Influence of cuff pressures of automatic sphygmomanometers on pulse oximetry measurements

Information about blood arterial oxygen saturation (SpO₂) is crucial in critical care settings or home health monitoring during the COVID-19 pandemic. Also, we need to identify the factors that affect the SpO₂ measurement. In this paper, the effect of compression of the cuff during noninvasive blood pressure (NIBP) measurement on the SpO₂ results was investigated. A custom-made system was used for simultaneous measurement of NIBP and SpO₂. The study was conducted on 213 subjects aged between 21 and 93, with a systolic blood pressure of (94 to 194) mmHg, diastolic blood pressure of (52-98) mmHg, and 994 NIBP readings were used for the analysis. During the NIBP measurement, momentary changes in SpO₂ can reach ±17% and are in most cases positive (mean 2.9%). The change was not correlated with sex, age, height, body weight, BMI, HR and blood pressure. The obtained results show that frequent NIBP measurements may lead to wrong conclusions about SpO₂. In our study, pressure measurements mainly caused the increase of blood oxygenation level.

Accuracy and feasibility of portable blood pressure monitoring in the detection of atrial fibrillation in hemodialysis patients

Atrial fibrillation (AF) is the most prevalent cardiac arrhythmia in clinical practice and is a common comorbidity in hemodialysis patients. AF contributes to cardiovascular complications; therefore, it is recommended to screen for AF in high-risk patients to prevent serious complications. As we currently lack a handy AF screening tool, the aim of this study was to assess the accuracy of a modified BP monitor (Omron M6), in detecting AF in hemodialysis patients. In a cross-sectional analysis conducted from October 2018 to February 2019, we enrolled all the hemodialysis patients, older than 18 years and maintained on hemodialysis for at least 3 months in four hemodialysis centers in Jordan. Logistic regression was used to predict the accuracy, while the R package (epiR) was used to determine the sensitivity and specificity of the Omron M6 in screening AF. A total of 227 patients participated in the study, with a median age of 57 years (42.8-67.3); among these, 44.5% were female. Of all the participants, 18 were detected with AF, which was confirmed by a 12-lead ECG. The prevalence of AF in our study was 7.9%, while the sensitivity, specificity and accuracy of the Omron M6 in detecting AF were calculated as 83.0% (95% CI, 59.0-96.0), 94.0% (95% CI, 90.0-97.0) and 93.4% (95% CI, 88.0-95.0) respectively. We concluded that Omron M6 has high sensitivity, specificity, and accuracy in screening AF among hemodialysis patients. However, further studies are required to ascertain and firmly establish this preliminary finding.

Brachial-cuff excess pressure is associated with carotid intima-media thickness among Australian children: a cross-sectional population study

Reservoir pressure parameters (i.e., reservoir pressure [RP] and excess pressure [XSP]) independently predict cardiovascular events in adults, but this has not been investigated in children. This study aimed to determine (1) the association of reservoir pressure parameters with carotid intima-media thickness (carotid IMT), a preclinical vascular phenotype, and (2) whether a multivariable regression model with or without reservoir pressure parameters fits better for estimating carotid IMT in children. Study participants were 11-12-year-old children (n = 1231, 50% male) from the Child Health CheckPoint study, a cross-sectional substudy of the population-based Longitudinal Study of Australian Children. RP and XSP were obtained using brachial-cuff oscillometry (SphygmoCor XCEL, AtCor, Sydney). Carotid IMT was quantified by vascular ultrasonography. XSP was associated with carotid IMT after adjusting for confounders including age, sex, BMI z-score, heart rate, pubertal stage, moderate-to-vigorous physical activity, and mean arterial pressure (β = 0.93 µm, 95% CI 0.30-1.56 for XSP peak and β = 0.04 µm, 95% CI 0.01-0.08 for XSP integral). The results of the likelihood ratio test indicated a trend that the model with XSP and the above confounders fit better than a similar model without XSP for estimating carotid IMT. Our findings indicate that brachial-cuff device-measured XSP is associated with carotid IMT independent of conventional cardiovascular risk factors, including standard BP. This implies that a clinically convenient cuff approach could provide meaningful information for the early assessment of cardiovascular risk among children.

Accuracy and Trending Ability of Cardiac Index Measured by the CNAP System in Patients Undergoing Abdominal Aortic Aneurysm Surgery

OBJECTIVES

The CNAP system is a noninvasive monitor that provides a continuous arterial pressure waveform using an inflatable finger cuff. The authors hypothesized that dramatic changes in systemic vascular resistance index during abdominal aortic aneurysm (AAA) surgery might affect the accuracy of noninvasive pulse contour monitors. The aim of this study was to evaluate the accuracy and trending ability of cardiac index derived by the CNAP system (CI_CN) in patients undergoing AAA surgery.

DESIGN

Prospective clinical study.

SETTING

Cardiac surgery operating room in a single cardiovascular center.

PARTICIPANTS

Twenty patients who underwent elective AAA surgery.

INTERVENTIONS

CI_CN and cardiac index measured using 3-dimensional images (CI_3D) were determined simultaneously at 8 points during the surgery. At aortic clamping and unclamping, the authors tested the trending ability of CI_CN using 4-quadrant plot analysis and polar plot analysis.

MEASUREMENTS AND MAIN RESULTS

The authors found a wide limit of agreement between CI_CN and CI_3D (percentage error: 85.0%). The cubic splines, which show the relationship between systemic vascular resistance index and percentage CI discrepancy [(CI_CN-CI_3D)/CI_3D], were sloped positively. Four-quadrant plot analysis showed poor trending ability for CI_CN at both aortic clamping and unclamping (concordance rate: 29.4% and 57.9%, respectively). In the polar plot analysis, the concordance rates at aortic clamping and unclamping were 15.0% and 35.0%, respectively.

CONCLUSIONS

CI_CN is not interchangeable with CI_3D in patients undergoing AAA surgery. The trending ability for CI_CN at aortic clamping and unclamping was below the acceptable limit. These inaccuracies might be secondary to the high systemic vascular resistance index during AAA surgery.

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.

Screening for Atrial Fibrillation During Routine Automated Blood Pressure Measurement in General Population Aged 65 Years and Above: EMENO National Epidemiological Survey in Greece

INTRODUCTION

Atrial fibrillation (AF) is common with advanced aging and is often asymptomatic and undiagnosed.

AIM

A blood pressure (BP) monitor with embedded algorithm for detecting AF with high diagnostic accuracy during routine automated BP measurement was used to screen individuals aged ≥ 65 years.

METHODS

The EMENO health survey (2013-2016) applied a multi-stage stratified random sampling method to select a random general adult population sample in Greece. Participants aged ≥ 65 years were screened for AF using an automated oscillometric device with AF detecting algorithm (Microlife BPA100 Plus AFIB) with triplicate measurements on a single occasion.

RESULTS

A total of 975 individuals with AF data on at least one BP measurement were analysed [(mean (SD) age 73.2 (6.6) years, men 45%, hypertensives 79.3%). AF was detected in all 3 BP readings in 65 individuals (6.3%, AF group), in none of 3 readings in 661 (73.6%, non-AF group), and in 1-2 readings of 3 or less readings in 249 (20.1%, uncertain AF group). AF group individuals were older (p < 0.001), had lower systolic BP (p < 0.05) and more frequent cardiovascular disease (p < 0.01) compared to the non-AF and uncertain AF group. Moreover, 44.6% were unaware of their AF and all required anticoagulant therapy (CHA2DS2-VASc ≥ 1/≥ 2, men/women).

CONCLUSIONS

About 6% of individuals aged ≥ 65 years in Greece appeared to have AF, and 44.6% of them were unaware and requiring anticoagulant treatment. AF screening during routine automated BP measurement appears to be a useful tool for early detection of asymptomatic AF in individuals aged ≥ 65 years.

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.

Validating the accuracy of Omron J760 electronic blood pressure monitor in the general population according to AAMI/ESH/ISO (ISO 81060-2:2018) + AMD1:2020

PURPOSE

The accuracy of the Omron J760 electronic blood pressure (BP) monitor for upper arm BP measurement in the adult general population was validated following the AAMI/ESH/ISO (ISO 81060-2:2018) + Amd1:2020 protocol. We expect that this device can be used for home blood pressure monitoring, with its measurements serving as a clinical reference.

METHODS

Subjects meeting the age, gender, BP, and cuff distribution criteria as specified by the AAMI/ESH/ISO (ISO 81060-2:2018) + Amd1:2020 were recruited. BP measurements were conducted using the same-arm sequential method. The test device cuff was suitable for arm circumferences ranging from 22.0 cm to 42.0 cm.

RESULTS

Eighty-nine participants were initially recruited, 85 were evaluated after excluding 4 participants. The mean age of the participants was 48.5 ± 15.17 years. For validation criterion 1, the mean ± standard deviation (SD) of the differences between the test device and the reference BP measurements were 0.2 ± 5.74 mmHg for systolic BP and -0.9 ± 4.69 mmHg for diastolic BP. These results met the AAMI/ESH/ISO (ISO 81060-2:2018)+Amd1:2020 standard, which requires differences of ≤5 ± ≤8 mmHg. For validation criterion 2, the mean differences between the test device and the reference device were 0.2 ± 5.10 mmHg for systolic BP and -0.9 ± 4.30 mmHg for diastolic BP. This criterion was satisfied with criterion 2 of ≤6.95 mmHg for systolic BP and ≤6.88 mmHg for diastolic BP.

CONCLUSION

The Omron J760 electronic BP monitor meets the requirements of the AAMI/ESH/ISO (ISO 81060-2:2018)+Amd 1:2020 validation standard.

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.

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.