Artificial organs最新文献

Background: The influence of operating modes on pump-induced hemolysis in continuous-flow left ventricular assist devices (LVADs) can be assessed using computational fluid dynamics (CFD) simulations alongside power law models derived from shearing device experiments. However, this conventional method incurs high computational costs, limiting the exploration of diverse operating conditions and hindering online hemolysis prediction. This work presents a CFD-free and trial-based methodology for determining online-capable hemolysis models for continuous-flow LVADs.

Methods: The trial-based hemolysis model is based on a modified power law model, with parameters identified from LVAD hemolysis trials. The dynamic behavior is modeled using the Lagrangian approach. Specifically, this model was determined for the Sputnik1 LVAD and integrated with a lumped-parameter model of the LVAD-supported cardiovascular system. Subsequently, hemolysis was predicted across various operating modes and patient conditions.

Results: The RMSE and the R² of the modified power law fit were 18.4 [%·mL/h] and 0.69, respectively. The relative error introduced by the Lagrangian approach was below 0.7%. For the Sputnik1, hemolysis decreased with reduced speed. Additionally, lower systemic resistance and diminished left ventricular contractility were associated with lower hemolysis, whereas speed modulation increased hemolysis across most profiles.

Discussion: The proposed hemolysis model allows to assess various LVAD operating modes and patient conditions, assisting in the selection of low-hemolysis treatment strategies. For Sputnik1 patients, it is advisable to maintain low pump speed and systemic resistance, while speed modulation should be reserved for those with low hemolysis markers. Integrating this model with online flow sensing would enable online hemolysis prediction.

Background: Heart valve diseases remain a leading cause of death in industrialized nations. Polycarbonate urethane (PCU) is a promising material for heart valve prostheses due to its biocompatibility and low calcification tendency. However, the impact of processing methods on calcification remains unclear.

Methods: PCU patches were fabricated via hot pressing or solution casting. Both groups (n = 3 each), along with bovine pericardium patches as positive controls (n = 3), were incubated for 10 weeks in a custom in vitro calcification fluid. Calcification, cytocompatibility, and material properties were assessed using light and electron microscopy, infrared spectroscopy, and gel permeation chromatography (GPC).

Results: Calcification was observed in hot-pressed PCU and control patches but not in solution-cast PCU. Both PCU types showed comparable cytocompatibility. Spectroscopy and GPC revealed chemical and structural changes in hot-pressed PCU, likely promoting calcification.

Conclusion: Hot pressing alters the chemical structure of PCU and increases its calcification propensity without affecting cytocompatibility. These findings highlight the importance of process control and in vitro screening during heart valve material development.

Background: Normothermic machine perfusion (NMP) could serve as a platform to assess deceased-donor kidney viability before transplantation, yet it remains unclear which parameters indicate renal viability. As vascular integrity is important for adequate renal function after transplantation, this study aimed to investigate the influence of warm ischemic injury on vascular smooth muscle cell (VSMC) responsiveness to vasoactive drugs during NMP.

Methods: Fourteen porcine kidneys (n = 7 per group) were exposed to either 30 or 60 min of warm ischemia (WI), followed by 3.5 h of cold machine perfusion. After cold perfusion, kidneys underwent 4 h of NMP (37°C). During NMP, vasoactive drugs were sequentially infused into the renal artery at 30-min intervals, starting with epoprostenol (10 μg), followed by dopamine (1 mg), sodium nitroprusside (2 mg), acetylcholine (1 mg), norepinephrine (10 μg), and finally verapamil (2.5 mg).

Results: Renal blood flow during NMP changed significantly in both groups after administration of dopamine, acetylcholine, norepinephrine, and verapamil, but not following epoprostenol and sodium nitroprusside infusion. In kidneys subjected to 30 min of WI, the response to dopamine and norepinephrine was more pronounced, and oxygen consumption and blood pH were higher compared to kidneys that sustained 60 min of WI.

Conclusion: This study indicates that prolonged WI damage diminishes the contractility of VSMCs through the α-adrenergic receptors. Our findings suggest that the renal vascular responses to dopamine and norepinephrine, as well as decreased oxygen consumption and blood pH, could serve as objective indicators to quantify warm ischemic injury during renal NMP.

Purpose: Significant advances have been made in the design and manufacture of artificial blood pumps. However, blood compatibility issues such as hemolysis, thrombosis, and inflammation during the clinical use of artificial blood pumps have reduced their reliability. Among these issues, hemolysis problems can lead to acute kidney injury, hyperkalemia, and in severe cases, even serious threats to life. To address hemolysis problems, blood transfusion, reduction of blood pump speed, and medication to promote erythropoiesis are generally used. This study explores the hemolysis problem from the perspective of the essence of problem solving, that is, the design of the blood pump structure.

Methods: A new centrifugal pump UJN-1 was designed based on empirical design theory and the velocity coefficient method of traditional centrifugal pumps. We used the commercial software Fluent to compare the data obtained from our simulation of FDA benchmark blood pumps with the results of other researchers to validate the accuracy of our simulation method. Based on the CFD numerical simulation method, we evaluated the hemolytic performance of three centrifugal pumps: Revolution, PuraLev 200SU, and UJN-1. The hydraulic performance of the designed UJN-1 blood pump was experimentally verified.

Results: The UJN-1 could provide a blood flow rate of 4-6 L/min and a blood pressure of 120 mmHg at 2500 rpm. The CFD numerical simulation and experimental results of the designed artificial blood pump UJN-1 were compared and verified, and the results showed that the error was small. The hemolysis results of the Revolution pump, 200SU pump, and UJN-1 pump were 3.35 × 10^-4%, 2.20 × 10^-4%, and 1.49 × 10^-4%, respectively. In a comparison of hemolysis among the three pumps, the UJN-1 pump had the lowest level of hemolysis.

Conclusion: This low hemolysis artificial blood pump design is important for long-term clinical use and high reliability of medical devices.

Background: Prolonged duration of polymyxin B hemoperfusion (PMX-HP) for septic shock is not widely investigated.

Methods: We used BEAT-SHOCK, a prospective registry including 309 adult patients with septic shock requiring high-dose norepinephrine (≥ 0.2 μg/kg/min). Our post hoc analysis included 82 patients that underwent PMX-HP, dichotomized into either the ultra-long PMX-HP group (first session duration ≥ 12 h; n = 53) or the non-ultra-long PMX-HP group (< 12 h; n = 29). The primary outcomes were changes in vasopressor/inotrope dosage, represented by vasoactive-inotropic score (VIS), and sequential organ failure assessment (SOFA) score from baseline to day 3.

Results: The median durations of the first PMX-HP session in the ultra-long and non-ultra-long PMX-HP groups were 1290 and 358 min, respectively. Their median baseline VIS was 38.3 (IQR 26.0-49.5) in the ultra-long group, 38.1 (IQR 30.9-55.6) in the non-ultra-long PMX-HP group. The median baseline SOFA score was 11 (IQR 9-13) in both groups. The changes in these scores from baseline to day 3 did not differ between them (adjusted difference -3.8 [95% confidence interval -9.0 to 11.3] for VIS and -0.0 [95% confidence interval -1.5 to 1.5] for SOFA score). The 90-day mortality rate was 24.7% in the ultra-long PMX-HP group and 21.1% in the non-ultra-long PMX-HP group (adjusted hazard ratio 1.35; 95% confidence interval 0.49-3.69).

Conclusions: Ultra-prolonged PMX-HP for ≥ 12 h was not associated with a greater reduction in vasopressor/inotrope dosage or improvement in organ dysfunction on day 3 than PMX-HP < 12 h in our patients with septic shock without endotoxin monitoring.

Trial registration: UMIN Clinical Trial Registry on 1 November 2019 (registration no. UMIN000038302).

Objectives: Extracorporeal Life Support (ECLS) has evolved into an established treatment for severe cardiogenic shock. As most patients have residual antegrade left ventricular output toward the descending aorta that meets the retrograde blood flow from the arterial ECLS cannula, they may develop differential hypoxemia. The location of the mixing cloud is critical for coronary and brain oxygenation. We analyzed the effects of the development of differential hypoxemia on morbidity and mortality of ECLS patients. Moreover, we analyzed the impact of two different treatment options for this phenomenon, including the administration of beta-blockers and the provision of a supplementary arterial cannula, on survival.

Methods: We performed a retrospective review of patient demographics, outcomes, laboratory, and respiratory parameters during and after ECLS support for 76 ECLS patients treated at our institution.

Results: Overall, 38 ECLS patients developed differential hypoxemia. Treatment of this phenomenon included either the administration of beta-blockers (n = 18) or the introduction of a second arterial ECLS cannula (n = 20). There were no significant differences in median SOFA-Scores (Sequential Organ Failure Assessment Scores) between groups (p = 0.072; ECLS vs. ECLS with differential hypoxemia patients). Under all respiratory and laboratory values analyzed, only bilirubin levels were significantly different (p = 0.020). Development of differential hypoxemia was associated with significantly decreased survival rates (p = 0.05). Moreover, insertion of a second arterial ECLS cannula was a risk factor for mortality (OR: 3.68, 95% CI 1.18-11.47, p = 0.025).

Conclusions: Development of differential hypoxemia is associated with significantly increased mortality rates among ECLS patients and should therefore be prevented as far as possible. Non-invasive administration of beta-blockers seems to be the more effective treatment option for differential hypoxemia, as the introduction of a second arterial ECLS cannula was a risk factor for mortality.

Background: Respiratory management of extremely low gestational age neonates (ELGANs) is a major challenge in neonatal intensive care, as they face high mortality and morbidity due to complications such as respiratory distress syndrome and bronchopulmonary dysplasia. Traditional respiratory support methods (e.g., mechanical ventilation) have limitations, potentially leading to adverse outcomes like chronic lung injury and intracranial hemorrhage. Artificial womb technology (AWT), based on extracorporeal membrane oxygenation (ECMO) principles, has emerged as a potential alternative by simulating the intrauterine environment to provide respiratory and circulatory support for ELGANs.

Methods: This narrative review systematically summarizes the development of AWT for respiratory support in ELGANs, analyzes its core technical principles (e.g., pumpless arteriovenous extracorporeal life support (V-A ECLS) and pump-driven veno-venous extracorporeal life support (V-V ECLS)), and explores key advancements and challenges in oxygenator design, anticoagulation strategies, cannulation techniques, and synthetic amniotic fluid regulation.

Results: Significant progress has been made in AWT over the past decade, with two main support modes (pumpless and pump-driven) developed, each showing advantages and disadvantages in gas exchange efficiency and animal model survival time. Improvements in oxygenator materials (e.g., hollow fiber membranes, polymethylpentene membranes) and miniaturized designs have optimized gas exchange and reduced priming volume. Advances in anticoagulation strategies (e.g., heparin alternatives, surface coating technologies) and monitoring systems (e.g., nano-sensors, near-infrared spectroscopy) have enhanced safety. Additionally, regulation of synthetic amniotic fluid composition and immunomodulatory mechanisms has preliminarily simulated the intrauterine environment, but issues such as intracranial hemorrhage and species-specific barriers in animal model translation remain.

Conclusions: AWT offers a new direction for respiratory support in ELGANs, but its clinical application requires addressing challenges in biocompatibility, long-term organ development monitoring, and ethical norms. With optimized system design, material innovation, and multimodal monitoring, AWT is expected to become a crucial tool for improving ELGANs' prognosis.

Background: A bone scaffold is used to treat critical size bone defects and demands contradictory physical and mechanical properties. It is difficult to achieve the desirable properties using a single material, and composite materials are used to develop the scaffolds.

Methods: A combination of bioceramics such as hydroxyapatite (HAP), calcium silicate (CS), or calcium phosphate (CP) with different percentages of multiwalled carbon nanotubes (MWCNT) is used to develop the scaffolds using Robocasting 3D printing to treat the cancellous bone defects. The bioceramics will enhance the biocompatibility and bone regeneration of the scaffold while the MWCNT will improve the mechanical properties. Compressive strength, density, shrinkage, and porosity are selected as deciding factors, and the analytic hierarchy process (AHP) and technique for order of preference by similarity to ideal solution (TOPSIS) are used to identify the best composite materials for the required properties.

Results: The scaffolds are printed and sintered and observed that CS with 1 mass % of MWCNT sintered at 1200°C, HAP with 0.5 mass % of MWCNT sintered at 1100°C, and CP with 0.5 mass % of MWCNT sintered at 1200°C are the best bone scaffold options.

Conclusion: The ideal processing parameters for developing bioceramic bone scaffolds using the robocasting technique are identified and reported.

Background: In recent decades, temporary mechanical circulatory support (tMCS) devices have garnered increasing interest for the treatment of cardiogenic shock. PulseCath-a pulsatile ventricular assist device-may address a critical unmet need within the tMCS array, offering an intermediate level of support between that of intra-aortic balloon pump (IABP) and more invasive tMCS devices (e.g., Impella and ECMO).

Methods: We conducted a systematic search of PubMed/MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, Web of Science, Scopus, and Google Scholar databases to retrieve available clinical and preclinical in vivo data regarding the implantation of PulseCath.

Results: Five preclinical in vivo studies (38 animal models) and 16 clinical studies (386 patients) were identified and retrieved. When implanted in humans, PulseCath was mostly employed with a "pre-emptive" strategy, particularly in the context of high-risk percutaneous coronary interventions. However, cases reporting its "bail-out" deployment in instances of hemodynamic instability were also identified.

Conclusions: While the underreporting of adverse events and of PulseCath use as a bailout strategy across literature constrains a definitive evaluation of the device, preliminary findings suggest an apparent ease of use. Therefore, further research is warranted to better delineate which specific patient population would most likely benefit from the implantation of such a device. As such, the integration of underlying pathophysiological data, individualized risk assessment, and more robust clinical studies may potentially expand its use.