Artificial lung assist devices have been hailed as lifesavers for people with respiratory failure. But these devices come with potential risks, including blood clots, bleeding, and sepsis. The answer to improving a device’s function while reducing side effects may lie in designing it so that it more closely mimics the human lung.
draper has done just that, making progress in an artificial lung technology called extracorporeal membrane oxygenation (ECMO). During ECMO, blood is drawn from the patient’s vascular system and distributed outside the body by a mechanical pump through an oxygenator and heat exchanger. Carbon dioxide (CO2) is removed and oxygen-saturated blood is returned to the body.
Despite decades of advances, ECMO still suffers from limitations. The device can become clogged with blood clots, decreasing the membrane’s ability to transfer oxygen and CO2. ECMO can have irregular blood flow and pressure through the device and require high levels of anticoagulant, which can lead to bleeding problems. Experts agree that reducing complications will improve outcomes for ECMO patients.
To develop its artificial lung technology, draper drawn from biomimetics, an interdisciplinary field in which the principles of engineering, chemistry and biology are applied to the synthesis of materials, synthetic systems and machines whose functions mimic biological processes.
Draper fabricated layers of silicone, patterned with networks of blood channels or gas channels, and bonded them together with a thin intervening gas transfer membrane. The multiple sandwich structures were stacked in a three-dimensional network connected by biomimetic blood delivery manifolds to produce a fully 3D, physiologically inspired blood circuit.
Draper researchers tested the Multi-Layer Microfluidic Blood Oxygenator at blood flow rates approaching clinically relevant levels. They found that a device coated with anticoagulant significantly reduced thrombus buildup and helped stabilize blood pressure, compared to an uncoated device. In a forthcoming article, Draper reports that his oxygenator operated at blood flow rates of up to 400 milliliters per minute, the highest ever in a complex microfluidic device.
Overall, Draper’s device retained critical dimensions such as gas transfer membrane thickness and blood channel geometries, and controlled levels of fluid shear within narrow ranges throughout the cartridge. These design features have allowed the device to improve a persistent performance issue with ECMO, where contact of blood proteins with artificial surfaces, such as oxygenator membrane or tubing, can cause clotting. some blood.
Engineer Joe Santos helped design the device, called BLOx.
“There is a critical need for low primary volume, low flow respiratory support devices. There is also an urgent need for simpler, safer, and more portable ECMO technologies for treating injuries in remote locations, such as battlefields and sites of natural disasters. Draper’s technology can transform the way ECMO is performed today,” says Santos.
Jeff Borenstein has worked on biomimetic microfluidic oxygenators for over a decade at Draper.
“We believe that microfluidic oxygenators have emerged as a potential promising avenue to improve the efficacy and safety of ECMO. Despite wide use, ECMO is limited in its accessibility because it is extremely complex and difficult to administer. We believe that our approach is simpler and safer, and will lead to wider use,” says Borenstein.
The American Society for Artificial Internal Organs recently recognized microfluidic blood oxygenator research by naming it Top Pulmonary Abstract of 2021.
This work was funded by the US Army Medical Research Acquisition Activity and supported by the US Army through the Peer-Reviewed Medical Research Program under award number W81XWH1910518. Draper’s $4.9 million four-year award is expected through July 2022. The opinions, interpretations, conclusions, and recommendations are those of the author and are not necessarily endorsed by the acquisition activity of US Army medical research.