Blood Pressure Measurement Methods Research Articles

May Measurement Month 2019: blood pressure screening results in Georgia, Europe.

May Measurement Month is a global campaign aimed at raising public awareness of hypertension and to improve the management of hypertension—the main risk factor for cardiovascular diseases in the population. Screening was carried out at 400 sites on a national scale. More than 500 volunteers, including physicians (80%) and students of medical universities (20%) participated in the screening. To familiarize them with the research tools and standard blood pressure (BP) measurement method, they were trained by the members of the Georgian Society of Hypertension and the National Center for Disease Control and Public Health’s staff. Medical societies, health-care professionals, public health workers, social mass media, and other stakeholders were actively involved in the recruitment process. A total of 13 267 (38.5% males and 61.5% females) individuals were screened. The mean age of participants was 54.7 years (SD 15.9). All participants were Caucasian. After imputation of missing BP readings, 8510 (64.1%) were found to have hypertension, out of whom 7269 (85.4%) were aware of their condition, 7232 (85.0%) were on medication, and 1278 (15.0%) were not taking any medication. Of those taking antihypertensive medication, 34.8% had their BP controlled (<140/90 mmHg). May Measurement Month detected a high proportion of participants with hypertension, with results indicating low rates of control in Georgia.

Development and validation of a deep learning-based automatic auscultatory blood pressure measurement method

Manual auscultatory is the gold standard for clinical non-invasive blood pressure (BP) measurement, but its usage is decreasing as it requires substantial professional skills and training, and its environmental concerns related to mercury toxicity. As an alternative, automatic oscillometric technique has been used as one of the most common methods for BP measurement, however, it only estimates BPs based on empirical equations. To overcome these problems, this study aimed to develop a deep learning-based automatic auscultatory BP measurement method, and clinically validate its performance. A deep learning-based method that utilized time-frequency characteristics and temporal dependence of segmented Korotkoff sound (KorS) signals and employed convolutional neural network (CNN) and long short-term memory (LSTM) network was developed and trained using KorS and cuff pressure signals recorded from 314 subjects. The BPs determined by the manual auscultatory method was used as the reference for each measurement. The measurement error and BP category classification performance of our proposed method were then validated on a separate dataset of 114 subjects. Its performance in comparison with the oscillometric method was also comprehensively analyzed. The deep learning method achieved measurement errors of 0.2 ± 4.6 mmHg and 0.1 ± 3.2 mmHg for systolic BP and diastolic BP, respectively, and achieved high sensitivity, specificity and accuracy (all > 90 %) in classifying hypertensive subjects, which were better than those of the traditional oscillometric method. This validation study demonstrated that deep learning-based automatic auscultatory BP measurement can be developed to achieve high measurement accuracy and high BP category classification performance.

Validation of the QMon-20 oscillometric blood pressure monitor for professional office use in the general population according to the ANSI/ESH/ISO 81060-2:2018 protocol.

we assessed the accuracy of the QMon-20 oscillometric upper-arm cuff device professional for office blood pressure (BP) in general population according to the Association for the Advancement of Medical Instrumentation/European Society of Hypertension/International Organization for Standardization (AAMI/ESH/ISO) Universal Standard (ISO 81060-2:2018). Subjects were recruited according to AAMI/ESH/ISO Universal Standard in general population using the same arm sequential BP measurement method. Two cuffs of the test device were used for arm circumference 22-31 (medium) and 32-42 cm (large). One-hundred and fourteen subjects were recruited and 106 were analyzed. For validation criterion 1, the mean ± SD of the differences between the test device and reference BP readings was 0.8 ± 5.4/-0.5 ± 4.2 mmHg (systolic/diastolic). For criterion 2, the SD of the mean BP differences between the test device and reference BP per subject was 4.34/3.48 mmHg (systolic/diastolic). The QMon-20 oscillometric device for office BPs measurement fulfilled all the requirements of the AAMI/ESH/ISO Universal Standard (ISO 81060-2:2018) in general population and can be recommended for clinical use.

Validation of the YuWell YE900 oscillometric blood pressure monitor for professional office use in adults and children according to the AAMI/ESH/ISO Universal Standard (ISO 81060-2:2018).

To evaluate the accuracy of the YuWell YE900 oscillometric upper-arm professional office blood pressure monitor in adults and children according to the Association for the Advancement of Medical Instrumentation/European Society of Hypertension/International Organization for Standardization (AAMI/ESH/ISO) Universal Standard (ISO 81060-2:2018). Subjects were recruited to fulfill the age, sex, blood pressure and cuff distribution criteria of the AAMI/ESH/ISO Universal Standard in adults and children (aged 3-12 years) using the same arm sequential blood pressure measurement method. Three cuffs of the test device were used for arm circumference 18-22 cm (small), 22-32 cm (medium) and 32-42 cm (large). Ninety-two subjects were recruited, and 85 (50 adults and 35 children) were analyzed. For validation criterion 1, the mean ± SD of the differences between the test device and reference blood pressure readings was 1.7 ± 6.62/3.1 ± 5.76 mmHg (systolic/diastolic). For validation criterion 2, the SD of the averaged blood pressure differences between the test device and reference blood pressure per subject was 5.25/5.13 mmHg (systolic/diastolic). The YuWell YE900 professional electronic blood pressure monitor has passed the requirements of the AAMI/ESH/ISO Universal Standard (ISO 81060-2:2018) in adults and children and can be recommended for clinical use.

Comparison of cuffless blood pressure measurement using an electrocardiogram monitor with photoplethysmography function with measurement by the Korotkov method: a pilot study

The aim. To evaluate the reliability of blood pressure (BP) measurement results using a cuffless blood pressure device (CardioQVARK®) in comparison with the values obtained using the Korotkov method.Materials and methods. An observational cross-sectional study of 50 patients (25 men, mean age 60 ± 14 years) with arterial hypertension was performed. Blood pressure was measured by the Korotkov method as a standard method, and a CardioQVARK® device, made in the form of a smartphone case, was used as a new method. The device records the electrocardiogram and the photoplethysmogram. Based on the parameters of the electrocardiogram and the photoplethysmogram the systolic and diastolic blood pressure (SBP and DBP) is calculated. Correlation analysis, Student’s t-test, Bland-Altman method were used for comparing the two methods, the standard deviation of the difference and a 95% confidence interval (95% CI) were calculated.Results. There were no statistically significant differences in the mean values of SBP and DBP for the two methods. There was a strong direct relationship between SBP (r = 0.976, p &lt; 0.0001) and DBP (r = 0.817, p &lt; 0.0001), measured by two methods. Bias for SBP and DBP measured by the new method was: –0.5 mm Hg (95% CI: –1.7; 0.7) and –0.3 mmHg (95% CI: –1.4; 0.7), respectively. The difference in DBP measurements depended on the blood pressure level (r = 0.302, p = 0.03). The underestimation of DBP values was more pronounced for low blood pressure from 55 to 75 mm Hg. At the time of the study, 13 (26%) patients had an increase in blood pressure. The sensitivity of the new method in detecting arterial hypertension was 77% (95% CI: 46; 95), specificity 100% (95% CI: 91; 100), accuracy 94% (95% CI: 83; 99).Conclusion. The blood pressure measurement method based on the analysis of the electrocardiogram and photoplethysmogram showed reliable blood pressure measurement results in comparison with the Korotkov method.

A comprehensive overview of the diagnosis and treatment of hypertension based on the latest hypertension guidelines

In recent years, non-communicable diseases (NCDs) have accounted for about 70% of the world's deaths. The most common NCDs are cardiovascular disease, cancer, diabetes mellitus, and chronic respiratory diseases. These diseases have four common risk factors, including inadequate physical activity, unhealthy diet, smoking, and excessive alcohol consumption. Cardiovascular diseases, despite their high prevalence, are the most preventable chronic diseases. The most common risk factor for cardiovascular disease is high blood pressure, which can be prevented if it is diagnosed and controlled carefully. Recent guidelines have changed the methods of blood pressure measurement, definition, and treatments. Recently, more emphasis has been placed on Out-of-Office Blood Pressure Measurement. Therefore, it is necessary to consider the methods of measuring blood pressure at home and 24-hour Holter blood pressure monitoring, as well as understanding its standards. The use of automatic arm sphygmomanometers to measure blood pressure is more acceptable than manual ones (mercury or Aneroid). The most accepted definitions of hypertension are BP≥140/90 mm Hg in the clinic, the average blood pressure at home≥135/85 mm Hg, and the average blood pressure in 24-hour Holter monitoring≥130/80 mm Hg. Proper treatment of hypertension by changing lifestyle and proper medication therapy can control blood pressure and prevent serious complications. Today, the use of combination drugs, especially a single pill in a single dose, has been emphasized. This study aimed to review the most recent hypertension treatment protocols based on the guidelines of the American Heart Association (AHA 2017), the European Society of Cardiology (ESC 2018), the British Heart Association (NICE 2019), and the International Society of Hypertension (ISH 2020). Furthermore, this study attempted to assess the symptoms, complications, methods of diagnosing, definitions, as well as pharmacological and non-pharmacological treatments of hypertension.

ATP2B1 gene polymorphisms rs2681472 and rs17249754 are associated with susceptibility to hypertension and blood pressure levels: A systematic review and meta-analysis.

Objective:The present study aimed to conduct a systematic review and meta-analysis to evaluate the relationships between ATP2B1 gene polymorphisms with blood pressure (BP) level and susceptibility to hypertension.Methods:PubMed, Web of Science, Embase and China National Knowledge Infrastructure (CNKI) Databases were systematically searched by 2 independent researchers to screen studies on ATP2B1 gene polymorphisms and BP related phenotypes. The records retrieval period was limited from the formation of the database to March 4, 2021. Pooled odds rations (ORs) or β and their 95% confidence intervals (95%CI) were calculated to assess the association between ATP2B1 gene polymorphisms and the risk of hypertension or BP levels. Publication bias and sensitivity analysis were conducted to find potential bias. All the statistical analysis were conducted with Stata version 11.0 software.Results:A total of 15 articles were ultimately included in the present study, including 15 polymorphisms of ATP2B1 gene. Nine articles (N = 65,362) reported the polymorphism rs17249754, and 7 articles(N = 91,997) reported rs2681472 (both loci were reported in 1 article). Meta-analysis showed that rs17249754 (G/A) and rs2681472 (A/G) were associated with the susceptibility to hypertension (rs17249754: OR = 1.19, 95%CI: 1.10–1.28; rs2681472: OR = 1.15, 95%CI: 1.12–1.17), and were positively associated with systolic BP (SBP) and diastolic blood pressure (DBP) (rs17249754: SBP, β=1.01, 95%CI: 0.86–1.16, DBP, β=0.48, 95%CI: 0.30–0.66; rs2681472: SBP, β=0.92, 95%CI: 0.77–1.07, DBP, β=0.50, 95%CI: 0.42–0.58) in the additive genetic model. Subgroup analysis stratified by race, population, sample size, and BP measurement method revealed that the association between A allele in rs2681472 polymorphism and risk of hypertension was slightly stronger in European (EUR) populations (OR = 1.16, 95%CI: 1.13–1.20) than in East Asians (OR = 1.14, 95%CI: 1.10–1.17). While in East Asians, relation between rs17249754 with risk of hypertension (OR = 1.19, 95%CI: 1.10–1.28) is stronger than rs2681472 (OR = 1.14, 95%CI: 1.10–1.17).Conclusions:Our study demonstrated that ATP2B1 gene polymorphism rs2681472 and rs17249754 were associated with BP levels and the susceptibility to hypertension.

BLOOD PRESSURE MEASUREMENT METHODS AND KNOWLEDGE, PERCEPTION, PRACTICE OF NURSES: ARE WE THERE YET?

Objective: Accurate Blood pressure measurement (BPM) is a fundamental aspect of hypertension management. Guidelines regarding BPM methods, namely home (HBPM), ambulatory (ABPM), office (OBPM) and automated (AOBP) are published by Hypertension Canada. Nurses commonly perform BPM, but little is known regarding their knowledge, perception and practice when considering all BPM methods. A recent scoping review concluded that insufficient data was available for all professionals, but specifically nurses. This descriptive study assessed knowledge, perception and practice of nurses regarding all BPM methods. Design and method: All nurses licensed to practice in primary care settings across Québec were targeted for this survey. A personalized email invitation, and 2 reminders, including a link to a secured platform was send between in December 2019. Data was collected using a validated and pretested questionnaire consisting of 48 questions for knowledge, perception and practice for all BPM methods in English and French. Results: A total of 447 nurses participated, with a response rate of 11%. The median age was 40.5 ± 11,5 years old and 92% were women. For knowledge and perception, the mean percentage score obtained are presented in Table 1. For practice, the most frequently recommended method was HBPM (47%), followed by ABPM (18%). One third (35%) nurses reported education for HBPM was frequently provided to their patients, while for ABPM it was only 18%. While AOBP is the preferred method in Canada, more than half (52%) never use it and only 57% use oscillometric device for OBPM, meaning that there are still a large number of measurements being performed manually by auscultation. Conclusions: Although nurses had positive perceptions about the use of out-of-office measurements there is still much room for improvement for knowledge and practice. Our results show that a gap remains between what is recommended, what is known, and what is actually done in the field. Further strategies should involve optimal use of educational resources such as BPM algorithm posters and booklets, optimizing patient centered care using team-based approach, incorporating HBPM and encouraging participation in certification programme offered by hypertension societies.

BLOOD PRESSURE MEASUREMENT AND MONITORING BY INTERNAL MEDICINE SPECIALISTS IN GERMANY IN VIEW OF THE SPRINT TRIAL

Objective: There are continuous discussions about the optimal target blood pressure values, not least due to the publication of the SPRINT study, where unattended ambulatory office blood pressure (AOBP) was used for blood pressure (BP) measurement. The aim of the following online survey was to examine how BP measurement and the management of hypertensive patients are handled in everyday practice by internal medicine specialists in Germany and to compare it with the current guidelines. Design and method: An online questionnaire with ten questions concerning methods of BP measurement was sent to 15,884 internal medicine specialists as an email via the mailing list of the German Society of Internal Medicine (DGIM). Of these, 731 took part in the survey, which corresponds to a response rate of 4 %. The statistical evaluation was carried out with MS Excel. Results: The standard auscultatory measurement with an aneroid manometer is the leading method used by 44 % and in 95 % of the cases, it is measured in the presence of medical staff, i.e., attended. With 53 %, more than half of the respondents only take one measurement. A group of 36 % take two or more measurements. Of these, the largest percentage with 28 % takes the last value, closely followed by 26 %, who use the average value. The first or lowest value is each used by 17 %, while a minority of 12 % use the highest value. A majority of two-thirds measures without any time reference to taking medication (66 %). Ambulatory and Home BP are used by the majority for therapy control, according to the survey (fig.) Conclusions: The guidelines are not implemented correctly in many places and the approach to managing hypertension patients varies considerably. Possible reasons for this might be a lack of time in everyday practice and not always specifically formulated specifications in the recommendations of the professional associations, which leads to ambiguities. Measurement using unattended AOBP is rarely used in Germany. To be able to transfer the results from SPRINT, this measurement method would first have to be established.

POS-412 ETIOLOGIES AND MANAGEMENT OF HYPERTENSION IN CHILDREN: ABOUT A SERIES OF 41 CASE

Hypertension is a very common finding in general pediatrics. A wide spectrum of etiologies is already known. But sometimes, finding the cause of hypertension and managing it can be challenging. We conducted a retrospective descriptive study including 41 children treated for hypertension from January 2015 to December 2019. We gathered data regarding the gender, age at onset, clinical manifestations, laboratory and radiology investigations, as well as management and outcome. The mean age a diagnosis was seven years, with 50% aged above 5 years. More than half of our patients were girls (60%). Symptoms at onset were mainly headache (25%), seizures (20%), ophthalmological manifestations (7.5%). The mean time between the onset of symptoms and diagnosis was 6 months. Meanwhile, the discovery of hypertension has been fortuitous in 55%. Causes of hypertension were divided as follows: chronic kidney disease in 50%, acute glomerulonephritis in 25%, segmental glomerular sclerosis in 12.5%, recessive renal polycystic disease in 5%. The remaining cases were hypertension caused by pheochromocytoma, hyperthyroidism, primary hyperaldosteronism, or renal artery stenosis. In one case, the cause was undetermined despite appropriate investigations. The majority (57%) of patients needed only one drug to control their blood pressure, while the others needed an association of two or more to reach blood pressure targets. Drugs mostly used to treat hypertension in our children were calcic inhibitors (50%), CEI/ARBs (33%), and diuretics (33%). Despite appropriate management, complications of hypertension (like hypertensive retinopathy, nephropathy, and/or stroke) were observed in about 37% of our children. At last, complete remission of hypertension (after specific treatment) was observed in 30% of patients, and those were the cases with acute glomerulonephritis, pheochromocytoma, and hyperparathyroidism. Childhood hypertension can be underdiagnosed in a lot of paucisymptomatic cases. This can lead to an increase in the incidence of the complications of chronic hypertension. That is why, to lower that risk and improve prognosis, sensibilization of all health practitioners to the right method of blood pressure measurement and interpretation in the pediatric population is mandatory.

WHAT ARE THE PREFERRED BLOOD PRESSURE MEASUREMENT METHODS BY DOCTORS TO DETECT, DIAGNOSE AND TREAT HYPERTENSION? A SURVEY STUDY IN A CHINESE POPULATION

Objective: Hypertension(HT) is the most common chronic disease and is the leading cause of morbidity and mortality. Its detection, diagnosis and management depend heavily on accurate blood pressure(BP) measurement. It is recommended that the diagnosis of HT should be confirmed or assisted by out-of-office BP measurement, including ambulatory BP measurement(ABPM) and home BP measurement(HBPM). When office BP is used, automated BP measurement(AOBP), which automatically provides an average of 3–5 BP readings, is preferred. This study aimed to describe the BP measurement methods used by doctors working in primary care to detect, diagnose and treat hypertension. Design and method: This is a cross-sectional survey. All doctors registered in the “Primary Care Directory” were mailed a questionnaire, asking their preferred methods to detect, diagnose and treat hypertension. Furthermore, the number of BP readings they usually obtained on office BP or HBPM to diagnose or manage HT was asked. Results: Four hundred and forty-five doctors responded. Manual measurement by a mercury or aneroid devices was the commonest method to detect(63.1%), diagnose(56.4%), and manage(72.4%) HT. There was an underuse of ABPM and only 1.6% of doctors used ABPM to diagnose HT. 22.2% of doctors used HBPM to diagnose HT; and 56.8% of doctors used HBPM to manage HT. A quarter (26.7%) of participants only obtained one BP reading when they used office BP. Only 40% of participants obtained at least 12 BP readings when HBPM was used. Doctors who obtained specialist qualification in family medicine were more likely to use AOBP in clinics and to obtain enough office BP readings for diagnosis and management of HT. Conclusions: Doctors in primary care in Hong Kong prefer to use manual office BP, especially mercury or aneroid devices, to screen, diagnose and treat HT. There is an underuse of AOBP and out-of-office BP. Studies are needed to understand the underlying reasons and to minimize the gap between real-life clinical practice and scientific advances.

VALIDATION OF THE INBODY BPBIO750 OSCILLOMETRIC BLOOD PRESSURE MONITOR FOR PUBLIC SPACES (KIOSK) ACCORDING TO THE AAMI/ESH/ISO UNIVERSAL STANDARD

Objective: To evaluate the accuracy of the upper-arm cuff oscillometric blood pressure (BP) monitor InBody BPBIO750 developed for self-measurement by adults in public spaces (kiosk) in general population according to the Association for the Advancement of Medical Instrumentation/European Society of Hypertension/International Organization for Standardization (AAMI/ESH/ISO) Universal Standard (ISO 81060-2:2018). Design and method: Subjects were recruited to fulfil the age, gender, BP and cuff distribution criteria of the AAMI/ESH/ISO Universal Standard in general population using the same arm sequential BP measurement method. The device has a fixed hole to insert the user's arm with a single implanted upper-arm cuff. Results: A total of 102 subjects were recruited and 85 were analyzed (mean age 56.7 ± 15.4 [SD] years, 40 men, arm circumference 32.3 ± 5.3 cm, range 22–42 cm). For validation Criterion 1, the mean ± SD of the differences between the test device and reference BP readings (N = 255) was 2.2 ± 6.1/-2.2 ± 5.2 mmHg (systolic/diastolic). For Criterion 2, the SD of the averaged BP differences between the test device and reference BP per individual (N = 85) was 5.00/4.63 mmHg (systolic/diastolic). Conclusions: The InBody BPBIO750 oscillometric device for BP measurement in public spaces fulfilled all the requirements of the AAMI/ESH/ISO Universal Standard (ISO 81060-2:2018) in general population and can be recommended for clinical use in adults.

24-hour ambulatory blood pressure monitoring and hypertension related risk among HIV-positive and HIV-negative individuals: cross sectional study findings from rural Uganda.

Hypertension is diagnosed and treated based on blood pressure (BP) readings obtained in the clinic setting. Positive HIV status is associated with a higher prevalence of abnormal diurnal blood pressure patterns, diagnosed with ambulatory BP monitoring rather than the conventional method of BP measurement. Little is known about ambulatory BP profiles in people living with HIV (PLHIV) in low-income countries, especially within sub-Saharan Africa. In this study, we compared 24-hour ambulatory blood pressure profiles of 140 HIV-positive individuals vs. profiles in 166 HIV negative individuals living in rural Uganda. HIV was well-controlled, with all HIV seropositive participants reporting use of anti-retroviral therapy, and approximately 123 (88%) having undetectable viral load. Most participants reported ART use duration of less than 10 years. Compared to HIV negative participants, HIV positive participants had lower median 24-hour systolic blood pressure (110.4 mmHg (IQR: 105.7, 118.7) vs 117.7 mmHg (IQR: 110.8, 129.8), p<0.001), and 24-hour diastolic blood pressure (69.2 mmHg (IQR: 65.0, 74.9) vs. 71.9 mmHg (IQR: 67.2, 78.1), p=0.004). Adjusted results showed greater percentage systolic nocturnal dipping among PLHIV compared to HIV negative individuals (difference=2.70 (IQR: 0.94, 4.47), p <0.05). Results of the adjusted Poisson regression suggested lower prevalence of 24-hour and night hypertension among HIV positives compared to HIV negative, but were not statistically significant. Our data suggest that continuous 24-hour blood pressure measurements are lower in PLHIV on ART compared to HIV negative individuals.

Cuff-less continuous blood pressure measurement based on multiple types of information fusion

Non-invasive and cuff-less real-time continuous blood pressure monitoring plays an important role in both intensive care unit (ICU) and the management of chronic diseases such as hypertension and cardiovascular disease. Although pulse wave transit time (PTT) and pulse waveform parameters (PWPs) can be extracted from photoplethysmography (PPG) and electrocardiographic (ECG) to estimate blood pressure, the value of blood pressure is also constrained by personal characteristics parameters (PCPs). For example, the blood pressure may vary with height, weight and age. In this paper, we present a cuff-less continuous blood pressure measurement method based on multiple types of information fusion. First, we recruited 186 volunteers and measured their personal data (PPG signal, ECG signal, height, age, weight, gender). Second, extract the PTT and PWPs from the PPG signal and ECG signal. Then, according to the extracted parameters, the blood pressure models of control group and experimental group were established respectively (the experimental group uses the multiple types of information fusion method to model, the control group only considers PTT and PWPs). Experiments show that, comparing with the control group, the experimental group systolic blood pressure (SBP) correlation was increased from 0.9355 to 0.9948, root mean square error (RMSE) was reduced from 5.2 mmHg to 1.5 mmHg, while the diastolic blood pressure (DBP) correlation was improved from 0.9331 to 0.9931, RMSE was reduced from 2.9 mmHg to 0.9 mmHg. Therefore, the modeling method proposed in this paper can get more accurate blood pressure values. Further promotion, to achieve the measurement with the "modeling" method, all "restriction" elements must be taken into account in order to obtain a more accurate and stable model.

Non-invasive cuff-less blood pressure machine learning algorithm using photoplethysmography and prior physiological data.

Conventional blood pressure (BP) measurement methods have a number of drawbacks such as being invasive, cuff-based or requiring manual operation. Many studies are focussed on emerging methods of noninvasive, cuff-less and continuous BP measurement, and using only photoplethysmography to estimate BP has become popular. Although it is well known that physiological characteristics of the subject are important in BP estimation, this has not been widely explored. This article presents a novel method which adopts photoplethysmography and prior knowledge of a subject's physiological features to estimate DBP and SBP. Features extracted from a fingertip photoplethysmography signal and prior knowledge of a subject's physiological characteristics, such as gender, age, height, weight and BMI is used to estimate BP using three different machine learning models: artificial neural networks, support vector machine and least absolute shrinkage and selection operator regression. The accuracy of BP estimation obtained when prior knowledge of the physiological characteristics are incorporated into the model is superior to those which do not take the physiological characteristics into consideration. In this study, the best performing algorithm is an artificial neural network which obtains a mean absolute error and SD of 4.74 ± 5.55 mm Hg for DBP and 9.18 ± 12.57 mm Hg for SBP compared to 6.61 ± 8.04 mm Hg for DBP and 11.12 ± 14.20 mm Hg for SBP without prior knowledge. The inclusion of prior knowledge of the physiological characteristics can improve the accuracy of BP estimation using machine learning methods, and the incorporation of more physiological characteristics enhances the accuracy of the BP estimation.

GRANGER CAUSALITY ANALYSIS BETWEEN INTRA-OSSEOUS PRESSURE AND ARTERIAL BLOOD PRESSURE IN AFRICAN GREY PARROTS (PSITTACUS ERITHACUS)

Monitoring blood pressure helps a clinical veterinarian assess various conditions in birds. Blood pressure is not only a bio-indicator of renal or cardiovascular disease but is also a vital indicator for anesthesia. Anesthetic- and sedation-related mortality is higher in birds than dogs or cats. The traditional method of blood pressure measurement in mammals mainly relies on indirect methods. However, indirect blood pressure measurement is not reliable in birds, making the direct method the only gold standard. Although an arterial catheter can provide continuous real-time arterial pressure in birds, the method requires technical skill and is limited by bird size, and is thus not practical in birds with circulatory collapse. Intra-osseous (IO) blood pressure is potentially related to arterial pressure and may be a much easier and safer technique that is less limited by animal size. However, the relationship between IO pressure and arterial blood pressure has not been established. This study used mathematical methods to determine the relationship between IO pressure and arterial blood pressure. The Granger causality (G.C.) theory was applied in the study and used to analyze which pressure signal was leading the other. Our findings suggest that IO pressure is G.C. by arterial blood pressure; thus, the use of IO pressure measurements as an alternative to arterial blood pressure measurement is a rational approach.

Feasibility of a Web-Based Platform (Trial My App) to Efficiently Conduct Randomized Controlled Trials of mHealth Apps For Patients With Cardiovascular Risk Factors: Protocol For Evaluating an mHealth App for Hypertension.

BackgroundMobile health (mHealth) interventions can improve health by improving cardiovascular risk factors, but their adoption in care by physicians and patients is untapped. Few mHealth apps have been evaluated in clinical trials, and due to the fast pace of technological development, those previously evaluated are often outdated by the time trial results are available. Given the rapid pace of change in this field, it is not feasible to rigorously evaluate mHealth apps with current methodologies.ObjectiveThe overall aim of this pilot study was to test the feasibility of using a web research platform called Trial My App to conduct efficient and rigorous web-based randomized controlled trials (RCTs) of mHealth apps relevant to patients with cardiovascular risk factors by evaluating an app that targets hypertension.MethodsFor this study, 200 participants with suboptimally controlled hypertension will be recruited through advertisements in newsletters, media, and the internet, as well as through referrals from their health care providers. Screening, consent, randomization, and collection of patient-important health confidence and self-management ability outcomes will be conducted online through the Trial My App research platform. Participants will be randomized into 2 groups: 100 that will use an mHealth app for tracking hypertension and 100 that will be considered as an educational control. All participants will complete questionnaires at 0, 1, 3 and 6 months after enrolment. A substudy to validate the method of blood pressure readings and the consistency of data entered through Trial My App will be conducted with 40 participants.ResultsThe development of the Trial My App web platform has been completed. The creation of survey instruments has been completed in collaboration with our patient partners and advisory board. Recruitment is expected to begin in the first quarter of 2021; data collection and analysis are expected to be completed approximately 1 year after study commencement. Results will be disseminated through conferences and publications. The primary outcomes of this study include the feasibility of conducting an RCT using the Trial My App platform by reporting recruitment, retention, and completion statistics. We will validate app-entered data with a standard 7-day home blood pressure measurement method. Lastly, the pilot, nonblinded RCT will assess the effectiveness of the mHealth app in improving the control of hypertension compared with the control of hypertension in the educational control group.ConclusionsThis study will determine if it is feasible to use the Trial My App web-based platform to evaluate the effectiveness of mHealth apps for patients with cardiovascular risk factors. As more mHealth apps are evaluated in RCTs, patients will be able to select apps that meet their needs and physicians will be able to make evidence-based recommendations to their patients for apps aimed at improving cardiovascular health.Trial RegistrationClinicalTrials.gov NCT04528654; https://clinicaltrials.gov/ct2/show/NCT04528654International Registered Report Identifier (IRRID)PRR1-10.2196/26155

Non-invasive cuff-less blood pressure estimation using a hybrid deep learning model

Conventional blood pressure (BP) measurement methods have different drawbacks such as being invasive, cuff-based or requiring manual operations. There is significant interest in the development of non-invasive, cuff-less and continual BP measurement based on physiological measurement. However, in these methods, extracting features from signals is challenging in the presence of noise or signal distortion. When using machine learning, errors in feature extraction result in errors in BP estimation, therefore, this study explores the use of raw signals as a direct input to a deep learning model. To enable comparison with the traditional machine learning models which use features from the photoplethysmogram and electrocardiogram, a hybrid deep learning model that utilises both raw signals and physical characteristics (age, height, weight and gender) is developed. This hybrid model performs best in terms of both diastolic BP (DBP) and systolic BP (SBP) with the mean absolute error being 3.23 ± 4.75 mmHg and 4.43 ± 6.09 mmHg respectively. DBP and SBP meet the Grade A and Grade B performance requirements of the British Hypertension Society respectively.

Testing a Patient-Specific In-Silico Model to Noninvasively Estimate Central Blood Pressure.

To show some preliminary results about the possibility to exploit a cardiovascular mathematical model-made patient-specific by noninvasive data routinely measured during ordinary clinical examinations-in order to obtain sufficiently accurate central blood pressure (BP) estimates. A closed-loop multiscale (0D and 1D) model of the cardiovascular system is made patient-specific by using as model inputs the individual mean heart rate and left-ventricular contraction time, weight, height, age, sex and mean/pulse brachial BPs. The resulting framework is used to determine central systolic, diastolic, mean and pulse pressures, which are compared with the beat-averaged invasive pressures of 12 patients aged 72 ± 6.61 years. Errors in central systolic, diastolic, mean and pulse pressures by the model are 4.26 ± 2.81, 5.86 ± 4.38, 4.98 ± 3.95 and 3.51±2.38 mmHg, respectively. The proposed modeling approach shows a good patient-specific response and appears to be potentially useful in clinical practice. However, this approach needs to be evaluated in a larger cohort of patients and could possibly be improved through more accurate oscillometric BP measurement methods.

Noninvasive Accelerometric Approach for Cuffless Continuous Blood Pressure Measurement

Pulse transit time (PTT) has been widely used for cuffless blood pressure (BP) measurement. However, it requires more than one cardiovascular signal involving more than one sensing device. In this article, we propose a method for cuffless continuous blood pressure measurement with the help of left ventricular ejection time (LVET). A microelectromechanical system (MEMS)-based accelerometric sensor acquires a seismocardiogram (SCG) signal at the chest surface, and then, the LVET information is extracted. Both systolic and diastolic BPs are estimated by calibrating the system with the original arterial BPs of the subjects. The performance evaluation is done using different statistical quantitative measures for the proposed method. The performance is also compared with two earlier approaches, where PTT intervals are measured from electrocardiogram (ECG)–photoplethysmogram (PPG) and SCG–PPG pairs. The performance results clearly show that the proposed method is comparable with the state-of-the-art methods. Also, the estimated BP is compared with the original one, measured through a reference system. It gives the mean errors of the systolic and diastolic BPs within the range of −0.197 ± 3.332 and −1.299 ± 2.578 mmHg, respectively. The BPs estimation errors satisfy the requirements of the IEEE standard 5 ± 8 mmHg deviation, and thus, our method may be used for ubiquitous continuous BP monitoring.