Estimation Of Pressure Research Articles

Continuous Estimation of Blood Pressure by Utilizing Seismocardiogram Signal Features in Relation to Electrocardiogram

There is an ongoing search for a reliable and continuous method of noninvasive blood pressure (BP) tracking. In this study, we investigate the feasibility of utilizing seismocardiogram (SCG) signals, i.e., chest motion caused by cardiac activity, for this purpose. This research is novel in examining the temporal relationship between the SCG-measured isovolumic moment and the electrocardiogram (PEPIM). Additionally, we compare these results with the traditionally measured pre-ejection period with the aortic opening marked as an endpoint (PEPAO). The accuracy of the BP estimation was evaluated beat to beat against invasively measured arterial BP. Data were collected on separate days as eighteen sets from nine subjects undergoing a medical procedure with anesthesia. Results for PEPIM showed a correlation of 0.67 ± 0.18 (p < 0.001), 0.66 ± 0.17 (p < 0.001), and 0.67 ± 0.17 (p < 0.001) when compared to systolic BP, diastolic BP, and mean arterial pressure (MAP), respectively. Corresponding results for PEPAO were equal to 0.61 ± 0.22 (p < 0.001), 0.61 ± 0.21 (p < 0.001), and 0.62 ± 0.22 (p < 0.001). Values of PEPIM were used to estimate MAP using two first-degree models, the linear regression model (achieved RMSE of 11.7 ± 4.0 mmHg) and extended model with HR (RMSE of 10.8 ± 4.2 mmHg), and two corresponding second-degree models (RMSE of 10.8 ± 3.7 mmHg and RMSE of 8.5 ± 3.4 mmHg for second-degree polynomial and second-degree extended, respectively). In the intrasubject testing of the second-degree model extended with HR based on PEPIM values, the mean error of MAP estimation in three follow-up measurements was in the range of 7.5 to 10.5 mmHg, without recalibration. This study demonstrates the method’s potential for further research, particularly given that both proximal and distal pulses are measured in close proximity to the heart and cardiac output. This positioning may enhance the method’s capacity to more accurately reflect central blood pressure compared to peripheral measurements.

Wave forces and dynamic pressures on pile-supported breakwaters with inclined perforated plates under regular waves

The use of pile-supported breakwaters can be a cost-effective solution for wave energy dissipation when traditional rubble mound breakwaters are not suitable. For a cost-effective design of these barriers, it is essential to obtain accurate estimates of dynamic pressures and wave forces. Laboratory experiments were conducted to investigate the dynamic pressures and forces on a novel pile-supported breakwater with inclined perforated plates. The analysis focused on various wave and structural parameters, including incident wave height, wave period, plate porosity, and plate configuration. For double-layer configurations with the same porosity, dynamic pressures on the single-layer or front plate were significantly higher than on the rear plate, with rear plate forces being 20% to 60% less. The dynamic pressure on the rear plate exhibited a uniform vertical distribution. Varying plate porosity at different locations significantly impacted structural forces. Gradually decreasing porosity improved wave dissipation and reduced forces on the plates, with front and back plate forces reaching approximately 70% of those on single-layer plates. Optimal protection across various wave periods can be achieved by adjusting porosity and plate arrangement. These findings provide valuable insights for designing pile-supported breakwaters in coastal protection engineering.

Shale pore pressure seismic prediction based on the Hydrogen generation and compaction-based rock physics model and Bayesian Hamiltonian Monte Carlo inversion method

The seismic prediction of formation pore pressure is critically important for the exploration and appraisal of shale oil and gas reservoirs, as well as for identifying optimal drilling targets within these formations. In particular, the complex pressure regimes of deep shale reservoirs introduce substantial challenges to traditional seismic prediction methodologies. A Bayesian Hamiltonian Monte Carlo pre-stack seismic inversion approach is proposed to enhance the accuracy of pore pressure estimations based on an advanced rock physics model that integrates compaction and hydrocarbon generation effects. Initially, a comprehensive petrophysical model is developed to account for the effects of hydrocarbon generation and compaction, establishing a robust framework for the normal compaction trend simulation. Subsequently, a novel formation pressure prediction model is derived based on integrating the Eaton model and the Bower stress hypothesis. Then, the Bayesian HMC seismic inversion method is proposed to predict formation pore pressure in shale reservoirs with elastic impedance data set. The proposed methodology is validated through application to actual well log and seismic data from the Fuling shale oil and gas reservoirs in the Sichuan Basin, which demonstrates significant potential of this method for enhancing the prediction of pore pressure in complex geological settings.

Noncontact Blood Pressure Estimation From the Carotid Pulse Wave Signal Using a Modified ResNet-18 Network With LFMCW Radar

Noncontact Blood Pressure Estimation From the Carotid Pulse Wave Signal Using a Modified ResNet-18 Network With LFMCW Radar

Comparison of proximal and distal BCG measurements for blood pressure estimation

Abstract This paper presents a comparison of the blood pressure estimation based on Ballistocardiography (BCG) measurements, acquired at two different body locations. The first BCG signal being the proximally measured BCG at the carotid artery, the second being the distally measured BCG at the foot. Parallel to the BCG measurement, the reference blood pressure is measured. Visual inspection of both BCG signals shows a decreased signal quality for the distal measurement. Moreover, in order to estimate the blood pressure based on BCG derived features for beat-to-beat intervals two neural networks are deployed. It is shown that Mean Absolut Error (MAE) is twice as large for the distal blood pressure estimation as for the proximal estimation and that the estimated pressure values of the proximal model show less variation when comparing the reference pressure and estimated pressure visually.

On time-periodic solutions to an interaction problem between compressible viscous fluids and viscoelastic beams

Abstract In this paper, we study a nonlinear fluid-structure interaction problem between a ‘square-root’ viscoelastic beam and a compressible viscous fluid. The beam is immersed in the fluid which fills a two-dimensional rectangular domain with periodic boundary conditions in both directions, while both the beam and the fluid are under the effect of time-periodic forces. By using a decoupling approach, at least one time-periodic weak solution to this problem is constructed which has a bounded energy and a fixed prescribed mass. The lack of a priori energy bounds is overcome by a series of estimates based on a careful choice of parameters. The most challenging one is the pressure estimate, which is obtained by utilizing the specific periodic geometry and the Bogovskiǐ operator on a fixed domain that has a uniform constant. With uniform estimates and improved regularity of the beam as in (Muha and Schwarzacher 2023 Ann. Inst. Henri Poin. Anal. Non Lineaire 39 1369–412), the time-periodic solution is constructed by a series of limit procedures, following the finite-dimensional time-space construction from (Feireisl et al 2012 Arch. Rational Mech. Anal. 204 74586).

Investigation of transonic flows through an idealized ORC turbine vane using Delayed Detached Eddy simulations

An idealized transonic blade configuration is studied using Delayed Detached Eddy Simulations (DDES), with focus on the loss mechanisms associated with the base pressure and turbulent wake development. The working fluid is Novec649, which is commonly used in low temperature Organic Rankine Cycle (ORC) power plants. Due to the molecular complexity of the fluid, a lower pressure ratio and exit Mach number are achieved compared to an air flow through the same geometry, a phenomenon that becomes more pronounced when considering thermodynamic operating conditions that lead to stronger non-ideal gas behavior, and which is well captured by models of standard use in ORC design and analysis, such as Reynolds-Averaged Navier–Stokes (RANS) models. Overall, as the fluid isentropic exponent and the exit Mach number decrease, the losses tend to increase. When performing a breakdown of the losses, the wake region provides the dominant contribution. Unlike RANS models, the DDES resolves the largest turbulent scales in the wake region, allowing fine-detail analysis of the unsteady wake dynamics, namely vortex shedding, and its influence on the loss coefficients. In the low supersonic Mach number range considered (M2∼1–2), the vortex shedding exhibits a flapping motion in the reattachment region behind the trailing edge. The Strouhal number, classically formed with the diameter of the trailing edge, is found to increase with increasing outlet Mach number. However, when introducing a new scaling based on the neck width of the reattachment region, directly related to the shape of the recirculation bubble and the associated reattachment shocks, the Strouhal number collapses to a relatively constant value of about 0.3 in all cases. DDES also shows that, due to the large heat capacity of Novec649, temperature fluctuations in the wake are greatly reduced, leading to the suppression of the so-called energy separation phenomenon occurring in air flows. While RANS simulations capture satisfactorily the main features and global quantities of the flow, they fail in describing the flow around the trailing edge. This results in inaccurate estimates of the back pressure, which ultimately leads to an underestimation of the losses by about 20%. Unsteady RANS simulations can predict the wake unsteadiness, but do not capture the couplings between large coherent structures, the recirculation, and the shocks, also resulting in inaccurate performance predictions. Thus, the present result showcase the importance of using advanced scale-resolving simulations for improved analysis and design of ORC turbines.

Assessing rainfall-triggered landslides considering small-scale depth to bedrock uncertainty: A random field approach

Depth to bedrock (DTB) is a critical factor for rainfall–induced slope failures. However, the influence of uncertainties in these measurements, particularly at a small–scale, has not been fully understood. Numerical modeling was conducted to assess the impact of a variable bedrock topography on the stability of a real–world unsaturated slope. The simulations included a three–dimensional pore–water pressure estimation, derived from the numerical solution of the Richards equation, coupled with a slope stability assessment using numerical limit analysis. The study explored the potential of incorporating random fields (RFs) into an established DTB model to improve the understanding of rainfall–triggered landslides. The proposed methodology was applied to the analysis of a small watershed within the Papagaio River basin in Brazil, an area historically subjected to landslides triggered by rainfall events. Our main findings reveal that small variations in DTB can significantly impact the safety factor and probability of failure estimations. Furthermore, they influence the shape, location and failure volume associated to predicted landslides. The incorporation of RFs effectively addresses small–scale uncertainty in DTB, controls bedrock morphology, and enhances the assessment of probabilistic numerical modeling for landslide susceptibility. This study highlights the importance of accurate and comprehensive DTB characterization for assessing rainfall–induced landslides at local slope scale.

Towards reliable subharmonic-aided pressure estimation: Simulation and experimental validation of microbubble dynamics

This study examines the reliability of subharmonic-aided pressure estimation (SHAPE) using polydisperse microbubbles. SHAPE utilizes the subharmonic response of ultrasound contrast agent microbubbles to estimate pressure non-invasively. Despite its potential, gaps in theoretical understanding and experimental inconsistencies with polydisperse microbubbles necessitate further investigation. This research explores the impact of microbubble distribution, excitation parameters, and contrast-enhanced ultrasound imaging modes on SHAPE’s signal consistency, measurement linearity, and sensitivity. A one-dimensional microbubble population model was developed to simulate microbubble behavior and the Hilbert transform demodulation technique was applied for subharmonic analyses. Variability in SHAPE was further assessed through flow phantom experiments using Sonazoid agents and a commercial SHAPE scanner. Findings indicate that bubble distribution in both size and location, microbubble interactions, and CEUS imaging modes significantly influence subharmonic responses. An excitation frequency of 3.5 MHz is recommended for robust SHAPE. Monte Carlo simulations confirmed the inherent variability of subharmonic amplitude signals due to dynamic bubble distributions. Using monodisperse microbubbles enhanced SHAPE sensitivity and consistency, without markedly reducing signal variability. These results underscore the necessity of further research to optimize SHAPE for clinical applications, focusing on microbubble characteristics and excitation conditions to enhance consistency and reliability.

Hotspots of human impact on the seafloor in the Southwestern Baltic Sea

The Southwestern Baltic Sea is a notable example of intense human impact on the seafloor in a confined shallow marine environment. Various marks left by dredging, dumping, fishing, anchoring, among others, reflect the different pressures on the seafloor. These activities represent cumulative stressors for marine ecosystems, potentially leading to habitat modification or loss. Characterizing and quantifying the extent of the different pressures is essential for understanding the system and evaluating the environmental status outlined by different legal frameworks. Here, the effects of different human activities on the seafloor in exemplary hotspots in the SW Baltic Sea are visualized and assessed. Actual anthropogenic marks are compared with assessments based on commonly accessible regional and local information from remote sensing data and institutional sources. About 36% of the seafloor of the investigated area is influenced, mainly by bottom trawling, propeller scouring, anchoring, and dumping. More than 91% of the human footprint corresponds to trawl marks, mainly affecting soft substrates. In addition, from 15% to 47% of the seafloor is disturbed in selected ‘detail areas' within the hotspots. Comparisons with indirect data used for regional pressure estimation demonstrate how hydroacoustic data can enhance assessments of seabed physical pressures. However, quantitative comparisons are challenging, especially when information on human activities is limited or when seafloor recovery rates in relation to the frequency of anthropogenic pressures are unknown.

Association between Myopia and Central Corneal Thickness among Patients in a Tertiary Care PAF Hospital

Objectives Central corneal thickness (CCT) measurement is important in the estimation of intraocular pressure (IOP). It is also important when decision has to be made regarding refractive surgery. Studies conducted to determine the relationship between myopia and CCT have produced debatable outcomes. While some studies have found a negative correlation between CCT and the degree of myopia, many others have reported no significant correlation between the two. We attempt to study the relationship between them among patients attending the Ophthalmology department of a tertiary care hospital in Pakistan. Methods This was a prospective cross-sectional study that was conducted at the department of Ophthalmology, PAF Hospital, E9 Islamabad. The study was conducted over a period of four months, from March to June, 2024. Participants were enrolled using non-probability, consecutive sampling. The central corneal thickness was measured and compared in myopic and emmetropic patients. Results In this study we examined 100 eyes of 50 participants. 50 eyes were myopic while the other 50 were emmetropic. There was a statistically significant difference between these two means (P=0.009) and so CCT was found to be thinner in myopic patients. However, no correlation was seen between CCT and the degree of myopia (P=0.055). Our study found no significant relation between CCT and age or gender. Conclusion There is a statistically significant difference between the mean CCT of emmetropes and myopes, with myopic eyes having thinner corneas. However, no significant difference is seen in the CCT according to the degree of myopia.

MIMIC-BP: A curated dataset for blood pressure estimation

Blood pressure (BP) is one of the most prominent indicators of potential cardiovascular disorders. Traditionally, BP measurement relies on inflatable cuffs, which is inconvenient and limit the acquisition of such important health-related information in general population. Based on large amounts of well-collected and annotated data, deep-learning approaches present a generalization potential that arose as an alternative to enable more pervasive approaches. However, most existing work in this area currently uses datasets with limitations, such as lack of subject identification and severe data imbalance that can result in data leakage and algorithm bias. Thus, to offer a more properly curated source of information, we propose a derivative dataset composed of 380 hours of the most common biomedical signals, including arterial blood pressure, photoplethysmography, and electrocardiogram for 1,524 anonymized subjects, each having 30 segments of 30 seconds of those signals. We also validated the proposed dataset through experiments using state-of-the-art deep-learning methods, as we highlight the importance of standardized benchmarks for calibration-free blood pressure estimation scenarios.

Esophageal pressure as estimation of pleural pressure: a study in a model of eviscerated chest

BackgroundTranspulmonary pressure is the effective pressure across the lung parenchyma and has been proposed as a guide for mechanical ventilation. The pleural pressure is challenging to directly measure in clinical setting and esophageal manometry using esophageal balloon catheters was suggested for estimation. However, the accuracy of using esophageal pressure to estimate pleural pressure is debated due to variability in the mechanical properties of respiratory system, esophagus and esophageal catheter. Furthermore, while a vertical pleural pressure gradient exists across lung regions, esophageal pressure balloon provides a single value, representing, at most, the pressure surrounding the esophagus.MethodsIn a swine model with a preserved esophagus and a single homogenous, easily measurable intrathoracic pressure, we evaluated esophageal pressure’s agreement with intrathoracic pressure at different positive end-expiratory pressure (PEEP) levels (0, 5, 10, 15 cmH2O). We assessed the improvement of measurement accuracy by correcting absolute esophageal values using a previously described technique, that accounts for the pressure generated by the esophageal wall in response to esophageal balloon inflation.The study involved five swine, wherein two different esophageal catheters were used alongside the four distinct PEEP levels. Swings, uncorrected and corrected absolute esophageal pressures (end-inspiratory, end-expiratory) were compared with their respective intrathoracic pressures. The effect of correction technique was assessed with manual incremental step inflation procedure.ResultsWe found that both catheters significantly overestimated absolute esophageal pressure compared to intrathoracic pressure (5.01 ± 3.32 and 6.06 ± 5.62 cmH2O at end-expiration and end-inspiration, respectively), with error increasing at higher positive end-expiratory pressure levels (end-expiration: 2.36 ± 2.03, 3.77 ± 1.37, 6.24 ± 2.51 and 7.69 ± 4.02 for each PEEP level, P < 0.0001; end-inspiration: 1.71 ± 2.10, 3.70 ± 1.73, 7.67 ± 3.62 and 11.14 ± 7.60 for each PEEP level, P = 0.0004).Applying the correction technique significantly improved agreement for absolute values (0.82 ± 1.62 and 1.86 ± 3.94 cmH2O at end-expiration and end-inspiration, respectively). Esophageal pressure swings accurately estimated intrathoracic pressure swings at low-medium intrathoracic pressures (-0.64 ± 0.62, -0.07 ± 0.53, 1.43 ± 1.51, and 3.45 ± 3.94 at PEEP 0, 5, 10 and 15 cmH2O, respectively; P = 0.0197).ConclusionsThe correction technique, based on the mechanical response of esophageal wall to the balloon inflation, is fundamental for obtaining reliable estimations of absolute intrathoracic pressure values, and for ensuring its correct application in clinical setting.

Can the Plantar Pressure and Temperature Data Trend Show the Presence of Diabetes? A Comparative Study of a Variety of Machine Learning Techniques

This study aimed to explore the potential of predicting diabetes by analyzing trends in plantar thermal and plantar pressure data, either individually or in combination, using various machine learning techniques. A total of twenty-six participants, comprising thirteen individuals diagnosed with diabetes and thirteen healthy individuals, walked along a 20 m path. In-shoe plantar pressure data were collected and the plantar temperature was measured both immediately before and after the walk. Each participant completed the trial three times, and the average data between the trials were calculated. The research was divided into three experiments: the first evaluated the correlations between the plantar pressure and temperature data; the second focused on predicting diabetes using each data type independently; and the third combined both data types and assessed the effect of such to enhance the predictive accuracy. For the experiments, 20 regression models and 16 classification algorithms were employed, and the performance was evaluated using a five-fold cross-validation strategy. The outcomes of the initial set of experiments indicated that the machine learning models were significant correlations between the thermal data and pressure estimates. This was consistent with the findings from the prior correlation analysis, which showed weak relationships between these two data modalities. However, a shift in focus towards predicting diabetes by aggregating the temperature and pressure data led to encouraging results, demonstrating the effectiveness of this approach in accurately predicting the presence of diabetes. The analysis revealed that, while several classifiers demonstrated reasonable metrics when using standalone variables, the integration of thermal and pressure data significantly improved the predictive accuracy. Specifically, when only plantar pressure data were used, the Logistic Regression model achieved the highest accuracy at 68.75%. Those predictions based solely on temperature data showed the Naive Bayes model as the lead with an accuracy of 87.5%. Notably, the highest accuracy of 93.75% was observed when both the temperature and pressure data were combined, with the Extra Trees Classifier performing the best. These results suggest that combining temperature and pressure data enhances the model’s predictive accuracy. This can indicate the importance of multimodal data integration and their potentials in diabetes prediction.

The mechanistic interaction between mechanical dyssynchrony and filling pressure in cardiac resynchronization therapy candidates.

Both left ventricular (LV) mechanical dyssynchrony and filling pressure have been shown to be associated with outcome in heart failure patient treated with cardiac resynchronization therapy (CRT). To investigate the mechanistic link between mechanical dyssynchrony and filling pressure and to assess their combined prognostic value in CRT candidates. Left atrial pressure (LAP) estimation and quantification of mechanical dyssynchrony were retrospectively performed in 219 CRT patients using echocardiography. LAP was elevated (eLAP) in 49% of the population, normal (nLAP) in 40%, and indeterminate (iLAP) in 11%. CRT response was defined as %-decrease in LV end-systolic volume after 12±6 months CRT. Clinical endpoint was all-cause mortality during 4.8 years (interquartile range: 2.7-6.0 years). To investigate the mechanistic link between mechanical dyssynchrony and filling pressure, the CircAdapt computer model was used to simulate cardiac mechanics and hemodynamics in virtual hearts with LBBB and various causes of increased filling pressure. Patients with nLAP had more significant mechanical dyssynchrony than those with eLAP. The combined assessment of both parameters before CRT was significantly associated with reverse LV remodeling and post-CRT survival. Simulations revealed that mechanical dyssynchrony is attenuated by increased LV operational chamber stiffness, regardless of whether it is caused by passive or active factors, explaining the link between mechanical dyssynchrony and filling pressure. Our combined clinical-computational data demonstrate that in patients with LBBB, the presence of mechanical dyssynchrony indicates relatively normal LV compliance and low filling pressure, which may explain their strong association with positive outcomes after CRT.

Cuffless Blood Pressure Estimation Model Based on Prior Information of Physiological Data and LSTM

Cuffless Blood Pressure Estimation Model Based on Prior Information of Physiological Data and LSTM

Effects of Different Gas Cores on the Ambient Pressure Sensitivity of the Subharmonic Response of SonoVue

ObjectiveSubharmonic Aided Pressure Estimation (SHAPE) is a noninvasive technique for estimating organ-level blood pressure using the strong correlation between the subharmonic signal and ambient pressure. The compressible gas core of microbubbles enables them to generate linear and nonlinear acoustic responses when exposed to ultrasound. Here, the sulfur hexafluoride (SF6) gas core of SonoVue (known as Lumason in the United States), a clinical contrast agent, was exchanged with a perfluorobutane (PFB) core to investigate its effect on the SHAPE response. MethodsExcitations of 25–700 kPa peak negative pressure (PNP) and 3 MHz transmission frequency were used to study in vitro the effects of overpressure changes ranging from 5 to 25 kPa (37–186 mm Hg). ResultsUnlike SonoVue with SF6, at low PNPs (<400 kPa), SonoVue with a PFB gas core exhibited no subharmonic at the atmospheric pressure, but during pressurization, a stable subharmonic response (maximum of 25 dB at 100 kPa PNP and 20 kPa Overpressure) appeared. SonoVue with a PFB gas core showed an increase in subharmonics with overpressure at high PNPs (>400 kPa), which was not observed before in normal SonoVue or other lipid microbubbles. With negligible size distribution difference between these two microbubbles, these effects on subharmonic generation are likely due to the gas core, casting new light on the mechanism by which ambient overpressure affects subharmonic. ConclusionThis study may inform future SHAPE technique developments.

Personalized blood pressure estimation using multiview fusion information of wearable physiological signals and transfer learning

Continuous blood pressure (BP) monitoring is crucial for individual health management, yet the significant inter-individual variations among patients pose challenges to achieving precision medicine. In response to this issue, we propose a parallel cross-hybrid architecture that integrates a convolutional neural network backbone and a Mix-Transformer backbone. This model, grounded in multi-view physiological signals and personalized fine-tuning strategies, aims to estimate BP, facilitating the capture of physiological information across diverse receptive fields and enhancing network expressive capabilities. Our proposed architecture exhibits superior performance in estimating systolic blood pressure and diastolic blood pressure, with average absolute errors of 3.94 mmHg and 2.24 mmHg, respectively. These results surpass existing baseline models and align with the standards set by the British Hypertension Society, the Association for the Advancement of Medical Instrumentation, and the Institute of Electrical and Electronics Engineers for BP measurement. Additionally, this study explores a personalized model fine-tuning strategy by adjusting specific layers and incorporating individual information, presenting an optimal solution. The model's generalization ability is validated through transfer learning across databases (public and self-made). To enhance the proposed architecture's usability in wearable devices, this study employs a knowledge distillation strategy for model lightweighting, with preliminary application in our designed real-time BP estimation system. This study provides an efficient and accurate solution for personalized BP estimation, exhibiting broad potential applications.

Novel subharmonic-aided pressure estimation for identifying high-risk esophagogastric varices.

Subharmonic-aided pressure estimation (SHAPE) is a technique for determining changes in ambient pressure. We aimed to analyze a novel SHAPE integrated into ultrasound diagnostic equipment to predict patients with liver cirrhosis at high risk of esophagogastric varices (EV). This prospective study included 111 patients with liver cirrhosis diagnosed between 2020 and 2023. We obtained liver stiffness measurements (LSM) and spleen stiffness measurements (SSM) using shear wave elastography and hepatic vein-portal vein (HV-PV) gradient using the SHAPE method. The EV risk was determined either as null, low, or high by esophagoscopy and Child-Pugh stage. HV-PV gradient increased concordantly with the increase in EV risk (-7.0dB in null-risk, -4.4dB in low-risk, and -2.0dB in high-risk) with statistically significant difference among any two groups. The most appropriate cut-off value of the HV-PV gradient was -3.5dB, and sensitivity, specificity, and positive and negative predictive values were 80.0%, 89.0%, 80.0%, and 88.0%, respectively. The areas under the curve values for predicting the high-risk EV were 0.920, 0.843, and 0.824 for the HV-PV gradient, LSM, and SSM, respectively. The novel SHAPE system demonstrated high accuracy in identifying patients with liver cirrhosis at a high risk of EV.

Blood pressure lowering efficacy of antihypertensive drugs and their combinations: a systematic review and meta-analysis of 500 randomised, double-blind placebo-controlled trials

Abstract Background Each 1 mmHg reduction in systolic blood pressure (SBP) reduces the risk of major cardiovascular disease events by about 2%. However, there are currently no tools to provide randomised trial-derived estimates of blood pressure (BP)-lowering efficacy of different antihypertensive regimens despite the vast number of possible drug-dose permutations. There has also been no attempt to classify efficacy of treatment regimens into low, moderate, and high intensity. Purpose We aimed to quantify the BP-lowering efficacy of the five major classes of antihypertensive drugs and their combinations. Methods We conducted a systematic review and meta-analysis of randomised double-blind placebo-controlled trials. CENTRAL, MEDLINE and Epistimonikos were searched from inception until December 2022 to identify trials, that compared angiotensin-converting-enzyme inhibitors, angiotensin II receptor blockers, beta-blockers, calcium channel blockers, and diuretics versus placebo, for 4-26 weeks. Primary outcomes were reduction in SBP and diastolic blood pressure (DBP). Doses were classified into standard dose based on the World Health Organisation Defined Daily Dose. BP-lowering efficacy was estimated for each drug and dose using fixed-effects meta-analyses and meta-regressions, standardised to baseline SBP 154 mmHg. Treatment regimens were categorised into low, moderate, and high intensity according to estimated SBP-lowering efficacy of &amp;lt;10, 10-19 and ≥20 mmHg, respectively. Results A total of 500 trials (106,358 participants, 44% female) were included, which included 66 single antihypertensive drugs (monotherapy) and 89 two drug (dual) combinations. The mean baseline BP was 154/100 mmHg and mean follow-up was 8.6 weeks. Monotherapy at one standard dose reduced SBP by 8.5 (95% CI, 8.2-8.9) mmHg, with an additional 1.2 (1.0-1.5) mmHg reduction for each 10 mmHg higher pre-treatment SBP, and an additional 1.5 (1.2-1.8) mmHg reduction with each doubling in dose. There was significant heterogeneity between monotherapies, and 72% were classified as low intensity efficacy. Dual combinations at one standard doses of both the drugs reduced SBP by 15.2 (13.4-17.1) mmHg, and an additional 2.6 (1.4-3.8) mmHg reduction with doubling the doses of both the drugs. There was considerable heterogeneity between dual combinations and 59% were classified as moderate, and 11% as high intensity efficacy. The BP lowering efficacy of adding additional drug classes was confirmed to be additive after accounting for pre-treatment SBP. Triple combinations were classified as high intensity efficacy based on meta-regression analyses. Conclusions There is significant variability in the efficacy of different BP-lowering regimens. The present analyses, available in an online tool, can estimate the BP lowering efficacy for any combination of drug(s) and dose(s), and can classify treatment regimens into low, moderate or high intensity.