Anti-thrombogenic Surface Coatings for Extracorporeal Membrane Oxygenation: A Narrative Review

Abstract

Extracorporeal membrane oxygenation (ECMO) is used in critical care to manage patients with severe respiratory and cardiac failure. ECMO brings blood from a critically ill patient into contact with a non-endothelialized circuit which can cause clotting and bleeding simultaneously in this population. Continuous systemic anticoagulation is needed during ECMO. The membrane oxygenator, which is a critical component of the extracorporeal circuit, is prone to significant thrombus formation due to its large surface area and areas of low, turbulent, and stagnant flow. Various surface coatings, including but not limited to heparin, albumin, poly­(ethylene glycol), phosphorylcholine, and poly­(2-methoxyethyl acrylate), have been developed to reduce thrombus formation during ECMO. The present work provides an up-to-date overview of anti-thrombogenic surface coatings for ECMO, including both commercial coatings and those under development. The focus is placed on the coatings being developed for oxygenators. Overall, zwitterionic polymer coatings, nitric oxide (NO)-releasing coatings, and lubricant-infused coatings have attracted more attention than other coatings and showed some improvement in in vitro and in vivo anti-thrombogenic effects. However, most studies lacked standard hemocompatibility assessment and comparison studies with current clinically used coatings, either heparin coatings or nonheparin coatings. Moreover, this review identifies that further investigation on the thrombo-resistance, stability and durability of coatings under rated flow conditions and the effects of coatings on the function of oxygenators (pressure drop and gas transfer) are needed. Therefore, extensive further development is required before these new coatings can be used in the clinic.

Anticoagulation Strategies during Extracorporeal Membrane Oxygenation: A Narrative Review

“…However, the surface coating does not eradicate the risk of thrombosis or bleeding due to the potential of systemic anticoagulation reduction [ 137 ].Extensive research is directed toward the development of new artificial surfaces in two main directions: the use of synthetic and natural polymers for the surfaces coating or their endothelialization. However, none of the non-heparin coatings showed superiority to heparin coatings, making heparin coatings the most popular in everyday practice [ 138 ].…”

“…Different surface coatings, such as heparin, albumin, phosphorylcholine, polyethylene glycol, and poly-2-methoxyethylacrylate, have been developed to minimize the potential of thrombus formation during ECMO support ( Table 2 ) [ 138 ]. Moreover, research on improving the hemocompatibility of commercially available membranes showed that grafting of the polymer brushes with the technique of single electron-transfer living radical polymerization can reduce recalcification time, reducing the adhesion of leukocytes and platelets [ 137 ].…”

“…Finally, ongoing research is focusing on other types of membrane and circuit coatings and includes C1-esterase inhibitors, tethered liquid perfluorocarbon, and zwitterionic coatings [ 137 , 147 , 148 ]. More detailed information on the novel surfaces in ECMO circuits can be found in the review from Ontaneda and Annich, or the comprehensive literature on the present and future perspectives of surface coatings [ 57 , 138 , 149 ]. An overview of the oxygenator and tubing surface modifications in extracorporeal membrane oxygenation is presented in Table 2 .…”

Antibiotics and ECMO in the Adult Population—Persistent Challenges and Practical Guides

“…The tubing is made of polyvinylchloride (PVC) with several coatings. Significant effort is taken to reduce a circuit-induced hypercoagulable state and immunogenicity via heparin or alternative coatings [30][31][32]. Transparency of the plastic tubing allows for visual inspection.…”

Investigation of heparin-loaded poly(ethylene glycol)-based hydrogels as anti-thrombogenic surface coatings for extracorporeal membrane oxygenation

“…8,16 However, so far, heparin coatings are the most widely used coatings in clinic, serving as the gold standard. 17 It should be noted that heparin coatings alone are not sufficient to eliminate the need for systemic anticoagulation, thus increasing the risk of bleeding, leading to an imbalance between bleeding and thrombosis and increased mortality. 18,19 Therefore, the pursuit of more effective haemocompatible coatings remains ongoing.…”