Pressure Ratio Research Articles

Carbon dioxide hydrate formation in porous media under dynamic conditions

AbstractInjecting carbon dioxide (CO2) into subsea water zones where the in situ temperatures are below the hydrate‐forming temperature of CO2 has been recently proposed to lock CO2 inside the water zones in solid hydrate form. It is a common concern that CO2 may form hydrates during the injection period that will reduce well injectivity. CO2 injection into sandstone cores under simulated subsea temperatures of 2°C and 3°C was investigated in this study. Experimental result shows that, at 2°C temperature, flowing CO2 at Darcy velocity 0.033 cm/s begins to form hydrate in the sandstone core at about 3.06 MPa (450 psi), which is much higher than the minimum required pressure of 1.5 MPa (220 psi) for CO2 to form hydrate in static condition. The pressure ratio is 450/220 = 2.05. At 3°C temperature, flowing CO2 at Darcy velocity 0.045 cm/s begins to form hydrate in sandstone core at about 3.67 MPa (540 psi), which is much higher than the minimum required pressure of 1.87 MPa (275 psi) for CO2 to form hydrate in static conditions. The pressure ratio is 540/275 = 1.96. The reason why the required minimum pressure for CO2 to form hydrates in dynamic conditions is about double the required hydrate‐forming pressure in static conditions is not fully understood. It is speculated that the shear rate effect of flowing fluids should slow down the growth of hydrate crystals or break down hydrate films, resulting in delayed formation of bulk CO2 hydrates. More investigations in this area are needed in the future.

Mid-Term Results of Pulmonary Valve-Sparing Repair for Tetralogy of Fallot With Pulmonary Stenosis.

The transannular patch remains the most common procedure performed for patients with Tetralogy of Fallot (TOF) with pulmonary stenosis. Pulmonary regurgitation has a negative impact on early and late outcomes. To address this issue pulmonary valve-sparing repair (PVSR) has been developed. Our study goal is to evaluate the mid-term outcomes (five years) of PVSR at our institution. The data were collected retrospectively from June 2014 to June 2022. A total of 390 patients had total repair of TOF. Among these, PVSR was performed in 154 (39.4%) patients. The mid-term outcomes on the status of the pulmonary valve gradient, degree of pulmonary regurgitation, reintervention rate, and mid-term survival after PVSR were investigated. The median age at time of TOF repair was 12 (interquartile range [IQR]: 8-48) months and the median weight was 7.9 (IQR: 3.1-49.5) kg. The mean preoperative right ventricular outflow tract (RVOT) gradient was 77 ± 19.6 mm Hg. All patients had a pulmonary valve Z score of more than -2.5. The post-repair mean RV/LV pressure ratio was 0.49 ± 0.12. There was no surgical mortality. The median follow-up was 3 years (6 months to 8 years). The reintervention rate on the pulmonary valve was 4/154 (2.6%) at five years. The freedom from reintervention and from developing moderate pulmonary valve regurgitation at 5 years was 95% (151/154) and 77% (119/154), respectively. Pulmonary valve-sparing repair gives good mid-term outcomes in a specific group of patients with TOF. Reintervention rates are very low and the peak gradient across the pulmonary valve came down in the majority of patients during mid-term follow up. An RVOT gradient more than 40mm Hg at discharge predicts a high risk of need for reintervention. We continue to monitor our patients for the long term outcome.

Horizontal walls effect on the subsonic flow around airfoil by the image method

The aim of this work consists in developing a new numerical method and a calculation program making it possible to determine the effect of one and two horizontal walls on the distribution of the pressure ratio, and the aerodynamics coefficients of a subsonic flow around airfoils. The model is considered for the perfect gas. The calculation is presented by adding the effect of one and two walls on the discretization of the airfoils boundary to obtain a closed surface. The method is called by the image method. So for the case of the existence of one wall, we will see a single image of the main airfoil, and in the case of two walls, we will have an infinity of images. The equation system is obtained by considering the effect of all images using alternating digital series, whose convergence is ensured numerically. We therefore obtain a large system of equations, the resolution of which is done by the Khaletski method to obtain the velocities and pressure. The application is made for some practical interest’s airfoils. Since the airfoils boundary is given by tabulated values, the cubic spline interpolation is used to obtain an analytical equation of the upper and the lower surfaces. The comparison is made with the case of open air flow by extending the distance between the walls and the airfoil chord towards infinity.

Experimental Characterization of a Bladeless Air Compressor

Abstract The Tesla compressor is an innovative technology that offers a unique approach to fluid compression. Unlike traditional compressors that use rotating blades, bladeless compressors utilize closely spaced disks to create compression. The purpose of this article is to design a prototype Tesla air compressor with optimal design parameters and investigate the performance and loss characteristics based on numerical analysis and experimental demonstration. The prototype model has been numerically investigated at different rotational speeds, and the results have been compared with those obtained in experiments. Computational fluid dynamics (CFD) simulations indicate that the rotor-only efficiency is greater than 90% at very low mass flowrates, while the coupling of the rotor and volute leads to a total-to-static efficiency of approximately 58% (without losses) at 14 g/s. At a nominal mass flow of 4 g/s, the highest total-to-static pressure ratio would be around 1.27. Experimental results indicate leakage losses greatly reduce net mass flow, while pressure ratio values are in good agreement with CFD predictions. During this experiment, a maximum isentropic efficiency of 32.4% is measured. Indeed, the prototype included ventilation and leakage losses, which were not modeled in the CFD analysis. It is remarkable that the compressor does not show any unstable behavior down to zero mass flow (closed valve test), where the CFD and the experiment show consistent pressure ratios. An estimation of the losses from end-wall friction and leakage flow is carried out using numerical simulations at different exit radial clearances. Increasing radial clearance results in an increase in leakage and end-wall power loss, the latter being driven mainly by the axial clearance with the casing, which remained unchanged. To minimize leakage, a Teflon ring has been used as a first measure. Numerical calculations have indicated that the leakage rate is approximately 6 g/s at design speed. A brush seal-type solution can improve the sealing system to reduce leakage.

Experimental Study on Cryogenic Compressed Hydrogen Jet Flames

Cryogenic compressed hydrogen (CcH2) technology combines the advantages of high pressure and low temperature to achieve high hydrogen storage density without liquefying the hydrogen, which has broad application prospects. However, the safety concerns related to cryogenic hydrogen need to be carefully addressed beforehand. In the present work, cryogenic hydrogen jet flames are experimentally investigated for various release pressures and initial temperatures. The flame length and thermal radiation flux were measured for horizontally releasing with nozzle diameters of 0.5–2 mm, temperatures ranging from 93 to 298 K, and initial pressures of 2–10 MPa. The results show that the flame length is dependent on the nozzle diameter, stagnation pressure and temperature. At a given pressure, the flame length, size and total radiant power increase with decreasing temperature, which is attributed to the lower jet flow velocity and higher density of low-temperature hydrogen. The normalized flame length Lf/D is correlated with the pressure ratio and temperature ratio. The correlation can be used to predict the flame length at various hydrogen pressures and temperatures. The normalized flame length of the cryogenic hydrogen jet flame is greater than that of the room-temperature hydrogen jet flame. The radiative heat flux of the flame can be predicted by the mass flow rate of the jet flow.

Forced Vibration Induced by Dynamic Response Under Different Inlet Distortion Intensities

Boundary layer ingestion propulsion systems have attracted much attention due to their significant potential to reduce the fuel consumption of future commercial aircraft. However, the aeroelastic stability of the fan blade is affected by the continuous non-uniform incoming flow induced by the ingestion of the boundary layer. When the fan blades rotate in the junction area between the distorted area and the clean area, blade pressure fluctuations occur. This phenomenon triggers a dynamic response process in the blade. Previous numerical investigations explored the influence of the distorted inflow on the blade vibration amplitude, and found that there are two sources of low-order excitation to the blades: the distorted inflow and the dynamic response of the blade. The results show that the low-order excitation existing in the distorted inflow varies sinusoidally with the distortion extent. However, as a new source of excitation, the key influence mechanism of dynamic response is still unclear. To explore this issue, calculations and analyses were conducted for different distorted inflow intensities. The results show that the blade vibration amplitude increases with the rise in distortion intensity. The total pressure at the leading and trailing edge of the rotor blade was extracted for analysis. It was found that when the blade enters or leaves the distorted area, there is a consistent lag in the change in total pressure at the trailing edge compared to the leading edge. This lag leads to an abrupt variation in the total pressure ratio, which constitutes the dynamic response process of the rotor blade. This periodic change generates a second-order excitation that causes the blade to vibrate.

The Exergo-Economic and Environmental Evaluation of a Hybrid Solar–Natural Gas Power System in Kirkuk

The increasing environmental challenges posed by the widespread use of fossil fuels and the fluctuating nature of renewable energy have driven the need for more efficient and sustainable energy solutions. Current research is actively exploring hybrid energy systems as a means to address these issues. One such area of focus is the integration of Organic Rankine Cycles (ORCs) with gas and steam turbines, utilizing both natural gas (NG) and solar parabolic trough collectors (PTCs) as energy sources. This study examines the performance of a hybrid system implemented in Kirkuk, Iraq, a region known for its substantial solar radiation. Previous research has shown that hybrid systems can effectively enhance energy conversion efficiency and reduce environmental impacts, but there is still a need to assess the specific benefits of such systems in different geographical and operational contexts. The analysis reveals a thermal efficiency of 59.32% and an exergy efficiency of 57.28%. The exergoeconomic analysis highlights the optimal energy cost at USD 71.93/MWh when the compressor pressure ratio is set to 8 bar. The environmental assessment demonstrates a significant reduction in CO2/emissions, with a carbon footprint of 316.3 kg CO2/MWh at higher compressor pressure ratios. These results suggest that integrating solar energy with natural gas can substantially improve electricity generation while being both cost-effective and environmentally sustainable.

Multi-scale reservoir response characteristics of coalbed methane development through stress relief via horizontal well cavity completion in tectonically deformed coals

China’s coalbed methane (CBM) resources hold significant potential. However, the widespread presence of soft and low-permeability tectonically deformed coal (TDC) presents a challenge to the efficient development of CBM. The development of CBM through stress relief via horizontal well cavity completion (HWCC) offers a promising innovative solution to this problem. To elucidate the multi-scale reservoir response characteristics of CBM development through stress relief via HWCC in TDCs, this article comprehensively employs particle discrete element and finite element numerical simulation methods, and carries out the numerical simulation studies of cyclic seepage at the specimen scale, HWCC at the coal seam scale, and CBM development at the coal seam group scale. The main findings are summarized as follows. Unlike the stress-compression specimens, which exhibited overall failure, the differential distribution of pressure gradients within the specimens during the gas seepage experiments resulted in the development of microcracks concentrated at the bottom of the specimens. With the escalation of coal body structural damage, the permeability stress compression coefficient during the elastic deformation stage shows an increasing trend. Upon entering the plastic deformation stage, the specimen’s permeability shifts from a decreasing to an increasing trend. Increasing the lower limit pressure ratio, upper limit pressure ratio, and cycle rate of gas injection pressure could accelerate the failure efficiency of the specimens. Increasing the lower limit pressure ratio has a more pronounced effect on the TDC specimens, while increasing the upper limit pressure ratio has a more significant impact on the primary undeformed and cataclastic coal specimens. In TDCs, the phenomenon of wellbore collapse and cavity expansion becomes more pronounced. The cavity volume tends to increase with the increase in the initial well diameter, in-situ stress, and alternating bottom-hole pressure differences. The HWCC could enhances reservoir permeability and production in both the cavity completed and adjacent coal seams. For two horizontal wells with cavity completions in the same layer, excessively close well spacing is unfavorable for fostering inter-well interference and reservoir pressure drop. When the HWCC is applied to thin coal seams, the enhancement of permeability and production is limited. Reasonable optimization of drainage rates could effectively mitigate the reservoir permeability velocity-sensitive damage. The research findings extend related theories and provide a robust reference for subsequent practical engineering applications.

Predictions of windage heating and flow characteristics in a high-speed rotating seal of aero-engine

The labyrinth seal plays a crucial role within the secondary air system of an aeroengine, significantly impacting its safety and reliability. This paper presents a comprehensive evaluation of the complex windage heating phenomenon within a high-speed rotating labyrinth seal system. Employing similarity criteria and dimensional analysis, the multifactorial influences on the seal system are thoroughly characterized. A dedicated high-speed rotating labyrinth seal test rig was constructed to conduct an experimental investigation into the windage heating characteristics of a four-tooth, stepped-slanted labyrinth seal. The results demonstrate a peak windage heating of 11.8 K and windage heating coefficient of 1.14 when the inlet temperature rose from ambient to 100 °C, under the rotating Mach number of 0.418 and pressure ratio of 1.1. Conversely, as the seal clearance increased from 0.2 mm to 0.6 mm, with a rotating Mach number of 0.487 and a pressure ratio of 2.0, the windage heating coefficient decreased to 0.57. Furthermore, five dimensionless operating cases were analyzed using similarity principles to elucidate the correlation between system performance and the combined effects of strong rotating flow and windage heating characteristics. The analysis revealed that the windage heating coefficient exhibited a decreasing trend with increasing flow Reynolds number, effective pressure ratio, inlet swirl ratio, and dimensionless clearance, as the effective pressure ratio increase from 1.1 to 5.0, with the rotating Mach number of 0.624 and flowing Reynolds number of 9600, the windage heating coefficient decrease from 1.831 to 0.797, representing a 56 % reduction. Conversely, the windage heating coefficient increased with a rising rotating Mach number, while the flowing Reynolds number demonstrated a minor influence.

A high-order physical-constraints-preserving arbitrary Lagrangian–Eulerian discontinuous Galerkin scheme for one-dimensional compressible multi-material flows

In this paper, a high-order physical-constraints-preserving arbitrary Lagrangian–Eulerian (ALE) discontinuous Galerkin scheme is proposed for one-dimensional compressible multi-material flows. Our scheme couples a conservative equation related to the volume-fraction model with the Euler equations for describing the dynamics of fluid mixture. The mesh velocity in the ALE framework is obtained by using an adaptive mesh method that can automatically concentrate the mesh nodes near the regions with large gradient values and greatly reduce the numerical dissipation near material interfaces. Using this adaptive mesh, the resolution of solution near some special regions such as material interfaces can be improved effectively by our scheme. With the appropriate time step condition and using a bound-preserving and positivity-preserving limiter, our scheme can ensure the positivity of density and pressure and the boundness of volume-fraction, which further ensures the computational robustness and degree of confidence of simulations under large density or pressure ratios and so on. In general, our scheme can be applied to the simulations of compressible multi-material flows efficiently with the essentially non-oscillatory property and physical-constraints-preserving (bound-preserving and positivity-preserving) property, and its steps are more concise compared to some other methods such as the indirect ALE methods. Some examples are tested to demonstrate the accuracy, essentially non-oscillatory property and physical-constraints-preserving property of our scheme.

Role of anxiolytic medications in maintaining perioperative blood pressure in total hip arthroplasty surgeries: case-control retrospective study

Background: Elevated blood pressure (BP) measurements seen in patients having total hip arthroplasty (THA), pose a significant issue for surgeons. The study objective was to investigate the effectiveness of preoperative anxiolytic medications in the maintenance of blood pressure and reduction of total blood loss in patients undergoing THA surgeries. Methods: A retrospective case-control cohort study in a tertiary care university hospital included patients who had THA and had either primary managed hypertension or were non-hypertensive. 190 patients who underwent primary THR; 103 controls and 87 treatment group (Oral 3 mg Bromazepam). Pearson’s chi-square, independent sample t-test, paired samples t-test, and a two- way repeated measures analysis of variance (ANOVA) was utilized in the analysis. Results: Bromazepam group had a significantly lowered ratio of systolic (SBP), diastolic (DBP), and mean arterial pressure (MAP) in the morning of the surgery (P<0.05). Bromazepam also reduced the ratio of SBP and MAP in theaters before anesthesia (P<0.05). A repeated measures ANOVA showed significant treatment effects for SBP and MAP but not DBP (P<0.001 for both). SBP, DBP, and MAP showed a significant time-treatment effect (P<0.001, 0.019, and<0.001, respectively). Conclusions: Oral bromazepam (anxiolytic) aids in the regulation of blood pressure in individuals with well-managed hypertension and in healthy patients having total hip arthroplasty without apparent adverse effects related to the medication. This could potentially reduce the number of uncontrolled hypertension-related surgery delays and patients on the surgical waiting list.

On the unsteady flow dynamics of a planar-plug nozzle with a semi-extended cowl

Experiments are conducted with a planar-plug nozzle having a 50% cowl extension, operating in over-expanded nozzle pressure ratios ζ=[p0/pa]=2,3, and 4 to study the unsteady flow dynamics on the ramp surface and acoustic features of the flow on the far-field as influenced by the partial cowl extension. Steady pressure measurements and high-speed Schlieren imaging indicated that the flowfield on the ramp surface has shock-boundary layer and shock-shear layer interactions. The three-dimensional flow features on the ramp surface are studied based on oil flow visualization. A proper orthogonal decomposition based modal analysis of the Schlieren images is conducted to identify the dominant spatiotemporal characteristics. Unsteady pressure fluctuations on the ramp surface acquired simultaneously with microphone measurements are analyzed to infer the jet unsteadiness and noise source. Investigations across different ζ reveal the presence of both incipient and complete separation of the jet flow on the ramp. Moreover, the cowl extension delays the ζ at which the dominant screech and jet flapping occur.

On how finite β and three-dimensional magnetic perturbations affect the instability of toroidal ion temperature gradient mode

Abstract The effects of finite β (the ratio of plasma kinetic pressure to magnetic pressure) and three-dimensional (3D) magnetic perturbations (MPs) on the instability of toroidal ion temperature gradient (ITG) mode are studied in this work. The expression of ion magnetic drift frequency ω_di modified by the effects from both finite β and 3D MPs is firstly derived based on the local 3D equilibrium model. Then, under the assumptions of adiabatic electrons and localized mode structure around the outboard mid-plane (ϑ_p=0), the dispersion equation of the long wavelength toroidal ITG mode with considering the parallel ion dynamics is derived and solved. The results show that the distribution of ω_di around the outboard mid-plane, including both ω_(di,0)=├ ω_di ┤|_(ϑ_p=0) and ω_(di,0)^''≡├ (d^2 ω_di \/dϑ_p^2 )┤|_(ϑ_p=0) (twist parameter quantifying the degree of concave or convex of ω_di), is the key for affecting the toroidal ITG mode instability. The diamagnetic effects from finite β and the effects from 3D MPs can suppress the instability by reducing |ω_(di,0) |. Via reducing |ω_(di,0)^'' | under the prerequisite of unchanged sign of ω_(di,0)^'', there also exist stabilization effects on the instability from 3D MPs and the modification of local magnetic shear by finite β effects. In addition, the stabilization effects induced by reducing |ω_(di,0)^'' | are closely associated with the global magnetic shear. The mechanisms for the effects of finite β and 3D MPs on the instability of toroidal ITG mode revealed in this work are helpful to the comprehensive understanding of the relationship between internal kink mode induced non-axisymmetric flux surface distortion and internal transport barrier physics in tokamak plasmas.

Optimization of LPCVD Deposition Conditions of Silicon-Rich Silicon Nitride to Obtain Suitable Optical Properties for Photoluminescent Coating

Silicon nitride is a commonly used material for ceramic applications and in the fabrication processes of integrated circuits (ICs). It has also increased in interest from the scientific community for use as a functional coating due to its physical, mechanical, electrical, and optoelectronic properties. In particular, silicon-rich silicon nitride (SRSN) has been considered in the photovoltaic industry as a down-conversion film for solar cells. In this work, SRSN films have been obtained by the Low-Pressure Chemical Vapor Deposition (LPCVD) technique at low to moderate deposition temperatures with a variation in the precursor gas pressure ratio. The SRSN films showed a wide photoluminescence (PL) in the visible region (without a high-deposition temperature or annealing process) and suitable optical properties (refractive index and absorption in the UV) to be used as photoluminescent coating on silicon solar cells. The absence of high-deposition temperatures could preserve the original structure of silicon solar cells, once the SRSN layer was applied. In addition, control of the reactive gas pressure ratio and deposition temperature showed an influence on the refractive index, the surface roughness, and the PL emission.

Performance improvement of a centrifugal compressor for cogeneration

This work presents the performance improvement of a centrifugal compressor designed for cogeneration applications. The study involves modifications to geometric parameters, including impeller and diffuser configurations, to enhance pressure ratio, temperature ratio, and overall efficiency using computational fluid dynamics to verify the improvement of those parameters. The study has examined the compressor’s behaviour under surge, design, and choke conditions, showcasing improved homogeneity, reduced low-velocity zones, and an extended operating range. The compressor maps are presented to graphically observe the impact of each proposed modification, facilitating the analysis of each of these and evaluating the performance under various operating conditions. The final compressor configuration exhibits notable improvements in key performance metrics, with pressure ratio, temperature ratio, and efficiency showing increases of 1.753%, 1.640%, and 1.760%, respectively.

Comprehensive Experimental Assessment Of Unsteady Pressure And Heat Flux In A Small-Core Turbine Over-Tip Shroud

Abstract For novel high-speed small core turbines, with tip clearance below 0.5mm, even small blade-to-blade tip clearance variation is significant. The assessment of these complex flows is pertinent to the design of the next generation of small-core turbines. This manuscript provides a thorough experimental analysis of the shroud?s unsteady heat flux and static pressure in a small-core squealer-tip blade turbine. Atomic Layer Thermopile sensors and fast response pressure transducers were used to perform high-frequency acquisition at 2MHz around the 51% axial blade chord on the shroud. Measurements were taken at engine-representative conditions at several operational conditions and tip clearances. The signals were phase-locked averaged over the revolution period and synchronized to identify individual blade and row signatures. The linear relationship between the rotational tip Reynolds and the static pressure ratio across the blade tip reveals the transition point to reverse over-tip flows. Total heat flux is decomposed into different steady and unsteady heat flux contributions. It is demonstrated that the adiabatic wall temperature governs the unsteady heat flux and contributes to one third of the total surface heat flux. A linear trend was observed between the unsteady heat flux and the tip clearance measured at the pressure and suction side rims. Similar trends were observed between the local heat flux and the pressure ratio across the tip. A comparison with CFD predictions highlights some limitations on resolving the detached and secondary flows, evidencing the necessity of complementary experimental data.

Multi-Objective Optimization of a Small-Scale ORC-VCC System Using Low-GWP Refrigerants

The increasing global demand for energy-efficient cooling systems, combined with the need to reduce greenhouse gas emissions, has led to growing interest in using low-GWP (global warming potential) refrigerants. This study conducts a multi-objective optimization of a small-scale organic Rankine cycle–vapor compression cycle (ORC-VCC) system, utilizing refrigerants R1233zd, R1244yd, and R1336mzz, both individually and in combination within ORC and VCC systems. The optimization was performed for nine distinct cases, with the goals of maximizing the coefficient of performance (COP), maximizing cooling power, and minimizing the pressure ratio in the compressor to enhance efficiency, cooling capacity, and mechanical reliability. The optimization employed the Non-dominated Sorting Genetic Algorithm III (NSGA-III), a robust multi-objective optimization technique that is well-suited for exploring complex, non-linear solution spaces. This approach effectively navigated trade-offs between competing objectives and identified optimal system configurations. Using this multi-objective approach, the system achieved a COP of 0.57, a pressure ratio around 3, and a cooling capacity exceeding 33 kW under the specified boundary conditions, leading to improved mechanical reliability, system simplicity, and longevity. Additionally, the system was optimized for operation with a cooling water temperature of 25 °C, reflecting realistic conditions for contemporary cooling applications.

Research on aerodynamic performance of centrifugal compressors for hydrogen-mixed natural gas.

Natural gas-doped hydrogen transportation has been widely used in industrial engineering. The change of the physical parameters of the conveying medium affects the working performance of the centrifugal compressor. This study aims to explore the aerodynamic performance of centrifugal compressors for hydrogen mixed natural gas, including the effects of hydrogen blending ratio (HBR) and inlet temperature on the pressure ratio and isentropic efficiency of compressors. The numerical simulation method is used and the results are compared with the experimental results to determine the reliability of the numerical simulation method. The results show that the pressure ratio decreases with the increase of HBR where the inlet temperature and rotation speed are constant. The pressure ratio and efficiency of the compressor are the highest when the conveying medium is pure natural gas (HBR = 0). The maximum pressure ratio reduction is 4.8% when the HBR is 5% and the inlet temperature is increased by 20 K. In summary, when the conveying medium of the compressor changes from pure natural gas to hydrogen-mixed natural gas, the working range and efficiency of the compressor will be reduced. Therefore, it is necessary to increase the rotation speed of the compressor or redesign the centrifugal compressor for hydrogen-mixed natural gas in order to achieve a constant flow rate at the outlet of the compressor.

Comparing predictive accuracy: systolic blood pressure to left ventricular end-diastolic pressure ratio versus TIMI score for short-term mortality after primary percutaneous coronary intervention

Abstract Objective Aim of this study was to evaluate the predictive performance of systolic blood pressure (SBP) to left ventricular end-diastolic pressure (LVEDP) ratio for the prediction of in-hospital and short-term mortality in a contemporary cohort of patients with ST-segment elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PCI) at a tertiary care cardiac center. Methods This study included a consecutive series of patients diagnosed with STEMI who underwent primary PCI. The SBP/LVEDP ratio and TIMI (Thrombolysis in Myocardial Infarction) score were calculated, and their ability to predict in-hospital and short-term mortality was evaluated by analyzing the area under the curve (AUC) on the receiver operating characteristics (ROC) curve. Results This study involved 977 patients, with 780 (79.8%) being male and a mean age of 55.6±11.5 years. Among them, 191 (19.5%) had an SBP/LVEDP ≤5.4. The in-hospital mortality rate was 4.3% (42), and the short-term all-cause mortality rate after a mean follow-up of 5.9±2.4 months was 15% (140). Patients with SBP/LVEDP ≤5.4 had higher in-hospital mortality rates (14.1% vs. 1.9%; p<0.001) and short-term mortality rates (35.1% vs. 9.8%; p<0.001) compared to those with SBP/LVEDP >5.4. The AUCs of SBP/LVEDP and TIMI for predicting in-hospital mortality were 0.766 [0.681-0.851] and 0.787 [0.713-0.861], respectively. For short-term mortality, the AUCs of SBP/LVEDP and TIMI were 0.731 [0.682-0.780] and 0.736 [0.690-0.782], respectively. Conclusion In conclusion, SBP/LVEDP showed sufficiently high predictive power comparable to the TIMI risk score. SBP/LVEDP is a readily available ratio that can rapidly provide valuable prognostic information during primary PCI.operating characteristics curveComparative distribution

Prognostic impact of the tricuspid annular plane systolic excursion/pulmonary arterial systolic pressure ratio in acute pulmonary embolism

Abstract Background Currently available risk stratification models for acute pulmonary embolism (PE) include hemodynamic status, cardiac biomarkers, right ventricle (RV) dysfunction on imaging, and clinical scores. Focusing on length-tension relationship of the ventricle might have a superior predictive capability over RV dysfunction in terms of mortality and classification of patients with acute PE. In this study, our hypothesis suggests that tricuspid annular plane systolic excursion (TAPSE)/systolic pulmonary artery pressure (sPAP) ratio has superior predictive capability for in-hospital mortality in patients with acute PE compared to TAPSE or sPAP as distinct measures. Methods This single-center study comprised retrospectively evaluated 703 patients referred to our tertiary cardiovascular center with acute PE. We divided patients into quartiles by TAPSE/sPAP ratio. Different models were developed to quantify the predictive relationship between in-hospital death and echocardiographic measurements. A base model was created with variables including risk status and RV/LV ratio >1. Then, to evaluate the predictive contribution of each measurement; TAPSE/sPAP, TAPSE, and sPAP were sequentially added to the base model. After that, the performance of each model was evaluated. Results Predictive and discriminative power was the highest in model containing TAPSE/sPAP. There was still a significant inverse association between TAPSE/sPAP and risk of in-hospital death even after adjusting by risk status and RV/LV ratio >1. ROC curve analysis for TAPSE/sPAP revealed the best cut-off value as 0.34. Conclusion The outcomes of our study reveals that the ratio of TAPSE/sPAP serves as a more potent predictor of mortality than either of the two measurements taken separately. The interpretation and utilization of the TAPSE/sPAP cut-off value in acute PE can assist in identifying patients at risk of deterioration and guide the consideration of more intensive treatment options across all risk groups.