Continuous Blood Pressure Monitoring Research Articles

Formula omitted]: Cuff-less and non-invasive blood pressure estimation via a generic deep convolutional architecture

Objective:The paper focuses on development of robust and accurate processing solutions for continuous and cuff-less blood pressure (BP) monitoring. In this regard, a robust deep learning-based framework is proposed for computation of low latency and continuous upper and lower bounds on the systolic and diastolic BP. Methods:Referred to as the BP-Net, the proposed framework is a novel convolutional architecture that provides longer effective memory while achieving superior performance due to incorporation of casual dialated convolutions and residual connections. To utilize the real potential of deep learning in extraction of intrinsic features (deep features) and enhance the long-term robustness, the BP-Net uses raw Electrocardiograph (ECG) and Photoplethysmograph (PPG) signals without extraction of any form of hand-crafted features as it is common in existing solutions. Results:By capitalizing on the fact that datasets used in recent literature are not unified and properly defined, a benchmark dataset is constructed from the MIMIC-I and MIMIC-III databases obtained from PhysioNet. The proposed BP-Net is evaluated based on this benchmark dataset demonstrating promising performance and shows superior generalizable capacity. Conclusion:The proposed BP-Net architecture is more accurate than canonical recurrent networks and enhances the long-term robustness of the BP estimation task. Significance:The proposed BP-Net architecture addresses key drawbacks of existing BP estimation solutions, i.e., relying heavily on extraction of hand-crafted features, such as pulse arrival time (PAT), and; Lack of robustness. Finally, the constructed BP-Net dataset provides a unified base for evaluation and comparison of deep learning-based BP estimation algorithms.

COMPARISON OF BLOOD PRESSURE AND PULSE PRESSURE VALUES IN THE BRACHIAL ARTERY AND IN CENTRAL AORTA MEASURED BY OUTPATIENT NON-INVASIVE METHODS IN DIFFERENT PATIENT POPULATION GROUP

Objective: The aim of our study was to compare the values of blood pressure (BP) and pulse pressure (PP) in the brachial artery and in the central aorta by outpatient non-invasive methods in different patients age groups and according to the presence of chronic renal disease and diabetes. Design and method: The study included 110 outpatients older than 18 years of age with diagnosed and treated arterial hypertension (AH), under the care of Clinical Hospital Centre Rijeka in the period from June 1 to December 1, 2021. Peripheral BP, PP, and central aortic pressure (CAP) were measured in all patients on the same day. The average values of peripheral arterial pressure and the corresponding PP were obtained by the method of continuous blood pressure monitoring (CBPM). CAP and associated PP were measured on the same day by the method of radial arterial tonometry. Patients were divided into three groups according to the age (18–44 years, group I; 45–64 years, group II, and > 65 years, group III). Systolic and diastolic peripheral blood pressure (SPBP, DPBP), systolic CAP and diastolic CAP (SCAP, DCAP), and both peripheral and central PP (PPP, CPP) were nalysed among groups and according to the presence of chronic kidney disease (CKD). Results: In total, 98 patients were nalysed (mean age 55,08 ± 15,52 years; 79,6% essential hypertension; diabetics 12,23%; 26,53% CKD; 48,98% men). There were significant positive correlations between SPBP and SCAP, DPBP and DCAP, and PPP and CPP in group I and group III. There was no significant correlation between SPBP and SCAP (r = 0,268), and there were significant correlations between DPBP and DCAP, and PPP and CPP in group II. According to the presence of CKD, there was no significant correlation between SPBP and SCAP (r = 0,104), and there were positive correlations between DPBP and DCAP, and PPP and CPP. Conclusions: There was no significant correlation between SPBP and SCAP in 45–65 years old and CKD group, which tells us in favor of the atherosclerosis variability in these patient groups, which was expected. Further research on greater number of patients should be done.

IgA vasculitis - similarities and differences to IgA nephropathy

IgA vasculitis - similarities and differences to IgA nephropathy Abstract. IgA vasculitis (IgAV), formerly called Henoch-Schönlein Purpura (HSP) is an immune complex-mediated vasculitis of small vessels typically affecting the skin, gastrointestinal tract, and the kidneys. Based on distinct histopathological and pathophysiological commonalities of IgAV and IgA nephropathy (IgAN) they are viewed as part of a spectrum of IgA-mediated inflammatory syndromes. While the disease course in children is most often benign, IgAV has a high risk of renal and gastrointestinal complications when first appearing in adulthood. Acute morbidity and mortality in IgAV are determined by gastrointestinal complications such as intussusception or perforation, while chronic morbidity depends on renal involvement. Nephritis symptoms can appear, subclinically, many weeks after the initial manifestation of IgAV, and can therefore be missed. Continuous monitoring of renal parameters and blood pressure is therefore recommended even after apparent remission of the disease. As there are no data from randomized controlled trials available, the treatment of IgAV is currently based on consensus-based expert opinions.

COMPARISON OF CONTINUOUS MEAN ARTERIAL PRESSURE BY A WEARABLE CUFF-LESS DEVICE AGAINST INTRA-ARTERIAL MEASUREMENTS

Objective: Wearable cuff-less blood pressure (BP) devices may overcome cuff limitations and offer continuous non-invasive BP monitoring. However, their accuracy in different clinical settings is not yet clarified. This study aimed to evaluate the accuracy of mean arterial pressure (MAP) measurements from a novel continuous cuff-less chest belt against intra-arterial measurements. Design and method: Patients in an intensive care unit with an indication of intra-arterial BP monitoring were included. Reference BP was measured with a radial artery catheter connected to a pressure transducer. Cuff-less measurements were obtained continuously with a chest belt, of which a model for BP estimation was trained on a non-intensive care unit population and consisted of a one-channel electrocardiogram, a photoplethysmography sensor and a tri-axis accelerometer. The data collection was monitored by an investigator to reliably exclude periods where the transducer was not properly levelled. Estimated MAP from the chest-belt was calibrated initially with intra-arterial MAP. In cases where the pressure transducer had to be repositioned, re-calibration was performed due to variability of the repositioned transducer levels. Pairwise comparisons of reference and cuff-less MAP were performed in 15-second epochs. Results: Preliminary data from 9 subjects were analysed. The subjects had a median (interquartile range) age of 64 (58–73) years, median BMI was 28.6 (25.4–32.7) kg/m2and 77.7% were males. A total of 21.5 h of data were analysed with an average of 2.39 ± 1.05 h per subject. The mean difference of estimated versus reference MAP was 3.9 ± 4.2 mmHg. The Bland-Altman bias was 2.06 mmHg with limits of agreement from -9.7 mmHg to 14 mmHg. The Figure displays typical data for one subject (A) and the Bland Altman plot for all subjects (B). Conclusions: After initial calibration with a reference measurement, the cuff-less chest belt estimated changes in mean arterial pressure in close agreement with reference intra-arterial measurements. This study illustrates the potential of a wearable cuff-less device for estimating mean arterial pressure continuously and non-invasively in ospitalised patients.

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.

A computationally efficient CNN-LSTM neural network for estimation of blood pressure from features of electrocardiogram and photoplethysmogram waveforms

Continuous blood pressure (BP) monitoring would significantly improve diagnosis and treatment of hypertension. Current at-home monitoring relies on uncomfortable and unreliable cuff-based devices, which are incapable of continuous measurement. In this work, we present a new hybrid neural network (NN) that combines convolutional layers with long short-term memory (LSTM) layers to classify systolic blood pressure (SBP), diastolic blood pressure (DBP) and mean arterial pressure (MAP), using 12 straightforward features extracted from electrocardiogram (ECG) and photoplethysmogram (PPG) waveforms. Our proposed network achieves mean absolute errors (MAEs) of 4.53 mmHg, 3.37 mmHg and 3.36 mmHg for SBP, DBP and MAP respectively. Additionally, our scheme passes the criteria outlined by the Association for the Advancement of Medical Instrumentation (AAMI) and achieves an A grade in accordance with the British Hypertension Society (BHS) protocol. These results provide a deep learning approach to BP estimation that could be implemented in low-power wearable devices.

0397 Autonomic Reflex Testing Confirms Autonomic Disturbances in a Cohort of Patients with Idiopathic Hypersomnia

Abstract Introduction Symptoms suggestive of autonomic nervous system (ANS) dysfunction have been previously described in patients with idiopathic hypersomnia (IH), however, objective ANS reflex testing data has not been reported. We aimed to better quantify symptoms of ANS dysfunction in a cohort of patients with IH through the use of standardized ANS reflex testing. Methods Patients diagnosed with IH based on ICSD-3 criteria using overnight video polysomnography and multiple sleep latency testing (MSLT) were consecutively enrolled in our study, regardless of ANS symptoms. All patients underwent ANS reflex testing, including measures of parasympathetic (heart rate variability with deep breathing and Valsalva ratio) and sympathetic adrenergic function (Valsalva blood pressure response and 10-minute head-up tilt at an angle of 70 degrees) with continuous blood pressure and heart rate monitoring. Eleven patients also underwent measures of sympathetic cholinergic function (quantitative sudomotor axon reflex testing). All medications that affect ANS function were held prior to ANS testing, including wake-promoting medications and sodium oxybate. Results Twenty patients with IH were enrolled. Fifty percent (10/20) were long sleepers (>11hrs). Mean sleep onset latency and number of sleep onset REM periods (SOREMs) on MSLT were 6.9 (± 3.1) mins and 0.2 (± 0.4), respectively. Mean duration of IH symptoms prior to the date of ANS testing was 6.3 (± 8.1) yrs. Eighty-five percent (17/20) of patients had abnormal ANS testing. Of these, 75% (15/20) had sympathetic adrenergic impairment, 64% (7/11) had sympathetic cholinergic impairment, and 5% (1/20) had parasympathetic impairment. Fifty-five percent (11/20) of patients were diagnosed with postural tachycardia syndrome (POTS), 45% (5/11) with small fiber neuropathy, 5% (1/20) with inappropriate sinus tachycardia and 15% (3/20) with neurally-mediated syncope. Seventy percent (14/20) of patients reported orthostatic intolerance regardless of autonomic diagnosis. Conclusion ANS dysfunction was common and severe in our cohort of IH patients, affecting all domains of ANS reflex testing, with more prominent impairment in sympathetic domains. POTS was the most common comorbid diagnosis, and most patients reported orthostatic intolerance. There was no association with IH disease duration, though our sample size was limited. Future studies will focus on ANS testing in larger cohorts of IH patients, specifically on shared pathophysiological mechanisms of hypersomnia and ANS dysfunction. Support (If Any)

Wearable Blood Pressure Sensing Based on Transmission Coefficient Scattering for Microstrip Patch Antennas.

Painless, cuffless and continuous blood pressure monitoring sensors provide a more dynamic measure of blood pressure for critical diagnosis or continuous monitoring of hypertensive patients compared to current cuff-based options. To this end, a novel flexible, wearable and miniaturized microstrip patch antenna topology is proposed to measure dynamic blood pressure (BP). The methodology was implemented on a simulated five-layer human tissue arm model created and designed in High-Frequency Simulation Software “HFSS”. The electrical properties of the five-layer human tissue were set at the frequency range (2–3) GHz to comply with clinical/engineering standards. The fabricated patch incorporated on a 0.4 mm epoxy substrate achieved consistency between the simulated and measured reflection coefficient results at flat and bent conditions over the frequency range of 2.3–2.6 GHz. Simulations for a 10 g average specific absorption rate (SAR) based on IEEE-Standard for a human arm at different input powers were also carried out. The safest input power was 50 mW with an acceptable SAR value of 3.89 W/Kg < 4W/Kg. This study also explored a novel method to obtain the pulse transit time (PTT) as an option to measure BP. Pulse transmit time is based on obtaining the time difference between the transmission coefficient scattering waveforms measured between the two pairs of metallic sensors underlying the assumption that brachial arterial geometries are dynamic. Consequently, the proposed model is validated by comparing it to the standard nonlinear Moens and Korteweg model over different artery thickness-radius ratios, showing excellent correlation between 0.76 ± 0.03 and 0.81 ± 0.03 with the systolic and diastolic BP results. The absolute risk of arterial blood pressure increased with the increase in brachial artery thickness-radius ratio. The results of both methods successfully demonstrate how the radius estimates, PTT and pulse wave velocity (PWV), along with electromagnetic (EM) antenna transmission propagation characteristics, can be used to estimate continuous BP non-invasively.

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.

Detection of Hemodynamic Status Using an Analytic Based on an Electrocardiogram Lead Waveform.

OBJECTIVES:Delayed identification of hemodynamic deterioration remains a persistent issue for in-hospital patient care. Clinicians continue to rely on vital signs associated with tachycardia and hypotension to identify hemodynamically unstable patients. A novel, noninvasive technology, the Analytic for Hemodynamic Instability (AHI), uses only the continuous electrocardiogram (ECG) signal from a typical hospital multiparameter telemetry monitor to monitor hemodynamics. The intent of this study was to determine if AHI is able to predict hemodynamic instability without the need for continuous direct measurement of blood pressure.DESIGN:Retrospective cohort study.SETTING:Single quaternary care academic health system in Michigan.PATIENTS:Hospitalized adult patients between November 2019 and February 2020 undergoing continuous ECG and intra-arterial blood pressure monitoring in an intensive care setting.INTERVENTIONS:None.MEASUREMENTS AND MAIN RESULTS:One million two hundred fifty-two thousand seven hundred forty-two 5-minute windows of the analytic output were analyzed from 597 consecutive adult patients. AHI outputs were compared with vital sign indications of hemodynamic instability (heart rate > 100 beats/min, systolic blood pressure < 90 mm Hg, and shock index of > 1) in the same window. The observed sensitivity and specificity of AHI were 96.9% and 79.0%, respectively, with an area under the curve (AUC) of 0.90 for heart rate and systolic blood pressure. For the shock index analysis, AHI’s sensitivity was 72.0% and specificity was 80.3% with an AUC of 0.81.CONCLUSIONS:The AHI-derived hemodynamic status appropriately detected the various gold standard indications of hemodynamic instability (hypotension, tachycardia and hypotension, and shock index > 1). AHI may provide continuous dynamic hemodynamic monitoring capabilities in patients who traditionally have intermittent static vital sign measurements.

Continuous Blood Pressure Estimation Based on Multi-Scale Feature Extraction by the Neural Network With Multi-Task Learning.

In this article, a novel method for continuous blood pressure (BP) estimation based on multi-scale feature extraction by the neural network with multi-task learning (MST-net) has been proposed and evaluated. First, we preprocess the target (Electrocardiograph; Photoplethysmography) and label signals (arterial blood pressure), especially using peak-to-peak time limits of signals to eliminate the interference of the false peak. Then, we design a MST-net to extract multi-scale features related to BP, fully excavate and learn the relationship between multi-scale features and BP, and then estimate three BP values simultaneously. Finally, the performance of the developed neural network is verified by using a public multi-parameter intelligent monitoring waveform database. The results show that the mean absolute error ± standard deviation for systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean arterial pressure (MAP) with the proposed method against reference are 4.04 ± 5.81, 2.29 ± 3.55, and 2.46 ± 3.58 mmHg, respectively; the correlation coefficients of SBP, DBP, and MAP are 0.96, 0.92, and 0.94, respectively, which meet the Association for the Advancement of Medical Instrumentation standard and reach A level of the British Hypertension Society standard. This study provides insights into the improvement of accuracy and efficiency of a continuous BP estimation method with a simple structure and without calibration. The proposed algorithm for BP estimation could potentially enable continuous BP monitoring by mobile health devices.

Wearable cuffless blood pressure monitoring devices: a systematic review and meta-analysis.

High blood pressure (BP) is the commonest modifiable cardiovascular risk factor, yet its monitoring remains problematic. Wearable cuffless BP devices offer potential solutions; however, little is known about their validity and utility. We aimed to systematically review the validity, features and clinical use of wearable cuffless BP devices. We searched MEDLINE, Embase, IEEE Xplore and the Cochrane Database till December 2019 for studies that reported validating cuffless BP devices. We extracted information about study characteristics, device features, validation processes, and clinical applications. Devices were classified according to their functions and features. We defined devices with a mean systolic BP (SBP) and diastolic BP (DBP) biases of <5 mmHg as valid as a consensus. Our definition of validity did not include assessment of device measurement precision, which is assessed by standard deviation of the mean difference-a critical component of ISO protocol validation criteria. Study quality was assessed using the Quality Assessment of Diagnostic Accuracy Studies version 2 tool. A random-effects model meta-analysis was performed to summarise the mean biases for SBP and DBP across studies. Of the 430 studies identified, 16 studies (15 devices, 974 participants) were selected. The majority of devices (81.3%) used photoplethysmography to estimate BP against a reference device; other technologies included tonometry, auscultation and electrocardiogram. In addition to BP and heart rate, some devices also measured night-time BP (n = 5), sleep monitoring (n = 3), oxygen saturation (n = 3), temperature (n = 2) and electrocardiogram (n = 3). Eight devices showed mean biases of <5 mmHg for SBP and DBP compared with a reference device and three devices were commercially available. The meta-analysis showed no statistically significant differences between the wearable and reference devices for SBP (pooled mean difference = 3.42 mmHg, 95% CI: -2.17, 9.01, I2 95.4%) and DBP (pooled mean = 1.16 mmHg, 95% CI: -1.26, 3.58, I2 87.1%). Several cuffless BP devices are currently available using different technologies, offering the potential for continuous BP monitoring. The variation in standards and validation protocols limited the comparability of findings across studies and the identification of the most accurate device. Challenges such as validation using standard protocols and in real-life settings must be overcome before they can be recommended for uptake into clinical practice.

Blockade of Trpm7 in the Carotid Body area attenuated intermittent hypoxia‐induced Hypertension

RATIONALEObesity leads to high cardiovascular morbidity and mortality via multiple mechanisms including obstructive sleep apnea (OSA) and hypertension. Intermittent hypoxia (IH), a hallmark manifestation of OSA, is an established cause of hypertension. The carotid body (CB) has been implicated in the pathogenesis of hypertension in IH and obesity. We discovered that obesity‐induced hypertension is mediated via the transient receptor potential melastatin 7 (TRPM7) channel in the glomus cells of CB. Here, we investigate the relevance of TRPM7 signaling in CB for the pathogenesis of hypertension by IH. We developed a novel technique allowing continuous sustained release of the TRPM7 inhibitor FTY720 into the CB area using a hydrogel formulation with a single injection abolishing hypertension in obesity for 3 weeks. We hypothesize that IH causes hypertension acting on CB TRPM7.METHODSC57BL/6J male mice (n = 9) were implanted with telemetry in the left femoral artery for continuous blood pressure monitoring and exposed to IH for 5 days. IH was administered by decreasing O2 levels from 21% to 6%, 60 cycles/hr, during the light phase, 9AM ‐9PM. FTY720 hydrogel (n = 5) or control hydrogel (N = 4) were applied locally to the CB region. Blood pressure was recorded at baseline and during IH and the measurement was repeated 2 weeks after hydrogel application.RESULTIH increased mean arterial pressure from 103.8±1.2 mmHg to 114.3±1.4 mmHg on Day 1 of IH and to 113.0±0.6 mmHg on Day 5 of IH respectively. FTY720 hydrogel abolished IH‐induced hypertension by decreasing blood pressure to 106.6±1.6 mmHg (p&lt;0.005) on Day 1 of IH and to 101.5±1.6 mmHg (p&lt;0.001) on Day 5 of IH. In contrast, control hydrogel had no effect on IH‐induced hypertension.CONCLUSIONOur study has shown that inhibition of TRPM7in the carotid bodies abolished IH‐induced hypertension.

Corn Bedding Mediates Protection from the Dahl Salt‐Sensitive Hypertensive and Renal Damage Phenotype

The Dahl Salt‐Sensitive (SS) rat is a well‐established translational model of human salt sensitive hypertension. When challenged with a high salt (4.0% NaCl) diet, Dahl SS develop an increase in mean arterial pressure (MAP) and renal damage, as assessed by an increase in albumin excretion and infiltration of immune cells in the kidneys. Our colony of Dahl SS recently moved to a new animal facility, and we observed that the SS rats challenged on a high salt diet showed an attenuation of the high salt‐induced increase in MAP and albumin excretion. Upon further investigation, differences in the animal bedding were noted between the locations. In the present study, the salt‐sensitive disease phenotype was examined in age‐matched, genetically‐identical male Dahl SS rats fed the same diets (AIN‐76A with 0.4% or 4.0% NaCl) maintained on either an aspen‐based wood bedding or a corn‐cob based bedding. Based upon the known protective effects of a plant‐based diet and observations that the rats were eating the corn‐cob bedding, we hypothesized that the change in bedding from wood to corn was providing a protective phenotype to the SS rats. We tested this hypothesis by comparing the disease phenotypes in Dahl SS maintained on the corn‐cob or wood bedding from birth until the end of the study. SS rats were instrumented at 7 weeks of age with radiotelemeters for continuous blood pressure monitoring and were allowed about a week to recover. While the rats were maintained on a low salt (0.4% NaCl) diet, there were no significant differences in MAP (123.2±1.1 vs 126.8±0.8 mmHg, n=13, 16) or albumin excretion rate (7.5±1.8 vs 18.8±3.5 mg/day, n=10, 17) in Dahl SS maintained on the corn‐cob vs the wood bedding, respectively. While MAP and albumin excretion significantly increased in all Dahl SS following a 21‐day high salt challenge, there was significantly reduced albumin excretion in the corn‐cob bedding rats (128±27 mg/day, n=10) when compared to the wood bedding rats (332±50 mg/day, n=17, p˂0.005). The SS rats maintained on the corn‐cob bedding also had significantly attenuated MAP at the end of the 21 day challenge when compared to the rats on the wood bedding (corn‐cob bedding: 141.1±4.2 mmHg vs wood bedding: 159.5±3.6 mmHg, p˂0.0001, n=12, 16 respectively). This was further characterized with a significant reduction in CD45+ leukocytes infiltrating in the SS rat kidneys on corn‐cob bedding by ~48% (p&lt;0.003). That occurred by a significant reduction observed in the CD11b/c+ macrophages/monocytes by ~49% (p&lt;0.003) and in CD45R+ B‐cells by ~64% (p&lt;0.004). There was no difference between the body weights of the rats between the different beddings (corn‐cob bedding: 336±6 g vs wood bedding: 339±5 g, n=13, 17) respectively but kidney weight was a significantly reduced by ~17% (p&lt;0.0001) in corn‐cob bedding compared to the SS rats on the wood bedding. This attenuated phenotype was also mirrored in female Dahl SS rats when maintained on the corn‐cob bedding compared to age‐matched females on the wood bedding. These data suggest that the change in bedding from wood to corn had a significant protective effect in the Dahl SS rat. Further work will need to be performed to determine the exact cause in the reduction of the salt‐sensitive phenotype when on a corn‐cob bedding. These data highlight the importance of controlling all environmental parameters in experimental work, and to consider environmental effects that may influence other disease phenotypes.

Ambiguities in blood pressure management in acute ischaemic stroke.

Blood pressure management in acute ischaemic stroke is crucial. Here we highlight uncertainties surrounding haemodynamic management in acute ischaemic stroke on the basis of current guidelines and the data available from recent studies. This review provides practical treatment options and suggestions for future research. The U-shaped relationship between baseline blood pressure value and patients' functional outcome or death is well established. Nonetheless, there is scant evidence for the benefits of early pharmacological intervention. Current guidelines differentiate blood pressure targets on the basis of implemented reperfusion treatment and allow blood pressure reduction in certain clinical situations. However, there is a substantial lack of evidence to guide management during acute stroke. Taking into account several aspects of blood pressure management can improve stroke care, although they are not included in current guidelines. To make an optimal decision as to whether to intervene regarding blood pressure, it is important to consider dehydration, recanalisation status, blood pressure variability, and autoregulation state as measured by novel imaging techniques. Further trials considering patient-specific factors with the use of continuous monitoring of blood pressure, as well as neurovascular imaging, are needed to resolve the current ambiguities.

Concatenated convolutional neural network model for cuffless blood pressure estimation using fuzzy recurrence properties of photoplethysmogram signals

Due to the importance of continuous monitoring of blood pressure (BP) in controlling hypertension, the topic of cuffless BP estimation has been widely studied in recent years. A most important approach is to explore the nonlinear mapping between the recorded peripheral signals and the BP values which is usually conducted by deep neural networks. Because of the sequence-based pseudo periodic nature of peripheral signals such as photoplethysmogram (PPG), a proper estimation model needed to be equipped with the 1-dimensional (1-D) and recurrent layers. This, in turn, limits the usage of 2-dimensional (2-D) layers adopted in convolutional neural networks (CNN) for embedding spatial information in the model. In this study, considering the advantage of chaotic approaches, the recurrence characterization of peripheral signals was taken into account by a visual 2-D representation of PPG in phase space through fuzzy recurrence plot (FRP). FRP not only provides a beneficial framework for capturing the spatial properties of input signals but also creates a reliable approach for embedding the pseudo periodic properties to the neural models without using recurrent layers. Moreover, this study proposes a novel deep neural network architecture that combines the morphological features extracted simultaneously from two upgraded 1-D and 2-D CNNs capturing the temporal and spatial dependencies of PPGs in systolic and diastolic BP estimation. The model has been fed with the 1-D PPG sequences and the corresponding 2-D FRPs from two separate routes. The performance of the proposed framework was examined on the well-known public dataset, namely, multi-parameter intelligent in Intensive Care II. Our scheme is analyzed and compared with the literature in terms of the requirements of the standards set by the British Hypertension Society (BHS) and the Association for the Advancement of Medical Instrumentation (AAMI). The proposed model met the AAMI requirements, and it achieved a grade of A as stated by the BHS standard. In addition, its mean absolute errors and standard deviation for both systolic and diastolic blood pressure estimations were considerably low, 3.05 ± 5.26 mmHg and 1.58 ± 2.6 mmHg, in turn.

Blood Pressure and Chronic Kidney Disease Progression: An Updated Review.

Hypertension (HTN) is common in chronic kidney disease (CKD), and it may aggravate CKD progression. The optimal blood pressure (BP) value in CKD patients is not established yet, although systolic BP ≤130 mmHg is acceptable as a target. Continuous BP monitoring is essential to detect the different variants of high BP and monitor the treatment response. Various methods of BP measurement in the clinic office and at home are currently used. One of these methods is ambulatory BP monitoring (ABPM), by which BP can be closely assessed for even diurnal changes.We conducted a non-systematic literature review to explore and update the association between high BP and the course of CKD and to review various BP monitoring methods to determine the optimal method for BP recording in CKD patients. PubMed, EMBASE, Google, Google Scholar, and Web Science were searched for published reviews and original articles on BP and CKD by using various phrases and keywords such as "hypertension and CKD", "CKD progression and hypertension", "CKD stage and hypertension", "BP control in CKD", "BP measurement methods", "diurnal BP variation effect on CKD progression", and "types of hypertension." We evaluated and discussed published articles relevant to the review objective. Before preparing the final draft of this article, each author was assigned a section of the topic to read, research deeply, and write a summary about the assigned section. Then a summary of each author's contribution was collected and discussed in several group sessions.Early detection of high BP is essential to prevent CKD development and progression. Although the latest Kidney Disease Improving Global Outcomes (KDIGO) guidelines suggest that a systolic BP ≤120 mmHg is the target toprevent CKD progression, systolic BP ≤130 mmHg is universally recommended.ABPM is a promising method to diagnose and follow up on BP control; however, the high cost of the new devices and patient unfamiliarity with them have proven to be major disadvantages with regard to this method.

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.

Pulse transit time-estimated blood pressure: a comparison of beat-to-beat and intermittent measurement

Pulse transit time (PTT), which refers to the travel time between two arterial sites within the same cardiac cycle, has been developed as a novel cuffless form of continuous blood pressure (BP) monitoring. The aim of this study was to investigate differences in BP parameters, including BP variability, between those assessed by beat-to-beat PTT-estimated BP (eBPBTB) and those assessed by intermittent PTT-estimated BP at fixed time intervals (eBPINT) in patients suspected of having sleep disordered breathing (SDB). In 330 patients with SDB (average age, 66.8 ± 11.9 years; 3% oxygen desaturation index [ODI], 21.0 ± 15.0/h) from 8 institutes, PTT-estimated BP was continuously recorded during the nighttime. The average systolic eBPBTB, maximum systolic and diastolic eBPBTB, standard deviation (SD) of systolic and diastolic eBPBTB, and coefficient variation (CV) of systolic and diastolic eBPBTB were higher than the respective values of eBPINT (all P < 0.05). Bland–Altman analysis showed a close agreement between eBPBTB and eBPINT in average systolic BP and SD and CV of systolic BP, while there were disagreements in both minimum and maximum values of eBPBTB and eBPINT in patients with high systolic BP (P < 0.05). Although systolic BP variability incrementally increased according to the tertiles of 3%ODI in both eBPBTB and eBPINT (all P < 0.05), there was no difference in this tendency between eBPBTB and eBPINT. In patients with suspected SDB, the difference between eBPBTB and eBPINT was minimal, and there were disagreements regarding both the minimum and maximum BP. However, there were agreements in regard to the index of BP variability between eBPBTB and eBPINT.

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.