Long-Term Artificial Lung Support: Will We Get There?

Artificial lungs are devices that achieve oxygen and carbon dioxide transfer directly with blood thereby providing respiratory support independently of the native lungs. Early artificial lungs used large interfacial areas of direct contact between blood and air to attain therapeutic levels of gas exchange. Membrane-based devices with a gas-permeable polymer separating blood and air eventually demonstrated the ability to provide much longer durations of support with fewer complications. Advances in membrane fabrication capabilities along with an improved understanding of gas transfer in blood have enabled continuous progression toward smaller and more efficient devices over the past 50 years. Modern-day artificial lungs utilizing microporous hollow fiber membranes can typically be used to provide weeks of support before a device exchange is necessary and are increasingly being used as a bridge to lung transplantation. A primary focus of current artificial lung research is extending the usable device lifetime which is most often limited by intra-device thrombosis. A variety of exciting approaches to selectively inhibiting contact-induced blood coagulation have shown promise in this regard. Additionally, the development of integrated and ultra-compact devices with high gas transfer efficiency is enabling progress toward mobile and wearable systems that may ease implementation of support outside of an intensive care setting. Lastly, research surrounding microchannel-based and biofabricated artificial lungs holds promise for more biomimetic devices that could offer improved support over current systems utilizing hollow fiber membranes.