Blood Purification Membranes Used in Liquid–Gas Environments: Artificial Lungs

Extracorporeal membrane oxygenation (ECMO), the key component of which is a membrane oxygenator, known as the artificial lung, could provide irreplaceable respiratory support for patients with cardiopulmonary failure. The membrane oxygenator serves as a barrier between blood and gas, and offers a means of CO2 and O2 exchange. This chapter systematically reviews the evolution of the membrane oxygenator, from blood-film to hollow-fiber membranes, and from silicone to the present polymethylpentene. In particular, the dilemma faced by membrane oxygenators in balancing antifouling, anticoagulation, and gas-exchange efficiency is discussed. Moreover, special attention is given to describe the most promising oxygenator materials, e.g. poly(vinylidene fluoride) (PVDF) and polyethersulfone (PES), along with membrane modification methods such as surface coating, blending, and geometry design. Typical assessment criteria for the performance of membranes with respect to gas permeation, selectivity, and anticoagulation are elucidated. Finally, a brief summary of and future prospects for membrane oxygenators are presented. This chapter provides a comprehensive introduction to artificial lung membranes, and may offer some inspirations for subsequent membrane oxygenator design.