariate analysis. Then, mean and standard deviation age-related equations were obtained for cfPWV using parametric regression methods based on fractional polynomials and age-specific (year-to-year) percentile curves that were defined using the standard normal distribution. Age-specific first, 2.5th, 5th, 10th, 25th, 50th, 75th, 90th, 95th, 97.5th, and 99th percentile curves were calculated. Finally, height-related cfPWV percentile curves for children and adolescents (<21 years) were established. After adjusting for age and blood pressure differences with respect to females, males showed higher cfPWV levels (6.60 vs 6.45 m/s; P < .01). Thus, specific RIs for males and females were reported. The study provides the largest database to date concerning cfPWV in healthy people from Argentina. Specific RIs and percentiles of cfPWV are now available according to age and sex. Specific percentiles of cfPWV according to body height were reported for people younger than 21 years.

Toward Ubiquitous Blood Pressure Monitoring via Pulse Transit Time: Predictions on Maximum Calibration Period and Acceptable Error Limits.

OBJECTIVE: Pulse transit time (PTT) is being widely pursued for ubiquitous blood pressure (BP) monitoring. PTT-based systems may require periodic cuff calibrations but can still be useful for hypertension screening by affording numerous out-of-clinic measurements that can be averaged. The objective was to predict the maximum calibration period that would not compromise accuracy and acceptable error limits in light of measurement averaging for PTT-based systems. METHODS: Well-known mathematical models and vast BP data were leveraged. Models relating PTT, age, and gender to BP were employed to determine the maximum time period for the PTT-BP calibration curve to change by <1 mmHg over physiological BP ranges for each age and gender. A model of within-person BP variability was employed to establish the screening accuracy of the conventional cuff-based approach. These models were integrated to investigate the screening accuracy of the average of numerous measurements of a PTT-based system in relation to the accuracy of its individual measurements. RESULTS: The maximum calibration period was about 1 year for a 30 year old and declined linearly to about 6 months for a 70 year old. A PTT-based system with a precision error of >12 mmHg for systolic BP could achieve the screening accuracy of the cuff-based approach via measurement averaging. CONCLUSION: This theoretical study indicates that PTT-based BP monitoring is viable even with periodic calibration and seemingly high measurement errors. SIGNIFICANCE: The predictions may help guide the implementation, evaluation, and application of PTT-based BP monitoring systems in practice.

A Literature Review on Current and Proposed Technologies of Noninvasive Blood Pressure Measurement.

BACKGROUND: Noninvasive continuous blood pressure (BP) measurement has become an evolving topic in the field of remote healthcare. The classical noninvasive BP measurement techniques provide spontaneous values of systolic and diastolic BP. On the other hand, intrusive type BP measurement techniques provide continuous values of systolic and diastolic BP. However, these techniques are very painful, cannot be used for long-term monitoring, and are obtainable only in an intensive care unit environment. With the advancement of the remote healthcare industry, there is a growing demand for noninvasive continuous BP monitoring. OBJECTIVE: The objective of this research was to present a compact literature review on the various prospective approaches of noninvasive continuous BP measurement techniques. MATERIALS & METHODS: The most contemporary and advanced technologies on noninvasive continuous BP measurement are Tactile Sensing, Vascular Unloading Technique, Pulse Transit Time, Photoplethysmography, Ultrasound-based BP measurement, BP measurement from image processing, etc. The literature search based on these technologies was conducted in EMBASE, Web of Science, IEEE, PubMed, and Ovid MEDLINE databases. In this study, each selected approach was evaluated and characterized using the following criteria: (1) accuracy; (2) cost; (3) portability; (4) comfort and convenience of use; (5) clinical health and safety; and (6) ability to integrate with the remote healthcare system. RESULTS: A detailed technical analysis was done to determine the advantages and limitations of each technique in the context of the abovementioned parameters. It was observed that BP measurement, using photoplethysmography (using camera or sensor or both), perhaps was the most promising technique among all. CONCLUSION: The study emphasized the fact that the noninvasive, continuous BP measurement technique needs to evolve further to make it reliable, accurate, and user-friendly. Lastly, a possible direction toward a more reliable and comfortable noninvasive continuous BP measurement technique has been discussed.

Accuracy, Precision, and Trending of 4 Pulse Wave Analysis Techniques in the Postoperative Period.

OBJECTIVE: The aim of this study was to analyze the accuracy, precision, and trending ability of the following 4 pulse wave analysis devices to measure continuous cardiac output: PiCCO2 ([PCCO]; Pulsion Medical System, Munich, Germany); LiDCORapid ([LCCO]; LiDCO Ltd, London, UK); FloTrac/Vigileo ([FCCO]; Edwards Lifesciences, Irvine, CA); and Nexfin ([NCCO]; BMEYE, Amsterdam, The Netherlands). DESIGN: Prospective, observational clinical study. SETTING: Intensive care unit of a single-center, teaching hospital. PARTICIPANTS: The study comprised 22 adult patients after elective coronary artery bypass surgery. INTERVENTIONS: Three measurement cycles were performed in all patient durings their immediate postoperative intensive care stay before and after fluid loading. Hemodynamic measurements were performed 5 minutes before and immediately after the administration of 500 mL colloidal fluid over 20 minutes. MEASUREMENTS AND MAIN RESULTS: PCCO, LCCO, FCCO, and NCCO were assessed and compared with cardiac output derived from intermittent transpulmonary thermodilution (ICO). One hundred thirty-two matched sets of data were available for analysis. Bland-Altman analysis using linear mixed effects models with random effects for patient and trial revealed a mean bias ±2 standard deviation (%error) of -0.86 ± 1.41 L/min (34.9%) for PCCO-ICO, -0.26 ± 2.81 L/min (46.3%) for LCCO-ICO, -0.28 ± 2.39 L/min (43.7%) for FCCO-ICO, and -0.93 ± 2.25 L/min (34.6%) for NCCO-ICO. Bland-Altman plots without adjustment for repeated measurements and replicates yielded considerably larger limits of agreement. Trend analysis for all techniques did not meet criteria for acceptable performance. CONCLUSIONS: All 4 tested devices using pulse wave analysis for measuring cardiac output failed to meet current criteria for meaningful and adequate accuracy, precision, and trending ability in cardiac output monitoring.

Proposed Cutoff Value of Brachial-Ankle Pulse Wave Velocity for the Management of Hypertension.

BACKGROUND: The optimal cutoff values of the brachial-ankle pulse wave velocity (baPWV) for predicting cardiovascular disease (CVD) were examined in patients with hypertension.Methods and Results:A total of 7,656 participants were followed prospectively. The hazard ratio for the development of CVD increased significantly as the baPWV increased, independent of conventional risk factors. The receiver-operating characteristic curve analysis showed that the optimal cutoff values for predicting CVD was 18.3 m/s. This cutoff value significantly predicted THE incidence of CVD. CONCLUSIONS: The present analysis suggests that the optimal cutoff value for CVD in patients with hypertension is 18.3 m/s.

Measurement of Aortic Pulse Wave Velocity With a Connected Bathroom Scale.

BACKGROUND: Measurement of arterial stiffness should be more available. Our aim was to show that aortic pulse wave velocity can be reliably measured with a bathroom scale combining the principles of ballistocardiography (BCG) and impedance plethysmography on a single foot. METHOD: The calibration of the bathroom scale was conducted on a group of 106 individuals. The aortic pulse wave velocity was measured with the SphygmoCor in the supine position. Three consecutive measurements were then performed on the Withings scale in the standing position. This aorta-leg pulse transit time (alPTT) was then converted into a velocity with the additional input of the height of the person. Agreement between the SphygmoCor and the bathroom scale so calibrated is assessed on a separate group of 86 individuals, following the same protocol. RESULTS: The bias is 0.25 m·s-1 and the SE 1.39 m·s-1. This agreement with Sphygmocor is "acceptable" according to the ARTERY classification. The alPTT correlated well with cfPTT with (Spearman) R = 0.73 in pooled population (cal 0.79, val 0.66). The aorta-leg pulse wave velocity correlated with carotid-femoral pulse wave velocity with R = 0.76 (cal 0.80, val 0.70). CONCLUSION: Estimation of the aortic pulse wave velocity is feasible with a bathroom scale. Further investigations are needed to improve the repeatability of measurements and to test their accuracy in different populations and conditions.