Search

Oxygenators are a lifesaving technology used for blood oxygenation and decarboxylation in case of acute respiratory failure, chronic lung disease, and during open-heart surgery. Devices typically consist of a bundle of thousands of fibre membranes in a housing, with gas flowing inside the fibres and blood flowing in the opposite direction outside the fibres. Both ends of the fibre-membranes are fixed with an adhesive to separate gas and blood. The shape of the volume through which the blood flows is determined by the housing of the oxygenator and the internal end surfaces of the fixed ends of the fibre-membrane bundle. The traditional potting process results in a volume shape that is associated with stagnation zones, which are known to promote thrombus formation. In this study, an adapted potting process is proposed which results in a blood compartment with bevelled end faces of the glued bundle parts. Using a numerical study, we have demonstrated that the novel oxygenator design results in optimized flow conditions. [ABSTRACT FROM AUTHOR]

Over decades of development, the modern drug delivery system continues to grapple with numerous challenges, including drug loading inefficiencies, issues of immunogenicity, and cytotoxicity. These limitations restrict its application across various systems. Microalgae, as a natural resource, are not only abundant in bioactive compounds but also possess multiple biological properties, including active surface, photosynthesis capabilities, and excellent biocompatibility. These attributes make microalgae highly promising as carriers for targeted drug delivery, offering significant potential for the diagnosis and treatment of various diseases. Therefore, leveraging the exceptional properties of microalgae for drug delivery and optimizing their qualities is of paramount importance. This article focuses on elucidating the biological characteristics of microalgae and their applications in drug delivery, with a particular emphasis on emerging strategies for efficient drug loading and precise targeted delivery. Microalgae, as a natural biomaterial, hold immense potential for both commercial and clinical applications.

The study proposes a fluid simulation and analysis of oxygenated membrane fabrics for Extracorporeal Membrane Oxygenation (ECMO) by applying knitting technology from the field of textile technology. This is aimed at addressing the lack of research on the impact of the oxygenator flow field before and after knitting of oxygenated membrane fabrics. For this investigation, a commercial oxygenator was selected, featuring a polymethylpentene (PMP) hollow fiber membrane as the oxygenator membrane material, along with a knitted yarn made of a 50D/24F polyester low-elasticity filament. The knitting organization utilized warp knitting technology with a pillar stitch/weft lining structure. Through the integration of theoretical geometric modeling and finite element analysis method of flow-solid coupling, the study examined the influence of knitting on the oxygenator before and after the knitting of the PMP membrane material. Extracorporeal membrane oxygenation (ECMO) technology represents a sophisticated equipment within the domain of in vitro medical treatment. The research findings indicated that the total pressure drop in the oxygenator's flow field was 472.6 Pa for the unknitted PMP membrane and 269.4 Pa for the knitted oxygenator fabric, signifying a near 40% reduction in pressure with the knitted PMP membrane. This reduction in pressure also led to a 50% decrease in turbulence within the flow field. The maximum displacement of the knitted PMP membrane within the flow field was measured at 0.16 mm, whereas the unknitted membrane displayed a maximum displacement of 0.37 mm. The knitted PMP membrane significantly enhanced the pressure and velocity uniformity of the oxygenator's flow field, resulting in decreased stress-strain effects and improved service life of the oxygenator. In conclusion, the study illustrates that knitting the PMP membrane can substantially improve the flow field distribution of ECMO oxygenators, leading to enhanced oxygenation efficiency and membrane durability. [ABSTRACT FROM AUTHOR]

The text discusses the feasibility of developing an anticoagulation-free artificial placenta device to improve outcomes for extremely premature infants. Current oxygenation systems face challenges related to blood clotting due to large surface areas, priming volumes, and non-uniform blood flow dynamics. Design considerations for future artificial placenta devices include scaling to patient size, utilizing surface coatings, exploring pumpless circuits, and optimizing blood flow paths. Microfluidic oxygenators show promise as next-generation technology, but further research is needed to determine their clinical feasibility. The development of an anticoagulation-free artificial placenta requires a multidisciplinary approach and a combination of strategies to enhance hemocompatibility. [Extracted from the article]

OBJECTIVES This study aimed to determine the oxygenator impact on alterations of remdesivir (RDV) in a contemporary neonatal/pediatric (1/4-inch) and adolescent/adult (3/8-inch) extracorporeal membrane oxygenation (ECMO) circuit including the Quadrox-i oxygenator. METHODS One-quarter--inch and a 3/8-inch, simulated closed-loop ECMO circuits were prepared with a Quadrox-i pediatric and Quadrox-i adult oxygenator and blood primed. Additionally, 1/4-inch and 3/8-inch circuits were also prepared without an oxygenator in series. A 1-time dose of RDV was administered into the circuits and serial preoxygenator and postoxygenator concentrations were obtained at 0 to 5 minutes, and 1-, 2-, 3-, 4-, 5-, 6-, 8-, 12-, and 24-hour time points. The RDV was also maintained in a glass vial and samples were taken from the vial at the same time periods for control purposes to assess for spontaneous drug degradation. RESULTS For the 1/4-inch circuits with an oxygenator, there was a 35% to 60% RDV loss during the study period. For the 1/4-inch circuits without an oxygenator, there was a 5% to 20% RDV loss during the study period. For the 3/8-inch circuit with and without an oxygenator, there was a 60% to 70% RDV loss during the study period. CONCLUSIONS There was RDV loss within the circuit during the study period and the RDV loss was more pronounced with the larger 3/8-inch circuit when compared with the 1/4-inch circuit. The impact of the oxygenator on RDV loss appears to be variable and possibly dependent on the size of the circuit and oxygenator. These preliminary data suggest RDV dosing may need to be adjusted for concern of drug loss via the ECMO circuit. Additional single- and multiple-dose studies are needed to validate these findings. [ABSTRACT FROM AUTHOR]

The aim of the study. To study the effect of high nitric oxide concentrations on hollow polypropylene fibers of oxygenators.Materials and methods. The study was conducted in two stages. At the first stage, we evaluated the stability of oxygenator membrane made of hollow polypropylene fibers after six hours of exposure to air-oxygen mixture containing NO at 500 parts per million, or 500 pro pro mille (ppm) concentration, using mass spectrometry and infrared spectroscopy. At the second stage, an experiment with cardiopulmonary bypass (CPB) was conducted on 10 pigs. In the study group (n=5) animals sweep gas was supplied to the oxygenator as an air-oxygen mixture with NO at 100 ppm. In the control group animals (n=5) an air-oxygen mixture was used without NO. The CPB lasted for 4 hours, followed by observation for 12 hours. NO, NO2 (at the inlet and outlet of the oxygenator), and the dynamics of methemoglobin were evaluated. After weaning of animals from CPB, the oxygenators were tested for leakproofness, and scanning electron microscopy (SEM) was performed.Results. The oxygenator made of polypropylene hollow fibers retained its gas transfer parameters after six hours of exposure to air-oxygen mixture containing NO at 500 ppm. Based on IR-Fourier spectroscopy findings, NO did not affect structural integrity of polypropylene membranes. NO added to gas mixture at 100 ppm did not increase NO2 to toxic level of 2 ppm in 91% of control tests during 4 hours CPB in pigs; mean value was 1.58 ± 0.28 ppm. Methemoglobin concentration did not exceed the upper limit of permissible level (3%), and there were no statistically significant differences with the control group. All tested oxygenators have passed the leakproofness test. According to SEM findings, larger amounts of fibrin deposits were found in the control group oxygenators vs study group.Conclusion. There were no negative effects of NO at 500 ppm concentration on the oxygenator membrane made of hollow polypropylene fibers. NO at 100 ppm in a gas-mixture supplied to oxygenators did not lead to an exceedance of safe NO2 and methemoglobin concentrations in an animal model. Reduced fibrin deposits on hollow fibers of polypropylene oxygenator membranes were observed when with NO at a level of 100 ppm was added to a gas mixture.

Small animal models are widely used in basic research. However, experimental hydrodynamic test benches, which include extracorporeal circuits, often have limitations associated with the size and filling volume of equipment. Thus, we aimed at developing and validating a miniature oxygenator as well as a low-volume hydrodynamic system for ex vivo perfusion of small animal lungs. A series of low-volume membrane oxygenators (n = 10) with 90–100 aligned microporous polypropylene hollow fibers, placed inside a sheath that is sealed at both ends to isolate the perfusing solution, was designed and manufactured. This design makes gas to flow through the hollow fibers and perfusate to circulate around the fibers. A low-volume hydrodynamic test bench was designed and assembled for isolated ex vivo lung perfusion and for evaluation of the performance characteristics of the oxygenators: gas and perfusate flow, perfusion pressure and temperature at 5–70 ml/min flow range.

The article proposes a new, interspecies interpretation of Joanna Rajkowska’s Oxygenator. Read as what Anna Tsing calls latent commons and problematized through Chantal Mouffe’s concept of agonistic spaces, the canonical piece of public art is shown to have been an experimental site of more-than-human resurgence.

Simple Summary: Animal experiments are essential for the development and optimization of innovative biomedical soft- or hardware. These technologies, not least in the field of intensive care, contribute to an enhanced quality of care and chances of survival. One prominent example that gained public attention due to the COVID-19 pandemic is extracorporeal membrane oxygenation, in short ECMO, as it supports the heart and lungs during severe disease. Even though ECMO is already in use, the components, e.g., the oxygenator that acts as an artificial lung, need further improvement. The basic functions of new devices, e.g., the oxygenation performance, do not necessarily require living animals for the evaluation; therefore, the present study aimed to develop a post-mortem rat cadaver perfusion model exclusively using surplus animals, e.g., from in-house breeding, to reduce the number of animals used for these models, according to the animal welfare principle (the 3Rs: Replace, Reduce, Refine). It was shown that the established rat cadaver model allowed organ perfusion for up to eight hours, making it a promising model for testing new biomedical technology and, thus, a welfare-friendly alternative for existing living rat perfusion models. The development of biomedical soft- or hardware frequently includes testing in animals. However, large efforts have been made to reduce the number of animal experiments, according to the 3Rs principle. Simultaneously, a significant number of surplus animals are euthanized without scientific necessity. The primary aim of this study was to establish a post-mortem rat perfusion model using extracorporeal membrane oxygenation (ECMO) in surplus rat cadavers and generate first post vivo results concerning the oxygenation performance of a recently developed ECMO membrane oxygenator. Four rats were euthanized and connected post-mortem to a venous–arterial ECMO circulation for up to eight hours. Angiographic perfusion proofs, blood gas analyses and blood oxygenation calculations were performed. The mean preparation time for the ECMO system was 791 ± 29 s and sufficient organ perfusion could be maintained for 463 ± 26 min, proofed via angiographic imaging and a mean femoral arterial pressure of 43 ± 17 mmHg. A stable partial oxygen pressure, a 73% rise in arterial oxygen concentration and an exponentially increasing oxygen extraction ratio up to 4.75 times were shown. Considering the 3Rs, the established post-mortal ECMO perfusion rat model using surplus animals represents a promising alternative to models using live animals. Given the preserved organ perfusion, its use could be conceivable for various biomedical device testing. [ABSTRACT FROM AUTHOR]

Membrane artificial lungs (oxygenators) are used in cardiopulmonary surgery as well as, in some cases, in severe lung disease to support the natural lung by means of ECMO (extracorporeal membrane oxygenation). The oxygen and carbon dioxide transfer rates of any oxygenator are usually assessed by considering several blood gas parameters, such as oxygen saturation, hemoglobin concentration, partial pressure of oxygen and carbon dioxide, bicarbonate concentration, and p H . Here, we report a set of semi-empirical equations that calculate such parameters directly from their partial pressures and assess the acid–base balance during ECMO. The implementation of this equation set permits the evaluation of any oxygenator, existing or prototypes in development, as well as the development of clinical decision-making tools for predicting the blood gas state and acid–base balance during surgical interventions and ECMO. The predicted results are then compared with experimental data obtained from in vitro gas exchange investigations with a commercial oxygenator using fresh porcine blood. The high correlation, R 2 > 0.95 , between the predicted and the experimental data suggests a possibility of using such empirical equations in the simulation of gas transfer in a cardiopulmonary system with an oxygenator for any venous inlet blood gas data and also for estimating the acid–base balance during such therapy. [ABSTRACT FROM AUTHOR]

The overall survival rate of extracorporeal life support (ECLS) remains at 60%. Research and development has been slow, in part due to the lack of sophisticated experimental models. This publication introduces a dedicated rodent oxygenator ("RatOx") and presents preliminary in vitro classification tests. The RatOx has an adaptable fiber module size for various rodent models. Gas transfer performances over the fiber module for different blood flows and fiber module sizes were tested according to DIN EN ISO 7199. At the maximum possible amount of effective fiber surface area and a blood flow of 100 mL/min, the oxygenator performance was tested to a maximum of 6.27 mL O2/min and 8.2 mL CO2/min, respectively. The priming volume for the largest fiber module is 5.4 mL, while the smallest possible configuration with a single fiber mat layer has a priming volume of 1.1 mL. The novel RatOx ECLS system has been evaluated in vitro and has demonstrated a high degree of compliance with all pre-defined functional criteria for rodent-sized animal models. We intend for the RatOx to become a standard testing platform for scientific studies on ECLS therapy and technology. [ABSTRACT FROM AUTHOR]

Towards the establishment of a long-term lung-assist device to be used both as a bridge and as an alternative to lung transplantation according to final destination therapy, we develop the biohybrid lung (BHL) on the technical basis of contemporary extracorporeal membrane oxygenation (ECMO). Here, to overcome the significant drawbacks of ECMO, in particular the missing hemocompatibility of the artificial surfaces, all blood-contacting areas need to be endothelialized sufficiently. In continuation of our recent accomplishments, demonstrating the feasibility of establishing a physiological acting endothelial cell (EC) monolayer on the hollow fiber membranes (HFMs) of the ECMO in vitro, the next step towards BHL translation is the endothelialization of the complete oxygenator, consisting of HFMs and the surrounding housing. Therefore, we assessed EC seeding inside our model oxygenator (MOx), which simulated the conditions in the assembled HFM oxygenators in order to identify the most important factors influencing efficient endothelialization, such as cell seeding density, cell distribution, incubation time and culture medium consumption. Overall, upon adjusting the concentration of infused ECs to 15.2 × 104/cm2 and ensuring optimal dispersion of cells in the MOx, viable and confluent EC monolayers formed on all relevant surfaces within 24 h, even though they comprised different polymers, i.e., the fibronectin-coated HFMs and the polysulfone MOx housing. Periodic medium change ensured monolayer survival and negligible apoptosis rates comparable to the reference within the assembled system. By means of these results, revealing essential implications for BHL development, their clinical translation is coming one step closer to reality. [ABSTRACT FROM AUTHOR]

Extracorporeal membrane oxygenation (ECMO) is an important rescue therapy method for the treatment of severe hypoxic lung injury. In some cases, oxygen saturation and oxygen partial pressure in the arterial blood are low despite ECMO therapy. There are case reports in which patients with such instances of refractory hypoxemia received a second membrane lung, either in series or in parallel, to overcome the hypoxemia. It remains unclear whether the parallel or serial connection is more effective. Therefore, we used an improved version of our full-flow ECMO mock circuit to test this. The measurements were performed under conditions in which the membrane lungs were unable to completely oxygenate the blood. As a result, only the photometric pre- and post-oxygenator saturations, blood flow and hemoglobin concentration were required for the calculation of oxygen transfer rates. The results showed that for a pre-oxygenator saturation of 45% and a total blood flow of 10 L/min, the serial connection of two identical 5 L rated oxygenators is 17% more effective in terms of oxygen transfer than the parallel connection. Although the idea of using a second membrane lung if refractory hypoxia occurs is intriguing from a physiological point of view, due to the invasiveness of the solution, further investigations are needed before this should be used in a wider clinical setting.

The use of extracorporeal oxygenation and CO2 removal has gained clinical validity and popularity in recent years. These systems are composed of a pump to drive blood flow through the circuit and a hollow fiber membrane bundle through which gas exchange is achieved. Mathematical modeling of device design is utilized by researchers to improve device hemocompatibility and efficiency. A previously published mathematical model to predict CO2 removal in hollow fiber membrane bundles was modified to include an empirical representation of the Haldane effect. The predictive capabilities of both models were compared to experimental data gathered from a fiber bundle of 7.9 cm in length and 4.4 cm in diameter. The CO2 removal rate predictions of the model including the Haldane effect reduced the percent error between experimental data and mathematical predictions by up to 16%. Improving the predictive capabilities of computational fluid dynamics for the design of hollow fiber membrane bundles reduces the monetary and manpower expenses involved in designing and testing such devices. [ABSTRACT FROM AUTHOR]

Resumen: Una placenta artificial es una plataforma de soporte vital para bebés prematuros o que tuvieron menos de 37 semanas de gestación completa. Aunque existe la posibilidad de utilizar esta plataforma para la reparación intraoperatoria de anomalías congénitas (p. ej., hernia diafragmática congénita) en bebés prematuros tardíos, o para el estudio del desarrollo fetal, el objetivo principal de esta tecnología es actualmente el tratamiento de bebés extremadamente prematuros, o aquellos nacidos durante el período peri-viable entre las 21-24 semanas de gestación completa.Los bebés que nacen en este período peri-viable, generalmente tienen malos resultados debido a la necesidad de ventilar mecánicamente sus pulmones extremadamente inmaduros, a menudo a altas presiones máximas. Las plataformas de soporte vital basadas en placenta artificial están diseñadas para evitar la necesidad de ventilar como un medio para facilitar el intercambio de gases y así evitar lesiones en el pulmón prematuro inmaduro. En cambio, el intercambio de gases altamente eficiente y fácilmente regulado se realiza mediante dispositivos de intercambio de gases conectados a la vasculatura fetal. Dependiendo de la forma del sistema utilizado, se han probado diseños de circuitos venoso-venosos y arterio-venosos, con los prototipos arterio-venosos más recientes que utilizan el corazón fetal, en lugar de una bomba externa, para generar la presión del circuito.A pesar de tener la apariencia de un concepto futurista, el trabajo de desarrollar una placenta artificial se ha llevado a cabo de forma intermitente desde al menos finales de los años 50. El hecho de que la tecnología aún no haya entrado en servicio clínico, a pesar de que han pasado más de 60 años, refleja los desafíos técnicos que rodean el desarrollo y uso de la placenta artificial. Esta demora en la introducción también refleja el panorama cambiante de la atención neonatal y, en particular, los avances en la ventilación mecánica y los modos de soporte respiratorio no invasivo, como la presión positiva continua en las vías respiratorias, la introducción de esteroides prenatales y la disponibilidad de terapia con surfactante exógeno.Como tal, es razonable argumentar que el grupo demográfico objetivo para la tecnología de placenta artificial ha cambiado significativamente desde que comenzó su desarrollo. Los bebés que antes se consideraban peri-viables y probables candidatos para la terapia con placenta artificial (es decir, los que nacieron antes de las 28 semanas de gestación) ahora tienen tasas mucho mejores de supervivencia libre de enfermedad con la tecnología disponible en la actualidad. El grupo demográfico con los peores resultados, y los posibles candidatos para la terapia de placenta artificial contemporánea, son aquellos nacidos de embarazos significativamente comprometidos (por ejemplo, infección intrauterina, sepsis, preeclampsia severa, insuficiencia placentaria severa) a las 21-24 semanas de gestación y con un peso de aprox. 300 gramos.Este artículo proporcionará una revisión del historial de desarrollo de la placenta artificial, un resumen de la situación actual y concluirá discutiendo los desafíos restantes que deberán abordarse antes de que esta tecnología pueda introducirse en la práctica clínica. Summary: An artificial placenta is a life support platform for babies born preterm, or prior to 37 weeks’ completed gestation. Although there is potential to use this platform for the intraoperative repair of congenital abnormalities (e.g. congenital diaphragmatic hernia) in late preterm babies, or for the study of fetal development, the primary target for this technology is currently treatment of extremely preterm infants, or those delivered during the peri-viable period between 21-24 weeks’ completed gestation.Babies born in this peri-viable period generally have poor outcomes due to the need to mechanically ventilate their extremely immature lungs–often at high peak pressures. Artificial placenta-based life support platforms are designed to obviate the need to ventilate as a means of facilitating gas exchange, and thus avoid injury to the immature preterm lung. Instead, highly efficient, and easily regulated gas exchange is performed by gas-exchange devices connected to the fetal vasculature. Depending on the form of the system used, venous-venous and arterio-venous circuit designs have been trialled, with the more recent arterio-venous prototypes using the fetal heart, rather than an external pump, to generate circuit pressure.Despite having the appearance of a futuristic concept, work to develop an artificial placenta has been undertaken intermittently since at least the late 1950s. That the technology is yet to enter clinical service, despite 60-plus years of work, reflects the technical challenges surrounding the development and use of the artificial placenta. This delay in introduction also reflects the changing neonatal care landscape, and notably advances in mechanical ventilation and non-invasive respiratory support modes such as continuous positive airway pressure, the introduction of antenatal steroids, and the availability of exogenous surfactant therapy.As such, it is reasonable to argue that the target demographic for artificial placenta technology has changed significantly since development first began. Babies once considered peri-viable and a probable candidate for artificial placenta therapy (i.e. those born below 28 weeks’ gestation) now have much improved rates of disease-free survival using currently available technology. The demographic with the poorest outcomes, and the likely candidates for contemporary artificial placenta therapy, are those born from significantly compromised pregnancies (e.g. intrauterine infection, sepsis, severe pre-eclampsia, severe placental insufficiency) at 21-24 weeks’ gestation and weighing as little as 300 grams.This paper will provide a review of the development history of the artificial placenta, a summary of the current state-of-play, and conclude by discussing the remaining challenges that will need to be addressed before this technology might be introduced to clinical practice.

The recent demonstration of normal development of preterm sheep in an artificial extrauterine environment has renewed interest in artificial placenta (AP) systems as a potential treatment strategy for extremely preterm human infants. However, the feasibility of translating this technology to the human preterm infant remains unknown. Here we report the support of 13 preterm fetal pigs delivered at 102 ± 4 days (d) gestation, weighing 616 ± 139 g with a circuit consisting of an oxygenator and a centrifugal pump, comparing these results with our previously reported pumpless circuit (n = 12; 98 ± 4 days; 743 ± 350 g). The umbilical vessels were cannulated, and fetuses were supported for 46.4 ± 46.8 h using the pumped AP versus 11 ± 13 h on the pumpless AP circuit. Upon initiation of AP support on the pumped system, we observed supraphysiologic circuit flows, tachycardia, and hypertension, while animals maintained on a pumpless AP circuit exhibited subphysiologic flows. On the pumped AP circuit, there was a progressive decline in umbilical vein (UV) flow and oxygen delivery. We conclude that the addition of a centrifugal pump to the AP circuit improves survival of preterm pigs by augmenting UV flow through the reduction of right ventricular afterload. However, we continued to observe the development of heart failure within a matter of days. [ABSTRACT FROM AUTHOR]

The recent demonstration of normal development of preterm sheep in an artificial extrauterine environment has renewed interest in artificial placenta (AP) systems as a potential treatment strategy for extremely preterm human infants. However, the feasibility of translating this technology to the human preterm infant remains unknown. Here we report the support of 13 preterm fetal pigs delivered at 102 ± 4 days (d) gestation, weighing 616 ± 139 g with a circuit consisting of an oxygenator and a centrifugal pump, comparing these results with our previously reported pumpless circuit (n = 12; 98 ± 4 days; 743 ± 350 g). The umbilical vessels were cannulated, and fetuses were supported for 46.4 ± 46.8 h using the pumped AP versus 11 ± 13 h on the pumpless AP circuit. Upon initiation of AP support on the pumped system, we observed supraphysiologic circuit flows, tachycardia, and hypertension, while animals maintained on a pumpless AP circuit exhibited subphysiologic flows. On the pumped AP circuit, there was a progressive decline in umbilical vein (UV) flow and oxygen delivery. We conclude that the addition of a centrifugal pump to the AP circuit improves survival of preterm pigs by augmenting UV flow through the reduction of right ventricular afterload. However, we continued to observe the development of heart failure within a matter of days.

Volatile anesthetics (VAs) protect myocardial cells during cardiovascular surgeries, including cardiopulmonary bypass (CPB). In CPB, blood is gradually transferred from the body to a CPB unit until the target cardiac index is achieved, following which human lung (HL) ventilation is stopped. This pilot study aimed to evaluate changes in the blood sevoflurane concentrations 5 min after the start of CPB when its delivery to the oxygenator began after HL ventilation with sevoflurane was completed. Six patients were recruited and participated in this study. For each patient, the equilibrated blood sample, collected 20 min after starting the delivery of 1.7% sevoflurane (HL group), and another blood sample, collected 5 min after starting the CPB, were analyzed using gas chromatography equipped with a flame ionization detector. The mean (± standard deviation) sevoflurane concentrations in the HL and 5 min after starting CPB groups were 58.6 ± 4.7 and 14.5 ± 5.0 μg/ml, respectively (P < 0.01). In conclusion, the equilibrated blood sevoflurane concentrations showed a rapid decrease when switching from sevoflurane ventilation for the HL to CPB unless it was introduced to the oxygenator until completion of the switch. [ABSTRACT FROM AUTHOR]

Copyright of Revista Médica Clínica Las Condes is the property of Editorial Sanchez y Barcelo and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper proposes a mathematical model for online prediction of the hematocrit- and temperature-based normal blood viscosity during cardiopulmonary bypass (CPB). Clinical trials were performed using a previously developed continuous blood viscosity monitoring system, and continuous pressure- and flow-based instantaneous viscosity (ηe) data were collected from 40 patients subjected to mild to moderate hypothermic CPB. The hematocrit and blood temperature data corresponding to ηe were also acquired. It was found that the blood viscosity-temperature curves for the different hematocrit levels can be well fitted using linear models, with the parameters of the linear model (slopes and intersects) also exhibiting linear relationships with the hematocrit. Based on these relationships, we were able to predict the hematocrit- and temperature-based normal viscosity (η0). To test the prediction accuracy, η0 was compared with ηe using the leave-one-out cross-validation procedure. Furthermore, η0 and the offline-measured viscosity (η), determined using a conventional viscometer, were compared for 20 patients subjected to mildly hypothermic CPB. η0 and ηe-two online blood viscosity monitoring methods based on different principles-showed good agreement (R2 = 0.74 and p 0 and η also showed good agreement (R2 = 0.69 and p

We present a 62-year-old patient with COVID-19 pneumonia on Veno-venous (VV) Extracorporeal Membrane Oxygenation (ECMO) with unique perturbations to pre and post oxygenator pressures due to fibrin deposition in despite being on a Heparin/Bivalirudin infusion and activated Partial Thromboplastin Time (aPTT) within therapeutic range of 60-80 seconds. On Day 8 of ECMO support, it was noticed that flows steadily decreased despite unchanged RPMs. Unlike typical blood flow to circuit pressure relationships, the circuit pressures did not correlate with the observed decreased flow. The Delta Pressure (ΔP) was not elevated. The patient's vitals were stable. On inspection post change-out, clots were noted in the oxygenator outlets. Oxygenator clots are usually associated with increased ΔP. In this scenario, clots in the oxygenator blocked 1 of the 4 outlets in the oxygenator causing the flow, pressures, and ΔP to drop consecutively. Due to reduced flow, the ΔP was not elevated despite extensive clots. The fibrin clot location in the CardioHelp ECMO circuit may lead to unexpected pressure and flow alterations. Sole reliance on ΔP as a marker for oxygenator clots may be misleading. Careful monitoring and timely diagnosis of coagulation status may lead to changes in anticoagulation goals and meaningfully impact patient outcomes. [ABSTRACT FROM AUTHOR]

Key points: The margin of human viability has extended to the extremes of gestational age (<24 weeks) when the lungs are immature and ventilator‐induced lung injury is common.Artificial placenta technology aims to extend gestation ex utero in order to allow the lungs additional time to develop prior to entering an air‐breathing environment.We compared the haemodynamics and cerebral oxygenation of piglets in the immediate period post‐oxygenator (OXY) transition against both paired in utero measures and uniquely against piglets transitioned onto mechanical ventilation (VENT).Post‐transition, OXY piglets became hypotensive with reduced carotid blood flow in comparison with both paired in utero measures and VENT piglets.The addition of a pump to the oxygenator circuit may be required to ensure haemodynamic stability in the immediate post‐transition period. Gestational age at birth is a major predictor of wellbeing; the lower the gestational age, the greater the risk of mortality and morbidity. At the margins of human viability (<24 weeks gestation) immature lungs combined with the need for early ventilatory support means lung injury and respiratory morbidity is common. The abrupt haemodynamic changes consequent on birth may also contribute to preterm‐associated brain injury, including intraventricular haemorrhage. Artificial placenta technology aims to support oxygenation, haemodynamic stability and ongoing fetal development ex utero until mature enough to safely transition to a true ex utero environment. We aimed to characterize the impact of birth transition onto either an oxygenator circuit or positive pressure ventilation on haemodynamic and cerebral oxygenation of the neonatal piglet. At 112 days gestation (term = 115 days), fetal pigs underwent instrumentation surgery and transitioned onto either an oxygenator (OXY, n = 5) or ventilatory support (VENT, n = 8). Blood pressure (BP), carotid blood flow and cerebral oxygenation in VENT piglets rose from in utero levels to be significantly higher than OXY piglets post‐transition. OXY piglet BP, carotid blood flow and carotid oxygen delivery (DO2) decreased from in utero levels post‐transition; however, cerebral regional oxygen saturation (rSO2) was maintained at fetal‐like levels. OXY piglets became hypoxaemic and retained CO2. Whether OXY piglets are able to maintain cerebral rSO2 under these conditions for a prolonged period is yet to be determined. Improvements to OXY piglet oxygenation may lie in maintaining piglet BP at in utero levels and enhancing oxygenator circuit flow. Key points: The margin of human viability has extended to the extremes of gestational age (<24 weeks) when the lungs are immature and ventilator‐induced lung injury is common.Artificial placenta technology aims to extend gestation ex utero in order to allow the lungs additional time to develop prior to entering an air‐breathing environment.We compared the haemodynamics and cerebral oxygenation of piglets in the immediate period post‐oxygenator (OXY) transition against both paired in utero measures and uniquely against piglets transitioned onto mechanical ventilation (VENT).Post‐transition, OXY piglets became hypotensive with reduced carotid blood flow in comparison with both paired in utero measures and VENT piglets.The addition of a pump to the oxygenator circuit may be required to ensure haemodynamic stability in the immediate post‐transition period. [ABSTRACT FROM AUTHOR]

To remove gaseous microemboli (GME) using an oxygenator with an integrated arterial filter, it is recommended by some manufacturers to purge the oxygenator as an additional safety feature while on bypass. In this in vitro study, we evaluated whether purging of oxygenators with an integrated arterial filter is efficient in reducing GME. Five different types of commercially available contemporary oxygenators with an integrated arterial filter based on progressive filter filtration (1), cascade filtration (1), screen filtration (2), or self-venting (1) were tested for their efficiency in removing GME while keeping the purge line open or closed. A bubble counter was used for pre- and post-oxygenator GME signaling, from which the filter efficiency was computed. Freshly drawn heparinized porcine blood was used at blood flow rates of 3 and 5 L/min. Three units of each oxygenator were tested with its specific reservoir at a fixed volume level of 1,500 mL. GME load was introduced into the venous line at 1,000 mL air/min. Measurements started as soon as GME were detected by the pre-oxygenator probe and then continued for 1 minute. There was no statistically significant difference in filter efficiency between the purged and nonpurged groups for specific oxygenators. At a blood flow of 3 L/min, the average filter efficiency stayed approximately invariable when comparing the non-purged and purged groups, where 89.1-88.2% indicated the largest difference between the groups. At a blood flow rate of 5 L/min, the filter efficiency changed in one screen filter group from an average of 55.7% in the nonpurged group to 42.4% in the purged group. Other filter efficiencies at the blood flow rate of 5 L/min for non-purged compared with purged groups were, respectively, 98.0 vs. 98.0% (screen filtration), 88.6 vs. 85.8% (self-venting filtration), 82.8 vs. 75.5% (progressive filter filtration), and 65.4 vs. 65.1% (cascade filtration). Based on these results, purging while confronted with continuous GME challenge did not result in an increased filter efficiency. [ABSTRACT FROM AUTHOR]

Carbon monoxide (CO) poisoning is the leading cause of poisoning-related deaths globally. The currently available therapy options are normobaric oxygen (NBO) and hyperbaric oxygen (HBO). While NBO lacks in efficacy, HBO is not available in all areas and countries. We present a novel method, extracorporeal hyperoxygenation therapy (EHT), for the treatment of CO poisoning that eliminates the CO by treating blood extracorporeally at elevated oxygen partial pressure. In this study, we proof the principle of the method in vitro using procine blood: Firstly, we investigated the difference in the CO elimination of a hollow fibre membrane oxygenator and a specifically designed batch oxygenator based on the bubble oxygenator principle at elevated pressures (1, 3 bar). Secondly, the batch oxygenator was redesigned and tested for a broader range of pressures (1, 3, 5, 7 bar) and temperatures (23, 30, 37 °C). So far, the shortest measured carboxyhemoglobin half-life in the blood was 21.32 min. In conclusion, EHT has the potential to provide an easily available and effective method for the treatment of CO poisoning.

The recent emergence of microfluidic extracorporeal lung support technologies presents an opportunity to achieve high gas transfer efficiency and improved hemocompatibility relative to the current standard of care in extracorporeal membrane oxygenation (ECMO). However, a critical challenge in the field is the ability to scale these devices to clinically relevant blood flow rates, in part because the typically very low blood flow in a single layer of a microfluidic oxygenator device requires stacking of a logistically challenging number of layers. We have developed biomimetic microfluidic oxygenators for the past decade and report here on the development of a high-flow (30 mL/min) single-layer prototype, scalable to larger structures via stacking and assembly with blood distribution manifolds. Microfluidic oxygenators were designed with biomimetic in-layer blood distribution manifolds and arrays of parallel transfer channels, and were fabricated using high precision machined durable metal master molds and microreplication with silicone films, resulting in large area gas transfer devices. Oxygen transfer was evaluated by flowing 100% O2 at 100 mL/min and blood at 0–30 mL/min while monitoring increases in O2 partial pressures in the blood. This design resulted in an oxygen saturation increase from 65% to 95% at 20 mL/min and operation up to 30 mL/min in multiple devices, the highest value yet recorded in a single layer microfluidic device. In addition to evaluation of the device for blood oxygenation, a 6-h in vitro hemocompatibility test was conducted on devices (n = 5) at a 25 mL/min blood flow rate with heparinized swine donor blood against control circuits (n = 3). Initial hemocompatibility results indicate that this technology has the potential to benefit future applications in extracorporeal lung support technologies for acute lung injury.

The large, densely packed artificial surface area of artificial lungs results in rapid clotting and device failure. Surface generated nitric oxide (NO) can be used to reduce platelet activation and coagulation on gas exchange fibers, while not inducing patient bleeding due to its short half-life in blood. To generate NO, artificial lungs can be manufactured with PDMS hollow fibers embedded with copper nanoparticles (Cu NP) and supplied with an infusion of the NO donor S-nitroso-N-acetyl-penicillamine (SNAP). The SNAP reacts with Cu NP to generate NO. This study investigates clot formation and gas exchange performance of artificial lungs with either NO-generating Cu-PDMS or standard polymethylpentene (PMP) fibers. One miniature artificial lung (MAL) made with 10 wt% Cu-PDMS hollow fibers and one PMP control MAL were attached to sheep in parallel in a veno-venous extracorporeal membrane oxygenation circuit (n = 8). Blood flow through each device was set at 300 mL/min, and each device received a SNAP infusion of 0.12 μmol/min. The ACT was between 110 and 180 s in all cases. Blood flow resistance was calculated as a measure of clot formation on the fiber bundle. Gas exchange experiments comparing the two groups were conducted every 24 h at blood flow rates of 300 and 600 mL/min. Devices were removed once the resistance reached 3x baseline (failure) or following 72 h. All devices were imaged using scanning electron microscopy (SEM) at the inlet, outlet, and middle of the fiber bundle. The Cu-PDMS NO generating MALs had a significantly smaller increase in resistance compared to the control devices. Resistance rose from 26 ± 8 and 23 ± 5 in the control and Cu-PDMS devices, respectively, to 35 ± 8 mmHg/(mL/min) and 72 ± 23 mmHg/(mL/min) at the end of each experiment. The resistance and SEM imaging of fiber surfaces demonstrate lower clot formation on Cu-PDMS fibers. Although not statistically significant, oxygen transfer for the Cu-PDMS MALs was 13.3% less than the control at 600 mL/min blood flow rate. Future in vivo studies with larger Cu–PDMS devices are needed to define gas exchange capabilities and anticoagulant activity over a long-term study at clinically relevant ACTs. In artificial lungs, the large, densely-packed blood contacting surface area of the hollow fiber bundle is critical for gas exchange but also creates rapid, surface-generated clot requiring significant anticoagulation. Monitoring of anticoagulation, thrombosis, and resultant complications has kept permanent respiratory support from becoming a clinical reality. In this study, we use a hollow fiber material that generates nitric oxide (NO) to prevent platelet activation at the blood contacting surface. This material is tested in vivo in a miniature artificial lung and compared against the clinical standard. Results indicated significantly reduced clot formation. Surface-focused anticoagulation like this should reduce complication rates and allow for permanent respiratory support by extending the functional lifespan of artificial lungs and can further be applied to other medical devices. [ABSTRACT FROM AUTHOR]

Blood Flow Adjustment through the Artificial Placenta to Account for Individual Extracorporea... Our miniaturized oxygenators for the artificial placenta are modular in nature and allow us to adapt the device size to the needs of each individual infant. Instead of applying positive pressure ventilation to newborn lungs which disrupts or impairs the lung growth and development required for normal adult life our artificial placenta will provide the desired extrapulmonary gas exchange giving lungs time to heal or to catch-up. Keywords: artificial placenta; blood oxygenation; oxygenator; respiratory distress EN artificial placenta blood oxygenation oxygenator respiratory distress 1 3 3 06/26/21 20210623 NES 210623 The goal of our manuscript "A Pumpless Microfluidic Neonatal Lung Assist Device for Support of Preterm Neonates in Respiratory Distress" is to present the first successful application of a microfluidic, artificial placenta type neonatal lung assist device in a newborn piglet model. [Extracted from the article]

Cardiopulmonary bypass (CPB) provides a bloodless field for cardiac surgery. It incorporates an extracorporeal circuit to provide physiological support in which venous blood is drained to a reservoir, oxygenated and sent back to the body using a pump. Team effort between surgeon, perfusionist and anaesthesiologist is paramount for the successful use of CPB. However, it also has its share of complications and strategies to reduce these complications are the area of the current research.

In this work a microfluidic cell cultivation device for perfused hypoxia assays as well as a suitable controlling unit are presented. The device features active components like pumps for fluid actuation and valves for fluid direction as well as an oxygenator element to ensure a sufficient oxygen transfer. It consists of several individually structured layers which can be tailored specifically to the intended purpose. Because of its clearness, its mechanical strength and chemical resistance as well as its well-known biocompatibility polycarbonate was chosen to form the fluidic layers by thermal diffusion bonding. Several oxygen sensing spots are integrated into the device and monitored with fluorescence lifetime detection. Furthermore an oxygen regulator module is implemented into the controlling unit which is able to mix different process gases to achieve a controlled oxygenation. First experiments show that oxygenation/deoxygenation of the system is completed within several minutes when pure nitrogen or air is applied to the oxygenator. Lastly the oxygen input by the pneumatically driven micro pump was quantified by measuring the oxygen content before and after the oxygenator.

Extracorporeal Membrane Oxygenation (ECMO) is a resource intensive, life-preserving support system that has seen ever-expanding clinical indications as technology and collective experience has matured. Clinicians caring for patients who develop pulmonary failure secondary to cardiac failure can find themselves in unique situations where traditional ECMO may not be the ideal clinical solution. Existing paracorporeal ventricular assist device (VAD) technology or unique patient physiologies offer the opportunity for thinking “outside the box.” Hybrid ECMO approaches include splicing oxygenators into paracorporeal VAD systems and alternative cannulation strategies to provide a staged approach to transition a patient from ECMO to a VAD. Alternative technologies include the adaptation of ECMO and extracorporeal CO2 removal systems for specific physiologies and pediatric aged patients. This chapter will focus on: (1) hybrid and alternative approaches to extracorporeal support for pulmonary failure, (2) patient selection and, (3) technical considerations of these therapies. By examining the successes and challenges of the relatively select patients treated with these approaches, we hope to spur appropriate research and development to expand the clinical armamentarium of extracorporeal technology.

Copyright of Medicina Neotloznyh Sostoanij is the property of Zaslavsky O.Yu and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Background: In this study, we have tried to demonstrate the effects of coating style used in oxygenators on various hematologic and clinical parameters. Materials and methods: Twenty-seven patients were included in the study, who had undergone operations because of elective coronary artery disease. Albumin-coated oxygenator was used in Group I. In Group II, a synthetic polypeptide-coated oxygenator was used. C1-inhib (complement), C3c, C4, interleukins (IL-1β, IL2, IL-6, IL-10), and tumor necrosis factor alpha (TNF-α) levels were examined at four different time intervals. Hemoglobin, hematocrit, leukocyte and platelet counts, drainage, and transfused blood volumes were analyzed. Results: Albumin levels were significantly lower in Group I than those in Group II 5 minutes after the removal of the cross-clamp. Twenty-four hours after the surgery, Group I patients also had a significantly higher white blood cell count compared to Group II patients. TNF-α levels in Group I were always expressed in considerably higher amounts than those in Group II. IL-6 levels were significantly higher in Group I, but IL-10 levels were observed to be higher in Group II (p