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Artificial Organs Nov 2010Extracorporeal membrane oxygenation (ECMO) is a well-established therapy for several lung and heart diseases in the field of neonatal and pediatric medicine (e.g., acute...
Extracorporeal membrane oxygenation (ECMO) is a well-established therapy for several lung and heart diseases in the field of neonatal and pediatric medicine (e.g., acute respiratory distress syndrome, congenital heart failure, cardiomyopathy). Current ECMO systems are typically composed of an oxygenator and a separate nonpulsatile blood pump. An oxygenator with an integrated pulsatile blood pump for small infant ECMO was developed, and this novel concept was tested regarding functionality and gas exchange rate. Pulsating silicone tubes (STs) were driven by air pressure and placed inside the cylindrical fiber bundle of an oxygenator to be used as a pump module. The findings of this study confirm that pumping blood with STs is a viable option for the future. The maximum gas exchange rate for oxygen is 48mL/min/L(blood) at a medium blood flow rate of about 300mL/min. Future design steps were identified to optimize the flow field through the fiber bundle to achieve a higher gas exchange rate. First, the packing density of the hollow-fiber bundle was lower than commercial oxygenators due to the manual manufacturing. By increasing this packing density, the gas exchange rate would increase accordingly. Second, distribution plates for a more uniform blood flow can be placed at the inlet and outlet of the oxygenator. Third, the hollow-fiber membranes can be individually placed to ensure equal distances between the surrounding hollow fibers.
Topics: Air Pressure; Blood Flow Velocity; Carbon Dioxide; Elasticity; Equipment Design; Extracorporeal Membrane Oxygenation; Heart-Assist Devices; Humans; Infant, Newborn; Materials Testing; Miniaturization; Oxygen; Oxygenators, Membrane; Prosthesis Design; Pulsatile Flow; Silicones; Time Factors
PubMed: 21092033
DOI: 10.1111/j.1525-1594.2010.01123.x -
ASAIO Journal (American Society For... 2011Extracorporeal membrane oxygenation can achieve sufficient gas exchange in severe acute respiratory distress syndrome. A highly integrated extracorporeal membrane...
Extracorporeal membrane oxygenation can achieve sufficient gas exchange in severe acute respiratory distress syndrome. A highly integrated extracorporeal membrane oxygenator (HEXMO) was developed to reduce filling volume and simplify management. Six female pigs were connected to venovenous HEXMO with a total priming volume of 125 ml for 4 hours during hypoxemia induced by a hypoxic inspired gas mixture. Animals were anticoagulated with intravenous heparin. Gas exchange, hemodynamics, hemolysis, and coagulation activation were examined. One device failed at the magnetic motor coupling of the integrated diagonal pump. In the remaining five experiments, the oxygenation increased significantly (arterial oxygen saturation [SaO2] from 79 ± 5% before HEXMO to 92% ± 11% after 4 hours) facilitated by a mean oxygen transfer of 66 ± 29 ml/dl through the oxygenator. The CO2 elimination by the HEXMO reduced arterial PaCO2 only marginal. Extracorporeal blood flow was maintained at 32% ± 6% of cardiac output. Hemodynamic instability or hemolysis was not observed. The plasmatic coagulation was only mildly activated without significant platelet consumption. The HEXMO prototype provided sufficient gas exchange to prevent hypoxemia. This proof of concept study supports further development and design modifications to increase performance and to reduce coagulation activation for potential long-term application.
Topics: Animals; Assisted Circulation; Biomedical Engineering; Blood Cell Count; Carbon Dioxide; Disease Models, Animal; Equipment Design; Equipment Failure; Extracorporeal Membrane Oxygenation; Female; Hemodynamics; Humans; Hypoxia; Miniaturization; Oxygen; Oxygenators, Membrane; Pulmonary Gas Exchange; Respiration; Respiratory Distress Syndrome; Swine
PubMed: 21317635
DOI: 10.1097/MAT.0b013e31820bffa9 -
Perfusion May 1994
Review
Topics: Blood Vessels; Humans; Oxygen; Oxygenators, Membrane
PubMed: 7949571
DOI: 10.1177/026765919400900305 -
The Annals of Thoracic Surgery Jun 1997A membrane oxygenator consisting of a microporous polypropylene hollow fiber with a 0.2-microm ultrathin silicone layer (cyclosiloxane) was developed. Animal...
BACKGROUND
A membrane oxygenator consisting of a microporous polypropylene hollow fiber with a 0.2-microm ultrathin silicone layer (cyclosiloxane) was developed. Animal experimental and preliminary clinical studies evaluated its reliability in bypass procedures.
METHODS
Five 24-hour venoarterial bypass periods were conducted on dogs using the oxygenator (group A). In 5 controls, bypass periods were conducted using the same oxygenator without silicone coating (group B). As a preliminary clinical study, 14 patients underwent cardiopulmonary bypass with the silicone-coated oxygenator.
RESULTS
Eight to 16 hours (mean, 12.2 hours) after initiation of bypass, plasma leakage occurred in all group B animals, but none in group A. The O2 and CO2 transfer rates after 24 hours in group A were significantly higher than at termination of bypass in group B (p < 0.005 and p < 0.03, respectively). Scanning electron microscopy of silicone-coated fibers after 24 hours of bypass revealed no damage to the silicone coating of the polypropylene hollow fibers. In the clinical study, the oxygenator showed good gas transfer, acceptable pressure loss, low hemolysis, and good durability.
CONCLUSIONS
This oxygenator is more durable and offers greater gas transfer capabilities than the previous generation of oxygenators.
Topics: Animals; Carbon Dioxide; Cardiopulmonary Bypass; Dogs; Equipment Design; Evaluation Studies as Topic; Extracorporeal Membrane Oxygenation; Hemoglobins; Materials Testing; Microscopy, Electron, Scanning; Oxygen; Oxygenators; Polypropylenes; Silicones
PubMed: 9205175
DOI: 10.1016/s0003-4975(97)00119-7 -
Scandinavian Journal of Thoracic and... 1975A simple membrane oxygenator for isolated organ perfusion is described. The membrane employed consisted of an ordinary silicone rubber tubing, 2 mm internal diameter,...
A simple membrane oxygenator for isolated organ perfusion is described. The membrane employed consisted of an ordinary silicone rubber tubing, 2 mm internal diameter, 0.3 mm wall thickness, the length of the tubing varying according to the required gas transfer. When describing the capacity of the oxygenator, it was found that the maximum gas transfer rate per unit membrane surface was an inadequate measure, since this would vary with both flow rate through the oxygenator and the gas binding capacity of the perfusate. The following formula for the function describing the relation between maximally possible change in gas concentration in the perfusate (C), flow rate (F) and actual change in gas concentration in the perfusate (U) was proposed: U=C-e(-bF), b being a constant specific for the gas and the membrane. This formula was tested by a series of in vitro experiments and proved to give a valid description of the capacity of the oxygenator. It was also found that carbon dioxide was always more easily transferred than oxygen, so that oxygen transfer capcity was the limiting factor in the use of the oxygenator. To facilitate the construction of the right size membrane, a nomogram was constructed for oxygen transfer.
Topics: Animals; Carbon Dioxide; Humans; Hydrogen-Ion Concentration; Models, Biological; Oxygen; Oxygenators, Membrane; Perfusion; Rabbits
PubMed: 1854
DOI: 10.3109/14017437509138642 -
BMJ Case Reports Dec 2016A 58-year-old man with medical history of thrombocytopenia was admitted to an outside hospital for a 6-day history of worsening dyspnoea requiring mechanical ventilator...
A 58-year-old man with medical history of thrombocytopenia was admitted to an outside hospital for a 6-day history of worsening dyspnoea requiring mechanical ventilator support. He was transferred to our institution for extracorporeal membrane oxygenation (ECMO) given his refractory hypoxaemia. On arrival, H1N1 influenza virus was confirmed and all measures to improve oxygenation were ineffective. Thus, the decision was made to start venovenous (VV)-ECMO. Although a low baseline platelet count was recognised (60-70×10/L), a sudden further decrease occurred (30×10/L) and platelet transfusion was initiated. A substantial increase in the pressure across the ECMO oxygenator was identified, and the diagnosis of type II heparin-induced thrombocytopenia was suspected and confirmed. Heparin was discontinued, the oxygenator was exchanged and argatroban was used for anticoagulation. After 28 days on VV-ECMO support, the decision was made to withdraw organ support in conjunction with the patient and family wishes.
Topics: Anticoagulants; Dyspnea; Equipment Failure; Extracorporeal Membrane Oxygenation; Heparin; Humans; Male; Middle Aged; Oxygen; Oxygenators; Thrombocytopenia
PubMed: 27986695
DOI: 10.1136/bcr-2016-218179 -
CRC Critical Reviews in Bioengineering Aug 1973
Review
Topics: Biological Transport; Carbon Dioxide; Diffusion; Extracorporeal Circulation; Heart-Lung Machine; Membranes, Artificial; Oxygen; Oxygen Consumption; Oxygenators; Oxygenators, Membrane; Partial Pressure
PubMed: 4581807
DOI: No ID Found -
Journal of Plant Physiology Aug 2011Respiratory metabolism includes the reactions of glycolysis, the tricarboxylic acid cycle and the mitochondrial electron transport chain, but is also directly linked... (Review)
Review
Respiratory metabolism includes the reactions of glycolysis, the tricarboxylic acid cycle and the mitochondrial electron transport chain, but is also directly linked with many other metabolic pathways such as protein and lipid biosynthesis and photosynthesis via photorespiration. Furthermore, any change in respiratory activity can impact the redox status of the cell and the production of reactive oxygen species. In this review, it is discussed how respiration is regulated and what alternative pathways are known that increase the metabolic flexibility of this vital metabolic process. By looking at the adaptive responses of respiration to hypoxia or changes in the oxygen availability of a cell, the integration of regulatory responses of various pathways is illustrated.
Topics: Cell Respiration; Cytochromes; Metabolic Networks and Pathways; Oxygen; Plant Proteins; Plants
PubMed: 21185623
DOI: 10.1016/j.jplph.2010.11.004 -
Current Opinion in Plant Biology Jun 2012Photorespiration is a Janus-headed metabolic process: it makes oxygenic photosynthesis possible by scavenging its major toxic by-product, 2-phosphoglycolate, but also... (Review)
Review
Photorespiration is a Janus-headed metabolic process: it makes oxygenic photosynthesis possible by scavenging its major toxic by-product, 2-phosphoglycolate, but also leads to high losses of freshly assimilated CO(2) from most land plants. Photorespiration has been often classified as a wasteful process but is now increasingly appreciated as a key ancillary component of photosynthesis and therefore the global carbon cycle. As such, the photorespiratory cycle is one of the major highways for the flow of carbon in the terrestrial biosphere. Recent research revealed that this important pathway originated as a partner of oxygenic photosynthesis billions of years ago and is multiply linked to other pathways of central metabolism of contemporary land plants.
Topics: Carbon; Cell Respiration; Glycolates; Light; Metabolic Networks and Pathways; Models, Biological; Oxygen; Photosynthesis; Plants
PubMed: 22284850
DOI: 10.1016/j.pbi.2012.01.008 -
ASAIO Journal (American Society For... 2000An asymmetric hollow fiber membrane was prepared from a newly synthesized fluorinated aromatic polyimide (6FDA-6FAP) by using a dry/wet phase inversion process. The...
An asymmetric hollow fiber membrane was prepared from a newly synthesized fluorinated aromatic polyimide (6FDA-6FAP) by using a dry/wet phase inversion process. The membrane was used in a membrane oxygenator over a long period of time. In this study, the potential of the membrane for intravascular membrane oxygenation (IVOX) was studied in respect to oxygen transfer. The gas permeance of the membrane and three commercially available hollow fiber membranes for membrane oxygenators was measured in a gas-gas system and a gas-liquid system and discussed relative to the membrane structures. The oxygen transfer rates of the IVOX devices using these four membranes were estimated by a mathematical kinetic model, with the oxygen permeance measured in the gas-liquid system. The results showed that the device using the 6FDA-6FAP hollow fiber membrane has the highest oxygen transfer rate and is believed to be applicable to IVOX. The methods to determine oxygen transfer rate of a hollow fiber membrane and the mathematical kinetic model, are useful for developing a hollow fiber membrane and a device for oxygenation.
Topics: Humans; Oxygen; Oxygenators, Membrane; Permeability
PubMed: 11016518
DOI: 10.1097/00002480-200009000-00021