Fluid Body Research Articles

Numerical analysis of the effect of tunnel hydrofoil - stern flap on the motion stability of a double M-craft in regular waves

Abstract The double M-craft is a new type of high-performance multi-hull vessel that combines the gliding characteristics of a planing boat with the resistance-reducing characteristics of a hovercraft. But it also suffers from motion instability in regular waves. At present, there is scarce study on the effect of appendage on the motion stability of double M-craft in regular waves. By using the software STAR-CCM+ to numerically simulate the pitching and heaving motions of a double M-craft installed with tunnel hydrofoils and stern flaps in regular waves. Based on the overset mesh technology, the volume of fluid (VOF) method is used to capture the water-gas two-phase flow field. The 2-degree of freedom (2-DOF) motion of the rigid body is simulated by dynamic fluid body Interaction (DFBI). After investigating the effects of these combined appendages on the hydrodynamic performance, running attitude, and motion response of a double M-craft in regular waves, the optimal mounting parameters of the combined appendage have been obtained. The results have shown that all nine types of combined appendages can reduce the heave and pitch. The optimal combined appendage installation parameters include a hydrofoil longitudinal mounting position of 1/8L, angle of attack of 3°, stern flap length of 1.5%L, and flap angle of 5°, which can effectively reduce the pitching response by about 8% and reduce the swaying response by about 2.6%, and enhance its longitudinal motion stability.

C-Reactive Protein-to-Serum Chloride Ratio: A Novel Marker of All-Cause Mortality in Maintenance Haemodialysis Patients

Background and Objectives: hypochloremia is an emerging risk factor for mortality in patients with chronic kidney disease. The pathophysiological mechanisms of this finding are not very clear. Some studies suggest the influence of inflammation as a synergistic factor, so we set out to analyse the association of a novel C-reactive protein-to-serum chloride ratio (CRP/Cl−) with the prognosis of maintenance haemodialysis patients and to assess its relationship with fluid status and body composition measured by bioimpedance. Materials and Methods: the present work is a retrospective cohort study of maintenance haemodialysis patients from our chronic outpatient haemodialysis programme between 1 January 2022 and 31 December 2022. (n = 281). Survival time was collected for all patients and analysed using the Kaplan–Meier method. A Cox proportional hazards regression model was used to evaluate survival probabilities. Variables included in the model were selected using a stepwise selection procedure based on the corrected Akaike information criterion (AICc), which balances model fit and complexity. Results: during a median follow-up of 306 days, 34 patients died. Patients in the fourth quartile of the CRP/Cl− (>0.118 mg/mEq) had higher overall mortality (log-rank test, p = 0.0011). In the Cox multivariate analysis, the variables significantly associated with higher mortality were higher modified Charlson index (MCI), lower body surface area (BSA), lower interdialytic weight gain (IDWG), and higher CRP/Cl− ratio. The latter variable was independently associated with higher overall mortality (adjusted hazard ratio = 1.027; 95% confidence interval [CI], 1.000–1.055 p = 0.0469). Conclusions: Higher CRP/Cl− ratio values were associated with higher all-cause mortality in our maintenance haemodialysis patients.

Barriers to Cardiac Rehabilitation Enrollment and Secondary Prevention Adherence in Patients with Coronary Heart Disease Following Percutaneous Coronary Intervention: A Cross-sectional Survey.

This study aimed to evaluate adherence to secondary prevention measures and to identify barriers to cardiac rehabilitation enrolment among patients with coronary heart disease after percutaneous coronary intervention. An observational cross-sectional survey was conducted through computer-assisted telephone interviews to assess recently treated percutaneous coronary intervention patients at the Prince Sultan Cardiac Center in Saudi Arabia. Out of 104 surveyed patients with coronary heart disease, 85 (82%) were male, with an average age of 59.5 years. The obesity rate was 28% (n = 29), with a high prevalence of comorbidities: 82 (79%), 63 (61%), and 62 (60%) patients had hyperlipidemia, diabetes, and hypertension, respectively. Despite high medication compliance (97%), adherence to secondary prevention measures was low (21%). Adherence to physical exercise and weight monitoring for fluid body build-up was notably poor at 35% and 9%, respectively. Only 11 (10.6%) patients were referred for cardiac rehabilitation, of whom only four (36.4%) attended. Significant barriers such as a lack of staff contact, insufficient physician support, and distance to cardiac rehabilitation facilities were particularly noted by 69% of rural patients. This study underscores the significant cardiac risk factors and low adherence to secondary prevention measures among post revascularization patients with coronary heart disease in Saudi Arabia. Low referral and other organizational barriers, as well as the travel distance to hospital-based cardiac rehabilitation, hinder program enrolment. To improve cardiac rehabilitation accessibility, it is crucial to revise the discharge plans, implement automated referral systems, expand the services across all regions, and utilize alternative delivery models.

The utility of disc space and vertebral body specimens cell count differential for the diagnosis of native vertebral osteomyelitis: a prospective cohort study.

Diagnostic methods for native vertebral osteomyelitis (NVO) often yield inconclusive results. Image-guided spine biopsies for culture are specific but diagnose NVO in only 50% of cases. Pre-exposure to antimicrobials further reduces diagnostic yield. Our study assesses the value of neutrophil percentage in disc space fluid and vertebral body (DS/VB) samples for diagnosing NVO. Adults referred for spine biopsy at Mayo Clinic from August 2022 to September 2023 were consented and enrolled at the time of biopsy. Following routine specimen collection, the biopsy needle was rinsed in saline into an EDTA tube for cell analysis. NVO diagnosis required organism identification in spine tissue or blood and/or positive histopathology, and consistent symptoms and imaging. Sixty-eight patients were prospectively enrolled, comprising 14 with NVO and 54 with alternative diagnoses. The median biopsy sample polymorphonuclear (PMN) percentage for NVO patients was 80.5% (IQR 72.5-85.2), compared to 64.5% (IQR 54.0-69.0) for those without NVO (p < 0.001). Nine (64.3%) NVO patients received antibiotics within 10 days prior to spine biopsy. As a continuous measure, PMN differential showed a moderately strong ability in classifying NVO status with an area under ROC curve of 0.795; an optimal point on the curve of 71.5% corresponded to a sensitivity of 78.6%, specificity of 79.6%, negative predictive value of 93.5% and positive predictive value of 50.0%. PMN differential in DS/VB biopsies may serve as an effective diagnostic tool in the evaluation of patients with NVO particularly in ambiguous cases with an initially negative spine biopsy. Future efforts will aim to implement these findings within routine clinical practice.

Bioelectrical Impedance Analysis (BIA) detects body resistance increase in dogs undergoing blood donation.

Using raw parameters of bioelectrical impedance analysis (BIA) and derived Phase Angle (PhA) has emerged as an alternative to conventional predictive BIA for body fluid volumes and body composition estimation in human patients, offering an approach independent of predictive equations. Classic predictive equation-based BIA remains unsuitable for veterinary clinical practice due to the high morphological variability within the canine species. This study aimed to validate the feasibility of BIA in dogs and assess its utility in detecting changes in body fluid volumes, particularly in blood donation. Sixty healthy blood donor dogs and ten controls were longitudinally assessed using BIA raw parameters with a portable analyzer at a 50kHz frequency. Measurements were performed before and after blood donation in donor dogs, whereas in controls, they were carried out at two time points, approximating the timing of a donation. Significant increases in raw bioelectrical parameters were observed after blood donation in the donor group, while differences were not statistically significant in controls. Hematocrit values did not significantly differ between the two time points in both groups. These findings suggest the feasibility of using BIA to detect changes in body fluid volumes in dogs undergoing blood donation, highlighting its potential application in veterinary medicine. Further research should explore the applicability of BIA in spontaneous pathological conditions involving fluid loss or retention and investigate the potential utility of PhA as a prognostic or monitoring tool in veterinary clinical practice. This study provides valuable insights into using BIA in canine medicine, paving the way for enhanced diagnostic and monitoring strategies in clinical practice.

Myxedema in Both Hyperthyroidism and Hypothyroidism: A Hormetic Response?

Myxedema is a potentially life-threatening condition typically observed in severe hypothyroidism. However, localized or diffuse myxedema is also observed in hyperthyroidism. The exact cause and mechanism of this paradoxical situation is not clear. We report here the analysis of body fluid distribution by bioelectrical impedance analysis (BIA) in 103 thyroid patients, subdivided according to their functional status. All BIA parameters measured in subclinical thyroid dysfunctions did not significantly differ from those observed in euthyroid controls. On the contrary, they were clearly altered in the two extreme, opposite conditions of thyroid dysfunctions, namely overt hyperthyroidism and severe hypothyroidism, indicating the occurrence of a typical hormetic condition. Surprisingly, differences in BIA parameters related to fluid body composition were even more evident in hyperthyroidism than in hypothyroidism. A hormetic response to thyroid hormone (TH)s was previously reported to explain the paradoxical, biphasic, time- and dose-dependent effects on other conditions. Our results indicate that myxedema, observed in both hypothyroid and hyperthyroid conditions, represents another example of a hormetic-type response to THs. BIA offers no additional valuable information in evaluating fluid body composition in subclinical thyroid dysfunctions, but it represents a valuable method to analyze and monitor body fluid composition and distribution in overt and severe thyroid dysfunctions.

Flow structure beneath periodic waves with constant vorticity under strong horizontal electric fields

While several articles have been written on Electrohydrodynamics (EHD) flows or flows with constant vorticity separately, little is known about the extent to which the combined effects of EHD and constant vorticity affect the flow. This study aims to shed light on this topic by investigating the combined influence of a horizontal electric field and constant vorticity on the free surface and the emergence of stagnation points. Using the Euler equations framework, we employ conformal mapping and pseudo-spectral numerical methods. Our findings reveal that increasing the electric field intensity eliminates stagnation points and smoothen the wave profile. This implies that a horizontal electric field acts as a mechanism for the elimination of stagnation points within the fluid body. Besides, we have identified regimes where three stagnation points appear on the free surface — something that cannot occur in purely gravity rotational waves.

Study on aerodynamic and coupled motion response characteristics of floating vertical axis wind turbine

ABSTRACT To improve the efficiency of a floating VAWT (FVAWT), the aerodynamic and coupled motion response characteristics of 5MW Φ-type FVAWT are studied in fully coupled system. Based on the computational fluid dynamics (CFD) method, the dynamic fluid body interaction (DFBI), overlapping grid and dynamic mesh technique are adopted for numerical simulations. Under wind-wave coupling conditions, the power coefficient (Cp) and motion response of FVAWTs with different tip speed ratios (TSR) and height-todiameter ratios (η) are analysed. The mechanism of platform heave motion on torque Q generation of VAWT is explored. The results show that the FVAWT with height-to-diameter ratio of 1.2 and tip speed ratio of 5 has optimal aerodynamic and motion performance. Under the optimal tip speed ratio, the Cp of the offshore FVAWT is 5.21% higher than that of the land VAWT. As the floating platform rises, the torque of wind turbine decreased correspondingly, and vice versa.

Mortality of cytomegalovirus infection among people living with HIV: A retrospective study from a tertiary hospital in Indonesia.

There are still many patients newly diagnosed with HIV at an advanced stage in Indonesia. We aimed to identify factors associated with 1-year mortality among cytomegalovirus (CMV)-infected people living with HIV (PLHIV). This retrospective cohort study was carried out at a tertiary-care hospital in Jakarta, Indonesia (January 2017 to December 2022). We included PLHIV with CMV end-organ disease (EOD) and CMV syndrome. The presence of CMV infection was confirmed by fulfilling one of the following criteria: (1) positive PCR from plasma, urine, cerebrospinal fluid, or other body fluids, or associated tissue for CMV EOD; (2) positive immunoglobulin M (IgM); or (3) consistent symptoms and signs of CMV retinitis. Out of 1737 PLHIV, 147 (8.5%, 95% CI: 7.2 to 9.9%) were diagnosed with CMV infection. Forty (27.2%, 95% CI: 20.6 to 35.1%) patients died within 1year of being diagnosed. Only anti-retroviral therapy (ART) defaulting (aHR 3.31, 95% CI: 1.12 to 9.73) was found to be significantly associated with 1-year mortality in multivariate analysis. Defaulted ART status is significantly associated with reduced 1-year survival after CMV infection diagnosis. Patients with low CD4 counts, especially those with <50 cells/μL, should be assessed for CMV infection, monitored, and treated accordingly.

VLF oscillation mechanism analysis of underwater vehicle based on overlapping grid

ABSTRACT The present study aims to investigate the VLF oscillation mechanism of underwater vehicles motion by conducting numerical simulation on the AFF-1. The straight-line simulations of AFF-1 were performed using RANS equations with a Reynolds stress turbulence model at different speeds, and an initial flow field with converged resistance results was obtained. Meanwhile, the accuracy of the numerical model and input parameters were validated by the resistance results. The sinuous motion of AFF-1 was simulated based on dynamic fluid body interaction (DFBI) and overlapping grid. The results indicated that the inherent instability of the AFF-1 significantly impacts its motion dynamics. Specifically, when AFF-1was in straight-line motion at a constant forward velocity, it was subjected to the influence of pressure component of hydrodynamic force and moment, resulting in slow trajectory divergence motion of AFF-1. In scenarios where manual manipulation is employed, this instability leads to the emergence of VLF oscillations.

Use of Bioimpedance Spectroscopy for Postoperative Fluid Management in Patients Undergoing Cardiac Surgery with Cardiopulmonary Bypass

ObjectiveTo assess whether bioimpedance spectroscopy analysis (BIA) can be used as a potential tool to guide postoperative fluid management in patients who undergo cardiac surgery. DesignAn observational study. SettingA single, tertiary hospital. ParticipantsPatients who underwent cardiac surgery with cardiopulmonary bypass between June to November 2023 who were able to undergo BIA measurements. InterventionsNone. Measurements and Main ResultsCorrelations between BIA measurements of extracellular fluid (ECF) and total body water (TBW) volumes and daily changes in weight and 24-hour net intake and output (I/O) of fluids were assessed. Correlations between pre-discharge ECF volume as a percentage of TBW volume (ECF%TBW) and pre-discharge Pro-BNP (Pro-BNP) levels and readmissions were analyzed. Changes in daily ECF volume significantly correlated with daily weight changes (p<0.01) and 24-hr I/O (p<0.01). TBW volume significantly correlated with daily weight changes (p<0.01) and with 24-hr I/O (p=0.04). Daily weight changes did not correlate with 24-hr I/O (p=0.06). The patients with pre-discharge ECF%TBW(%) greater than or equal to 51 had significantly higher pre-discharge Pro-BNP than those with ECF%TBW(%) less than 51 (p<0.01). Patients who had heart failure revisits or admissions after discharge had a higher pre-discharge ECF%TBW(%) on index admission compared to patients that did not have heart failure readmissions (p=0.01). ConclusionsUtilization of BIA measurements in postoperative cardiac surgery patients may be a valuable tool to quantitatively determine fluid status to help guide fluid management in this patient population. Further studies validating the use of BIA for postoperative care in this population are warranted.

Increasing Resistance of Nosocomial and Community-Acquired Escherichia coli in Clinical Samples from Hospitals and Clinics in Sana’a City

Antimicrobial resistance in Escherichia coli presents a global challenge associated with nosocomial infections and increased mortality rates. Understanding resistance profiles is crucial for guiding treatment strategies and ensuring effective antibiotic use. This study aimed to investigate the prevalence and in vitro resistance of E. coli to community-acquired and nosocomial infections. Various clinical samples from 700 patients were cultured on MacConkey’s medium and blood agar. The disk diffusion method was used to determine the antibiotic susceptibility profile of the E. coli isolates following the guidelines of the Clinical and Laboratory Standards Institute (CLSI). Urine, pus, seminal fluid, vaginal swabs, and other body fluids were among the clinical samples analyzed. Of the 112 E. coli isolates, 48.2% were from inpatients and 51.8% were from outpatients, with the majority (66%) isolated from urine samples. Higher resistance levels were observed in the urinary isolates than that in the previously recorded data from the same institutions. Notably, isolates exhibited high resistance to penicillin (98.2%), ampicillin (97.3%), first-generation cephalosporins (90.2%), erythromycin (72.2%), and roxithromycin (95.4%), whereas lower resistance was noted against piperacillin-tazobactam (25.0%), nitrofurantoin (12.5%), and imipenem (9.8%). The overall multidrug resistance rate was 62.5%, with higher rates observed in nosocomial infections (70%) compared to community-acquired isolates (55.6%). However, this difference was not statistically significant (p&gt;0.05). This study underscores the prevalence of E. coli isolates (27.0%) and highlights the concerning level of resistance, particularly to older antibiotics. These findings emphasize the importance of judicious antibiotic use and ongoing surveillance.

Three-dimensional trajectories of irregular-shaped tunnel lining fragments in the flow environment caused by high-speed trains

High-speed railway tunnel lining fragments can cause collisions with trains and track blockages, severely affecting train operation. When a train passes through a tunnel where lining fragment is likely to occur, the train wind effect may significantly affect the trajectory of the lining fragment, making the location where the lining fragment is difficult to predict. For safety purpose, this study aims to analyze the impact of the initial circumferential position and shape of irregular-shaped lining fragments on their aerodynamic performance. Using on-site scanning and mathematical statistical methods, the shape characteristics and probability distribution of actual lining fragments in the tunnel are obtained. The aerodynamic behavior of irregular-shaped lining fragments with different initial positions and three typical aspect ratios (ARs) are investigated based on the overset grid method and the dynamic fluid–body interaction model framework as a high-speed train passes. The study found that the most representative lining fragments with an AR of three have a mass of 1.5 kg and are located 2.5 m from the tunnel centerline. The flight behavior of lining fragments shows distinct three-dimensional features, with both translation and rotation significantly affected by the aerodynamic effects of the train and the geometric shape of the fragments. The longitudinal and lateral translational distances of lining fragments at the top of the train decrease as their initial position moves further from the tunnel's centerline. With an increase in AR, both the longitudinal and lateral flight distances and average flight velocities of the fragments increase. The macroscopic flow field within the tunnel directly influences the motion characteristics of the lining fragments. Complex flow separation and circulation phenomena near the fragments result in uneven pressure differences acting on the smooth and rough surfaces of the lining fragments, causing irregular motion. The conclusions of this study provide a theoretical basis for assessing and preventing the impact of lining fragments on the operational safety of trains.

Hydrodynamic and kinematic characteristics of high-speed inclined water-exit process in wave environment

Aiming at the process of underwater vehicle crossing the water-air interface based on the computational fluid dynamics(CFD) method, integrating the volume of fluid(VOF) and dynamic fluid body interaction(DFBI) models, a numerical simulation method for the trans-media process in a wave environment was studied. The motion simulation method of underwater vehicle under the action of complex fluid environment was established. The simulation of the water-exit process of the underwater vehicle in a wave environment has been realized. The accuracy verification of the wave-making and trans-media processes has been completed. The hydrodynamic and kinematic characteristics of the vehicle during the water-exit process have been obtained. The influences of the wave phase and velocity on the force and motion characteristics of the underwater vehicle were obtained, which provides technical support for designing the unmanned vehicles.

The Comparison of the Clinical Efficacy and Drug Tissue Distribution of Furazolidone and Tetracycline-quadruple Therapy in Helicobacter pylori Eradication: A Randomized Controlled Trial.

Helicobacter pylori (H. Pylori) is considered a main causative organism of gastric ulcers, gastric cancer and duodenal ulcers. The current treatment relies on a combination of antimicrobial agents and acid suppressant agents, but the eradication effect is not satisfactory. To clarify the concentration of antibiotics at the lesion site, we investigate the clinical efficacy and drug tissue distribution of the combination therapy of furazolidone and tetracycline in eradicating H. Pylori. Patients with H. pylori infection (n = 60) were randomized to either group A or B. Bismuth potassium citrate capsules 220mg, omeprazole enteric-coated capsules 20mg, amoxicillin capsules 1000mg, each twice per day, and furazolidone tablets 500mg were administered to group A. Group B was treated with bismuth potassium citrate capsules 220mg, omeprazole enteric-coated capsules 20mg, amoxicillin capsules 1000mg, and tetracycline tablets 500mg each twice per day for 2 weeks. The serum and gastric juice, gastric antrum, gastric horn, and gastric body samples were taken under a gastroscope on the 14th day. The antimicrobial concentrations in serum and tissue samples were determined by high-performance liquid chromatography. In the negative group of furazolidone, the concentrations of gastric antrum, gastric body, and gastric angle were significantly higher than those in the positive group (P = 0.017, 0.015, and 0.028). The concentrations of furazolidone in gastric fluid, gastric antrum, gastric angle, and gastric body were ∼421 times, 82 times, 17 times, and 51 times higher than those in serum, respectively. The concentrations of tetracycline in the serum and gastric angle of the tetracycline negative group were significantly higher than those in the positive group (P = 0.036 and 0.042), and the tetracycline concentrations in the gastric horn and gastric body were about 4 and 6 times higher than those in the serum, respectively. The concentration of amoxicillin in group B was higher than that in group A, especially in serum, gastric juice, gastric angle, and gastric body (P < 0.05). Furazolidone is mainly concentrated and sequentially distributed in gastric juice, gastric antrum, and gastric body tissue, and tetracycline is mainly distributed in serum, gastric angle, and gastric body, whereas amoxicillin is mainly distributed in serum, gastric juice, gastric angle, and gastric body. Improving the concentration and tissue distribution of antibacterial drugs in the human gastric mucosa is the key to ensuring the ideal eradication rate of quadruple therapy.

Coupled dynamic response and energy conversion characteristics of 10 MW floating vertical axis wind turbine with different configurations

Vertical axis wind turbines (VAWTs) are superior because they have compact structure, good wind adaptability and strong scalability. The coupling dynamic response mechanisms between different configurations of wind turbines and floating platforms are different. Based on the CFD method, dynamic fluid body interaction (DFBI), overlapping grid and dynamic grid techniques are used for numerical simulations. The force characteristics and self-starting features of H-type and Φ-type VAWTs are compared. The aerodynamic performance and motion response of the floating VAWT (FVAWT) are studied under different tip-speed ratios (TSR) and aspect ratios (η). The results show that the power coefficient (Cp) of H-type and Φ-type FVAWTs reaches the peak when TSR = 6 and TSR = 7, respectively. The optimal η for both is 1.2. The H-type FVAWT improves the Cp by 34.3% compared to Φ-type FVAWT. H-type FVAWT has a large thrust and excellent stability. The Φ-type FVAWT requires less initial thrust, and the self-starting performance is 12% superior to H-type FVAWT. With the increase of TSR and η, the heave motion of both FVAWTs is almost unaffected, but the pitch motion sensitivity is stronger. The heave amplitude of H-type FVAWT is 282% larger than Φ-type FVAWT, which has a gain effect on energy conversion. The Φ-type FVAWT has better safety. The strengthened structure of Φ-type VAWT has a noticeable impact on velocity and vortex distribution. In addition, the aerodynamic and hydrodynamic performance of the FVAWT is improved.

Study on Aerodynamic Performance and Wake Characteristics of a Floating Offshore Wind Turbine in Wind–Wave Coupling Field

Floating offshore wind turbines (FOWTs) exhibit complex motion with multiple degrees of freedom due to the interaction of wind and waves. The aerodynamic performance and wake characteristics of these turbines are highly intricate and challenging to accurately capture. In this study, dynamic fluid body interaction (DFBI) and overset grid technology are employed to investigate the dynamic motion of a 5 MW FOWT. We use the volume of fluid (VOF) method and improved delayed detached eddy simulation (IDDES) model to investigate the aerodynamic performance and wake evolution mechanism for various wave periods and heights. According to the findings, the magnitude of the pitch motion increases with the period and height of the waves, leading to a decrease in both the power output and thrust; the maximum power was reduced by nearly 6.8% compared to a wind turbine without motion. The value of power and thrust reduction varies for different wave periods and heights, and is influenced by the relative speed and pitch angle, which play a crucial role. Wind–wave coupling has a significant impact on the evolution of both wake and vortex structures for FOWT. The wake shape downstream is also dynamically influenced by the waves. In the presence of wind and wave coupling, the interaction between the wind turbine and the wake is heightened, leading to the merger of two unstable vortex rings into a single, larger vortex ring. The research unveils a comprehensive picture of the offshore wind energy dynamics and wake field, which holds immense significance for the design of floating wind turbines and the optimization of wind farm layout.

Rotating solutions to the incompressible Euler–Poisson equation with external particle

We consider a two-dimensional, incompressible fluid body, together with self-induced interactions. The body is perturbed by an external particle with small mass. The whole configuration rotates uniformly around the common center of mass. We construct solutions, which are stationary in a rotating coordinate system, using perturbative methods. In addition, we consider a large class of internal motions of the fluid. The angular velocity is related to the position of the external particle and is chosen to satisfy a non-resonance condition.

Sodium-Glucose Cotransporter 2 Inhibitor Combined with Conventional Diuretics Ameliorate Body Fluid Retention without Excessive Plasma Volume Reduction.

We previously reported that sodium-glucose cotransporter 2 (SGLT2) inhibitors exert sustained fluid homeostatic actions through compensatory increases in osmotic diuresis-induced vasopressin secretion and fluid intake. However, SGLT2 inhibitors alone do not produce durable amelioration of fluid retention. In this study, we examined the comparative effects of the SGLT2 inhibitor dapagliflozin (SGLT2i group, n = 53) and the combined use of dapagliflozin and conventional diuretics, including loop diuretics and/or thiazides (SGLT2i + diuretic group, n = 23), on serum copeptin, a stable, sensitive, and simple surrogate marker of vasopressin release and body fluid status. After six months of treatment, the change in copeptin was significantly lower in the SGLT2i + diuretic group than in the SGLT2i group (-1.4 ± 31.5% vs. 31.5 ± 56.3%, p = 0.0153). The change in the estimated plasma volume calculated using the Strauss formula was not significantly different between the two groups. Contrastingly, changes in interstitial fluid, extracellular water, intracellular water, and total body water were significantly lower in the SGLT2i + diuretic group than in the SGLT2i group. Changes in renin, aldosterone, and absolute epinephrine levels were not significantly different between the two groups. In conclusion, the combined use of the SGLT2 inhibitor dapagliflozin and conventional diuretics inhibited the increase in copeptin levels and remarkably ameliorated fluid retention without excessively reducing plasma volume and activating the renin-angiotensin-aldosterone and sympathetic nervous systems.

#2057 Sex differences in bioimpedance-spectroscopy-derived fluid status and body composition of maintenance hemodialysis patients

Abstract Background and Aims Bioimpedance-spectroscopy-(BIS)-derived estimates of fluid status and body composition are associated with mortality in patients undergoing maintenance hemodialysis (HD). Previously, thresholds for improved survival were identified for volume overload (VO, &amp;lt;2.5 L), VO relative to extracellular water (VO/ECW, &amp;lt;15%), lean tissue index (LTI, 15-20 kg/m2) and fat tissue index (4-15 kg/m2). However, these thresholds did not distinguish between sexes. Considering current efforts to untangle differences between male and female kidney disease patients, we aimed to analyze BIS data stratified by sex. Method We retrospectively evaluated pre-HD BIS measurements using the whole-body “Body Composition Monitor” device (Fresenius Medical Care). Measurements were conducted at the “Vienna Dialysis-Center”, a large tertiary dialysis center in Vienna, Austria. Continuous variables were described as medians and interquartile ranges and compared between sexes using Wilcoxon tests. Differences in proportions of males and females within the above-mentioned target ranges of body composition parameters were tested using Chi-Square tests and Fisher's exact tests. Results In November 2022, the Vienna Dialysis-Center cared for 304 patients, 159 of whom underwent BIS measurements. A total of 137 patients remained for analysis after excluding erroneous results (62% male, 38% female). The median [interquartile range] age among analyzed male and female patients was 60.0 years [48.0; 72.0] and 65.5 years [57.8; 75.3], and the median dialysis vintage was 28.9 months [12.1; 52.7] and 27.2 months [14.8; 61.9], respectively. VO (2.7 vs 1.9 L, p = 0.025), LTI (13.4 vs. 11 kg/m2, p &amp;lt; 0.001) and FTI (11.1 vs. 14.2 kg/m2, p = 0.036) differed significantly between males and females but VO/ECW did not (14.3 vs. 12%, p = 0.4). 27.1% of males (n = 23) were within 15-20 kg/m2 LTI compared to 7.7% of females (n = 4, p = 0.007). Differences in the proportions of male and female patients within optimal ranges of VO (43.5% vs. 61.5%, p = 0.062) and FTI (67.9% vs. 50.0%, p = 0.058) were close to reaching statistical significance. Conclusion We discovered relevant differences in fluid status and body composition among patients undergoing maintenance HD not only in absolute numbers, but also in the proportion of patients within the optimal range of LTI. Considering sex differences in body composition but (on average) equal mortality among HD patients, optimum target ranges of BIS measurements may differ between sexes. Our findings from this relatively small cohort call for large-scale sex-specific analyses of fluid status, body composition and outcomes in maintenance HD patients.