Clinical performance of microporous polypropylene hollow-fiber oxygenator

3D porous structure imaging of membranes for medical devices using scanning probe microscopy and electron microscopy: from membrane science points of view

The evolution of hemodialysis membranes (dialyzer, artificial kidney) was remarkable, since Dow Chemical began manufacturing hollow fiber hemodialyzers in 1968, especially because it involved industrial chemistry, including polymer synthesis and membrane manufacturing process. The development of hemodialysis membranes has brought about the field of medical devices as a major industry. In addition to conventional electron microscopy, scanning probe microscopy (SPM), represented by atomic force microscopy (AFM), has been used in membrane science research on porous membranes for hemodialysis, and membrane science contributes greatly to the hemodialyzer industry. Practical studies of membrane porous structure-function relationship have evolved, and methods for analyzing membrane cross-sectional morphology were developed, such as the ion milling method, which was capable of cutting membrane cross sections on the order of molecular size to obtain smooth surface structures. Recently, following the global pandemic of SARS-CoV-2 infection, many studies on new membranes for extracorporeal membrane oxygenator have been promptly reported, which also utilize membrane science researches. Membrane science is playing a prominent role in membrane-based technologies such as separation and fabrication, for hemodialysis, membrane oxygenator, lithium ion battery separators, lithium recycling, and seawater desalination. These practical studies contribute to the global medical devices industry.

A novel poly (4-methyl-1-pentene)/polypropylene (PMP/PP) thin film composite (TFC) artificial lung membrane for enhanced gas transport and excellent hemo-compatibility

Extracorporeal membrane oxygenation is a technique that provides short-term supports to the heart and lungs. It removes CO₂ from the blood and provides enough oxygen, which is a huge help in the fight against COVID-19. As the key component, the artificial lung membranes have evolved in three generations including silicon, polypropylene and poly (4-methyl-1-pentene). Herein, we for the first time design and fabricate a novel poly (4-methyl-1-pentene)/polypropylene (PMP/PP) thin film composite (TFC) membrane with the anticoagulant coating composed of poly (sodium 4-styrenesulfonate) and cross-linked poly (vinyl alcohol). Poly (sodium 4-styrenesulfonate) provides sulfonic acid groups to inhibit the coagulant factors (FVIII and FXII), and cross-linked poly (vinyl alcohol) increase the stability of the anticoagulant coating and further improve the hydrophilicity via abundant hydroxyl groups to depress the protein adsorption. Long-term anticoagulant property was demonstrated by whole human blood for 28 days. Blood compatibility was evaluated by hemolysis rate, anticoagulation activity (APTT, TT and PT), complement activation, platelet activation and contact activation. Pure CO₂, O₂ and N₂ permeation rates were determined to evaluate the mass transfer properties of PMP/PP TFC membranes. Gas permeation results revealed that gas permeation flux increased in the TFC membranes because of the decrease of crystallinity. Overall, the so prepared PMP/PP membrane shows good CO₂/O₂ selectivity and blood compatibility as novel TFC artificial lung membrane.

Volatile Anesthesia Versus Total Intravenous Anesthesia During Cardiopulmonary Bypass: A Narrative Review on the Technical Challenges and Considerations

The Mortality in Cardiac Surgery Randomized Controlled Trial of Volatile Anesthetics (MYRIAD) demonstrated that cardiac surgery with either volatile anesthesia or intravenous anesthesia techniques can be comparable with respect to morbidity and mortality. Maintaining anesthesia during cardiopulmonary bypass (CPB) with either approach requires appreciation of the nuances that are unique to each. This narrative review addresses these technical challenges and other considerations.

The evolution of extracorporeal life support as a bridge to lung transplantation

The use of extracorporeal membrane oxygenation (ECMO) as a bridge to lung transplantation was reported for the first time more than three decades ago; nevertheless, its use in lung transplantation was largely abandoned because of poor patient survival and frequent complications. The outcomes of patients bridged to lung transplantation using ECMO have substantially improved in the last 5 years. Recent advances in extracorporeal life support technology now allow patients with end-stage lung disease to be successfully supported for prolonged periods of time, preventing the use of mechanical ventilation and facilitating physical rehabilitation and ambulation while the patients awaits lung transplantation. This review briefly describes the evolution of ECMO use in lung transplantation and summarizes the available technology and current approaches to provide ECMO support.

Oxygen transfer efficiency of three microporous polypropylene membrane oxygenators

The purpose of this investigation was to compare the oxygen transfer efficiency of three different membrane oxygenators, each utilizing microporous polypropylene as its gas transfer material. Gross oxygen transfer was compared for each membrane with their performance when differences in surface area were taken into account. It was found that when hollow fibres were used, with blood flow around the fibres, efficiency was maximized. Our study technique offers an additional objective approach in the evaluation of oxygen transfer for membrane oxygenators.

The current status of mechanical circulatory support

In summary, techniques for support of a failing circulation have advanced steadily over the past thirty years. Just as the use of the intra-aortic balloon pump has permitted successful treatment of certain groups of high-risk patients, so increasing application of more invasive techniques of mechanical circulatory support has extended the range of surgical endeavour. Nevertheless, it is evident that further advances in the design and construction of mechanical circulatory support devices are most likely to occur in conjunction with developments in bioengineering technology. These advances will in turn demand analysis by means of careful animal and clinical investigations. Although the general clinical use of an off-the-shelf mechanical ventricular support will give rise to major financial and ethical problems it is likely that application of these devices may herald a new era in the field of artificial organ replacement.

Clinical evaluation of the microporous hollow fiber oxygenator

This report concerns a clinical evaluation for a newly devised hollow fiber oxygenator, Capiox II. It functions on a one-pump system, and is simple to set up and operate. This equipment was used for 118 patients undergoing cardiac surgery at Tokyo University Hospital from February 1982 through February 1983. The gas transfer capacity proved to be satisfactory. The employment of an air-oxygen blender prevented overoxygenation, and reasonable levels of PaO2 and PaCO2 were demonstrated with a FiO2 0.7, V/Q ratio 0.7 at normothermia. The destruction of platelets was much less with the use of this oxygenator, as compared to findings with the BOS-10. Hemolysis by Capiox II appeared to be lower than that by BOS-10, but the difference was not statistically significant. Differences were distinct in the amount of microbubbles; strikingly, no bubble was evidenced in Capiox II by the ultrasound bubble detector, during general procedures. We conclude that Capiox II is of excellent clinical value, and should be used especially for infants as well as adult patients with possible long perfusions. The merits and demerits of this equipment are given attention.