Continuous Blood Pressure Research Articles

Continuous Blood Pressure Monitoring in Patients Having Surgery: A Narrative Review.

Hypotension can occur before, during, and after surgery and is associated with postoperative complications. Anesthesiologists should thus avoid profound and prolonged hypotension. A crucial part of avoiding hypotension is accurate and tight blood pressure monitoring. In this narrative review, we briefly describe methods for continuous blood pressure monitoring, discuss current evidence for continuous blood pressure monitoring in patients having surgery to reduce perioperative hypotension, and expand on future directions and innovations in this field. In summary, continuous blood pressure monitoring with arterial catheters or noninvasive sensors enables clinicians to detect and treat hypotension immediately. Furthermore, advanced hemodynamic monitoring technologies and artificial intelligence-in combination with continuous blood pressure monitoring-may help clinicians identify underlying causes of hypotension or even predict hypotension before it occurs.

Assessment of daily blood pressure parameters in patients after injury

ABSTRACT. Many studies have highlighted the impact of various significant risk factors on the occurrence of arterial hypertension. However, few papers have examined the effect of psychoemotional factors as important contributors to the risk of arterial hypertension for such a specific population group as contracted servicemen performing military service under conditions of performing special tasks. Furthermore, there is a lack of data on the daily profile of blood pressure in this particular group of individuals. This thesis aims to substantiate the claim that injury, as a risk factor, greatly influences changes in the daily profile of blood pressure. The study examined 118 patients, divided into an experimental group (65 people) and a control group (53 people). The daily profile of blood pressure was assessed using continuous ambulatory blood pressure monitoring. Questionnaires were used to evaluate the quality of sleep, anxiety, and depression. The findings indicated that the patients of the experimental group, following trauma, exhibited a higher index of systolic and diastolic blood pressure duration, while the mean values remained within the normal range. Additionally, these patients more frequently exhibited a blood pressure profile characterized by an insufficient nocturnal decrease in blood pressure, known as non-dipping. This could be attributed to impaired sleep quality, as well as subclinically significant manifestations of anxiety and depression caused by stress. The early detection of changes in the index of systolic and diastolic blood pressure duration, along with deviations in the daily blood pressure profile observed through continuous ambulatory blood pressure monitoring, would enable specialists to promptly address alterations in the hemodynamics of these patients and prescribe appropriate therapy. Therefore, psychoemotional stress in people who have experienced trauma is one of the trigger mechanisms for increased blood pressure. If left unaddressed, this can progress to persistent arterial hypertension.

Noninvasive Cuffless Blood Pressure Monitoring. How Mechanism-Driven and Data-Driven Models Can Help in Clinical Practice

Continuous noninvasive cuffless blood pressure (BP) monitoring is essential for early detection and treatment of hypertension. In this paper, we provide an overview of the recent advancements in cuffless BP sensors. These include contact wearable sensors such as electrocardiography (ECG), photoplethysmography (PPG), contact non-wearable sensors such as ballistocardiography (BCG), and contactless sensors such as video plethysmography (VPG). These sensors employ different measuring mechanisms such as pulse arrival time (PAT), pulse transit time (PTT), and pulse wave analysis (PWA) to estimate BP. However, challenges exist in the effective use and interpretation of signal features to obtain clinically reliable BP measurements. The correlations between signal features and BP are obtained by mechanism-driven models which use physiological principles to identify mathematical correlations, and data-driven models which use machine learning algorithms to analyze observational data to identify multidimensional correlations. On the one hand, applying mechanism-driven models to non-linear scenarios and incomplete or noisy data is challenging On the other hand, data-driven models require a large amount of data in order to prevent physically inconsistent predictions, resulting in poor generalization. From this perspective, this paper proposes to combine the strengths of mechanism-driven and data-driven approaches to obtain a more comprehensive approach, the physiology-informed machine-learning approach, with the goal of enhancing the accuracy, interpretability, and scalability of continuous cuffless BP monitoring. This holds promise for personalized clinical applications and the advancement of hypertension management.

Patent landscape review of non-invasive medical sensors for continuous monitoring of blood pressure and their validation in critical care practice.

Continuous non-invasive monitoring of blood pressure is one of the main factors in ensuring the safety of the patient's condition in anesthesiology, intensive care, surgery, and other areas of medicine. The purpose of this work was to analyze the current patent situation and identify directions and trends in the application of non-invasive medical sensors for continuous blood pressure monitoring, with a focus on clinical experience in critical care and validation thereof. The research results reflect data collected up to September 30, 2022. Patent databases, Google Scholar, the Lens database, Pubmed, Scopus databases were used to search for patent and clinical information. An analysis of the patent landscape indicates a significant increase in interest in the development of non-invasive devices for continuous blood pressure monitoring and their implementation in medical practice, especially in the last 10 years. The key players in the intellectual property market are the following companies: Cnsystems Medizintechnik; Sotera Wireless INC; Tensys Medical INC; Healthstats Int Pte LTD; Edwards Lifesciences Corp, among others. Systematization of data from validation and clinical studies in critical care practice on patients with various pathological conditions and ages, including children and newborns, revealed that a number of non-invasive medical sensor technologies are quite accurate and comparable to the "gold standard" continuous invasive blood pressure monitoring. They are approved by the FDA for medical applications and certified according to ISO 81060-2, ISO 81060-3, and ISO/TS 81060-5. Unregistered and uncertified medical sensors require further clinical trials. Non-invasive medical sensors for continuous blood pressure monitoring do not replace, but complement, existing methods of regular blood pressure measurement, and it is expected to see more of these technologies broadly implemented in the practice in the near future.

Automatic and continuous blood pressure monitoring via an optical-fiber-sensor-assisted smartwatch

Automatic and continuous blood pressure monitoring is important for preventing cardiovascular diseases such as hypertension. The evaluation of medication effects and the diagnosis of clinical hypertension can both benefit from continuous monitoring. The current generation of wearable blood pressure monitors frequently encounters limitations with inadequate portability, electrical safety, limited accuracy, and precise position alignment. Here, we present an optical fiber sensor-assisted smartwatch for precise continuous blood pressure monitoring. A fiber adapter and a liquid capsule were used in the building of the blood pressure smartwatch based on an optical fiber sensor. The fiber adapter was used to detect the pulse wave signals, and the liquid capsule was used to expand the sensing area as well as the conformability to the body. The sensor holds a sensitivity of -213µw/kPa, a response time of 5 ms, and high reproducibility with 70,000 cycles. With the assistance of pulse wave signal feature extraction and a machine learning algorithm, the smartwatch can continuously and precisely monitor blood pressure. A wearable smartwatch featuring a signal processing chip, a Bluetooth transmission module, and a specially designed cellphone APP was also created for active health management. The performance in comparison with commercial sphygmomanometer reference measurements shows that the systolic pressure and diastolic pressure errors are -0.35 ± 4.68 mmHg and -2.54 ± 4.07 mmHg, respectively. These values are within the acceptable ranges for Grade A according to the British Hypertension Society (BHS) and the Association for the Advancement of Medical Instrumentation (AAMI). The smartwatch assisted with an optical fiber is expected to offer a practical paradigm in digital health.

Noninvasive Cuffless Blood Pressure Estimation With Dendritic Neural Regression.

Blood pressure (BP) is one of the most important indicators of health. BP that is too high or too low causes varying degrees of diseases, such as renal impairment, cerebrovascular incidents, and cardiovascular diseases. Since traditional cuff-based BP measurement techniques have the drawbacks of patient discomfort and the impossibility of continuous BP monitoring, noninvasive cuffless continuous BP measurement has become a popular topic. The common noninvasive approach uses machine-learning (ML) algorithms to estimate BP by using the features extracted from simultaneous photoplethysmogram (PPG) and electrocardiogram (ECG) signals, such as the pulse transit time and pulse wave velocity. This study investigates the BP estimation performance of the novel dendritic neural regression (DNR) method proposed by us. Unlike conventional neural networks, DNR utilizes the multiplication operator as the excitation function in each dendritic branch, inspired by biological neuron phenomena, and can effectively capture nonlinear relationships between distinct input features. In addition, AMSGrad is used as the optimization algorithm to further enhance the dendritic neural model's performance. The experimental results show that by being fed a combination of the raw features extracted from the ECG and PPG signals and the components of the BP mathematical models, DNR can increase the accuracy of systolic BP, diastolic BP, and mean arterial pressure estimation significantly, which are superior to the state-of-the-art ML techniques. According to the British Hypertension Society protocol, DNR achieves a grade of A for the long-term BP estimation. Considering its architectural simplicity and powerful performance, the proposed method can be regarded as a reliable tool for estimating long-term continuous BP in a noninvasive cuffless way.

A Baseline-Tracking Single-Channel I/Q Impedance Plethysmogram IC for Neckband-Based Blood Pressure and Cardiovascular Monitoring

An impedance plethysmogram (IPG) IC with wide-range fine baseline tracking capability is proposed to provide continuous blood pressure (BP) and cardiovascular monitoring just by wearing a neckband wearable device. For the baseline tracking, a mixed-mode baseline cancellation (MM-BC) scheme is proposed to achieve wide dynamic range (DR) and high SNR performance, where an artifact-detecting continuous-time (CT)- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Delta \Sigma $</tex-math> </inline-formula> ADC is included together for high-resolution conversion. For cost-effective IPG design, a phase synchronizer concept is introduced to provide I/Q detection capability with single readout channel, supporting both configurations of two-electrode and four-electrode. A proposed readout integrated circuit (ROIC) prototype for the proposed IPG was fabricated, where an electrocardiogram (ECG) readout path is integrated together. The proposed IPG schemes were experimentally verified to achieve good performances of 145.2-dB DR and 103.5-dB SNR. For system-level feasibility, a neckband device prototype was also manufactured, and its cardiovascular monitoring functionality was functionally verified. Based on its IPG and ECG measurements, continuous BP measurement based on the pulse arrival time (PAT) was experimentally verified with a reference BP device.

A novel interpretable feature set optimization method in blood pressure estimation using photoplethysmography signals

Blood pressure (BP) estimation based on photoplethysmography (PPG) signals enables continuous and comfortable BP measurement, which is important for the clinical management of hypertension. The purpose of this study is to propose a novel and interpretable feature optimization method to improve the performance of the PPG-based model for BP estimation. The PPG signals of 152 subjects were selected from a public database. Feature detection was performed on the signals after FIR band-pass filtering. A total of 172 features extracted from ten feature dimensions were used to construct a feature set, including features from the raw PPG signals, PPG derivative signals, and statistical information. Light Gradient Boosting Machine (LightGBM) was used as this work's prediction model. To further improve the performance of the LightGBM model, Shapley Additive Explanations (SHAP) were utilized for feature optimization to achieve the purpose. The number of features corresponding to the lowest model error was defined as the optimal feature set, and this was utilized for training the model to obtain BP estimation. Compared to the validated BP, the mean and standard deviation (SD) of the estimation errors for systolic blood pressure (SBP) and diastolic blood pressure (DBP) were −0.73 ± 6.50 mmHg and 0.37 ± 3.83 mmHg, respectively. According to the British Hypertension Society (BHS) criteria, SBP and DBP are within the range of B and A grades, respectively. We propose a novel feature optimization method to reduce the feature dimension for BP estimation. The algorithm can effectively prevent overfitting and improve the model's performance.

A mixed attention-gated U-Net for continuous cuffless blood pressure estimation

A mixed attention-gated U-Net for continuous cuffless blood pressure estimation

A Hemodynamic Pulse Wave Simulator Designed for Calibration of Local Pulse Wave Velocities Measurement for Cuffless Techniques.

Devices for cuffless blood pressure (BP) measurement have become increasingly widespread in recent years. Non-invasive continuous BP monitor (BPM) devices can diagnose potential hypertensive patients at an early stage; however, these cuffless BPMs require more reliable pulse wave simulation equipment and verification methods. Therefore, we propose a device to simulate human pulse wave signals that can test the accuracy of cuffless BPM devices using pulse wave velocity (PWV). We design and develop a simulator capable of simulating human pulse waves comprising an electromechanical system to simulate the circulatory system and an arm model-embedded arterial phantom. These parts form a pulse wave simulator with hemodynamic characteristics. We use a cuffless device for measuring local PWV as the device under test to measure the PWV of the pulse wave simulator. We then use a hemodynamic model to fit the cuffless BPM and pulse wave simulator results; this model can rapidly calibrate the cuffless BPM's hemodynamic measurement performance. We first used multiple linear regression (MLR) to generate a cuffless BPM calibration model and then investigated differences between the measured PWV with and without MLR model calibration. The mean absolute error of the studied cuffless BPM without the MLR model is 0.77 m/s, which improves to 0.06 m/s when using the model for calibration. The measurement error of the cuffless BPM at BPs of 100-180 mmHg is 1.7-5.99 mmHg before calibration, which decreases to 0.14-0.48 mmHg after calibration. This study proposes a design of a pulse wave simulator based on hemodynamic characteristics and provides a standard performance verification method for cuffless BPMs that requires only MLR modeling on the cuffless BPM and pulse wave simulator. The pulse wave simulator proposed in this study can be used to quantitively assess the performance of cuffless BPMs. The proposed pulse wave simulator is suitable for mass production for the verification of cuffless BPMs. As cuffless BPMs become increasingly widespread, this study can provide performance testing standards for cuffless devices.

“The peripheral perfusion index discriminates haemodynamic responses to induction of general anaesthesia”

Induction of general anaesthesia is often accompanied by hypotension. Standard haemodynamic monitoring during anaesthesia relies on intermittent blood pressure and heart rate. Continuous monitoring systemic blood pressure requires invasive or advanced modalities creating a barrier for obtaining important information of the circulation. The Peripheral Perfusion Index (PPI) is obtained non-invasively and continuously by standard photoplethysmography. We hypothesized that different patterns of changes in systemic haemodynamics during induction of general anaesthesia would be reflected in the PPI. Continuous values of PPI, stroke volume (SV), cardiac output (CO), and mean arterial pressure (MAP) were evaluated in 107 patients by either minimally invasive or non-invasive means in a mixed population of surgical patients. 2 min after induction of general anaesthesia relative changes of SV, CO, and MAP was compared to the relative changes of PPI. After induction total cohort mean(± st.dev.) MAP, SV, and CO decreased to 65(± 16)%, 74(± 18)%, and 63(± 16)% of baseline values. In the 38 patients where PPI decreased MAP was 57(± 14)%, SV was 63(± 18)%, and CO was 55(± 18)% of baseline values 2 min after induction. In the 69 patients where PPI increased the corresponding values were MAP 70(± 15)%, SV 80(± 16)%, and CO 68(± 17)% (all differences: p < 0,001). During induction of general anaesthesia changes in PPI discriminated between the degrees of reduction in blood pressure and algorithm derived cardiac stroke volume and -output. As such, the PPI has potential to be a simple and non-invasive indicator of the degree of post-induction haemodynamic changes.

Barriers to Technology Adoption by Patients and Providers in Diabetes and Hypertension Care Management

Remote monitoring has been demonstrated to be an effective tool for decreasing costs and improving outcomes, however, both patients and providers have shown a reluctance to embrace technology. This survey-based, cross-sectional designed study assessed the barriers faced by patients and providers in the District of Columbia for technology adoption in remote monitoring. The patients had a diagnosis of either diabetes, hypertension, or both conditions, and utilized the technology of a home blood glucose monitor, continuous glucose monitor or ambulatory blood pressure monitor. The surveyed providers included staff engaged in chronic disease management of patients with diabetes and hypertension. An adapted version of the Barriers to Health Promoting Activities for Disabled Persons Scale (BHADP)was administered to study participants and statistically analyzed. Data analysis compared and contrasted demographics and survey responses and revealed that there is a discordance in the ways that patients perceive the barriers to technology as compared to the ways that providers perceive them. Data analysis also revealed significant system barriers that limited providers use of remote monitoring technologies. A model is proposed that identifies inputs and barriers experienced by the patient in their journey to initiate or continue a technology (adapted from Moore et al.’s 2021 Conceptual Model).

Contactless and continuous blood pressure measurement according to caPTT obtained from millimeter wave radar

Continuous measurement of blood pressure (BP) is very important for assessing the health of the cardiovascular system. In this paper, a new system is first-time established to contactlessly and continuously measure BP according to the central-artery pulse transit time (caPTT) which is acquired from the neck and chest areas simultaneously with single millimeter wave (mmWave) radar. The two signals are separated by beam-component focusing and then BP is estimated by regression fitting. The correlation of the PTT’s variation measured by radar and contact device is verified by data from 16 subjects. The effectiveness of BP estimation is evaluated by data from 27 subjects. It is illustrated that the correlation of PTT’s variation is up to 0.91 and the errors of SBP and DBP are 5.54±7.62 mmHg and 4.68±6.15 mmHg respectively. The developed system in this work suggested that single radar has the potential to continuously measure BP in daily life.

Towards continuous non-invasive blood pressure measurements-interpretation of the vasculature response to cuff inflation.

Blood pressure (BP) surrogates, such as pulse transit time (PTT) or pulse arrival time (PAT), have been intensively explored with the goal of achieving cuffless, continuous, and accurate BP inference. In order to estimate BP, a one-point calibration strategy between PAT and BP is typically used. Recent research focuses on advanced calibration procedures exploiting the cuff inflation process to improve calibration robustness by active and controlled modulation of peripheral PAT, as measured via plethysmograph (PPG) and electrocardiogram (ECG) combination. Such methods require a detailed understanding of the mechanisms behind the vasculature's response to cuff inflation; for this, a model has recently been developed to infer the PAT-BP calibration from measured cuff-induced vasculature changes. The model, while promising, is still preliminary and only partially validated; in-depth analysis and further developments are still needed. Therefore, this work aims to improve our understanding of the cuff-vasculature interaction in this model; we seek to define potential opportunities and to highlight which aspects may require further study. We compare model behaviors with clinical data samples based on a set of observable characteristics relevant for BP inference and calibration. It is found that the observed behaviors are qualitatively well represented with the current simulation model and complexity, with limitations regarding the prediction of the onset of the distal arm dynamics and behavior changes at high cuff pressures. Additionally, a sensitivity analysis of the model's parameter space is conducted to show the factors that influence the characteristics of its observable outputs. It was revealed that easily controllable experimental variables, such as lateral cuff length and inflation rate, have a significant impact on cuff-induced vasculature changes. An interesting dependency between systemic BP and cuff-induced distal PTT change is also found, revealing opportunities for improved methods for BP surrogate calibration. However, validation via patient data shows that this relation does not hold for all patients, indicating required model improvements to be validated in follow up studies. These results provide promising directions to improve the calibration process featuring cuff inflation towards accurate and robust non-invasive blood pressure estimation.

EFFECT OF BAROREFLEX ACTIVATION THERAPY ON BLOOD PRESSURE: THE BAT-STUDY – A RANDOMIZED SHAM CLINICAL PILOT TRIAL

Objective: To explore the effects of baroreflex activation therapy (BAT) on blood pressure in individuals with refractory hypertension. Design and method: This investigator-initiated randomized, double-blinded sham-controlled pilot trial included five Finnish patients with refractory hypertension. Participants were found eligible if they were 18 - 70 years old with a daytime systolic ambulatory blood pressure (ABP) of 145 mmHg or higher, and/or a daytime diastolic ABP of 95 mm Hg or higher. Patients were on 3 or more antihypertensive drugs including a diuretic. A witnessed drug intake prior to ABPM was implemented. The Barostim Neo System was implanted for modulation of the autonomic nervous system by direct electrical stimulation of the carotid baroreceptors. After 1 month following implantation, all participants were randomized to either 8 months of baroreflex activation therapy (BAT-system on) or continuous pharmacotherapy (BAT-system off) followed by continuous BAT-therapy for all participants for 8 months. The complete design is outlined in the Figure. 24-hour ABP-measurements were performed per protocol. The primary outcome was defined as a change in ambulatory systolic blood pressure after 8 months of BAT, compared to pharmacotherapy. Results and conclusions: After 8 months of follow-up BAT decreased mean systolic daytime blood pressure by 11.8 mmHg in three participants randomized to BAT, while in the two remaining participants randomized to continuous pharmacotherapy mean systolic daytime blood pressure increased by 8.7 mmHg. When pooling all daytime systolic 24-hour ABP-measurements across the entire follow-up, BAT-therapy was associated with a 9.2 mmHg lower mean blood pressure as compared to continuous pharmacotherapy (143.5 mmHg [95% CI:142.2 - 144.9] vs 152.7 mmHg [151.1 - 154.2], P &lt; 0.0001). In linear mixed models with the BAT-system's status as a fixed effect, day-time systolic blood pressure recordings from 24-hour ABP-measurements at baseline and after 8 months of follow-up were compared between individuals on BAT and continuous pharmacotherapy. Here, BAT-therapy was associated with a reduction in mean systolic day-time blood pressure of -11.7 mmHg (P &lt; 0.0001). In conclusion, BAT-therapy may be a promising tool in lowering systolic blood pressure in individuals with refractory hypertension. Figure. Study design. ABPM = ambulatory blood pressure measurement. Device = Control of Device.

DAYTIME SUPINE BLOOD PRESSURE NORMALIZED BY 24-HOUR VALUES INDEPENDENTLY PREDICTS FUNCTIONAL OUTCOME AFTER ISCHEMIC STROKE

Objective: Blood pressure (BP) after ischemic stroke (IS) may follow various patterns. Post-event acute BP alterations mirror both stroke and patient characteristics, and resolve over time, yet their clinical significance is low or uncertain. Whether individual BP variations, based on a single standardized measurement normalized by a background BP course, have a distinct significance for stroke outcome remains unknown. We hypothesized that the BP difference index (BPD) between daytime supine resting and a series of surrounding BP values (daytime, 24-hour (24h)) in the subacute phase of IS is associated with functional outcome. Design and method: we included 131 IS patients [age 60.8 ± 12.5 years, median (NIHSS) score 5 (3-8)]. Office BP measurements and continuous 24-hour BP monitoring were performed on day 7 after stroke onset. The daytime period was defined as the interval from 6 a.m. to 10 p.m. Functional outcome was evaluated 90 days after stroke using the modified Rankin Scale (mRS) with an mRS score of 3 to 6 (dependency or death) considered as a poor outcome. Results: In a univariate analysis, high BPD was significantly associated with a poor stroke outcome (p = 0.001, 0.003, and 0.002 for systolic, diastolic, and mean BP, respectively, irrespective of the normalization subperiod (daytime, 24h). In a multivariate analysis, the predictive value of BPD remained significant only for systolic BP [SBP] normalized by daytime or 24h mean (OR, 1.06; 95% CI, 1.01-1.11; p = 0.02) after adjustment for covariates. Moreover, the relationship was stronger in a subgroup of patients able to walk independently (mRS 0-2) on day 7 after stroke onset (adjusted OR, 1.08; 95% CI, 1.01-1.17; p = 0.049 for SBP normalized by daytime or adjusted OR, 1.09; 95% CI, 1.01-1.18; p = 0.03 for SBP normalized by 24h mean). Conclusions: We found that the higher difference between supine resting and daytime or diurnal mean BP in patients in the subacute phase of ischemic stroke is independently associated with a poor outcome. This BP index might be useful in clinical practice, including therapeutic decisions, but needs broader studies in patient populations of stroke subtypes.

REFLECTION MAGNITUDE AND ITS ASSOCIATION WITH INCIDENT HYPERTENSION AND BLOOD PRESSURE CHANGES IN A MULTI-ETHNIC COHORT: THE HELIUS STUDY

Objective: A higher reflection magnitude (RM), defined as the ratio of the backward and forward moving pressure wave, is associated with hypertension and incident heart failure. Whether RM is predictive of future hypertension and blood pressure (BP) increase is unknown. We assessed the association between RM, incident hypertension and BP increase over time. Design and method: Data of the Healthy Life in an Urban Setting study was analysed focusing on the six major ethnic groups living in Amsterdam, The Netherlands, aged between 18 and 70 years. Central arterial blood pressure was reconstructed from non-invasive continuous finger BP measurements. RM was calculated through wave separation analysis. Logistic regression models were created to investigate the association between RM and incident hypertension in the normotensive individuals. Linear regression was used to investigate the association between RM and changes in BP, which was corrected for the use of antihypertensive medication. All models were corrected for age, sex, ethnicity and baseline BP. The association between RM and delta SBP was additionally corrected for BMI. Results: A total of 5,779 participants were included for analysis, median age was 48 years (IQR 37-55), 54.6% were female and 67% were normotensive at baseline. In normotensive participants aged &lt; 50 years at baseline, a 10% increase in RM resulted in an increased odds ratio (OR) of 1.37 (95% CI 1.09 – 1.72 for developing incident hypertension, which attenuated to 1.12 (95% CI 0.88 – 1.42) following adjustment for baseline SBP. Additionally, in individuals below 50 years an increase in RM of 10% was associated with a 1.77 mmHg (95% CI 1.00 – 2.53) increase in SBP (figure 1). No significant association between delta SBP and RM was found in the participants aged 50 or older. Conclusions: In a multi-ethnic cohort, RM is positively associated with the development of hypertension in individuals aged &lt; 50 years. However, additional correction for baseline SBP attenuated this association. In addition, RM is predictive of SBP increase, with significant interaction for ethnicity.

DESIGNING A CLINICAL TRIAL PROTOCOL INCLUDING PHYSICAL AND MENTAL ACTIVITIES TO EXPLORE BLOOD PRESSURE DYNAMICS FOR MEDICAL DEVICE DEVELOPMENT

Objective: Cuff blood pressure monitoring is uncomfortable, limited for daily-routine and it provides sparse measurements in time. To enable continuous non-invasive monitoring, a new cuffless blood pressure (BP) meter based on photoplethysmography (PPG) is assessed in a first clinical trial. It aims at exploring the relationship between BP variations and optical features, including a wide range of intra-individual BP variations. Design and method: The initial cohort of the clinical trial (NCT05393401, approved by Human Research Review Board (CPP SM I) and Health French Ministry) includes five healthy subjects (1F/4M, age [37-60] years). Each subject is monitored with a medical-grade continuous BP meter, and a multi-sensing homemade platform integrating gold standard cuff measurements. The latter gathers PPG sensors, an ECG, a nasal cannula. The subject undertakes the following exercises: rest, static and dynamic strength exercises with a Pilates fitness ring, mental calculation, guided relaxation, and wall sit exercise. Each phase lasts 3 minutes, except the relaxation (10 minutes) and is followed by a 3-minute recovery. Results: The impact of each activity is quantified by the range of mean arterial pressure (MAP), i.e. the difference between the initial value and the extremum during the interval. As the table shows, the highest median impact is achieved with the dynamic ring (+39 mmHg) and the wall sit (+33mmHg). The static ring and the stress occurred by the calculation exercise have a lower impact with an increase of 21mmHg and 19mmHg. Finally, the effect of the relaxation is verified with a median decrease of 13 mmHg. Conclusions: These preliminary results (trial still running) show that building an accurate BP meter requires exploring the full range of BP in response to various physiological mechanisms. Therefore, it is necessary to combine relaxing and physical activities. Their impact vary among subjects and activities and illustrate that special care should be taken using real-time monitoring.

Hemodynamic effects of intraoperative 30% versus 80% oxygen concentrations: an exploratory analysis.

Supplemental oxygen leads to an increase in peripheral vascular resistance which finally increases systemic blood pressure in healthy subjects and patients with coronary artery disease, heart failure, undergoing heart surgery, and with sepsis. However, it is unknown whether this effect can also be observed in anesthetized patients having surgery. Thus, we evaluated in this exploratory analysis of a randomized controlled trial the effect of 80% versus 30% oxygen on intraoperative blood pressure and heart rate. We present data from a previous study including 258 patients, who were randomized to a perioperative inspiratory FiO2 of 0.8 (128 patients) versus 0.3 (130 patients) for major abdominal surgery. Continuous arterial blood pressure values were recorded every three seconds and were exported from the electronic anesthesia record system. We calculated time-weighted average (TWA) and Average Real Variability (ARV) of mean arterial blood pressure and of heart rate. There was no significant difference in TWA of mean arterial pressure between the 80% (80 mmHg [76, 85]) and 30% (81 mmHg [77, 86]) oxygen group (effect estimate -0.16 mmHg, CI -1.83 to 1.51; p = 0.85). There was also no significant difference in TWA of heart rate between the 80 and 30% oxygen group (median TWA of heart rate in the 80% oxygen group: 65 beats.min-1 [58, 72], and in the 30% oxygen group: 64 beats.min-1 [58; 70]; effect estimate: 0.12 beats.min-1, CI -2.55 to 2.8, p = 0.94). Also for ARV values, no significant differences between groups could be detected. In contrast to previous results, we did not observe a significant increase in blood pressure or a significant decrease in heart rate in patients, who received 80% oxygen as compared to patients, who received 30% oxygen during surgery and for the first two postoperative hours. Thus, hemodynamic effects of supplemental oxygen might play a negligible role in anesthetized patients. https://clinicaltrials.gov/ct2/show/NCT03366857?term=vienna&cond=oxygen&draw=2&rank=1.

Exploring the Potential of Pulse Transit Time as a Biomarker for Sleep Efficiency through a Comparison Analysis with Heart Rate and Heart Rate Variability.

The relationship between sleep dynamics and blood pressure (BP) changes is well established. Moreover, sleep efficiency and wakefulness during sleep (WASO) events have a significant impact on BP dipping. Despite this knowledge, there is limited research on the measurement of sleep dynamics and continuous blood pressure (CBP). This study aims to explore the relationship between sleep efficiency and cardiovascular function indicators such as pulse transit time (PTT), as a biomarker of CBP, and heart rate variability (HRV), measured using wearable sensors. The results of the study conducted on 20 participants at the UConn Health Sleep Disorders Center suggest a strong linear relationship between sleep efficiency and changes in PTT (r2 = 0.8515) and HRV during sleep (r2 = 5886). The findings of this study contribute to our understanding of the relationship between sleep dynamics, CBP, and cardiovascular health.