Optimizing time-in-target-range assessment for blood pressure: insights from a large-scale study with continual cuffless monitoring.

Introduction: Blood pressure (BP) time-in-target-range (TTR) is an emerging predictor of cardiovascular risk. Conventional BP methods are fundamentally unable to provide an optimal assessment of TTR, using irregular measurements separated by lengthy intervals. We investigated the optimal duration and frequency for reliable, practical TTR assessment in clinical settings using continual monitoring. Methods: This retrospective study analyzed 2.3 million BP readings from 5,189 European home users (55 ± 11 years, 82% male, BMI 28.0 ± 5.8) using a cuffless BP monitor (Aktiia SA). Systolic BP (SBP) data over 15 consecutive days were assessed (29 ± 11 readings/subject/24-h; 434 + 132 readings/subject/15-day). Subjects were classified into risk-related TTR groups based on 15-day SBP data (24-h, target 90-125 mmHg; ≥6 daytime readings). Various measurement frequencies and durations (1-14 days; 24-h/daytime; 2, 4 or ≥ 6 readings/day) were compared to this reference. Two specific configurations paralleling ambulatory ("One-Day-24 h") and home ("One-Week-Daytime") BP monitoring were selected for detailed analysis. Results: The reference TTR classified 63.0% of the subjects as high risk, 19.0% intermediate, and 18.0% low. "One-Day-24 h" schedule inaccurately classified 26% of subjects compared to the reference TTR, and "One-Week-Daytime" schedule inaccurately classified 45%. Classification accuracy with both schedules was high for subjects with very low or very high reference TTR, but poor otherwise. Accuracy of ≥90% in TTR classification only occurred with 7 days of continual 24-h monitoring. Discussion: For the first time, with the benefit of a cuffless device that measures BP with sufficient frequency and duration, practical use of TTR is enabled as a potentially enhanced metric to manage hypertension.

Sex difference in nocturnal blood pressure dipping in adolescents with varying degrees of adiposity.

BACKGROUND: For adolescents, abnormal dipping patterns in blood pressure (BP) are associated with early-onset organ damage and a higher risk of cardiovascular disorders in adulthood. Obesity is one of the most common reasons for abnormal BP dipping in young people. However, it is unknown whether the severity of obesity is associated with BP dipping status and whether this association is sex-dependent. METHODS: 499 participants between 12 and 17 years old with overweight or obesity underwent ambulatory blood pressure monitoring (ABPM) between April 2018 and January 2019 in Beijing and Baoding. Participants were grouped by body mass index (BMI) into overweight (BMI 85th-95th percentile), obese (BMI ≥ 95th percentile) and severely obese (BMI ≥ 120% of 95th percentile or ≥ 35 kg/m2) groups. Non-dipping was defined as a < 10% reduction in BP from day to night. The interaction effect between sex and obesity degree was also analyzed. RESULTS: 326 boys and 173 girls were included, of whom 130 were overweight, 189 were obese, and 180 were severely obese. Girls with severe obesity had a higher prevalence of non-dipping, but boys showed no significant differences in BP dipping status between obesity categories. In addition, as obesity severity went up, a more evident increase in night-time SBP was observed in girls than in boys. CONCLUSIONS: Severely obese is associated with a higher prevalence of non-BP dipping patterns in girls than in boys, which suggests that the relationship between the severity of obesity and BP dipping status might be sex-specific.

Diagnostic accuracy for detecting atrial fibrillation using a novel machine learning algorithm in a blood pressure monitor.

BACKGROUND: Early detection of atrial fibrillation (AF) is key for preventing strokes. Blood pressure monitors (BPMs) with built-in AF screening features have the potential for early detection at home. Recently, 2 BPMs (HEM-7371T1-AZ and HEM-7372T1-AZAZ, Omron Healthcare Co., Ltd.) that share a novel AF screening feature have been developed. Their AF screening feature utilizes an algorithm that incorporates machine learning, with the potential to improve diagnostic accuracy. OBJECTIVE: The purpose of this study was to evaluate the performance of this AF screening feature in a multicenter, prospective clinical study at 5 sites in the United States. METHODS: A total of 559 subjects were enrolled for this study: 267 in AF cohort and 292 in the non-AF cohort. AF screening was performed in all subjects by the 2 Omron BPMs and by 1 Microlife BPM (BP 3MX1-3, WatchBP Home A, Microlife Corp.), and a simultaneous 12-lead electrocardiogram (ECG) was recorded for comparison. All 12-lead ECGs were interpreted by a board-certified cardiologist who was blinded to the BPM results. Sensitivity, specificity, and accuracy for the diagnosis of AF were calculated. RESULTS: Omron HEM-7371T1-AZ BPM had sensitivity of 95.1% (95% confidence interval [CI] 91.8%-97.4%), specificity 98.6% (95% CI 96.6%-99.7%), and accuracy of 97.0% (95% CI 95.2%-98.2%). Equivalent results were obtained with the Omron HEM-7371T1-AZAZ BPM. This compared favorably to the Microlife BPM (sensitivity 78.5%, 95% CI 73.1%-83.3%; specificity 97.6%, 95% CI 95.1%-99.0%; accuracy 88.4%, 95% CI 85.5%-91.0%). CONCLUSION: These data support both home and professional use of these novel Omron BPMs for the detection of AF.

Diagnostic Performance of an Automated Blood Pressure Monitor With an Irregular Heartbeat Algorithm Designed to Detect Atrial Fibrillation.

Background: Early detection of atrial fibrillation (AF) remains an unsolved challenge and because the greatest risk factor for AF is hypertension, blood pressure (BP) monitors with AF detectors have been developed. We evaluated the clinical performance of an irregular heartbeat (IHB) algorithm built into an A&D automated BP monitor for AF diagnosis. Methods and Results: Each of the 239 enrolled patients underwent BP measurement 3 times using the A&D UM-212 with the IHB algorithm. Real-time 3-lead ECG was recorded using automated ECG analysis software. Independent of the ECG analysis software results, 2 cardiologists interpreted the ECG and made the final diagnosis. Of the 239 patients, 135 were in sinus rhythm, 31 had AF, and 73 had non-AF arrhythmias. The respective sensitivity, specificity, and accuracy of the IHB algorithm for AF diagnosis were 98.9%, 91.2%, and 92.2% for the per-measurement evaluation, and 96.8%, 95.7%, and 95.8% for the per-patient evaluation (3/3 positive measurements). The respective sensitivity, specificity, and accuracy of the ECG analysis software for AF diagnosis were 91.4%, 97.9%, and 97.1% for the per-measurement evaluation, and 77.4%, 99.5%, and 96.7% for the per-patient evaluation (3/3 positive measurements). Conclusions: The IHB algorithm built into an A&D automated BP monitor had high diagnostic performance for AF in general cardiology patients, especially when multiple measurements were obtained.

AcumenTM hypotension prediction index guidance for prevention and treatment of hypotension in noncardiac surgery: a prospective, single-arm, multicenter trial.

BACKGROUND: Intraoperative hypotension is common during noncardiac surgery and is associated with postoperative myocardial infarction, acute kidney injury, stroke, and severe infection. The Hypotension Prediction Index software is an algorithm based on arterial waveform analysis that alerts clinicians of the patient's likelihood of experiencing a future hypotensive event, defined as mean arterial pressure < 65 mmHg for at least 1 min. METHODS: Two analyses included (1) a prospective, single-arm trial, with continuous blood pressure measurements from study monitors, compared to a historical comparison cohort. (2) A post hoc analysis of a subset of trial participants versus a propensity score-weighted contemporaneous comparison group, using external data from the Multicenter Perioperative Outcomes Group (MPOG). The trial included 485 subjects in 11 sites; 406 were in the final effectiveness analysis. The post hoc analysis included 457 trial participants and 15,796 comparison patients. Patients were eligible if aged 18 years or older, American Society of Anesthesiologists (ASA) physical status 3 or 4, and scheduled for moderate- to high-risk noncardiac surgery expected to last at least 3 h. MEASUREMENTS: minutes of mean arterial pressure (MAP) below 65 mmHg and area under MAP < 65 mmHg. RESULTS: Analysis 1: Trial subjects (n = 406) experienced a mean of 9 ± 13 min of MAP below 65 mmHg, compared with the MPOG historical control mean of 25 ± 41 min, a 65% reduction (p < 0.001). Subjects with at least one episode of hypotension (n = 293) had a mean of 12 ± 14 min of MAP below 65 mmHg compared with the MPOG historical control mean of 28 ± 43 min, a 58% reduction (p< 0.001). Analysis 2: In the post hoc inverse probability treatment weighting model, patients in the trial demonstrated a 35% reduction in minutes of hypotension compared to a contemporaneous comparison group [exponentiated coefficient: - 0.35 (95%CI - 0.43, - 0.27); p < 0.001]. CONCLUSIONS: The use of prediction software for blood pressure management was associated with a clinically meaningful reduction in the duration of intraoperative hypotension. Further studies must investigate whether predictive algorithms to prevent hypotension can reduce adverse outcomes. TRIAL REGISTRATION: Clinical trial number: NCT03805217. Registry URL: https://clinicaltrials.gov/ct2/show/NCT03805217 . Principal investigator: Xiaodong Bao, MD, PhD. Date of registration: January 15, 2019.

Ambulatory blood pressure levels in individuals with uncontrolled clinic hypertension across Bangladesh, Pakistan, and Sri Lanka.

Hypertension is a leading risk factor for cardiovascular disease in South Asia. The authors aimed to assess the cross-country differences in 24-h ambulatory, daytime, and nighttime systolic blood pressure (SBP) among rural population with uncontrolled clinic hypertension in Bangladesh, Pakistan, and Sri Lanka. The authors studied patients with uncontrolled clinic hypertension (clinic BP ≥ 140/90 mmHg) who underwent ambulatory blood pressure monitoring (ABPM) during the baseline assessment as part of a community-based trial. The authors compared the distribution of ABPM profiles of patients across the three countries, specifically evaluating ambulatory SBP levels with multivariable models that adjusted for patient characteristics. Among the 382 patients (mean age, 58.3 years; 64.7% women), 56.5% exhibited ambulatory hypertension (24-h ambulatory BP ≥ 130/80 mmHg), with wide variation across countries: 72.6% (Bangladesh), 50.0% (Pakistan), and 51.0% (Sri Lanka; P < .05). Compared to Sri Lanka, adjusted mean 24-h ambulatory, daytime, and nighttime SBP were higher by 12.24 mmHg (95% CI 4.28-20.20), 11.96 mmHg (3.87-20.06), and 12.76 mmHg (4.51-21.01) in Bangladesh, separately. However, no significant differences were observed between Pakistan and Sri Lanka (P > .05). Additionally, clinic SBP was significantly associated with 24-h ambulatory (mean 0.38, 95% CI 0.28-0.47), daytime (0.37, 0.27-0.47), and nighttime SBP (0.40, 0.29-0.50) per 1 mmHg increase. The authors observed substantial cross-country differences in the distribution of ABPM profiles among patients with uncontrolled clinic hypertension in rural South Asia. The authors findings indicated the need to incorporate 24-h BP monitoring to mitigate cardiovascular risk, particularly in Bangladesh.

Diagnostic Performance of Automated Blood Pressure Monitor for Detection of Atrial Fibrillation.

Background Atrial fibrillation (AF) is a type of heart disease characterized by an irregular cardiac rhythm. The complications of AF are associated with significant morbidity, mortality, and medical expenses. This emphasizes the significance of detecting AF early using a feasible device. Methods A total of 123 patients who attended cardiology and INR clinics were enrolled, with 51 of them having AF. The blood pressure of all patients was measured three times using the Rossmax X5, while a single-lead electrocardiogram (ECG) was monitored simultaneously. Following that, a 12-lead ECG was performed on all patients. A cardiologist confirmed the irregular rhythm. Results Compared to the 12-lead ECG method, Rossmax X5 has an accuracy of 99.3%, a sensitivity of 100%, and a specificity of 98.6%. The positive and negative predictive values were also significant, which were 98.1% and 100%, respectively. Conclusion The Rossmax X5 automated blood pressure monitor has a high detection accuracy for AF. Therefore, Rossmax X5 can be recommended for use in the clinical setting as a screening tool for early AF detection.

Nocturnal blood pressure dipping, blood pressure variability, and cognitive function in early and middle-aged adults.

Higher nighttime blood pressure (BP), less BP dipping, and higher BP variability have been linked with worse cognitive function in the elderly. The goal of this study is to explore whether this relationship already exists in early and middle adulthood. We further examined whether ethnic differences between African Americans and European Americans in BP parameters can explain ethnic differences in cognitive function. 24-h ambulatory BP monitoring and cognitive function were obtained from 390 participants (average age: 37.2 years with a range of 25-50; 54.9% African Americans; 63.6% females). We observed that higher nighttime BP, decreased dipping, and higher variability were significantly associated with lower scores on the Picture Sequence Memory Test. Significant negative associations between variability and overall composite scores were also observed. No significant associations between average 24-h or daytime BP and cognitive function were observed. Ethnic differences in nighttime diastolic pressures and dipping can explain 6.81% to 10.8% of the ethnicity difference in the score of the Picture Sequence Memory Test (ps < .05). This study suggests that the associations of nighttime BP, dipping, and variability with cognitive function already exist in young and middle-aged adults. Ethnic differences in nighttime BP and dipping can at least partially explain ethnic differences in cognitive function. The stronger association of these parameters with cognitive function than daytime or average BP in this age range raises the importance of using ambulatory BP monitoring for more precise detection of abnormal BP patterns in young adulthood.

Parkinson's disease patients with absence of normal dipping status were more vulnerable to cognitive impairment from the early stages.

INTRODUCTION: The objective of this study was to determine the characteristics of cognitive function in Parkinson's disease (PD) patients with different dipping statuses. METHODS: Consecutive PD patients were recruited for this study. All participants underwent 24-h ambulatory blood pressure monitor (ABPM). Corresponding scales were employed to evaluate both motor and non-motor symptoms. The subjects were categorized into reverse, reduced, normal, and extreme dipping groups based on dipping patterns. Additionally, they were divided into early and non-early stage groups according to the disease duration being more than 5 years. RESULTS: The proportions of the four dipping groups in the early and non-early stage groups exhibited no significant differences. The Montreal Cognitive Assessment (MoCA) scores in the reverse group were significantly lower than those in the normal dipping group (16.2 ± 5.8 vs 21.1 ± 6.1,P = 0.003). The attention as well as delayed recall scores in the reverse dipping group were significant lower than those in the normal dipping group (P = 0.042; P < 0.001). The multivariate linear regression analysis revealed that absence of normal dipping was an independent risk factor (OR = -2.252; P = 0.027) for MoCA scores for PD patients. CONCLUSIONS: PD patients with absence of normal dipping status were more vulnerable to cognitive impairment from the early stages of the disease. The 24-h ABPM is recommended for early detection of abnormal dipping status and identification of individuals at risk for cognitive decline.

Feasibility and Effectiveness of a Ring-Type Blood Pressure Measurement Device Compared With 24-Hour Ambulatory Blood Pressure Monitoring Device.

BACKGROUNDS AND OBJECTIVES: This study aimed to evaluate the applicability and precision of a ring-type cuffless blood pressure (BP) measurement device, CART-I Plus, compared to conventional 24-hour ambulatory BP monitoring (ABPM). METHODS: Forty patients were recruited, and 33 participants were included in the final analysis. Each participant wore both CART-I Plus and ABPM devices on the same arm for approximately 24 hours. BP estimation from CART-I Plus, derived from photoplethysmography (PPG) signals, were compared with the corresponding ABPM measurements. RESULTS: The CART-I Plus recorded systolic blood pressure (SBP)/diastolic blood pressure (DBP) values of 131.4±14.1/81.1±12.0, 132.7±13.9/81.9±11.9, and 128.7±14.6/79.3±12.2 mmHg for 24-hour, daytime, and nighttime periods respectively, compared to ABPM values of 129.7±11.7/84.4±11.2, 131.9±11.6/86.3±11.1, and 124.5±13.6/80.0±12.2 mmHg. Mean differences in SBP/DBP between the two devices were 1.74±6.69/-3.24±6.51 mmHg, 0.75±7.44/-4.41±7.42 mmHg, and 4.15±6.15/-0.67±5.23 mmHg for 24-hour, daytime, and nighttime periods respectively. Strong correlations were also observed between the devices, with r=0.725 and r=0.750 for transitions in SBP and DBP from daytime to nighttime, respectively (both p<0.001). CONCLUSIONS: The CART-I Plus device, with its unique ring-type design, shows promising accuracy in BP estimation and offers a potential avenue for continuous BP monitoring in clinical practice. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT06084065.

The HOPE Asia Network consensus on blood pressure measurements corresponding to office measurements: Automated office, home, and ambulatory blood pressures.

For adopting recently introduced hypertension phenotypes categorized using office and out of office blood pressure (BP) for the diagnosis of hypertension and antihypertension drug therapy, it is mandatory to define the corresponding out of office BP with the specific target BP recommended by the major guidelines. Such conditions include white-coat hypertension (WCH), masked hypertension (MH), white-coat uncontrolled hypertension (WUCH), and masked uncontrolled hypertension (MUCH). Here, the authors review the relevant literature and discuss the related issue to facilitate the use of corresponding BPs for proper diagnosis of WCH, MH, WUCH, and MUCH in the setting of standard target BP as well as intensive target BP. The methodology of deriving the corresponding BP has evolved from statistical methods such as standard deviation, percentile value, and regression to an outcome-based approach using pooled international cohort study data and comparative analysis in randomized clinical trials for target BPs such as the SPRINT and STEP studies. Corresponding BPs to 140/90 and 130/80 mm Hg in office BP is important for safe and strict achievement of intensive BP targets. The corresponding home, daytime, and 24-h BPs to 130/80 mm Hg in office BP are 130/80, 130/80, and 125/75 mm Hg, respectively. However, researchers have found some discrepancies among the home corresponding BPs. As tentative criterion for de-escalation of antihypertensive therapy as shown in European guidelines was 120 mm Hg in office BP, corresponding home, daytime, and 24-h systolic BPs to 120 mm Hg in office systolic BP are 120, 120, and 115 mm Hg, respectively.

Head-to-head comparison of the WHO STEPwise approach with immediate unattended and delayed unattended automated blood pressure measurements during household-based screening: a diagnostic accuracy study in Lesotho.

Background: WHO introduced the STEPwise approach to surveillance (STEPS) to monitor trends in non-communicable diseases. For arterial hypertension, the STEPS protocol takes the average of the last two out of three standard blood pressure measurements (SBPM). This study assesses the diagnostic accuracy of SBPM, same-day and next-day unattended automated measurement (uABP), with 24 h ambulatory measurement (24 h-ABPM) as reference. Methods: This diagnostic accuracy study was done within a population-based household survey on cardiovascular risk factors in two districts in Northern Lesotho. Adults (aged ≥ 18 years) with elevated SBPM (defined as ≥140/90 mmHg), and 2:1 age- and sex-matched participants with normal SBPM during the survey were recruited. Following SBPM, first uABP readings were obtained on survey day. Afterwards, participants received a 24 h-ABPM device. Second uABP readings were taken 24 h later, after retrieval of the 24 h-ABPM. The main outcome was overall diagnostic accuracy of all screening measurements (SBPM, first uABP, and second uABP), determined using area under the receiver operating characteristic curve (AUROC), with 24 h-ABPM as a reference. Findings: Between November 2, 2021 and August 31, 2022, 275 participants (mean age 58 years (SD: 16 years), 163 (59%) female) were enrolled, 183 of whom had elevated and 92 had normal SBPM. Mean difference between systolic daytime 24 h-ABPM and screening measurements was highest for SBPM (mean difference: -13 mmHg; 95% CI: -14 to -11). Mean difference between diastolic daytime 24 h-ABPM and diastolic SBPM was -2 mmHg (95% CI: -4 to -1), whereas no difference was found for mean diastolic first uABP (mean difference: -1 mmHg; 95% CI: -2.0 to 0.3); and mean diastolic second uABP (mean difference: 1.0 mmHg; 95% CI: -0.4 to 2.3). White coat hypertension was highest with SBPM (55 [20%]), followed by first uABP (27 [9.8%]), and second uABP (18 [6.5%]). Using systolic daytime 24 h-ABPM as a reference, the uABPs had higher AUROC (first uABP: 87% [95% CI: 83-91]; second uABP: 88% [95% CI: 84-92]); SBPM: (79% [95% CI: 74-85]). This difference was significant between first uABP and SBPM (P = 0.0024), and between second uABP and SBPM (P = 0.0017). Interpretation: uABP had better diagnostic performance than SBPM. Integration of uABP into STEPS protocol should be considered. Funding: Swiss Agency for Development and Cooperation under the ComBaCaL project, and the World Diabetes Foundation.

Improving Access to Home Blood Pressure Monitors at a Federally Qualified Health Center.

Background: Self-monitoring of blood pressure (BP) clinically decreases BP. However, cost can limit access, especially in underserved populations. Objective: This mixed-methods pilot study aims to determine the impact of providing home BP monitors free of charge to patients at a federally qualified health center (FQHC) by quantifying the effect on BP and surveying patients to measure satisfaction and engagement. Methods: One hundred eighty patients with clinically diagnosed hypertension received BP monitors. Patient charts were reviewed to collect demographics and office BP readings 3 months before and after receiving a monitor. A 13-question phone survey was conducted to a sample of patients addressing satisfaction and engagement. Answers were based on a Likert scale and dichotomous yes/no. Results were analyzed with descriptive statistics and paired t tests. Results: The chart review demonstrated a significant mean decrease in systolic BP by 5.44 mm Hg (P < 0.001, -8.03 to -2.84) and a mean decrease in diastolic BP by 2.70 mm Hg (P < 0.001, -4.08 to -1.32) after the intervention. For those included who responded to the survey (13%), there was a significant mean increase in the frequency of checking BP per week by 1.5 Likert points (P < 0.00001, -1.0 to -1.9), and a majority (57.8%) felt slightly or much more active in their health care in addition to other benefits. Conclusion: Providing BP monitors to FQHC patients free of charge may have contributed to a significantly decreased office BP, improved engagement, and satisfaction. This program removed cost barriers and allowed patients to be more active in their health care.

Aktiia cuffless blood pressure monitor yields equivalent daytime blood pressure measurements compared to a 24-h ambulatory blood pressure monitor: Preliminary results from a prospective single-center study.

In this preliminary study, we compared daytime blood pressure (BP) measurements performed by a commercially available cuffless-and continual-BP monitor (Aktiia monitor, Neuchâtel, Switzerland) and a traditional ambulatory BP monitor (ABPM; Dyasis 3, Novacor, Paris, France) from 52 patients enrolled in a 12-week cardiac rehabilitation (CR) program (Neuchâtel, Switzerland). Daytime (9am-9pm) systolic (SBP) and diastolic (DBP) BP from 7-day averaged data from Aktiia monitor were compared to 1-day averaged BP data from ABPM. No significant differences were found between the Aktiia monitor and the ABPM for SBP (µ ± σ [95% confidence interval]: 1.6 ± 10.5 [-1.5, 4.6] mmHg, P = 0.306; correlation [R2]: 0.70; ± 10/ ± 15 mmHg agreements: 60%, 84%). Marginally non-significant bias was found for DBP (-2.2 ± 8.0 [-4.5, 0.1] mmHg, P = 0.058; R2: 0.66; ±10/±15 mmHg agreements: 78%, 96%). These intermediate results show that daytime BP measurements using the Aktiia monitor generate data comparable to that of an ABPM monitor.

Upper-Arm Photoplethysmographic Sensor with One-Time Calibration for Long-Term Blood Pressure Monitoring.

Wearable cuffless photoplethysmographic blood pressure monitors have garnered widespread attention in recent years; however, the long-term performance values of these devices are questionable. Most cuffless blood pressure monitors require initial baseline calibration and regular recalibrations with a cuffed blood pressure monitor to ensure accurate blood pressure estimation, and their estimation accuracy may vary over time if left uncalibrated. Therefore, this study assessed the accuracy and long-term performance of an upper-arm, cuffless photoplethysmographic blood pressure monitor according to the ISO 81060-2 standard. This device was based on a nonlinear machine-learning model architecture with a fine-tuning optimized method. The blood pressure measurement protocol followed a validation procedure according to the standard, with an additional four weekly blood pressure measurements over a 1-month period, to assess the long-term performance values of the upper-arm, cuffless photoplethysmographic blood pressure monitor. The results showed that the photoplethysmographic signals obtained from the upper arm had better qualities when compared with those measured from the wrist. When compared with the cuffed blood pressure monitor, the means ± standard deviations of the difference in BP at week 1 (baseline) were -1.36 ± 7.24 and -2.11 ± 5.71 mmHg for systolic and diastolic blood pressure, respectively, which met the first criterion of ≤5 ± ≤8.0 mmHg and met the second criterion of a systolic blood pressure ≤ 6.89 mmHg and a diastolic blood pressure ≤ 6.84 mmHg. The differences in the uncalibrated blood pressure values between the test and reference blood pressure monitors measured from week 2 to week 5 remained stable and met both criteria 1 and 2 of the ISO 81060-2 standard. The upper-arm, cuffless photoplethysmographic blood pressure monitor in this study generated high-quality photoplethysmographic signals with satisfactory accuracy at both initial calibration and 1-month follow-ups. This device could be a convenient and practical tool to continuously measure blood pressure over long periods of time.

Usability Evaluation of Connected Health Devices in Home Monitoring: Toward Devices Adapted to the Characteristics of Informal Caregivers.

While an increasing number of Informal CareGivers (ICGs) are assisting their dependent loved ones with the daily living tasks and medical care, they are rarely considered in the medical devices design process. The objective of this study is to identify the characteristics of ICGs impacting the use of the iHealth® Sense BP7 medical device, namely a connected wrist blood pressure monitor. For this purpose, user tests were conducted with 29 potential or actual ICGs. First, the participants filled out a socio-demographic questionnaire and then handled the blood pressure monitor. Finally, they completed the System Usability Scale questionnaire. The results revealed an impact of technophilia and age on usability dimensions. To conclude, the consideration of the ICG population in the design process of connected medical devices is discussed, particularly the age and level of technophilia.

Components of Oranta-AO software expert system for innovative application of blood pressure monitors.

The authors developed and substantiated the original methods of arterial oscillography, which were implemented in the developed Oranta-AO information system. The methods of application to the arterial oscillogram registered at measurement of arterial pressure gives the possibility to carry out the supplementary systematic assessment of health, functional state of cardiovascular system, its reserve possibilities etc. The authors also developed an Expert System (based on machine-learning methods) for the differential diagnosis of risks of heart, lung, mental illness and prognosis of some blood parameters. Oranta-AO software system was created based on research results due to methods and algorithms that were innovate. For the mathematical modeling of arterial oscillograms used cyclic random processes. Methods of arterial oscillograms processing based on its model in the form of a cyclic random process was developed. The method of evaluation of the rhythm function of arterial oscillograms and statistical methods for estimating the probabilistic characteristics of arterial oscillograms were developed. To solve the clustering problem, the Python k-means and k-means++ algorithm were used. Oranta-AO information system consists of three interrelated parts: mobile application, computing kernel and web system. Computing kernel and web system are deployed on AWS servers and have been tested already. The developed environment aims to be integrated into every new model of electronic meters in the world. Certification (EN 62304:2014, ISO 13485: 2018) in Ukraine is completed, PCT priority is completed. The next step will be to establish cooperation with manufacturers of electronic pressure monitors, patenting and certification in world.

Assessment of a Calibration-Free Method of Cuffless Blood Pressure Measurement: A Pilot Study.

This study proposes a low-cost, high-sensitivity sensor of beat-to-beat local pulse wave velocity (PWV), to be used in a cuffless blood pressure monitor (BPM). OBJECTIVE: We design an adaptive algorithm to detect the feature of the pulse wave, making it possible for two sensors to measure the local PWV in the radial artery at a short distance. Unlike the cuffless BPM that needs to use a regression model for calibration. METHOD: We encapsulate the piezoelectric sensor material in a cavity and design an analog front-end circuit. This study used color ultrasound imaging equipment to measure radial arterial parameters, including the diameter and wall thickness, to aid the estimation of blood pressure (BP) using the Moens-Korteweg (MK) equation of hemodynamics. RESULTS: We compared the blood pressure estimated by the MK equation with the reference BP measured using an aneroid sphygmomanometer in a test group of 32 people, resulting in a mean difference of systolic BP of -0.63 mmHg, and a standard deviation of ±5.14 mmHg, a mean difference of mean arterial pressure (MAP) of 0.97 mmHg, with a standard deviation of ±3.54 mmHg, and a mean difference of diastolic BP of -1.14 mmHg, with a standard deviation of ±4.08 mmHg. This study has verified its compliance with ISO 81060-2. CONCLUSIONS: A new type of wearable continuous calibration-free BPM can replace the situation that requires the use of traditional ambulatory BPM and reduce patient discomfort. CLINICAL IMPACT: In this study can provide long-term continuous blood pressure monitoring in the hospital.

Seasonal variation of ambulatory blood pressure in Chinese hypertensive adolescents.

Background: Blood pressure (BP) exhibits seasonal variation with lower levels at higher temperatures and vice versa. This phenomenon affects both sexes and all age groups. So far, only a few research studies have investigated this condition in adolescents and none of them were based on hypertensive population or ever applied ambulatory blood pressure monitor (ABPM). Therefore, we carried out the first study that used ABPM to record seasonal variation of blood pressure in hypertensive adolescents. Methods: From March 2018 to February 2019, 649 ABPMs from hypertensive adolescents between 13 and 17 years who were referred to wear an ABPM device in Beijing and Baoding were extracted. Seasonal change in ambulatory BP value, dipping status, and prevalence of different BP phenotypes were analyzed and compared. Results: Mean age of participants was 14.9 ± 1.5 years and 65.8% of them were boys. Of the participants, 75.3% met the criteria of overweight or obesity. From summer to winter, average 24-hour, day-time, and night-time BP showed significant rise, which was 9.8/2.8, 9.8/3.0, and 10.9/3.4 mmHg, respectively. This seasonal effect on BP was not dependent on the obesity degree. In addition, higher prevalence of nondippers and risers existed in winter while white coat hypertension was more frequent in warmer seasons. Conclusion: Hypertensive adolescents showed evident seasonal change in their ABPM results, which was featured by elevated BP level and more frequent abnormal dipping patterns in winter. On the contrary, higher prevalence of white coat hypertension was found in warmer seasons. Physicians should take seasonal variation into consideration when managing adolescent hypertension.