Continuous Blood Pressure Measurement Research Articles

Abstract P075: Functional NOX2 In T Cells Amplifies Salt-Sensitive Hypertension And Associated Renal Damage

Infiltrating T cells in the kidney amplify salt-sensitive (SS) hypertension and renal damage, but the mechanisms are not known. Genetic deletion of T cells (SS CD247-/- ) or the p67phox subunit of NOX2 (SS p67phox-/- ) attenuates salt-sensitive hypertension in the Dahl SS rat. We hypothesized that reactive oxygen species (ROS) produced by NOX2 in T cells drive the SS phenotype and renal damage. T cells were reconstituted by adoptively transferring ~10 million splenocytes from the Dahl SS (SS→CD247, n=14), the SS p67phox-/- (p67phox→CD247, n=19), or PBS only (PBS→CD247, n=8), into the peritoneum of SS CD247-/- rats on postnatal day 5. Animals were instrumented with radiotelemeters at 8 weeks of age. After a week of recovery, blood pressure and albumin excretion were measured while rats were fed a low salt (LS, 0.4% NaCl) diet. Rats were then switched to a high salt (HS, 4.0% NaCl) diet for 21 days, with continuous blood pressure measurements and urine collections every 7 days. On day 22, the rats were euthanized, and their kidneys were perfused and collected for histology and renal immune cell characterization by flow cytometry. At baseline there was no detectable difference in mean arterial pressure (MAP) between groups (124±2 vs 123±2 vs 116±2 mmHg; SS→CD247 vs p67phox→CD247 vs PBS→CD247, respectively). After 21 days of HS, MAP was significantly greater in the SS→CD247 compared to the p67phox→CD247 rats (155±3 vs 144±2 mmHg; p<0.001) and the PBS→CD247 rats (155±3 vs 141±3 mmHg; p<0.001). Indices of renal damage identified no difference in albuminuria between SS→CD247 and p67phox→CD247 on LS (25.8±4.7 vs 23.2±3.2 mg/day). After 21 days of HS, albuminuria was significantly greater in the SS→CD247 (242.8±30.3 mg/day) compared to the p67phox→CD247 (175.5 ± 14.3 mg/day, p<0.03) and PBS→CD247 (135.9±27.8 mg/day, p<0.005). There was no difference between p67phox→CD247 and PBS→CD247 in albuminuria or MAP during LS or HS. The lack of CD3+ cells in the PBS→CD247 but presence of CD3+ cells in rats receiving the T cell transfer demonstrated the effectiveness of the adoptive transfer. These results indicate that ROS production by T cells participates in the amplification of salt-sensitive hypertension and renal damage.

Multi-Dimensional Feature Combination Method for Continuous Blood Pressure Measurement Based on Wrist PPG Sensor.

The cuff-less blood pressure (BP) monitoring method based on photoplethysmo- gram (PPG) makes it possible for long-term BP monitoring to prevent and treat cardiovascular and cerebrovascular events. In this paper, a portable BP prediction system based on feature combination and artificial neural network (ANN) is implemented. The robustness of the model is improved from three aspects. Firstly, an adaptive peak extraction algorithm was used to improve the accuracy of peaks and troughs detection. Secondly, multi-dimensional features were extracted and fused, including three groups of PPG-based features and one group of demographics-based features. Finally, a two-layer feedforward artificial neural networks algorithm was used for regression. Thirty-three subjects distributed in the three BP groups were recruited. The proposed method passed the European Society of Hypertension International Protocol revision 2010 (ESP-IP2). Experimental results show that the proposed method exhibits good accuracy for a diverse population with an estimation error of -0.07 ± 4.47 mmHg for SBP and 0.00 ± 3.61 mmHg for DBP. Moreover, the model tracked the BP of two subjects for half a month, laying the foundation work for daily BP monitoring. This work will contribute to the long-term wellness management and rehabilitation process, enabling timely detection and improvement of the user's physical health.

A Novel CNN-LSTM Model Based Non-Invasive Cuff-Less Blood Pressure Estimation System.

PPG (Photoplethysmography) and ECG (Electro-cardiogram) physiological signals have been known to have certain indicators for establishing blood pressure (BP) levels. Continuous monitoring of blood pressure (BP) is highly valuable for cardiovascular patients; however the existing non-invasive cuff-based blood pressure monitoring system is discreet and applies artificial pressure on patients' arms that is uncomfortable. The other invasive method is highly interventional in nature and is highly disturbing when the patient is recuperating in the hospital wards or elsewhere. A non-invasive cuff-less, non-disturbing, and continuous BP measurement system targeted toward surgical, clinical, and domestic usage are proposed in this work. A convolutional neural network (CNN) followed by a long short-term memory layer (LSTM) was designed and applied to ECG and PPG signals to present accurate systolic blood pressure (SBP), and diastolic blood pressure (DBP). For developing the CNN-LSTM layers, a novel and open-source dataset was compiled that consisted of PPG and ECG signals from 30 healthy participants and is made publicly available for further usage to the research community. The novel CNN-LSTM based cuff-less blood pressure evaluation system presented a mean absolute error (MAE) of 2.57 mmHg and 3.44 mmHg for SBP and DBP respectively with similar standard-deviation (SD) metrics. The characterized error metrics of the proposed system are the lowest to date when compared to other prior work. Clinical Relevance- A cuff-less BP estimation system allows patients to have easy access to blood pressure evaluation as well as aid in determining unsafe health ailments like hypertension. Ready access to such system will not only allow practitioners to continuously monitor BP in hospitals but also help patients to regularly monitor BP more frequently at their convenience.

Cuff-less and continuous blood pressure measurement based on pulse transit time from carotid and toe photoplethysmograms

Blood pressure (BP) is a vital health parameter that varies throughout the day. As a single reading of high BP may not indicate hypertension, continuous monitoring of BP is usually recommended by medical doctors to confirm the diagnosis of hypertension. In the last few decades, researchers have investigated cuff-less and continuous BP measurements based on pulse transit time (PTT). The main purpose of this research is to develop an autoregressive (ARX) system identification (SI)-based PTT calculation model using two PPG signals acquired from carotid and toe. The signals were recorded from 65 subjects with an age range between 20 and 60 years. The results of the study have been validated in two stages. The first validation comprised the estimated BP from PTT using SI compared to the measured BP using the cuff-based method for all subjects. The results of the estimated BP using the proposed method compared to the measured BP obtained using the standard BP cuff measurement method are highly correlated to both systolic blood pressure (R 2 = 0.8132) and diastolic blood pressure (R 2 = 0.8357). The second validation consisted of comparing PTT values using system identification to the results of the PTT derived from the ECG–PPG method. The results showed that both methods are highly correlated (R 2 = 0.7808), and there is no significant difference between them (p < 0.05) with a slightly better PTT estimation related to DBP in the proposed method. Our results have proven that the PTT obtained from the carotid PPG and toe PPG using the system identification approach yielded SBP and DBP estimations that are consistent with the values of the conventional BP cuff method. The newly proposed method has the advantage of being cuff-less and able to provide continuous BP measurements.

Wearable Multimodal Vital Sign Monitoring Sensor With Fully Integrated Analog Front End

Cardiovascular disease (CVD) is a widespread disease and the leading cause of death worldwide. Home care is essential for patients with CVD, and it involves the daily monitoring of important CVD-related vital signs using methods including electrocardiography (ECG), heart rate monitoring, pulse oximetry (SpO2), and continuous blood pressure measurement. However, a wearable device that can monitor these parameters simultaneously remains unavailable; herein, we propose a lightweight, highly integrated sensor that can do so. In this sensor, an analog front end (AFE) integrated chip (IC) is implemented in the sensor to detect one-lead ECG and two-wavelength photoplethysmography (PPG) signals. The highly integrated IC minimizes both the size and power requirement of the sensor. Moreover, its comprehensive functions include adjustable gain, current compensation, lead off, and fast recovery—all of which are crucial for wearable applications in large populations. Accordingly, the sensor can apply the adaptive adjust method to automatically adjust the IC parameters to suit a range of applications and users. In addition, the heart rate is calculated from the R-R interval from the ECG signals, whereas the SpO2 is calibrated with a univariate quadratic equation with less than 1% mean error. Our sensor can also calculate the systolic blood pressure (SBP) and diastolic blood pressure (DBP) by using a support vector machine based calibration-less model with the features of infrared PPG and ECG signals. The model is trained on our pre-collected wearable dataset and has a mean error ± standard deviation of −2.10 ± 7.07 mmHg for SBP and 0.04 ± 7.34 mmHg for DBP in 16 volunteers. In conclusion, this paper reports on a multimodal, vital sign monitoring sensor—with small size, low power, and dynamic compatibility—suitable for patients with CVD under home care.

PPG-based blood pressure estimation can benefit from scalable multi-scale fusion neural networks and multi-task learning

The continuous measurement of blood pressure (BP) plays an important role in preventing cardiovascular diseases. However, common cuff-based devices with cumbersome operations are difficult to realize continuous BP monitoring. We propose a continuous BP estimation method based on the end-to-end multi-scale fusion and multi-task learning neural network (MSF-MTLNet). It can use the 8-second PPG segment and its derivatives as input and automatically learn their multi-scale features to improve BP accuracy. The proposed method implements feature extraction by adaptively fusing multiple convolution kernels with different sizes through the attention mechanism. Simultaneously, multi-task learning was introduced to discover task-relevant features. A total of 277,600 segments from 1825 patients in the University of California, Irvine database are used for experiments. They are divided into the independent training set, validation set, and test set according to the ratio of 8:1:1 in an inter-subject manner. The mean and standard deviation of estimation error for systolic blood pressure and diastolic blood pressure are 0.97 ± 8.87 mmHg and 0.55 ± 4.23 mmHg, respectively, which outperforms the current cutting-edge method. Our approach almost meets the Association for the Advancement of Medical Instrumentation standard. Considering the British Hypertension Society standards, it achieves an 'A' grade for DBP estimation and a 'B' grade for SBP estimation. Experimental results show that MSF-MTLNet can obtain promising precision in cuffless and continuous BP estimation.

ARE COMMERCIAL CUFFLESS BLOOD PRESSURE DEVICES BEING VALIDATED?

Objective: Hypertension is an increasingly prevalent global disease with an overwhelming burden on society and the healthcare system. Undiagnosed hypertension and poor adherence to monitoring have been highlighted in the literature to be a key factor in addressing this issue. Wearable devices are a potential solution to this problem through offering continuous and convenient blood pressure (BP) measurements, unlike current cuff-based approaches. However, the validity of such novel devices is a limiting factor to their integration as a medical tool. This literature review aims to highlight the lack of validity of current commercial cuffless BP devices and the resulting impact on BP measurement and monitoring. Design and method: Investigators generated a list of commercial cuffless BP devices and search terms based on a preliminary search performed in Google and literature databases. Google Scholar, PubMed and Scopus were then systematically searched. Articles were included following a criterion on the basis that they must mention a cuffless BP device and have performed a comparison of measurements with a reference device, either cuff-based or invasive. Statistical analyses were then undertaken. Results: Two hundred and five search terms were generated. Following the systematic search there were 932 articles captured. After the inclusion and exclusion criteria was applied more than 90% of papers were excluded on the basis that they did not perform a validation, were in another language and/or were not relevant to blood pressure measurement. Of the 205 commercial devices initially searched only 11 of these had performed some sort of validity test. None of the devices had undertaken a validity test in accordance with the 2014 IEEE Standard for Wearable, Cuffless BP Measuring Devices or the 2019 amendment. Conclusions: Current cuffless BP devices lack published validity and as a result clinical utility. Performing stringent testing on the accuracy and reliability of devices will result in the progression and acceptance of such devices with the capacity to revolutionise BP measurement and therefore hypertension.

Mechanical Energy Harvesting System from the Human Arm Movement for Continuous Blood Pressure Measurement

Background: In this article, an approach to harvesting electrical energy from a mechanically excited piezoelectric element has been described. Three PMN-xPT compositions were used with x taking the values of 0.31, 0.33, and 0.35 in order to study the most important properties of piezoelectric PMN-PT in energy harvesting. Objectives: This study uses a detailed analysis of three Relaxer (1-x)PMN-xPT ceramic compositions, emphasizing the influence of content on piezoelectric, dielectric, and electromechanical characteristics. Methods: Prototypes have been made and characterized, validating these energy thresholds. From this comparative analysis of the three compositions, it was found that PMN-35PT has the highest recoverable energy density. On the other hand, the pressure change in the radial artery was calculated using the pressure sensitivity of the sensor and systolic and diastolic characteristic points in the pressure pulse wave (PPW). Results: The results show that piezoelectric, dielectric, and electromechanical properties are all directly associated with chemical composition and that the examined ceramics outperform their PZT counterparts, making them very suitable for energy harvester systems and sensing device applications. Therefore, the structure developed is an external patch of 5x3cm², placed on the arm and able to recover 3.46 mW for PMN-35PT during human walking. Conclusion: Results indicate that the suggested method demonstrated reliable accuracy of systolic blood pressure (SBP). The technology has the potential to be used for long-term continuous blood pressure monitoring. The piezoelectric sensor was placed on the skin above the radial artery and measured for 10 sec to obtain the continuous pressure waveform.

Non-invasive continuous arterial pressure monitoring during transcatheter atrial fibrillation ablation: a feasibility prospective study

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Transcatheter atrial fibrillation (AF) ablation is still carried out with continuous invasive radial arterial blood pressure (BP) monitoring in many centers. Continuous noninvasive blood pressure (CNBP) measurement using the volume-clamp method is a non invasive alternative method used in ICU. No data on CNBP reliability are available in the electrophysiology lab during AF ablation, where rhythm variations are common. Purpose The objective of the present study was to compare continuous noninvasive arterial pressure measured with the ClearSight device with invasive radial artery pressure, used as the reference method during AF ablation. Methods We prospectively enrolled 55 consecutive patients (age 62±11 years, 79% male) undergoing transcatheter AF ablation (62% paroxysmal, 38% persistent) at our center. Standard of care invasive BP monitoring via a radial cannula and a contro-lateral non-invasive finger volume-clamp continuous BP measurement device were positioned simultaneously in all patients for the entire procedure. Bland-Altman analysis was used to analyze agreement between the two techniques. Results A total of 1219 paired measurements for systolic, diastolic, and mean arterial pressure were obtained in 55 subjects, with a mean (SD) of 22 (9) measurements per patient. Mean bias (SD) was -12,97 (13,89) mmHg for systolic pressure (level of agreement -14,24–40,20; correlation coefficient 0,84), -1,85 (8,52) mmHg for diastolic pressure (level of agreement -18,54–14,84; correlation coefficient 0,77) and 2,31 (8,75) mmHg for mean pressure (level of agreement -14,84–19,46; correlation coefficient 0,85). Conclusion In patients undergoing AF ablation, non-invasive finger volume-clamp continuous BP monitoring with the ClearSight device showed acceptable agreement with standard of care invasive BP monitoring. Larger studies are needed to confirm potential clinical implications of a continuous non-invasive BP monitoring during AF ablation.

Acetaminophen-induced hypotension in sepsis

BackgroundAcetaminophen-induced hypotension has been reported in critically ill patients; however, it remains unclear whether mannitol, present as a stabilizing compound in acetaminophen formulations, affects hemodynamic changes. The objectives of this study were to clarify the direct effect of acetaminophen on blood pressure by comparing blood pressure changes after acetaminophen and intravenous immunoglobulin (IVIG) administration, both containing mannitol, in patients with sepsis and understand the risk factors for reduced blood pressure following acetaminophen administration.MethodsThis was a retrospective cohort study. Adult patients who were diagnosed with sepsis at Nippon Medical School Hospital, and who were undergoing continuous arterial blood pressure measurement and received intravenous acetaminophen or IVIG, were included.ResultsOverall, 185 patients were included, with 92 patients in the IVIG group and 93 in the acetaminophen group. The incidence of hypotension was 36.9% in the IVIG group (34 of 92 patients) and 58.0% in the acetaminophen group (54 of 93 patients) (OR = 8.26, p = 0.004). In a propensity score-matched cohort, 80 matched patients were selected. The incidence of hypotension was 37.5% in the IVIG group (15 of 40 patients) and 67.5% in the acetaminophen group (27 of 40 patients) (OR = 7.21, p = 0.007).ConclusionsAcetaminophen induced substantially greater hypotension than IVIG in patients with sepsis, with both containing mannitol. Further studies are needed to clarify the effects on hemodynamics of mannitol contained in acetaminophen formulations.

Acute Cannabigerol Administration Lowers Blood Pressure in Mice

Cannabigerol (CBG) is a cannabinoid compound that is synthesized from Cannabis sativa L. and acts as a substrate for both Δ9‐tetraydrocannabinol (Δ9‐THC) and cannabidiol (CBD) formation. Given that it does not exhibit psychoactive effects, emerging research has focused on CBG as a potential therapeutic for health conditions including algesia, epilepsy, anxiety, and cancer. While CBG can bind to cannabinoid receptors CB1 and CB2, it has also been described as an agonist at α2‐adrenoreceptors (A2‐AR), which when activated inhibit the release of norepinephrine from α‐adrenergic neurons. This raises the concern that CBG could act at A2‐AR to reduce norepinephrine release to cardiovascular end organs, such as the heart and kidneys, causing a reduction in blood pressure. Despite this possibility, there are no reports examining cardiovascular effects of CBG. In this study, we tested the hypothesis that acute CBG administration can lower blood pressure. To test this, six male C57BL/6J mice underwent surgery at 8‐10 weeks of age to implant a radiotelemetry probe, which allows for continuous measurement of blood pressure, heart rate and locomotor activity in conscious, freely moving mice. Following 10 days of recovery, baseline measurements were obtained and then mice were randomized to receive intraperitoneal injections of CBG (3.3, 5.6, and 10 mg/kg) and vehicle in a crossover design, with at least one‐week washout between treatments. Changes in blood pressure, heart rate, and locomotor activity were measured for two hours post‐injection. We found that acute CBG significantly lowered blood pressure compared with vehicle (‐12±5 mmHg vehicle vs. ‐28±2 mmHg at 10 mg/kg CBG; p=0.018), with no apparent dose responsiveness at the doses used in this study (‐22±2 mmHg at 3.3 mg/kg CBG; ‐28±4 at 5.6 mg/kg CBG). The greatest blood pressure reduction was seen at 90‐minutes post‐CBG administration, which is consistent with reports for peak plasma concentrations of this compound in rodents. The blood pressure lowering effects of CBG occurred in the absence of changes in heart rate or locomotor activity. These overall findings suggest acute CBG may lower blood pressure in phenotypically normal young adult male mice, which may provide caution for the potential of hypotension as an adverse effect of CBG administration. Additional studies are needed to determine if the blood pressure lowering effects of CBG are via an A2‐AR mechanism.

Sympathetic transduction of blood pressure during graded lower body negative pressure in young healthy adults.

Sympathetic transduction of blood pressure (BP) is correlated negatively with resting muscle sympathetic nerve activity (MSNA) in cross-sectional data, but the acute effects of increasing MSNA are unclear. Sixteen (4 female) healthy adults (26 ± 3 years) underwent continuous measurement of heart rate, BP, and MSNA at rest and during graded lower body negative pressure (LBNP) at -10, -20, and -30 mmHg. Sympathetic transduction of BP was quantified in the time (signal averaging) and frequency (MSNA-BP gain) domains. The proportions of MSNA bursts firing within each tertile of BP were calculated. As expected, LBNP increased MSNA burst frequency (P < 0.01) and burst amplitude (P < 0.02), although the proportions of MSNA bursts firing across each BP tertile remained stable (all P > 0.44). The MSNA-diastolic BP low-frequency transfer function gain (P = 0.25) was unchanged during LBNP; the spectral coherence was increased (P = 0.03). Signal-averaged sympathetic transduction of diastolic BP was unchanged (from 2.1 ± 1.0 at rest to 2.4 ± 1.5, 2.2 ± 1.3, and 2.3 ± 1.4 mmHg; P = 0.43) during LBNP, but diastolic BP responses following nonburst cardiac cycles progressively decreased (from -0.8 ± 0.4 at rest to -1.0 ± 0.6, -1.2 ± 0.6, and -1.6 ± 0.9 mmHg; P < 0.01). As a result, the difference between MSNA burst and nonburst diastolic BP responses was increased (from 2.9 ± 1.4 at rest to 3.4 ± 1.9, 3.4 ± 1.9, and 3.9 ± 2.1 mmHg; P < 0.01). In conclusion, acute increases in MSNA using LBNP did not alter traditional signal-averaged or frequency-domain measures of sympathetic transduction of BP or the proportion of MSNA bursts firing at different BP levels. The factors that determine changes in the firing of MSNA bursts relative to oscillations in BP require further investigation.

An Artificial Intelligence-Enhanced Blood Pressure Monitor Wristband Based on Piezoelectric Nanogenerator.

Hypertensive patients account for about 16% to 37% of the global population, and about 9.4 million people die each year from hypertension and its complications. Blood pressure is an important indicator for diagnosing hypertension. Currently, blood pressure measurement methods are mainly based on mercury sphygmomanometers in hospitals or electronic sphygmomanometers at home. However, people’s blood pressure changes with time, and using only the blood pressure value at the current moment to judge hypertension may cause misdiagnosis. Continuous blood pressure measurement can monitor sudden increases in blood pressure, and can also provide physicians with long-term continuous blood pressure changes as a diagnostic reference. In this article, we design an artificial intelligence-enhanced blood pressure monitoring wristband. The wristband’s sensors are based on piezoelectric nanogenerators, with a high signal-to-noise ratio of 29.7 dB. Through the transformer deep learning model, the wristband can predict blood pressure readings, and the loss value is lower than 4 mmHg. By wearing this blood pressure monitoring wristband, we realized three days of continuous blood pressure monitoring of the subjects. The blood pressure monitoring wristband is lightweight, has profound significance for the prevention and treatment of hypertension, and has wide application prospects in medical, military, aerospace and other fields.

Development of a Portable Infrared-Type Noncontact Blood Pressure Measuring Device and Evaluation of Blood Pressure Elevation during Driving

Hypertension has been established as a major risk factor for cardiovascular morbidity and mortality. Therefore, prevention of hypertension is an urgent matter to maintain people’s health and avoid death, and out-of-office blood pressure measurement is said to be an integral part of the diagnosis and management of hypertension. Hypertension not only causes loss of productivity and economic loss but is also a major cause of road accidents. Therefore, it is important to develop an in-vehicle noncontact blood pressure measurement system for drivers. In addition to measurement accuracy, proper detection timing is also important, and there must be no difference between noncontact and contact detection times. In this study, we introduce an infrared cuffless and portable noncontact blood pressure monitoring system, its measurement principle, and performance evaluation. A total of 13 male adults participated in the experiment to evaluate the effect of time lag between the use of the infrared blood pressure monitoring system and the contact blood pressure monitoring system using a driving simulator. The changepoint method was applied to detect the first change point in the blood pressure time series data caused by the unexpected first appearance of the vehicle. The results showed that the detection time of the developed system was about 2.5 s shorter than that of the contact-type continuous blood pressure measurement system, with no significant difference.

An Evaluation of the NICCI Monitor in Providing Continuous, Noninvasive Blood Pressure Readings in Children During Intraoperative Anesthetic Care

BackgroundIn specific clinical scenarios or with patient comorbid conditions, continuous blood pressure (BP) monitoring may be required as it can be expected to provide superior physiologic monitoring to intermittent techniques. However, continuous BP monitoring requires an arterial cannula (AC) placement, which may be time-consuming, technically challenging, or associated with adverse events. Various noninvasive BP devices have been developed which provide a continuous BP reading. The current study evaluates the accuracy of a novel continuous BP device, the NICCI monitor (NM), in pediatric patients weighing 10 - 40 kg.MethodsThe study cohort included pediatric patients weighing between 10 and 40 kg, scheduled for surgery for which placement of an AC was planned. Systolic (SBP), diastolic (DBP), and mean arterial (MAP) blood pressure readings were captured from the AC and the NM every second during anesthetic care.ResultsThe study cohort included 24 pediatric patients undergoing major orthopedic, cardiac, and neurosurgical procedures. A total of 146,562 pairs of SBP, DBP, and MAP values from the AC and NC were analyzed. The absolute difference for the NM and the AC’s SBP, DBP, and MAP values were 11 ± 9, 10 ± 7, and 10 ± 7 mm Hg, respectively. The difference between the BP values from the NM and the AC was ≤ 10 mm Hg for 57% of the SBP readings, 60% of the DBP readings, and 56% of the MAP readings. The bias was 4, 4, and 6 mm Hg for the SBP, DBP, and MAP, respectively.ConclusionsAlthough there were some technical limitations given patient size, potentially resulting in variation in accuracy, the NM provided a continuous noninvasive BP measurement within clinically useful limits during a significant portion of anesthetic care compared to values obtained from an AC. Ongoing modification of the technology to improve its application in pediatric patients will likely increase its accuracy.

Intelligent Bio-Impedance System for Personalized Continuous Blood Pressure Measurement.

Continuous blood pressure (BP) measurement is crucial for long-term cardiovascular monitoring, especially for prompt hypertension detection. However, most of the continuous BP measurements rely on the pulse transit time (PTT) from multiple-channel physiological acquisition systems that impede wearable applications. Recently, wearable and smart health electronics have become significant for next-generation personalized healthcare progress. This study proposes an intelligent single-channel bio-impedance system for personalized BP monitoring. Compared to the PTT-based methods, the proposed sensing configuration greatly reduces the hardware complexity, which is beneficial for wearable applications. Most of all, the proposed system can extract the significant BP features hidden from the measured bio-impedance signals by an ultra-lightweight AI algorithm, implemented to further establish a tailored BP model for personalized healthcare. In the human trial, the proposed system demonstrates the BP accuracy in terms of the mean error (ME) and the mean absolute error (MAE) within 1.7 ± 3.4 mmHg and 2.7 ± 2.6 mmHg, respectively, which agrees with the criteria of the Association for the Advancement of Medical Instrumentation (AAMI). In conclusion, this work presents a proof-of-concept for an AI-based single-channel bio-impedance BP system. The new wearable smart system is expected to accelerate the artificial intelligence of things (AIoT) technology for personalized BP healthcare in the future.

Continuous Noninvasive Remote Automated Blood Pressure Monitoring With Novel Wearable Technology: A Preliminary Validation Study.

BackgroundWearable continuous monitoring biosensor technologies have the potential to transform postoperative care with early detection of impending clinical deterioration.ObjectiveOur aim was to validate the accuracy of Cloud DX Vitaliti continuous vital signs monitor (CVSM) continuous noninvasive blood pressure (cNIBP) measurements in postsurgical patients. A secondary aim was to examine user acceptance of the Vitaliti CVSM with respect to comfort, ease of application, sustainability of positioning, and aesthetics.MethodsIncluded participants were ≥18 years old and recovering from surgery in a cardiac intensive care unit (ICU). We targeted a maximum recruitment of 80 participants for verification and acceptance testing. We also oversampled to minimize the effect of unforeseen interruptions and other challenges to the study. Validation procedures were according to the International Standards Organization (ISO) 81060-2:2018 standards for wearable, cuffless blood pressure (BP) measuring devices. Baseline BP was determined from the gold-standard ICU arterial catheter. The Vitaliti CVSM was calibrated against the reference arterial catheter. In static (seated in bed) and supine positions, 3 cNIBP measurements, each 30 seconds, were taken for each patient with the Vitaliti CVSM and an invasive arterial catheter. At the conclusion of each test session, captured cNIBP measurements were extracted using MediCollector BEDSIDE data extraction software, and Vitaliti CVSM measurements were extracted to a secure laptop through a cable connection. The errors of these determinations were calculated. Participants were interviewed about device acceptability.ResultsThe validation analysis included data for 20 patients. The average times from calibration to first measurement in the static position and to first measurement in the supine position were 133.85 seconds (2 minutes 14 seconds) and 535.15 seconds (8 minutes 55 seconds), respectively. The overall mean errors of determination for the static position were –0.621 (SD 4.640) mm Hg for systolic blood pressure (SBP) and 0.457 (SD 1.675) mm Hg for diastolic blood pressure (DBP). Errors of determination were slightly higher for the supine position, at 2.722 (SD 5.207) mm Hg for SBP and 2.650 (SD 3.221) mm Hg for DBP. The majority rated the Vitaliti CVSM as comfortable. This study was limited to evaluation of the device during a very short validation period after calibration (ie, that commenced within 2 minutes after calibration and lasted for a short duration of time).ConclusionsWe found that the Cloud DX’s Vitaliti CVSM demonstrated cNIBP measurement in compliance with ISO 81060-2:2018 standards in the context of evaluation that commenced within 2 minutes of device calibration; this device was also well-received by patients in a postsurgical ICU setting. Future studies will examine the accuracy of the Vitaliti CVSM in ambulatory contexts, with attention to assessment over a longer duration and the impact of excessive patient motion on data artifacts and signal quality.Trial RegistrationClinicalTrials.gov NCT03493867; https://clinicaltrials.gov/ct2/show/NCT03493867

Continuous Monitoring of Blood Pressure Using a Wrist-Worn Cuffless Device.

Measuring an accurate blood pressure (BP) in ambulatory patients is critical for therapeutic decisions. An accurate noninvasive device that measures BP continuously could provide a more comprehensive assessment of BP. The aim of this study was to determine whether the LiveOne device, a cuffless wristband that provides continuous BP measurements, is accurate in comparison to an invasive arterial line (A-line). We enrolled hospitalized patients and healthy volunteers in this multicenter study. All patients had an invasive A-line. Waveforms were simultaneously downloaded from the A-line and LiveOne device. The primary outcome was the correlation between the LiveOne device and the A-line for systolic BP (SBP) and diastolic BP (DBP). Thirty-four patients with 233 measurement periods were included. Mean age was 60.7 ± 15.2 years, and 15 (44%) were female. The correlation for SBP was 0.91 and for DBP was 0.85. The mean band error was 0.0 ± 6.9 mm Hg for SBP and 1.2 ± 5.7 mm Hg for DBP. The mean absolute error was 8.2 ± 5.8 mm Hg for SBP and 6.4 ± 3.9 mm Hg for DBP. For SBP, 98% of LiveOne measurements were within 15 mm Hg and for DBP, 92% of LiveOne measurements were within 10 mm Hg. The LiveOne device provides continuous, noninvasive BP measurements that are accurate in comparison to A-line measurements. The portability and unobtrusive nature of this device and the ability to provide continuous BP measurements may offer advantages over currently available BP monitors. Trial Number NCT03919136.

Reduced baroreflex sensitivity and increased splenic activity in patients with severe obstructive sleep apnea

Background and aimsSevere obstructive sleep apnea (OSA) is associated with an increased risk of cardiovascular disease. Experimental evidence suggests that this risk may be mediated by chronic sympathetic hyperactivation and systemic inflammation, but the precise mechanisms remain to be unraveled. Our aim was to evaluate whether severe OSA patients are characterized by increased sympathetic and hematopoietic activity, potentially driving atherosclerosis. MethodsUntreated patients with severe OSA (apnea-hypopnea index (AHI) > 30 per hour) were matched with mild OSA patients (AHI<15 & >5 per hour) according to age, sex, and body mass index. Study objectives were to assess baroreflex sensitivity (BRS) and heart-rate variability (HRV) using continuous finger blood pressure measurements, hematopoietic activity in the bone marrow and spleen, and arterial inflammation with 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT). ResultsA total of 34 subjects, 17 per group, were included in the analysis. Mean age was 60.7 ± 6.2 years, 24 (70.6%) were male. Mean AHI was 40.5 ± 12.6 per hour in the severe OSA group, and 10.5 ± 3.4 per hour in the mild OSA group. Participants with severe OSA were characterized by reduced BRS (5.7 [4.6–7.8] ms/mmHg in severe vs 8.2 [6.9–11.8] ms/mmHg in mild OSA, p = 0.033) and increased splenic activity (severe OSA 18F-FDG uptake 3.56 ± 0.77 vs mild OSA 3.01 ± 0.68; p = 0.036). HRV, bone marrow activity and arterial inflammation were comparable between groups. ConclusionsPatients with severe OSA are characterized by decreased BRS and increased splenic activity. Randomized controlled trials are warranted to assess whether OSA treatment reduces sympathetic and splenic activity.

Feasibility of Diagnosing Initial Orthostatic Hypotension Using a Continuous Blood Pressure Device in Geriatric Rehabilitation Inpatients: RESORT

Background: Initial orthostatic hypotension (IOH) is highly prevalent in older adults and may interfere with the ability to regain function after acute hospitalization. IOH assessment requires a non-invasive, beat-to-beat continuous blood pressure device, which is not widely used in geriatric rehabilitation. Our aim was to test the feasibility of diagnosing IOH using a continuous blood pressure device in geriatric rehabilitation inpatients. Methods: Geriatric rehabilitation inpatients of the REStORing Health of Acutely Unwell AdulTs (RESORT) cohort admitted to a tertiary hospital were randomly selected to undergo continuous blood pressure monitoring (Finapres) for 5 min in the supine position and 3 min of standing or sitting when unable to stand. Interventions to warm hands and adjusting the cuff pressure sizes were attempted if no signal was obtained or an error message occurred. Results: Of 37 randomly selected inpatients, 29 {55.2% female; mean age 82.8 (standard deviation [SD]) 6.6 years} agreed to the continuous blood pressure measurement. Successful measurements were achieved in 20 out of 29 inpatients, two after hand warming. Patients with unsuccessful measurements were likely to be older (mean age 87.2 [SD] 4.4 years, p = 0.03), have cerebrovascular disease (p = 0.006), lower body mass index (p = 0.012), and a lower short physical performance battery score (p = 0.039). Eight out of 20 patients had IOH. Conclusion: The number of unsuccessful continuous blood pressure measurements was high in a population with high IOH prevalence despite multiple interventions to establish a signal. Future research should focus on improving the efficiency of continuous blood pressure devices in hospitalized patients with unsuccessful signals.