Blood Oxygenation

Warning: The oxygenators described on this page and elsewhere on this site are not approved by the FDA for use in humans. Membrane modules should not be used for blood oxygenation in humans under any circumstances.
 

Long term extracorporeal membrane oxygenation or ECMO (more generally referred to as extracorporeal life support) is a term used to describe prolonged but temporary (1-30 days) support of the heart and lung function using mechanical devices. ECMO can be used for mechanical and respiratory assistance during cardiac and pulmonary failure occurring in newborn infants, older children, or adults. With the outbreak of H1N1 virus (swine flu) in 2009, a significant number of adults and children who developed RDS were successfully treated with ECMO as an alternative to potentially harmful high pressure/ high O₂ ventilation.

Blood is drawn from a patient and pumped through an oxygenator where oxygen and CO₂ are transferred. The arterialized blood then returns to the patient, either to the venous or arterial circulation depending on the need for cardiac support.

ECMO is almost always partial bypass as opposed to total bypass which is required for CPB operations. With circulation and gas exchange supported mechanically, the heart and lungs are not needed for life support and are allowed to rest. Extracorporeal support continues until the heart or lung function improves. Many days may be required for the heart and lungs to regain adequate function.

Under the auspices of the National Institutes of Health, MedArray has further built upon it's proprietary membrane forming techniques and membrane device designs to improve long term blood oxygenating technology for extracorporeal membrane oxygenation (ECMO) oxygenators. Because MedArray's membrane hollow fibers are made from dense silicone, they are not susceptible to plasma leakage when used for extended periods, unlike microporous membranes which wet-out and leak  plasma when used in long term applications. Under NIH SBIR grant, we optimized membrane utilization and flow patterns in three ECMO oxygenator designs suitable for neonatal, pediatric, and adult patients requiring long term extracorporeal support. We used computational fluid dynamics (CFD), gas exchange models,  flow visualization, in-vitro, and in-vivo testing to enable the development of greatly improved ECMO oxygenators, suitable for replacing current FDA approved ECMO oxygenators with designs which date back to the early sixties.

CFD simulations of the blood pressure field in the fiber bundle at rated flow. Note that the isobars are concentric indicating uniform radial flow.

    Our results have shown that our three ECMO oxygenators designs can provide the necessary gas exchange and replace six currently commercially available ECMO oxygenators (Medtronic models) with significantly less membrane surface area, blood priming volume, hemodynamic pressure drop, and platelet consumption.  The tables below summarize results obtained in Phase II. Our goal is to further improve our designs and to conduct the necessary pre-clinical testing required for an eventual FDA submission for clinical use.

Table 1. Gas exchange performance comparison for MedArray's ECMO oxygenator designs.