Cuff Under Pressure for Greater Accuracy.

PURPOSE OF REVIEW: To present the evidence that describes what is being measured by upper-arm cuff blood pressure (BP) and the level of accuracy compared with invasive central aortic and brachial BP. Potential causes of inaccuracy and emerging methods are also discussed. RECENT FINDINGS: On average cuff systolic BP systematically underestimates invasive brachial systolic BP, although in a given individual it may substantially under- or over-estimate central aortic systolic BP. Such errors may affect individual health management outcomes and distort population level data on hypertension prevalence and control. Oscillometric cuff BP is particularly susceptible to inaccuracy in people with high arterial stiffness and with pathophysiological BP waveform shapes. Emerging cuff-less BP methods will be susceptible to inaccuracy if oscillometric cuff BP is used for calibration. The original purpose of cuff BP was to estimate central aortic BP. Recent evidence has shown substantial inaccuracy of oscillometric cuff BP exists for the measurement of invasive central aortic and brachial BP. Thus, development of more accurate BP methods, through better understanding of oscillometric and BP waveform morphology, is needed to improve health outcomes related to high BP.

Lack of Strategic Funding and Long-Term Job Security Threaten to Have Profound Effects on Cardiovascular Researcher Retention in Australia.

BACKGROUND: Cardiovascular disease is the leading cause of death in Australia. Investment in research solutions has been demonstrated to yield health and a 9.8-fold return economic benefit. The sector, however, is severely challenged with success rates of traditional peer-reviewed funding in decline. Here, we aimed to understand the perceived challenges faced by the cardiovascular workforce in Australia prior to the COVID-19 pandemic. METHODS: We used an online survey distributed across Australian cardiovascular societies/councils, universities and research institutes over a period of 6 months during 2019, with 548 completed responses. Inclusion criteria included being an Australian resident or an Australian citizen who lived overseas, and a current or past student or employee in the field of cardiovascular research. RESULTS: The mean age of respondents was 42±13 years, 47% were male, 85% had a full-time position, and 40% were a group leader or laboratory head. Twenty-three per cent (23%) had permanent employment, and 82% of full-time workers regularly worked >40 hours/week. Sixty-eight per cent (68%) said they had previously considered leaving the cardiovascular research sector. If their position could not be funded in the next few years, a staggering 91% of respondents would leave the sector. Compared to PhD- and age-matched men, women were less likely to be a laboratory head and to feel they had a long-term career path as a cardiovascular researcher, while more women were unsure about future employment and had considered leaving the sector (all p<0.05). Greater job security (76%) and government and philanthropic investment in cardiovascular research (72%) were highlighted by responders as the main changes to current practices that would encourage them to stay. CONCLUSION: Strategic solutions, such as diversification of career pathways and funding sources, and moving from a competitive to a collaborative culture, need to be a priority to decrease reliance on government funding and allow cardiovascular researchers to thrive.

Pulsatile interaction between the macro-vasculature and micro-vasculature: proof-of-concept among patients with type 2 diabetes.

PURPOSE: It is widely thought that excess pulsatile pressure from increased stiffness of large central arteries (macro-vasculature) is transmitted to capillary networks (micro-vasculature) and causes target organ damage. However, this hypothesis has never been tested. We sought to examine the association between macro- and micro-vasculature waveform features in patients with type 2 diabetes (i.e., those with elevated stiffness; T2D) compared with non-diabetic controls. METHODS: Among 13 T2D (68 ± 6 years, 39% male) and 15 controls (58 ± 11 years, 40% male) macro-vascular stiffness was determined via aortic pulse wave velocity (aPWV) and macro-vascular waveforms were measured using radial tonometry. Forearm micro-vascular waveforms were measured simultaneously with macro-vascular waveforms via low power laser Doppler fluxmetry. Augmentation index (AIx) was derived on macro- and micro-vascular waveforms. Target organ damage was assessed by estimated glomerular filtration rate (eGFR) and central retinal artery equivalent (CRAE). RESULTS: aPWV was higher among T2D (9.3 ± 2.5 vs 7.5 ± 1.4 m/s, p = 0.046). There was an obvious pulsatile micro-vascular waveform with qualitative features similar to macro-vasculature pressure waveforms. In all subjects, macro- and micro-vasculature AIx were significantly related (r = 0.43, p = 0.005). In T2D alone, micro-vasculature AIx was associated with eGFR (r = - 0.63, p = 0.037), whereas in controls, macro-vasculature AIx and AP were associated with CRAE (r = - 0.58, p = 0.025 and r = - 0.61, p = 0.015). CONCLUSIONS: Macro- and micro-vasculature waveform features are related; however, micro-vasculature features are more closely related to markers of target organ damage in T2D. These findings are suggestive of a possible interaction between the macro- and micro-circulation.

Availability, Cost, and Consumer Ratings of Popular Nonvalidated vs Validated Blood Pressure-Measuring Devices Sold Online in 10 Countries.

This study examines the availability, cost, and consumer ratings of blood pressure­measuring devices relative to validation status across 10 countries.

Validity of Home Blood Pressure Devices Sold in Canada.

Background: Measurement of home blood pressure is an important tool for the management of hypertension. However, the validity of home devices is of concern. The Recommended Blood Pressure Devices Program of Hypertension Canada reviews and recommends blood pressure devices using international validation standards. We sought to determine the proportion of Hypertension Canada-recommended devices available for purchase in pharmacies and online. Methods: We visited 16 community pharmacies in the Edmonton area to record the blood pressure devices they sold. We also reviewed the 50 most popular devices from online retailers (Amazon, Walmart, Best Buy, and Canadian Tire). All devices were referenced against the Recommended Blood Pressure Device Program of Hypertension Canada (www.hypertension.ca/bpdevices) to determine if the models were recommended. Results: We reviewed 170 devices. Of those sold in pharmacies, 61 of 68 (89.7%) were Hypertension Canada-recommended devices, whereas online retailers had only 46 of 102 (45.1%) recommended devices; P < 0.001. Conclusions: Most blood pressure devices sold in pharmacies are Hypertension Canada recommended, in contrast to less than one-half from online retailers. The lack of validation of many home blood pressure devices could have important clinical implications, leading to over- or undertreatment of hypertension. Clinicians should advise patients on the importance of home blood pressure device validation and direct them to resources such as Hypertension Canada (https://hypertension.ca/public/recommended-devices) for guidance.

Contexte: La mesure de la pression artérielle au domicile est un outil important dans la prise en charge de l'hypertension. Or, il semble que les appareils utilisés à la maison à cette fin ne soient pas toujours des dispositifs validés. Dans le cadre de son Programme de recommandation d'appareils de mesure de la pression artérielle, Hypertension Canada analyse et recommande des tensiomètres selon des normes de validation internationales. Nous avons donc cherché à déterminer la proportion des tensiomètres recommandés par Hypertension Canada qu'il est possible d'acheter dans les pharmacies et en ligne. Méthodologie: Nous avons rendu visite à 16 pharmacies communautaires dans la région d'Edmonton pour recenser les tensiomètres qui y étaient vendus. Nous avons également analysé les 50 tensiomètres les plus vendus par des détaillants en ligne (Amazon, Walmart, Best Buy et Canadian Tire). Nous avons vérifié si chacun des modèles faisait partie de la liste des appareils recommandés par Hypertension Canada (www.hypertension.ca/bpdevices). Résultats: Nous avons passé en revue 170 appareils. Dans les pharmacies, 61 appareils sur 68 (89,7 %) étaient recommandés par Hypertension Canada, alors qu'en ligne, cette proportion n'était que de 46 sur 102 (45,1 %); p < 0,001. Conclusions: La plupart des tensiomètres vendus dans les pharmacies sont recommandés par Hypertension Canada, contrairement à moins de la moitié de ceux qui sont vendus en ligne. L'absence de validation pour de nombreux tensiomètres pourrait avoir d'importantes conséquences cliniques, menant à un traitement excessif ou insuffisant de l'hypertension. Les cliniciens doivent informer les patients de l'importance d'utiliser un tensiomètre validé à la maison et les orienter vers des ressources comme Hypertension Canada (https://hypertension.ca/public/recommended-devices) pour guider leur choix.

Accuracy of methods to estimate central aortic SBP via upper arm cuff: a systematic review and meta-analysis.

OBJECTIVES: Central aortic BP may predict cardiovascular outcomes better than upper arm brachial BP. In recent years, technology has enabled central BP estimation by recording a peripheral BP waveform from a standard upper arm cuff. The accuracy of these devices is not well documented, and this study aimed to address this issue. METHODS: This study was a systematic review, conducted according to PRISMA guidelines, of observational studies published between 2008 and 2023 that reported accuracy testing of cuff-based central BP devices, compared with reference invasive aortic BP. The primary analysis was stratified according to each commercially available device. Pooled estimates were calculated using random-effects models based on mean differences and standard errors. RESULTS: Six thousand four hundred and fifteen studies were screened, and 27 studies met inclusion criteria (plus one unpublished study). This generated data for seven devices that are commercially available, which were tested among 2125 adult participants. There was very high heterogeneity when all devices were pooled ( I2  = 97.5%), and, when stratified by device, the accuracy of estimated central BP was highly device-dependent (range of accuracy across different devices -12.4 mmHg (-16.3 to -8.5) to 3.2 mmHg (0.2-6.1). Two of the seven commercially available devices had not undergone external validation testing. CONCLUSION: The accuracy of commercially available cuff-based central BP devices is highly device-specific and not all are accurate for the estimation of central SBP. These findings have major implications for the appropriate interpretation of studies that use cuff-based estimated central BP.

Absolute cardiovascular risk assessment using 'real world' clinic blood pressures compared to standardized unobserved and ambulatory methods: an observational study.

Clinic blood pressure (BP) is recommended for absolute cardiovascular disease (CVD) risk assessment. However, in 'real-world' settings, clinic BP measurement is unstandardised and less reliable compared to more rigorous methods but the impact for absolute CVD risk assessment is unknown. This study aimed to determine the difference in absolute CVD risk assessment using real-world clinic BP compared to standardised BP methods. Participants were patients (n = 226, 59 ± 15 years; 58% female) with hypertension referred to a BP clinic for assessment. 'Real-world' clinic BP was provided by the referring doctor. All participants had unobserved automated office BP (AOBP) and 24-h ambulatory BP monitoring (ABPM) measured at the clinic. Absolute CVD risk was calculated (Framingham) using systolic BP from the referring doctor (clinic BP), AOBP and ABPM, with agreement assessed by Kappa statistic. Clinic systolic BP was 18 mmHg than AOBP and daytime ABPM and 22 mmHg higher than 24-h ABPM (p < 0.001). Subsequently, absolute CVD risk scores using clinic BP were higher compared to AOBP, daytime ABPM and 24-h ABPM (10.4 ± 8.1%, 7.8 ± 6.4%, 7.8 ± 6.3%, and 7.3 ± 6.1%, respectively, P < 0.001). As a result, more participants were classified as high CVD risk using clinic BP (n = 89, 40%) compared with AOBP (n = 44, 20%) daytime ABPM (n = 38, 17%) and 24-h ABPM (n = 38, 17%) (p < 0.001) with weak agreement in risk classification (κ = 0.57[0.45-0.69], κ = 0.52[0.41-0.64] and κ = 0.55[0.43-0.66], respectively). Real-world clinic BP was higher and classified twice as many participants at high CVD risk compared to AOBP or ABPM. Given the challenges to high-quality BP measurement in clinic, more rigorous BP measurement methods are needed for absolute CVD risk assessment.

Innovations in blood pressure measurement and reporting technology: International Society of Hypertension position paper endorsed by the World Hypertension League, European Society of Hypertension, Asian Pacific Society of Hypertension, and Latin American Society of Hypertension.

Blood pressure (BP) is a key contributor to the lifetime risk of preclinical organ damage and cardiovascular disease. Traditional clinic-based BP readings are typically measured infrequently and under standardized/resting conditions and therefore do not capture BP values during normal everyday activity. Therefore, current hypertension guidelines emphasize the importance of incorporating out-of-office BP measurement into strategies for hypertension diagnosis and management. However, conventional home and ambulatory BP monitoring devices use the upper-arm cuff oscillometric method and only provide intermittent BP readings under static conditions or in a limited number of situations. New innovations include technologies for BP estimation based on processing of sensor signals supported by artificial intelligence tools, technologies for remote monitoring, reporting and storage of BP data, and technologies for BP data interpretation and patient interaction designed to improve hypertension management ("digital therapeutics"). The number and volume of data relating to new devices/technologies is increasing rapidly and will continue to grow. This International Society of Hypertension position paper describes the new devices/technologies, presents evidence relating to new BP measurement techniques and related indices, highlights standard for the validation of new devices/technologies, discusses the reliability and utility of novel BP monitoring devices, the association of these metrics with clinical outcomes, and the use of digital therapeutics. It also highlights the challenges and evidence gaps that need to be overcome before these new technologies can be considered as a user-friendly and accurate source of novel BP data to inform clinical hypertension management strategies.

How to find and use validated blood pressure measuring devices.

Clinically validated, automated arm-cuff blood pressure measuring devices (BPMDs) are recommended for BP measurement. However, most BPMDs available for purchase by consumers globally are not properly validated. This is a problem because non-validated BPMDs are less accurate and precise than validated ones, and therefore if used clinically could lead to misdiagnosis and mismanagement of BP. In response to this problem, several validated device lists have been developed, which can be used by clinicians and consumers to identify devices that have passed clinical validation testing. The purpose of this review is to describe the resources that are available for finding validated BPMDs in different world regions, to identify the differences between validated device lists, and describe current gaps and challenges. How to use validated BPMDs properly is also summarised.

Global proliferation and clinical consequences of non-validated automated BP devices.

Professional societies, guideline writing committees, and other interested parties emphasize the importance of accurate measurement of blood pressure for clinical and public health decisions related to prevention, treatment, and follow-up of high blood pressure. Use of a clinically validated instrument to measure blood pressure is a central component of measurement accuracy and precision. Despite this, most regulatory authorities do not specify validation requirements that manufacturers must meet to sell their blood pressure measurement devices. Likewise, device validity is not a major area of focus for most consumers and healthcare providers, perhaps because they assume it is a pre-requisite for market approval. This has led to a global proliferation of non-validated blood pressure measurement devices, with only a small minority of blood pressure measurement devices having passed internationally accepted validation protocols. The clinical consequences are likely to be significant because non-validated devices are more likely to provide inaccurate estimates of blood pressure compared with validated devices. Even small inaccuracies in blood pressure measurement can result in substantial misdiagnosis and mistreatment of hypertension. There is an urgent need for clinical validation of blood pressure measurement devices prior to marketing them to consumers. There is also need for simplification of the process for consumers and healthcare providers to determine whether a blood pressure measurement device has successfully met an internationally accepted test of validity.

Perceptions of pharmacists on the quality of automated blood pressure devices: a national survey.

A recent study found that only 23.8% of blood pressure (BP) devices available for purchase from Australian pharmacies were validated for accuracy. The extent to which pharmacists are aware of this, and other issues related to the accuracy of BP devices, is not known and gathering this information was the aim of this study. An online survey of Australian pharmacists was distributed via the Pharmaceutical Society of Australia between 1 October and 25 November 2020. Questions were focused on the views of pharmacists related to the accuracy of BP devices. Two hundred and ten pharmacists completed the survey. The accuracy of BP devices sold by pharmacists was considered 'quite' or 'extremely important' to most respondents (94%). However, most respondents (90%) were unaware that less than one-quarter of BP devices sold by Australian pharmacies were validated, and this was 'quite' or 'extremely surprising' to many (69%). Many respondents (64%) associated a particular brand of BP device with greater accuracy. There was low awareness on proper ways to identify accurate BP devices, such as checking reputable online databases (43%). BP devices were stocked in respondents' pharmacies based on perceived quality (50%), accuracy (40%), or as determined by the pharmacy chain (36%). In conclusion, providing accurate BP devices to consumers is important to pharmacists, but they were generally unaware that most devices available from pharmacies were not validated for accuracy. Pharmacist education, alongside advocacy for policies including regulations and strategic action, is required to ensure only validated BP devices are sold in Australia.

Accuracy of cuff blood pressure and systolic blood pressure amplification.

Automated cuff measured blood pressure (BP) is the global standard used for diagnosing hypertension, but there are concerns regarding the accuracy of the method. Individual variability in systolic BP (SBP) amplification from central (aorta) to peripheral (brachial) arteries could be related to the accuracy of cuff BP, but this has never been determined and was the aim of this study. Automated cuff BP and invasive brachial BP were recorded in 795 participants (74% male, aged 64 ± 11 years) receiving coronary angiography at five independent research sites (using seven different automated cuff BP devices). SBP amplification was recorded invasively by catheter and defined as brachial SBP minus aortic SBP. Compared with invasive brachial SBP, cuff SBP was significantly underestimated (130 ± 18 mmHg vs. 138 ± 22 mmHg, p < 0.001). The level of SBP amplification varied significantly among individuals (mean ± SD, 7.3 ± 9.1 mmHg) and was similar to level of difference between cuff and invasive brachial SBP (mean difference -7.6 ± 11.9 mmHg). SBP amplification explained most of the variance in accuracy of cuff SBP (R2 = 19%). The accuracy of cuff SBP was greatest among participants with the lowest SBP amplification (ptrend < 0.001). After cuff BP values were corrected for SBP amplification, there was a significant improvement in the mean difference from the intra-arterial standard (p < 0.0001) and in the accuracy of hypertension classification according to 2017 ACC/AHA guideline thresholds (p = 0.005). The level of SBP amplification is a critical factor associated with the accuracy of conventional automated cuff measured BP.

Stagnating rates of blood pressure control in Australia: insights from opportunistic screening of 10 046 participants of the May Measurement Month campaigns.

BACKGROUND: Raised blood pressure (BP) remains the single most important modifiable risk factor contributing to cardiovascular and all-cause mortality in Australia and worldwide. May Measurement Month , a global BP measurement and screening campaign initiated by the International Society of Hypertension and carried out in Australia since its inception in 2017, aimed at obtaining standardized BP measurements from members of the community to increase awareness of high BP and its associated risks. METHOD: Adults participants (≥18 years) were recruited through opportunistic sampling across Australia during the month of May in 2017, 2018 and 2019. Trained volunteers recorded BP readings in a standardized manner and collected data on demographic, lifestyle factors and comorbidities. Hypertension was defined as SBP of at least 140 mmHg, or DBP of at least 90 mmHg, or taking antihypertensive medication. Data were collated centrally and analysis was carried out using regression models to evaluate the associations between BP and participant characteristics. RESULTS: A total of 10 046 participants were screened, of whom 3097 (31.0%) had hypertension, only 48.5% were aware of their condition and 44.4% were taking antihypertensive medication. Of those taking antihypertensive medication, 53.2% were controlled to less than 140/90 mmHg, whereas the remaining 46.8% of participants had BP of at least 140/90 mmHg suggestive of inadequately treated hypertension. CONCLUSION: Consecutive data obtained over a 3-year period in Australia demonstrated stagnating awareness, treatment and control rates with the latter two being substantially lower than global rates and those in other high-income countries. Concerted efforts from all stakeholders will be required to help overcome the unacceptably poor rates of BP treatment and control in Australia.

Country experiences on the path to exclusive use of validated automated blood pressure measuring devices within the HEARTS in the Americas Initiative.

The aim of the HEARTS in the Americas initiative is to promote the adoption of global best practices in the prevention and control of cardiovascular diseases, and improve the control of hypertension. HEARTS is being implemented in 21 countries and a diverse set of actions and measures are in progress to improve exclusive access in primary health care facilities to automated blood pressure measuring devices that have been validated for accuracy. The purpose of this manuscript is to illustrate these efforts, mainly in the regulatory and public procurement arena, and to present information on common challenges and solutions identified. Examples from six countries confirm the need for not only a robust regulatory framework to increase availability of validated automated blood pressure measuring devices but also a comprehensive strategic approach that involves relevant stakeholders, includes a multi-pronged approach and is associated with a national program to prevent and control non communicable diseases.

Cardiovascular and health cost impacts of cuff blood pressure underestimation and overestimation of invasive aortic systolic blood pressure.

OBJECTIVE: Hypertension management is directed by cuff blood pressure (BP), but this may be inaccurate, potentially influencing cardiovascular disease (CVD) events and health costs. This study aimed to determine the impact on CVD events and related costs of the differences between cuff and invasive SBP. METHODS: Microsimulations based on Markov modelling over one year were used to determine the differences in the number of CVD events (myocardial infarction or coronary death, stroke, atrial fibrillation or heart failure) predicted by Framingham risk and total CVD health costs based on cuff SBP compared with invasive (aortic) SBP. Modelling was based on international consortium data from 1678 participants undergoing cardiac catheterization and 30 separate studies. Cuff underestimation and overestimation were defined as cuff SBP less than invasive SBP and cuff SBP greater than invasive SBP, respectively. RESULTS: The proportion of people with cuff SBP underestimation versus overestimation progressively increased as SBP increased. This reached a maximum ratio of 16 : 1 in people with hypertension grades II and III. Both the number of CVD events missed (predominantly stroke, coronary death and myocardial infarction) and associated health costs increased stepwise across levels of SBP control, as cuff SBP underestimation increased. The maximum number of CVD events potentially missed (11.8/1000 patients) and highest costs ($241 300 USD/1000 patients) were seen in people with hypertension grades II and III and with at least 15 mmHg of cuff SBP underestimation. CONCLUSION: Cuff SBP underestimation can result in potentially preventable CVD events being missed and major increases in health costs. These issues could be remedied with improved cuff SBP accuracy.

Sex Differences in Blood Pressure and Potential Implications for Cardiovascular Risk Management.

BACKGROUND: Accurate blood pressure (BP) measurement is critical for optimal cardiovascular risk management. Age-related trajectories for cuff-measured BP accelerate faster in women compared with men, but whether cuff BP represents the intraarterial (invasive) aortic BP is unknown. This study aimed to determine the sex differences between cuff BP, invasive aortic BP, and the difference between the 2 measurements. METHODS: Upper-arm cuff BP and invasive aortic BP were measured during coronary angiography in 1615 subjects from the Invasive Blood Pressure Consortium Database. This analysis comprised 22 different cuff BP devices from 28 studies. RESULTS: Subjects were 64±11 years (range 40-89) and 32% women. For the same cuff systolic BP (SBP), invasive aortic SBP was 4.4 mm Hg higher in women compared with men. Cuff and invasive aortic SBP were higher in women compared with men, but the sex difference was more pronounced from invasive aortic SBP, was the lowest in younger ages, and the highest in older ages. Cuff diastolic blood pressure overestimated invasive diastolic blood pressure in both sexes. For cuff and invasive diastolic blood pressure separately, there were sex*age interactions in which diastolic blood pressure was higher in younger men and lower in older men, compared with women. Cuff pulse pressure underestimated invasive aortic pulse pressure in excess of 10 mm Hg for both sexes in older age. CONCLUSIONS: For the same cuff SBP, invasive aortic SBP was higher in women compared with men. How this translates to cardiovascular risk prediction needs to be determined, but women may be at higher BP-related risk than estimated by cuff measurements.

Sex differences in pressure and flow waveform physiology across the life course.

Cardiovascular disease (CVD) has long been deemed a disease of old men. However, in 2019 CVD accounted for 35% of all deaths in women and, therefore, remains the leading cause of death in both men and women. There is increasing evidence to show that risk factors, pathophysiology and health outcomes related to CVD differ in women compared with men, yet CVD in women remains understudied, underdiagnosed and undertreated. Differences exist between the sexes in relation to the structure of the heart and vasculature, which translate into differences in blood pressure and flow waveform physiology. These physiological differences between women and men may represent an important explanatory factor contributing to the sex disparity in CVD presentation and outcomes but remain understudied. In this review we aim to describe sex differences in arterial pressure and flow waveform physiology and explore how they may contribute to differences in CVD in women compared to men. Given that unfavourable alterations in the cardiovascular structure and function can start as early as in utero, we report sex differences in waveform physiology across the entire life course.