Pressure Recovery Research Articles

Investigation of Flow Control in an Ultra-Compact Serpentine Inlet with Fluidic Oscillators

For optimal aerodynamic efficiency of specific ultra-compact serpentine intake, fluid oscillators are utilized to regulate airflow. This study employs advanced numerical simulation techniques to examine the effects of various control positions, jet angles, and excitation pressures on flow control efficacy. Control position significantly impacts the flow field structure within the intake, with a lower surface jet configuration outperforming an upper surface scheme. Optimal performance is achieved with the upper and lower surface jet angles set at 20° and 25°, respectively, under an input pressure of 2.5 times the total inlet pressure. This configuration enhances the total pressure recovery coefficient and reduces the steady-state circumferential distortion index and circumferential total pressure distortion coefficient. However, the flow rate ratio coefficient is notably high. While higher excitation pressures for the fluid oscillator do not inherently exhibit greater effectiveness, careful calibration is essential to accommodate varying positions. Optimal excitation pressure is established for the upper surface, while the control effect on the lower surface improves with increasing excitation pressure. Jet angles significantly affect the fluid oscillator’s control mechanism; small-angle jets effectively add energy to the separation zone, mitigating flow separation, whereas larger jet angles introduce excessive disturbances that outweigh their benefits. Overall, smaller jet angles enhance control effectiveness.

Experimental and numerical investigation of a novel inlet for boundary layer ingesting propulsion systems

Boundary Layer Ingestion (BLI) propulsion systems have the potential to significantly enhance aircraft performance, particularly by improving fuel efficiency and reducing emissions. However, the high total pressure losses and distortions at the outlet of the BLI inlet normally restricts the development of BLI propulsion systems. This paper introduces and investigates a high-performance dual-sided BLI inlet configuration suitable for a large amount of boundary layer ingesting through a combination of computational and experimental methods. The dual-sided BLI inlet has two air entrances located at the top and bottom of the aircraft's rear fuselage, with the two ducts from the upper and lower inlets deflecting towards each other and converging at the same annular outlet. Simulation results indicate that the dual-sided BLI inlet prevents the concentration of low-energy flow observed with single-sided inlets, thereby reducing outlet distortion. Additionally, high-speed wind tunnel tests were conducted to validate the design's feasibility. The test results indicate that the dual-sided BLI inlet demonstrates good performance at the design point (Mfar=0.75, MAIP=0.50, δ/h≈45 %). The total pressure recovery coefficient σfar=0.907 and σin=0.995, the outlet total pressure distortion index DC60=0.24, and the outlet swirl intensity is minor. In conclusion, the novel BLI inlet maintains robust performance under designed conditions, fulfilling the engine's stability requirements.

Autonomic nervous system dysfunction in idiopathic REM sleep behavior disorder as a short-term risk for a synucleinopathy.

Idiopathic REM sleep behavior disorder (iRBD) is a prodromal marker of the alpha-synucleinopathies, in which autonomic nervous system (ANS) involvement may occur. We aimed to characterize the presence and severity of subjective and objective ANS dysfunction in iRBD and assess its capacity to predict short-term clinical progression to a synucleinopathy. Prospective study of patients with polysomnography-confirmed iRBD in whom symptomatic ANS involvement was assessed using the Composite Autonomic Symptom Score (COMPASS-31) and objective dysfunction with the Composite Autonomic Severity Score (CASS). Baseline ANS data were compared between those who later developed a synucleinopathy and those who did not. We evaluated 25 subjects with iRBD without risk factors for autonomic neuropathy and at least 6months of follow-up (mean: 19months). At the end of the study, seven (28%) patients developed a synucleinopathy, namely Parkinson's disease (n = 5) and dementia with Lewy bodies (n = 2). 73.7% of patients had COMPASS-31 scores above the normal cut-off, while no score differences regarding phenoconversion status were observed. At baseline, 85.7% of the subjects who phenoconverted exhibited at least one abnormal result in the CASS score, compared to 38.9% of subjects who remained disease-free (p = 0.035). Adrenergic dysfunction evaluated by an impaired overshoot in Valsalva phase IV and by pressure recovery time was associated with the development of overt synucleinopathy (p = 0.032 and 0.033, respectively). Symptomatic and subclinical ANS dysfunctions are common in iRBD. ANS dysfunction affecting mainly the adrenergic system seems to be a short-term risk for the development of a synucleinopathy.

Analysis of geometrical parameter sensitivity and mechanism of flow loss in exhaust volute based on particle swarm optimization

To investigated the mechanism of flow loss occurs in gas-turbine exhaust volute, comprehensive analysis was conducted based on the traces of parametric optimizations. An original volute was parameterized by depicting the core-part with 6 parameters. Concerning the coefficients of total pressure loss and static pressure recovery, the volute was optimized, as a start of the investigation, by Particle Swarm Optimization (PSO) to generate 56 exhaust volute designs and 8 geometric parameter traces. The geometry evolution history was fully recorded by these traces during the optimization. Based on this, parameter sensitivity analyses were conducted by single, double and K-means-clustering-based comprehensive parameters. Furthermore, partial dependence plot (PDP) and individual conditional expectation plot (ICEP) were applied to enhance the expression of parameter sensitivity. This enables the detailed discussion of the mechanisms of flow loss occurs in exhaust volute. The results demonstrate that the Particle Swarm Optimization (PSO) algorithm is highly effective for optimizing the exhaust volute. After six rounds of optimization with eight particles per round, the total pressure loss coefficient at the exhaust volute outlet was reduced by 35%, while the static pressure recovery coefficient increased by 79%. The sensitivity analysis reveals that geometric parameters exhibit varying degrees of influence on aerodynamic performance, with diffuser length being the most critical factor. Notably, a shorter diffuser, constrained by the same external dimensions, tends to result in lower flow losses. Flow loss within the collector accounts for 71.7% of the total loss, which can be attributed to surface friction and turbulent dissipation. The latter is primarily driven by turbulent viscous dissipation, predominantly occurring in the collector section. Additionally, the size of large-scale vortices in the curved parts of the diffuser and collector, which contribute to turbulent dissipation, as well as the ratio of the average flow velocity to circulation speed in the collector, which affects wall friction, are key factors in flow loss generation.

Flow field reconstruction of compressor blade cascade based on deep learning methods

In the design process of compressors, calculating the S1 flow surface involves solving the Navier-Stokes equations, which results in slow convergence and makes determining cascade characteristics time-consuming. However, deep learning offers significant advantages in flow field reconstruction by not only automatically extracting complex flow features and reducing prediction time but also providing high accuracy in reconstruction. This paper implements the rapid reconstruction of the compressor S1 flow surface cascade flow field using two deep learning models: U-Net and 1D-CNN. Using a double-circular arc airfoil as an example, we selected four key design parameters that define the geometry and position of the airfoil, ultimately designing 5,292 sets of cascade geometries. By performing batch meshing and CFD simulations, we built a cascade flow field dataset. The U-Net neural network uses design parameters as input and outputs the aerodynamic distribution of the cascade flow field. After training, it can directly predict the flow field based on the design parameters. Since the U-Net model cannot directly obtain the aerodynamic parameter distribution and flow field aerodynamic coefficients on the airfoil surface, a 1D-CNN model is used as a complementary approach. The 1D-CNN model takes the design parameters as input and outputs the aerodynamic parameter distribution on the airfoil surface and the flow field aerodynamic coefficients. The prediction results show that the U-Net model achieves an average relative error of less than 1% in cascade flow field reconstruction, while the 1D-CNN model achieves an average relative error of less than 1% in predicting the pressure recovery coefficient and less than 2% in predicting the total pressure loss coefficient. This study presents a method for the rapid reconstruction of compressor blade cascade flow fields, which helps improve design efficiency and shorten the design cycle.

Segregating Laterals for Efficient Gas Re-Injection in Shale Plays Using Smart Completion

There is a strong global demand for oil and gas resources, and forecasts indicate robust growth in oil demand in the coming years. Meeting this demand necessitates the exploitation of unconventional resources and enhancing the recovery of existing oil and gas fields. Field trials indicate that traditional gas injection in shale wells has low sweeping efficiency. Emerging technologies play an exceedingly significant role in solving the challenges of gas EOR in shale and tight formations. Among these advancements, smart or intelligent well technology has emerged as a promising solution to enhance field development outcomes. This study focuses on improving gas flooding efficiency in the Bakken formation by utilizing smart completions to reduce the gas–oil ratio (GOR) and increase oil recovery. An economic assessment of gas re-injection is conducted, considering both gas storage and enhanced oil recovery, with analysis incorporating capital expenditures, operating costs, and revenue from increased production. Reservoir simulations were employed to determine the most effective gas injection scenarios for maximizing recovery and storage efficiency. Simulation results demonstrate that 20% of perforated laterals account for 80% of the injected gas. To address this challenge, this work proposes using smart completions to segregate lateral sections, thereby optimizing gas injection efficiency, and unlocking additional oil in tight formations. Segregating horizontal laterals for gas re-injection using smart completion technology can achieve gas injection efficiencies of up to 0.25 barrels per Mcf of gas injected, with lower incremental gas production. The optimal injection rate is between 1 MMcfd and 3 MMcfd, with an injection period ranging from one to three years. It was also found that injecting gas into the toe section results in high bottom hole pressure but lower oil recovery due to reduced gas injection efficiency. From an economic perspective, the project yielded favorable outcomes, with a positive net present value (NPV) at a 7% discount rate. Even at lower oil prices (USD 50 per barrel), the Internal Rate of Return (IRR) was calculated to be 170%, indicating strong potential profitability.

Numerical study on the performance of a new integrated afterburner under a wide range of bypass ratio conditions

To improve the performance of the afterburner under a wide range of bypass ratio conditions, a new afterburner integrated with a mixer and a strut flameholder was proposed in this paper. The dry and thermal-state performance of the afterburner under different bypass ratio conditions were studied through numerical simulation with RANS CFD. The results showed that the mixing forms changed as bypass ratio increased. The integrated afterburner primarily achieved mixing by forming a recirculation region at the wake of the strut flameholder. As the bypass ratio increased, more vortices shed at the wake of the strut, increasing turbulent kinetic energy in the downstream area. This enhanced mixing between the inner and bypass gas flows, improved the thermal mixing performance, and increased total pressure loss. In the range of bypass ratio from 0.1 to 0.9, the mixing performance of the afterburner and total pressure loss both gradually increased with the increase of bypass ratio. When the bypass ratio was 0.55, the total pressure recovery coefficient was still more than 0.90, and the mixing performance reached 0.94. Following the rise in bypass ratio, the air from the mixer outlet in the integrated afterburner increased the oxygen content at the end of the strut, in the inclined cavity, near the center cone, and in the area of the wall flameholder, allowing more fuel to participate in combustion and thus improving combustion efficiency. When the bypass ratio was 0.50, the combustion efficiency was up to 0.954. However, as the bypass ratio continued to increase, the cold air from the mixer outlet impacted the pilot flame at the wake of the strut flameholder, reducing the degree of combustion reaction in the region and reducing the combustion efficiency.

Cutaneous phosphorylated-synuclein: an early diagnostic biomarker for pure autonomic failure

BackgroundPure autonomic failure (PAF) presents with progressive autonomic failure without other neurological features. Atypical presentations may lead to diagnostic uncertainty. We studied whether cutaneous phosphorylated-alpha-synuclein (p-syn) could distinguish between PAF,...

A Comprehensive Systematic Review of CO2 Reduction Technologies in China’s Iron and Steel Industry: Advancing Towards Carbon Neutrality

The iron and steel industry, a major energy consumer, faces significant pressure to reduce CO2 emissions. As the world’s largest steel producer, China must prioritize this sector to meet its carbon neutrality goals. This study provides a comprehensive review of various carbon reduction technologies to drive decarbonization in the steel industry. China’s iron and steel sector, which accounted for approximately 15% of the country’s total CO2 emissions in 2022, predominantly relies on coke and coal combustion. This study provides a comprehensive review of a variety of carbon reduction technologies to advance decarbonization in the iron and steel industry. This study categorizes carbon reduction technologies in the steel sector into low-carbon, zero-carbon, and negative-carbon technologies. Low-carbon technologies, which are the most widely implemented, are further divided into energy structure adjustment, material structure adjustment, energy efficiency improvement technologies, etc. This study specifically reviews dry quenching technology, high-scale pellet technology for blast furnace, and top pressure recovery turbine power generation technology. As a zero-carbon technology, hydrometallurgy is a central focus of this study and a key area of research within China’s iron and steel industry. While negative-carbon technologies are primarily centered around carbon capture, utilization technologies are still in early stages. By presenting the latest advancements, this study offers valuable insights and guidance to facilitate the iron and steel industry’s transition to a low-carbon future, crucial for mitigating global climate change.

Determining optimal pretreatment in cardiac surgery: an experimental study.

Heart failure patients with reduced ejection fraction are currently treated with four drug combinations: angiotensin receptor/neprilysin inhibitors, beta-blockers, mineralocorticoid receptor antagonists, and sodium-glucose cotransporter 2 inhibitors, resulting in improved survival outcomes. Herein, we examined whether myocardial protection by esaxerenone or sacubitril/valsartan may present a counter-effect to the harm caused by cardioplegic arrest. Male Wistar rats fed a normal diet were orally administered esaxerenone (3mg/kg; Esax) or sacubitril/valsartan (68mg/kg; SaV) once a day for 2weeks from 6weeks of age. Age-matched, untreated male Wistar rats served as controls (Control). Isolated rat hearts were aerobically Langendorff-perfused and subjected to 2min of St Thomas' Hospital 2 cardioplegia (STH2) infusion and 28min of normothermic global ischemia followed by 60min of reperfusion. The recovery of function was measured during 60min of reperfusion. Additionally, troponin T levels were measured after reperfusion as myocardial injury. The final recovery of left ventricular developed pressure (presented as the percentage of preischemic value) in the Control, Esax, and SaV groups was 50.7 ± 6.2%, 68.5 ± 7.4%*, and 69.3 ± 14.3%*, respectively (*p < 0.05 vs. Control). Troponin T (ng per gram wet weight) levels in the Control, Esax, and SaV groups were 166.8 ± 78.1, 77.0 ± 14.6*, and 74.2 ± 36.6*, respectively (*p < 0.05 vs. Control). Oral administration of esaxerenone or sacubitril/valsartan to rats 2weeks prior to surgery enhanced the myocardial protection afforded by STH2 and may attenuate the myocardial injury caused by hyperkalemic cardioplegic arrest.

Efficacy of compound sodium acetate Ringer’s solution in early fluid resuscitation for children with septic shock: a preliminary retrospective cohort study

BackgroundThe effectiveness of acetated Ringer’s solution in pediatric shock has received little attention. This study aimed to assess the clinical outcomes of using compound sodium acetate Ringer’s solution (AR) for fluid resuscitation in children with septic shock.MethodsWe retrospectively analyzed the clinical data of children with septic shock admitted to the pediatric intensive care unit of the Affiliated Hospital of Southwest Medical University from December 2019 to January 2023. Based on the resuscitation fluid administered, the participants were categorized into the compound AR and normal saline (NS) groups. We compared blood circulation conditions, internal environment parameters (arterial blood pH, lactic acid, serum sodium, chloride, calcium, magnesium, potassium, and blood glucose), and 28-day clinical outcomes between the two groups.ResultsThis study included 40 children, with 13 and 27 in the compound AR and NS groups, respectively. The two groups showed no significant differences in sex, age, body weight, body mass index, primary inflammation level, or Pediatric Sequential Organ Failure Assessment on admission. Similarly, no significant difference was observed in resuscitation fluid volume administered during the first hour (compound AR group: 250.00 mL [100.00, 390.00]; NS group: 250.00 mL [100.00, 500.00]). The total amount of crystalloid and colloid fluids administered within 24 h, vasoactive drug use, and blood pressure recovery post-resuscitation did not significantly differ between the groups. However, at 6 h post-resuscitation, the compound AR had considerably lower lactate level than the NS group (1.12 vs. 2.20 mmol/L). There were no significant differences in arterial blood pH, serum sodium, chloride, calcium, magnesium, potassium, and blood glucose levels between the groups. After treatment, in the compound AR group, 3 patients died, 2 improved, and 8 were cured. In the NS group, 7 patients died, 8 improved, and 12 were cured. The 28-day treatment outcomes (mortality rate, improvement rate, cure rate, or side effects) showed no significant differences between the groups.ConclusionsCompound AR was as effective as NS as a resuscitation fluid in pediatric septic shock, demonstrating similar intravascular volume restoration and hemodynamic stability maintenance. However, it caused a faster decline in arterial lactate levels without obvious side effects.

Multi‐Scenario Applications of Multi‐Dimensional Yarn‐Based Wearable Integrated Sensors

Abstract1D yarn sensors, crucial for smart textiles, face challenges in achieving diverse functionalities, multiple applications, and durability in harsh environments. Herein, a simple strategy is proposed to prepare reduced graphene oxide‐polyimide yarns (rGO‐PYs), constructing functional and multi‐dimensional sensors for multi‐scenario applications. rGO‐PYs can detect multiple mechanical stimuli, and exhibit a broad bending and pressure response range (0°–180° and 0.12–62.39 KPa), quick response and recovery time (both &lt;100 ms), and excellent cyclic stability. It features real‐time monitoring of human activities, such as joint movements, speech, writing, respiratory, pulse, and heart rate. rGO‐PYs exhibit a remarkable resilience to harsh environments, whether in liquid nitrogen (−196 °C), high temperature (300 °C), acid, or base. Crucially, expanded into an integrated 2D fabric, rGO‐PYs maintain their exceptional multi‐dimensional sensing. The point contact pressure sensor (PCPS) and pressure sensing array showed remarkable sensing performance in identifying pressure and its distribution. This work establishes a comprehensive system from preparation to application, encompassing 1D yarns large‐scale fabrication, functional sensing validation, integration into multi‐dimensional sensors, and diverse cross‐scenario applications. The innovative system would transform traditional yarns into intelligent fabrics, further advancing functional yarns into multi‐dimensional sensors (1D to 2D and 3D), enabling their diverse multi‐scenario applications.

Isolator shape transition impact on hypersonic internal waverider intake flow distortion

This paper examines the impact of scramjet isolator shape transition on hypersonic internal waverider (IWR) intake. The IWR intake is designed using the osculating axisymmetric flows and streamline-tracing methods. The new Internal Conical Flow “M” basic flowfield is utilized to provide the flow information for the design method. The intake is equipped with three isolators: one with a constant cross section and two with variable cross sections with circular and rectangular exits. The entrance shape and area of the three isolators are fixed to the intake throat shape and area. The exit area of the three isolators is maintained as the entrance one. Numerical computations of three-dimensional configurations reveal that the isolators with variable cross section shapes demonstrate a higher uniformity index than those with constant cross section shape. Thus, the isolator shape transition has decreased the flow distortion of the hypersonic IWR intake system. The three isolators exhibit varied wall pressure distribution depending on the isolator cross section shape, and the total pressure recovery ratios at the three isolators' exit planes are similar. The wall pressure distributions and key performance parameters at the intake throat section, including total pressure recovery, compression ratio, and Mach number, remained consistent across the first part of the intakes. Therefore, changing the cross section shape of the isolator while keeping the area constant could enhance the flow uniformity of compressed air without negatively impacting the intake system's performance. This allows a separate shape selection of the IWR intake throat and the scramjet combustor entrance to fulfill their special requirements.

Aerodynamic study of a bifurcated turboprop engine inlet with a propeller for flow at ground suction conditions

An advanced turboprop inlet with a bypass duct plays a crucial role in preventing foreign object damage and ensuring a high-quality airflow to the engine. However, it also introduces an increased flow complexity and design challenge due to the interaction between the propeller and the bifurcated ducts. To address these issues, a combined experimental and computational fluid dynamics (CFD) study was conducted on the aerodynamic performance and flowfield characteristics of a turboprop inlet equipped with a bypass duct considering the propeller interference. A ground suction test bench was utilized for generating the working conditions and the performance was measured by using total pressure rakes and pressure scanners. It is found that the rotational propeller on the one hand does work on and thus increases the total pressure recovery of the inlet, however, on the other hand causes a turning effect on the inlet flowfield structure along the direction of rotation and increases total pressure and swirling flow distortions in the engine duct. Besides, the engine duct and the bypass duct interact with each other. The combined influence of suction effect and the profile induction of the inlet leads to the majority of the shed vortices being drawn into the engine duct. Lastly, the presence of deflectors installed in the engine duct is found to effectively mitigate the secondary flow, thereby reducing the swirl distortion within the engine duct. This study may provide a significant reference to the design and optimization of advanced turboprop inlets with bypass ducts.

The Influence of a Divergent Slot on the Near-Wake Region of a Circular Cylinder

Controlling flow around a circular cylinder is essential for reducing drag, alleviating lift fluctuations, and enhancing aerodynamic efficiency in various engineering applications. In the present work, the effect of localized passive air-jet injection at different azimuthal angles on the near-wake region of circular cylinder was numerically investigated at subcritical Reynolds numbers Re = 3900 and 20000 using ANSYS-FLUENT commercial software. The slot angle was varied from 70o to 130o with an increment of 10o. To insure the reliability of the current numerical model, the simulation results were validated with available experimental and numerical literature. The results revealed that the slot can significantly affect the flow structure in the near-wake region and pressure distribution around the cylinder at slot angles 100o ≤ θs ≤ 130o. It was found that the optimum slot angle was 130o at which a good pressure recovery on the rear surface of the cylinder was achieved. Moreover, turbulent kinetic energy in the very near-wake region showed a substantial decrease of 40% compared to the BL case at lower tested Reynolds number, as well as an 11% reduction in the extent of the recirculation region. The drag analysis showed that the drag can be reduced by 26% when the slot inclined at 130o. It can be concluded that the position of the slot induced jet plays a vital role on the flow structure, pressure distribution, and drag coefficient. Additional experimental studies are required to further explore the impact of the slot on the wake region. Specifically, investigating the combined effect of 70° and 130° slot angles could provide deeper insights, potentially leading to a more significant influence on the wake region

Distortion Control in Intakes Subject to Strong Crosswinds Using Steady Vortex Generator Jets

Flow separation over the intake lip often occurs in gas turbine engines at off-design conditions such as crosswinds. The distortion transferred to the fan face detrimentally impacts the engine performance. The current study explores the efficacy of steady vortex generator jets (VGJ) to alleviate this flow distortion using high-fidelity implicit large-eddy simulations on a quasi-3D intake. The study reveals that VGJs, strategically placed on the windward side of the intake, induce coherent structures that include cylindrical jet shear layers, horseshoe vortices, and counter-rotating vortex pairs similar to transverse jets in crossflow. Parametric studies are carried out to identify the optimal VGJ location and blowing ratios. Superior flow control is achieved when the VGJs are placed on the windward side closer to the leading edge, reducing the distortion coefficient by ≈17% compared to the uncontrolled case. In contrast, when the VGJs are placed farther from the leading edge, the flow relaminarizes and the coherent structures decay rapidly due to severe acceleration over the intake lip. Consistent with experiments, our computations at higher blowing ratios (VR1.5 and VR2) show an improved pressure recovery decreasing the distortion coefficient by ≈40% due to deeper jet penetration and enhanced mixing.

Analysis of the effects of combined suction on hypersonic inlet starting performance

Abstract Taking a two-dimensional inlet (Case 1) as the original inlet, the combined suction schemes are designed and their influences on the self-starting ability of the inlet are studied. The flow fields at the design point and the self-starting progress of the inlets are calculated by the numerical simulation method. The results show that the three-slot combination scheme (Case 2) leads to the reduction of the mass flow rate of the throat at the design point by 1.15% and the increase of the total pressure recovery coefficient by 6.73%. The self-starting Mach number of the inlet decreases from 4.6 to 3.2, which indicates that the self-starting ability is improved significantly by the three-slot combination scheme. In order to illustrate the role of each slot in improving the self-starting ability, three two-slot combination schemes, which are called Case 3, Case 4, and Case 5, are set up by closing Slot 1, Slot 2, and Slot 3 in turn and their self-starting processes are simulated. The results indicate that the self-starting Mach numbers of Case 3, Case 4, and Case 5 are 3.6, 4.1, and 4.5 respectively, which are 0.4, 0.9, and 1.3 higher than that of Case 2 respectively. Slot 3 has the greatest influence on the self-starting ability. When the incoming Mach number rises to 4.2, a closed separation zone is induced between Slot 2 and the throat by the reflected shock wave on the cowl side of Case 5. Due to the lack of lip overflow, which is an important flow regulation mechanism, the separation zone has a strong self-sustaining ability, and the inlet keeps unstart until the incoming Mach number rises to 4.5. In addition, in the absence of Slot 1 or Slot 2, the large-scale separation zone will not disappear until the incoming flow pressure increases to a certain value.

Impact of sex-specific thresholds for low flow in assessment of prognosis in concordantly and discordantly graded aortic valve stenosis.

Sex-specific low flow was recently defined as stroke volume index (SVi) ≤40 ml/m² in men and ≤32 ml/m² in women. We tested the prognostic association of these cut-offs in patients with aortic stenosis (AS) with concordantly and discordantly graded AS (CGASEL and DGASEL) based on pressure recovery adjusted aortic valve area (energy loss, EL). Data from 1351 patients with asymptomatic AS, peak jet velocity <4m/s and preserved left ventricular ejection fraction enrolled in the Simvastatin and Ezetimibe in AS study was used. DGASEL was defined as EL <1.0 cm² with mean aortic gradient <40 mmHg, and CGASEL as EL ≥1.0 cm² with mean aortic gradient <40mmHg. Patients were further grouped into normal and low flow. Outcome was combined all-cause death and hospitalization for heart failure. CGASEL with normal/low flow was present in 915/253 patients, and DGASEL with normal/low flow in 57/126 patients. During median 4.3 years follow-up, event-free survival was lower in patients with DGASEL irrespective of flow compared to CGASEL with normal flow (p<0.05). In Cox regression analysis, DGASEL with normal or low flow were both associated with increased risk of all-cause death and hospitalization for heart failure after adjustment for age, sex, heart rate, randomized study treatment, hypertension, aortic valve replacement and aortic valve calcification (p<0.05). No survival difference was found between patients with normal vs. low flow within groups of DGASEL or CGASEL. Identification of low flow by the proposed sex-specific thresholds of SVi needs more prognostic validation before application in clinical practice.

Insights from the assessment of anatomic valve orifice area after transcatheter aortic valve implantation using transesophageal echocardiography

Abstract Background Although transthoracic echocardiography (TTE) is the gold standard for evaluating effective valve orifice area (EOA) after transcatheter aortic valve implantation (TAVI), the continuous formula is inherently different from anatomic valve orifice area because it implies a minimum jet width through the aortic valve. It has also been reported that the doppler method with TTE overestimates the mean gradient due to pressure recovery and is even less accurate after TAVI. On the other hand, recent technological developments have improved image resolution, making valve morphology possible using transesophageal echocardiography (TEE). Purpose The purpose of this study was to compare transcatheter aortic valve (TAV) area using TEE and TTE to evaluate whether there is a significant difference in each area and to explore factors that influence the difference in area. Methods Patients who underwent TEE-guided TAVI and SAPIEN3 implantation between February 2019 and March 2023 and had aortic valve evaluation with TTE before discharge were included. We retrospectively evaluated the TAV after TAVI using TTE and TEE. Aortic valve orifice area was calculated by two methods: EOA index (doppler-area: DA) calculated by the continuous doppler formula using TTE and t-AVA index (trace-area: TA) derived by the trace method using TEE. TAV tracing was performed in early systole on the short-axis image of the aortic valve. The TAV tracing was performed by physicians specializing in echocardiography, and multiple physicians were blinded to the same case to eliminate inter-rater error. The percentage change between the two groups was calculated from the difference in area by TTE and TEE, and the 75th percentile of the percentage change was defined as the cutoff value for the group with the large difference in TAV area. Results Patients whose TAV was difficult to observe by TEE were excluded, and 464 patients were finally analyzed. TA was significantly larger than DA (1.56±0.28 cm2/m2 vs 1.18±0.26 cm2, p&amp;lt;0.001) and similar for all TAV sizes. However, even though TA expanded as valve size increased, the largest area of DA was observed in the 26mm TAV, and the 29mm TAV was comparable to the 26mm TAV. Only a weak correlation was shown between DA and TA (correlation coefficient: 0.356). There were 43 cases of moderate prosthetic valve-patient mismatch (PPM: EOA-i&amp;lt;0.85cm) in DA, but only 1 case in TA. In multivariate logistic regression analysis, women (OR 2.25, 95% CI 1.17-4.34, p &amp;lt; 0.015) and LV mass index (OR 1.01, 95% CI 1.00-1.02, p &amp;lt; 0.041) were independent factors for the large difference in TAV area. Conclusion After TAVI, the TAV area with TEE was larger than the EOA-i with TTE, and PPM was rarely seen. Depending on valve size, patient background, and cardiac morphology, there are cases of overestimation of postoperative AS in TTE, which may need to be carefully evaluated in women and patients with larger LV mass index.

Use of esketamine for tracheoscopic drug injection: a randomized controlled trial.

Sufentanil may induce hypotensive bradycardia and other adverse reactions in elderly patients during anesthesia, while esketamine exhibits sedative and analgesic effects with minimal impact on respiration and circulation. The objective of this study was to investigate the impact of these two anesthetics on vital signs in patients undergoing bronchoscopy and lavage under general anesthesia. This study was a randomized controlled trial with a parallel design. A total of 100 patients aged ≥60 years with ASAI or II who were undergoing bronchoscopy and lavage were randomly assigned to two groups: group A (esketamine, n = 50) and group B (sufentanil, n = 50). During anesthesia induction, both groups received intravenous infusion of propofol at a dose of 1.5 mL/kg and atracurium. In group A, esketamine at a dose of 0.3 mg/kg was injected; in group B, sufentanil at a dose of 0.2 μg/kg was injected intravenously. Subsequently, a laryngeal mask was inserted and connected to an anesthesia machine for mechanical ventilation. Anesthesia maintenance involved continuous intravenous infusion of propofol at a dose of 3 mL/kg. The mean arterial pressure (MAP), heart rate (HR), and blood oxygen saturation (SpO2) were recorded at various time points: before anesthesia injection (T0), after laryngeal mask insertion (T1), 5 min after the operation started (T2), 15 min after the operation started (T3), and before the end of the operation (T4). Additionally, the recovery time was recorded. The blood pressure of patients in the esketamine group exhibited higher levels compared to those in the sufentanil group at multiple time points during the operation, while maintaining a more stable intraoperative blood pressure and shorter postoperative recovery time than that observed in the sufentanil group. The blood pressure and heart rate of patients in the esketamine group exhibited significant fluctuations after laryngeal mask implantation compared to pre-anesthesia induction, with a statistically significant increase observed. Conversely, no significant changes were observed in the sufentanil group. The heart rate and oxygen saturation showed no significant differences between the two groups, nor did the amount of propofol administered during the procedure. The utilization of esketamine during the induction phase of bronchoscopy and lavage under general anesthesia can enhance hemodynamic stability and reduce the occurrence of hypotension, thereby facilitating postoperative anesthetic recovery.