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Artificial Organs Jan 2009To provide respiratory support for patients with lung failure, a novel compact integrated pump-oxygenator is being developed. The functional and biocompatibility...
To provide respiratory support for patients with lung failure, a novel compact integrated pump-oxygenator is being developed. The functional and biocompatibility performances of this device are presented. The pump-oxygenator is designed by combining a magnetically levitated pump/rotor with a uniquely configured hollow fiber membrane bundle to create an assembly free, ultracompact, all-in-one system. The hemodynamics, gas transfer and biocompatibility performances of this novel device were investigated both in vitro in a circulatory flow loop and in vivo in an ovine animal model. The in vitro results showed that the device was able to pump blood flow from 2 to 8 L/min against a wide range of pressures and to deliver an oxygen transfer rate more than 300 mL/min at a blood flow of 6 L/min. Blood damage tests demonstrated low hemolysis (normalized index of hemolysis [NIH] approximately 0.04) at a flow rate of 5 L/min against a 100-mm Hg afterload. The data from five animal experiments (4 h to 7 days) demonstrated that the device could bring the venous blood to near fully oxygen-saturated condition (98.6% +/- 1.3%). The highest oxygen transfer rate reached 386 mL/min. The gas transfer performance was stable over the study duration for three 7-day animals. There was no indication of blood damage. The plasma free hemoglobin and platelet count were within the normal ranges. No gross thrombus is found on the explanted pump components and fiber surfaces. Both in vitro and in vivo results demonstrated that the newly developed pump-oxygenator can achieve sufficient blood flow and oxygen transfer with excellent biocompatibility.
Topics: Animals; Carbon Dioxide; Equipment Design; Magnetics; Materials Testing; Oxygen; Oxygenators, Membrane; Sheep
PubMed: 19178439
DOI: 10.1111/j.1525-1594.2008.00672.x -
Radiation Research Apr 2001There is now abundant evidence that oxygenation in rodent, canine and human tumors is improved during and for up to 1-2 days after heating at mild temperatures. An... (Review)
Review
There is now abundant evidence that oxygenation in rodent, canine and human tumors is improved during and for up to 1-2 days after heating at mild temperatures. An increase in tumor blood perfusion along with a decline in the oxygen consumption rate appears to account for the improvement of tumor oxygenation by mild hyperthermia. The magnitude of the increase in tumor pO(2), determined with oxygen-sensitive microelectrodes, caused by mild hyperthermia is less than that caused by carbogen breathing. However, mild hyperthermia is far more effective than carbogen breathing in increasing the radiation response of experimental tumors, probably because mild hyperthermia oxygenates both (diffusion-limited) chronically hypoxic and (perfusion-limited) acutely hypoxic cells, whereas carbogen breathing oxygenates only the chronically hypoxic cells. Mild hyperthermia is also more effective than nicotinamide, which is known to oxygenate acutely hypoxic cells, in enhancing the radiation response of experimental tumors. The combination of mild hyperthermia with carbogen or nicotinamide is highly effective in reducing the hypoxic cell fraction in tumors and increasing the radiation response of experimental tumors. A primary rationale for the use of hyperthermia in combination with radiotherapy has been that hyperthermia is equally cytotoxic toward fully oxygenated and hypoxic cells and that it directly sensitizes both fully oxygenated and hypoxic cells to radiation. Such cytotoxicity and such a radiosensitizing effect may be expected to be significant when the tumor temperature is elevated to at least 42-43 degrees C. Unfortunately, it is often impossible to uniformly raise the temperature of human tumors to this level using the hyperthermia devices currently available. However, it is relatively easy to raise the temperature of human tumors into the range of 39-42 degrees C, which is a temperature that can improve tumor oxygenation for up to 1-2 days. The potential usefulness of mild hyperthermia to enhance the response of human tumors to radiotherapy by improving tumor oxygenation merits continued investigation.
Topics: Animals; Carbon Dioxide; Cell Hypoxia; Combined Modality Therapy; Dogs; Humans; Hyperthermia, Induced; Mice; Mice, Inbred C3H; Neoplasms; Niacinamide; Oxygen; Partial Pressure; Radiation-Sensitizing Agents; Rats; Regional Blood Flow; Vasodilator Agents; Xenograft Model Antitumor Assays
PubMed: 11260653
DOI: 10.1667/0033-7587(2001)155[0515:iotobm]2.0.co;2 -
ASAIO Transactions 1991A new miniature membrane oxygenator (Kuraray KMO, size, 0.3 m2, with a priming volume of 47 ml, compliance of less than 0.1 ml/100 mmHg, and pressure loss of 45 mmHg)...
A new miniature membrane oxygenator (Kuraray KMO, size, 0.3 m2, with a priming volume of 47 ml, compliance of less than 0.1 ml/100 mmHg, and pressure loss of 45 mmHg) with improved gas transfer and mechanical durability was developed and tested. The membrane material is a hollow fiber double layer polyolefin. The testing procedures determined by the AAMI were followed, and the results showed improved O2 and CO2 transfer (70 ml/min and 55 ml/min, respectively). Hemolysis was within acceptable limits, and plasma leakage was undetectable after 7 days of perfusion. Clinical study demonstrated satisfactory performance.
Topics: Carbon Dioxide; Equipment Design; Extracorporeal Membrane Oxygenation; Hemolysis; Humans; Infant, Newborn; Miniaturization; Oxygen; Oxygenators, Membrane
PubMed: 1751211
DOI: No ID Found -
Journal of Biomechanical Engineering Mar 2017This paper numerically investigates non-Newtonian blood flow with oxygen and carbon dioxide transport across and along an array of uniformly square and staggered...
This paper numerically investigates non-Newtonian blood flow with oxygen and carbon dioxide transport across and along an array of uniformly square and staggered arranged fibers at various porosity (ε) levels, focussing on a low Reynolds number regime (Re < 10). The objective is to establish suitable mass transfer correlations, expressed in the form of Sherwood number (Sh = f(ε, Re, Sc)), that identifies the link from local mass transfer investigations to full-device analyses. The development of a concentration field is initially investigated and expressions are established covering the range from a typical deoxygenated condition up to a full oxygenated condition. An important step is identified where a cut-off point in those expressions is required to avoid any under- or over-estimation on the Sherwood number. Geometrical features of a typical commercial blood oxygenator is adopted and results in general show that a balance in pressure drop, shear stress, and mass transfer is required to avoid potential blood trauma or clotting formation. Different definitions of mass transfer correlations are found for oxygen/carbon dioxide, parallel/transverse flow, and square/staggered configurations, respectively. From this set of correlations, it is found that transverse flow has better gas transfer than parallel flow which is consistent with reported literature. The mass transfer dependency on fiber configuration is observed to be pronounced at low porosity. This approach provides an initial platform when one is looking to improve the mass transfer performance in a blood oxygenator without the need to conduct any numerical simulations or experiments.
Topics: Blood Circulation; Carbon Dioxide; Equipment Design; Models, Cardiovascular; Oxygen; Oxygenators; Porosity
PubMed: 28005133
DOI: 10.1115/1.4035535 -
Perfusion Sep 2003Open-heart surgery (OHS) requires cardiopulmonary bypass (CPB) in most patients. Membrane oxygenators are a critical component of the CPB system. Despite advancements in... (Clinical Trial)
Clinical Trial Comparative Study Randomized Controlled Trial
Open-heart surgery (OHS) requires cardiopulmonary bypass (CPB) in most patients. Membrane oxygenators are a critical component of the CPB system. Despite advancements in CPB technology, injury to blood components during CPB still occurs and may result in complications after surgery. The purpose of the present study was to evaluate the performance of the Medtronic Affinity NT with Trillium coating and the Cobe Optima XP oxygenators and compare their influence on blood components. Two hundred and fifty-six male and female patients scheduled for urgent or elective cardiac surgery with CPB were randomly assigned to either the Affinity NT or the Optima XP oxygenators. Outcomes included platelets, hemoglobin, leukocyte counts, and O2 transfer, measured preoperatively and at 15, 45 and 75 min of CPB time. Blood loss was measured at six and 12 hours postoperatively. A modified intention-to-treat analysis was conducted. The two groups were similar for age, sex, height, weight, body surface area, and blood components at baseline. There were no differences between the Affinity NT and Optima XP for any outcome measure, although a significant change with time was seen in platelets, hemoglobin, hematocrit and leukocytes, as well as O2 transfer for both groups (p < 0.001). The Affinity NT oxygenator had a significantly lower difference in pressure across the membrane (p < 0.001) compared with the Optima XP. In conclusion, the two oxygenators performed similarly with respect to their impact on blood components, O2 transfer, and blood loss postoperatively during OHS with CPB. The Affinity NT had the smaller transmembrane pressure drop of the two.
Topics: Aged; Blood Cell Count; Blood Loss, Surgical; Cardiac Surgical Procedures; Female; Hemoglobins; Humans; Male; Membranes, Artificial; Middle Aged; Oxygen; Oxygenators, Membrane; Treatment Outcome
PubMed: 14604250
DOI: 10.1191/0267659103pf681oa -
ASAIO Journal (American Society For... 1996To facilitate the handling of cardiopulmonary bypass (CPB) and simplify the circuit, the authors have developed a new membrane oxygenator with a hemofiltration function....
To facilitate the handling of cardiopulmonary bypass (CPB) and simplify the circuit, the authors have developed a new membrane oxygenator with a hemofiltration function. The hollow fiber units for gas exchange and hemofiltration were combined in concentric circles in a cylindrical housing. The total priming volume was 190 ml. Because the authors adopted a silicon coated hollow fiber membrane for gas exchange, this oxygenator was completely resistant to serum leakage, even after treatment to make the device hydrophilic. Both units possess a blood-outside perfusion system. Filtered fluid was collected easily through a stopcock mechanism. The oxygen transfer rate was 312 ml/min at a blood flow rate of 6 L/min, and the ultrafiltration rate was 3.5 L/hr at a blood flow rate of 4 L/min with a 25% hematocrit and 200 mmHg transmembrane pressure in an in vitro study. The pressure drop was 62 mmHg at a blood flow rate of 4 L/min. The authors found no adverse effects in an in vivo study using a mongrel dog. In conclusion, this durable, combined device could achieve excellent and simplified hemoconcentration through having all the blood in the unit flow through the hemofiltration portion, and was useful not only in cardiopulmonary bypass during open heart surgery, but also in extracorporeal membrane oxygenation.
Topics: Animals; Cardiopulmonary Bypass; Cattle; Dogs; Equipment Design; Evaluation Studies as Topic; Extracorporeal Membrane Oxygenation; Hematocrit; Hemofiltration; Humans; In Vitro Techniques; Oxygen; Oxygenators, Membrane; Pressure; Ultrafiltration
PubMed: 8944950
DOI: 10.1097/00002480-199609000-00057 -
Surgery Dec 1972
Topics: Bender-Gestalt Test; Blood Cell Count; Blood Platelets; Carbon Dioxide; Cardiac Output; Cardiac Surgical Procedures; Coronary Artery Bypass; Disposable Equipment; Embolism, Air; Heart-Lung Machine; Hemoglobinometry; Humans; Hydrogen-Ion Concentration; Hypothermia, Induced; Intelligence Tests; Membranes, Artificial; Oxygen; Oxygenators, Membrane; Respiration; Ultrasonography
PubMed: 4539001
DOI: No ID Found -
Artificial Organs May 1982A bubble oxygenator (the TM or the OCVC oxygenator) has been produced with development efforts focused particularly on reduction of the nonphysiological characteristics...
A bubble oxygenator (the TM or the OCVC oxygenator) has been produced with development efforts focused particularly on reduction of the nonphysiological characteristics of this type of oxygenator. The structural features of the apparatus are: (1) a reduction to the minimum of adequate priming volume, (2) an oxygen disperser designed to ensure evenly dispersed, uniform-sized bubbles, (3) a volume-control system for the oxygenating chamber (the OCVC system) based on extensive experimental oxygenation studies, and (4) an integrated double microfilter of the gravity-drainage type. Clinical features are: (1) ease of operation in perfusion, (2) reduction in hemolysis and postoperative blood loss, and (3) fewer complications associated with microemboli. Clinical use on over 200 infants and children proved generally very satisfactory. The background of its development is briefly described as are future modification plans.
Topics: Cardiac Surgical Procedures; Child; Child, Preschool; Embolism; Hemolysis; Humans; Infant; Oxygen; Oxygenators; Transposition of Great Vessels
PubMed: 7125963
DOI: 10.1111/j.1525-1594.1982.tb04083.x -
ASAIO Journal (American Society For... 2009A silicone hollow fiber oxygenator was evaluated to characterize gas transfer and biocompatibility. The device's fiber bundle was composed of MedArray's silicone hollow...
A silicone hollow fiber oxygenator was evaluated to characterize gas transfer and biocompatibility. The device's fiber bundle was composed of MedArray's silicone hollow fibers with a 320 microm outside diameter, a 50 microm wall thickness, a surface area of 0.45 m, and a 0.49 void fraction. An in vitro gas exchange study was performed comparing the MedArray device (n = 9) with the Medtronic 0600 oxygenator (n = 6) using Association for the Advancement of Medical Instrumentation standards and blood flow rates of 0.5-1.75 L/min, and an oxygen to blood flow ratio of two. Biocompatibility and resistance studies were performed in vivo using a swine venovenous extracorporeal membrane oxygenation model (MedArray n = 5, Medtronic n = 5). Average O(2) transfer at 1 L/min was 86 ml/min/m in the MedArray device and 101.1 ml/min/m in the Medtronic device. At 0.5 L/min the MedArray and Medtronic device average resistance was 15.5 and 148.5 mm Hg/(L/min), respectively. Both devices had similar platelet consumption and hemolysis. Results indicate that the MedArray device has lower O(2) transfer efficiency, similar biocompatibility, and lower resistance than the Medtronic 0600 oxygenator. Optimization of the MedArray fiber bundle and housing design is necessary to improve O(2) transfer efficiency while maintaining lower device resistance than the Medtronic oxygenator.
Topics: Animals; Biocompatible Materials; Equipment Design; Extracorporeal Membrane Oxygenation; Hemoglobins; Inflammation; Materials Testing; Membranes, Artificial; Oxygen; Oxygenators; Oxygenators, Membrane; Pulmonary Gas Exchange; Silicones; Swine; Temperature
PubMed: 19381081
DOI: 10.1097/MAT.0b013e3181a44263 -
Perfusion Mar 2017There is no acceptable method of testing oxygen transfer performance in membrane oxygenators quickly and easily during cardiopulmonary bypass. Pre-clinical testing of...
BACKGROUND
There is no acceptable method of testing oxygen transfer performance in membrane oxygenators quickly and easily during cardiopulmonary bypass. Pre-clinical testing of oxygenators is performed under controlled situations in the laboratory, correlating oxygen transfer to blood flow using 100% oxygen. This laboratory method cannot be used clinically as oxygen transfer values vary significantly at each blood flow and the FiO is not kept at 1. Therefore, a formula was developed which corrects the existing FiO to attain a PaO of 150 mmHg: the corrected FiO at 150 mmHg. In graph form, this corrected FiO (x-axis) is correlated to the patient's oxygen consumption levels (y-axis), which determines the membrane oxygenator oxygen transfer performance.
METHODS
Blood gas and hemodynamic parameters taken during cardiopulmonary bypass using the Medtronic Fusion were used to calculate the oxygen consumption (inlet conditions to the oxygenator) and the corrected FiO for a PaO of 150 mmHg. Validation of the formula "FiO-PaO/(Pb-pHO)+0.21" was carried out by plotting the calculated values on a graph using PaO values between 145 to 155 mmHg and then, using the corrected FiO for PaOs outside of this range.
RESULTS
All trend-lines correlated significantly to confirm that the Medtronic Fusion had an extrapolated oxygen transfer of 419 milliliters O/min at an FiO of 1 to achieve a PaO of 150 mmHg.
CONCLUSIONS
Use of the corrected FiO correlated to the oxygen transfer conditions of the membrane oxygenator can easily be used on a routine basis, providing valuable information clinically. When used by the manufacturer under laboratory conditions, further clinically relevant data is provided in terms of FiO and resultant PaOs instead of the present limitations using blood flow. In this way, a clinically justifiable method has been developed to finally establish a standard in testing membrane oxygenator performance.
Topics: Aged; Blood Gas Analysis; Cardiopulmonary Bypass; Hemodynamics; Humans; Middle Aged; Oxygen; Oxygen Consumption; Oxygenators, Membrane
PubMed: 27600701
DOI: 10.1177/0267659116668400