International Journal of Artificial Organs最新文献

Heart failure is among the most widespread diseases globally. With the rapid rise in the number of affected individuals and the significant disparity between organ demand and supply, the relevance of implantable devices has grown each year. However, these devices face various regulatory restrictions, and obtaining approval requires outstanding performance. This paper focuses on optimizing the design parameters of a rotor for an axial flow ventricular assist device (VAD) currently under development. The parameters investigated include splitters, inlet blade angle, outlet blade angle, blade count, rotational speed, clearance gap, blade thickness, and rotor length. The study aims to maximize pressure rise and hydraulic efficiency while minimizing the torque required to drive the rotor. The D-optimal method was employed to create an experimental design for the simulations. By comparing R², adjusted R², and RMS error across different regression models, the quadratic regression model emerged as the most effective for deriving a suitable mathematical model from the numerical results. The validity of these models was confirmed through the consistency between predicted and observed outcomes.

Clinical studies have shown that hemodiafiltration reduces morbidity and mortality of dialysis patients compared to hemodialysis alone. This is attributed to its superior middle molecule clearance compared to standard hemodialysis. However, doubts arose as to whether a high convective flux through the dialyzer membrane has an influence on the equilibrium concentration of small ions, especially that of sodium. Due to the presence of negatively charged impermeable proteins on the blood side, the Gibbs-Donnan effect leads to an asymmetric distribution of membrane permeable ions on both sides of the membrane. In thermodynamic equilibrium, the concentrations of those ions can easily be calculated. However, the convective fluid flow leads to deviations from thermodynamic equilibrium. In this article, the effect of a convective flow on the ion distribution across a semipermeable membrane is analyzed in a theoretical model. Starting from the extended Nernst-Planck equation, including diffusive, convective, and electrostatic effects, a set of differential equations is derived. An approximate solution for flow speeds up to 0.1 ms^-1 as well as a numerical solution are given. The results show that in any practical dialysis setting the convective flow has negligible influence on the electrolyte concentrations.

This study presents four different impeller designs to compare hydrodynamic forces. Numerical simulation studies are performed via computational fluid dynamics to specify and investigate the hydraulic forces impacting the impeller of the mixed-flow blood pump with a volute. The design point of this pump is that the flow rate is 5 L/min, the rotational speed is 8000 rpm, and the manometric head is 100 mmHg. The designed impellers are placed in the same volute and simulation studies are performed with the same mesh size (17.3 million cells) of the pumps. The simulation studies have been conducted in setting 1050 kg/m³ blood density, 35 cP fluid viscosity, and SST-kω turbulence model. Additionally, this study examines the changes in hydraulic forces and hydraulic efficiency with fluid viscosity. As a result of experimental simulation studies, the highest hydraulic efficiencies of 40.87% and 39.5% are achieved in the case of the shaftless-grooveless and shafted-grooveless impeller, respectively. The maximum axial forces are obtained from the pump with the shaftless-grooveless impeller. Whereas radial forces, maximum values are calculated in the pump with the shaftless-outer groove impeller for all flow rates. Finally, the wall shear stresses, which are important for blood pump designs, are evaluated and the maximum value of 227 Pa is observed in the pump impeller with a shaftless-grooved.

Current online hemodiafiltration devices can be used to determine the absolute blood volume in clinical practice using the dialysate bolus method. Most of publications on this method have focused on preventing intradialytic complications. The influence of absolute blood volume on long-term prognosis has not been reported yet. A total of 79 participants in a previous study about absolute blood volume were followed for 5 years. Patients with a specific blood volume above (n = 45) and below 75 ml/kg (n = 34) respectively were compared with regard to survival using Kaplan-Meier analysis. Patients with a specific blood volume below 75 ml/kg had a significantly higher overall 5-year survival rate than patients above 75 ml/kg (70% vs 39%, p = 0.0233). In patients without cardiac dysfunction, there were no significant differences in 5-year survival between a specific blood volume below or above 75 ml/kg (66% vs 51%). A specific blood volume above 75 ml/kg was associated with an increased mortality in patients with mildly impaired left-ventricular systolic ejection fraction of 40%-59%, whereas in patients with normal blood volume this cardiac impairment did not impact mortality (22% vs 90% 5-year survival, p = 0.0036). This demonstrates the significance of optimum volume control for long-term survival particularly in cases of reduced cardiac function.

Objective: This systematic review and meta-analysis aimed to identify the risk factors for acute kidney injury (AKI) in patients with severe acute pancreatitis (SAP).

Methods: A comprehensive literature search was conducted using the PubMed, Embase and Cochrane Library databases for case-control studies comparing the clinical characteristics of patients with SAP with and without AKI. The quality of the included studies was assessed using the Newcastle-Ottawa Scale (NOS). Pooled odds ratios (ORs) with 95 % confidence intervals (CIs) were calculated using fixed- or random-effects models, based on heterogeneity.

Results: Five studies involving 795 patients with SAP were included, of whom 173 (21.8 %) developed AKI. All studies were of high quality according to the NOS. Among the 17 potential risk factors that were analysed, a history of alcohol consumption (OR = 2.36, 95% CI = 0.54-10.43, p < 0.001), elevated serum amylase (OR = 4.50, 95% CI = 1.77-11.43, p = 0.002) and Acute Physiology and Chronic Health Evaluation II (APACHE II) score (OR = 1.57, 95% CI = 0.49-2.64, p = 0.004) were significantly associated with an increased risk of AKI. However, hypertension (OR = 1.14, 95% CI = 0.60-2.16, p = 0.69) and diabetes (OR = 1.88, 95% CI = 0.51-6.95, p = 0.34) were not significantly associated with AKI risk. Based on funnel plots, no obvious publication bias was detected.

Conclusions: A history of alcohol consumption, elevated serum amylase and APACHE II score are significant risk factors for AKI in patients with SAP. For early intervention, clinical physicians should be vigilant about the risk of AKI in patients with SAP with these factors. More high-quality studies are needed to validate these findings and explore other potential risk factors.

This study aims to develop an effective hemostatic agent in the management of irregular and deep wounds that can accelerate the hemostatic process. The background revealed the importance of rapid treatment of bleeding, with data showing a significant risk of death from blood loss. Current treatments use conventional hemostatic dressings, but they are less effective on irregular surgical wounds. Several studies have developed chitosan, hyaluronic acid, and CaCl₂-based hydrogels that have hemostatic, regenerative, and antibacterial potential. However, there is still a need to develop hydrogels that are thermally stable, biocompatible, and able to accelerate the hemostatic process. This research will synthesize self-healing hydrogels by modifying the structure of chitosan and hyaluronic acid, using a certain ratio of ingredients. The research procedure was carried out with the preparation of N-succinyl chitosan (NSC) and oxidized hyaluronic acid (OHA) as the main ingredients which were then added with CaCl₂ to produce self-healing injectable hydrogel. First, NSC and OHA were dissolved in phosphate buffer solution (pH = 7.4 PBS) to obtain 60 mg/mL NSC and OHA solution respectively. Calcium chloride was then dissolved in water to obtain 120 mg/mL CaCl₂ solution. Then NSC-OHA-CaCl₂-based hydrogels were synthesized through rapid and full solution mixing above room temperature with the composition of (1-1-0.1; 1-1-0.2; and 1-1-0.3). The targeted findings of this research are sample characterization results that explain and prove the best NSC-OHA-CaCl₂ composition variation that can be used as a hemostatic agent for irregular and deep wounds. The results of the analysis obtained FTIR test data with the formation of C = N functional groups in the four samples; blood clotting time test for sample K0, K1, K2, and K3 with time 4.6, 3.33, 2.66, and 1 s; MTT assay with cell viability percentage of 77.82% for sample K0, 84.18% for sample K1, 89.30% for sample K2, and 89.50% for sample K3; hemolysis index percentage of 0.373% for sample K0, 0.555% for sample K1, 0.625% for sample K2, and 0.201% for sample K3; Viscosity test obtained data of 13 dPa s for sample K0, 15 dPa s for sample K1, 16 dPa s for sample K2, and 18 dPa. The injectability test yielded an injectability percentage of 96.84% for sample K0, 95.03% for sample K1, 94.78% dPa s for sample K2, and 94.61% for sample K3; the DSC test results of the four samples obtained a transition peak at the exothermic peak of 62.27°C for sample K0, 70.23°C for sample K1, 73.77°C for sample K2, and 74.49°C for sample K3; and the characteristic graph of the TGA test results, the weight profile of the hydrogel during heating which showed a mass change of 21.64 mg in sample K0, 16.89 mg in sample K1, 15.37 mg in sample K2, and 11.43 mg in sample K3 (°C).

Background: Patients with continuous flow left ventricular assist devices (CF-LVADs) are at increased risk of gastrointestinal bleeding (GIB). Statins are commonly prescribed in LVAD patients for cardiovascular disease prevention. However, their impact on GIB events is controversial. Importantly, literature regarding statins impact on GIB in CF-LVAD patients is lacking.

Methods: A single-center, retrospective review of adult patients who underwent CF-LVAD implantation between May 2016 and January 2020 was performed. Patients were categorized based on statin use throughout the study period. The primary outcome was the composite of arteriovenous malformation confirmed GIB and major GIB events for up to 1-year post-LVAD implantation.

Results: Of 123 patients included in the final analysis, 66 (54%) received statin therapy during the study period. No difference was observed in the primary outcome between the statin and control groups (RR: 1.73; 95% CI: 0.75-3.98; p=0.20). Multivariable Cox regression revealed that older age and higher baseline creatinine were associated with an increased risk of GIB within 1-year of CF-LVAD implantation.

Conclusion: Among patients with CF-LVADs, there was no significant difference in the incidence of major GIB events associated with the use of statin therapy. Further studies are needed to assess whether a true association exists.

Introduction: New dialysis membranes with new properties are being developed to improve efficacy and tolerance. The hemocompatibility of a polymeric biomaterial is influenced by the layer of water at the blood membrane interface. The new dialyzer TORAY NV-U^® has a membrane Hydrolink™, designed to suppress platelet adhesion and to improve the hemocompatibility. Until now, there is no experience in online hemodiafiltration (OL-HDF).The objective of the present study is to evaluate the efficacy of this new membrane in OL-HDF therapy compared to another membrane commonly used. Other objectives are to evaluate the inflammatory response, hemodynamic tolerance, and the anticoagulation regimes.

Methods: This is a prospective pilot study performed in five anuric patients receiving OL-HDF. For 1 month patients were kept with their usual dialyzer FX1000^® (FMC). Subsequently, the dialyzer was changed to TORAY NV-U^® (Hydrolink^®) for 1 month. In the last dialysis session of each dialyzer, blood tests were performed to evaluate inflammation and depurative capacity.

Results: We did not find differences in medium size removal molecules and convective volume: FX1000^®: 31 ± 9 l per session and Hydrolink™ 30 ± 8 l; p = 0.7); β2microglobulin reduction ratio (RR) FX1000^® FMC 83 ± 3%; Hydrolink™ 79 ± 4; p = 0.14; Myoglobin RR FX1000^® FMC 72 ± 7%; Hydrolink™ 76 ± 4; p = 0.28. We did not find differences in inflammation parameters: serum IL6 with FX1000^® 6.0 ± 4.2 pg/mL; Hydrolink™ 7.6 ± 5.0 pg/mL; p = 0.3.During all sessions with the two dialyzers there was adequate plasmatic filling, reaching 85 % filling. All patients had "good" dialyzer status in all dialysis sessions with TORAY NV-U^®, while the dialyzer status with FX1000^® was "good" in 20% of the sessions, "medium" in 30%, and "dirty" in the remaining 50% dialysis sessions.

Conclusions: The new dialyzer Hydrolink™, TORAY NV-U^® is not inferior to perform OL-HDF compared to dialyzers usually used for this therapy, and could allow decrease heparin doses. Further studies with a bigger sample size and longer follow-up will answer if Hydrolink improves inflammation and assess a better hemodynamic tolerance.

Tissue phantoms play an important role in validating biomedical imaging techniques. For optical imaging systems such as optical coherence tomography, creating layers of phantoms with different refractive indices is important. This paper explored various phantom materials to create eye-mimicking phantoms. The phantom also included microfluidic channels to mimic vasculature. To verify the optical properties of the created phantom, the transmission and reflection spectroscopy was performed using a photoluminescent spectrometer studying the complete visible and near infrared spectrum. We created a 3D model to house multiple layers that mimicked the retina at one end and the contact lens at the other, representing the anterior segment of the eye. A realistic retinal layer-mimicking, which, among other things, may pave the way for new combined imaging modalities.

Objective: The interaction between blood from end-stage renal failure patients undergoing hemodialysis treatment and the hemodialysis (HD) membranes used may lead to DNA damage, contingent upon the biocompatibility of the membranes. Given that this process could impact the disease's course, it is crucial to assess the efficacy of DNA repair mechanisms.

Methods: In our study, we investigated the gene expression levels of XRCC1 and PARP1 enzymes, which are involved in the base excision repair (BER) repair mechanism crucial for repairing oxidative DNA damage, in 20 end-stage renal disease (ESRD) patients undergoing HD treatment both before and after dialysis sessions. Additionally, we compared our findings with those from 20 healthy controls. We assessed gene expression levels using real-time polymerase chain reaction (qRT-PCR).

Results: We observed that the HD process utilizing a polysulfone membrane did not impact the expression levels of genes. However, we noted a lower expression level of the PARP1 gene in ESRD patients undergoing HD compared to the control group (0.021 ± 0.005 vs 0.0019 ± 0.0013, p = 0.0001).

Conclusion: Although our study findings indicate that HD membranes do not affect gene expression overall, the specific decrease in PARPI gene expression suggests that the effectiveness of the BER DNA repair mechanism is impaired in ESRD patients, which may play a significant role in the progression of the disease.