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Advantages and Disadvantages in Anticoagulation and Coating Methods Used in Extracorporeal Life Support Devices

In the previous few decades, the usage of extracorporeal life support (ECLS) technologies has skyrocketed.

In the previous few decades, the usage of extracorporeal life support (ECLS) technologies has skyrocketed. Despite medical and scientific breakthroughs, the intricate interplay between the human body, blood, and artificial materials remains a major problem in the ECLS sector. Blood exposure to artificial surfaces does cause an imbalanced activation of the coagulation cascade, which can result in hemorrhagic and thrombotic events. In the case of cardio-circulatory or respiratory refractory impairment, ECLS devices are utilized to provide cardiac and pulmonary support as a bridge until recovery, surgery, or treatment. 


Clotting inside the circuit or vessel thrombosis can happen, as in the case of oxygenator failure. Anticoagulation is thus required to avoid these complications. Bleeding incidents are likewise widespread, and they're twice as common as thrombotic incidents. As a result, ECLS clinical results must be improved in tandem with a reduction in thrombotic and hemorrhagic adverse events. Despite tremendous progress, clinical evidence indicates that more study on hemocompatibility and anticoagulant medications in ECLS is still needed. This narrative review presents an overview of currently available anticoagulant drugs, as well as the most recent advancements in circuit hemocompatibility and their predicted future developments.


Patients are given systemic anticoagulation to reduce the chance of thrombosis or clotting in the circuit, which could lead to the ECLS system failing. An ideal anticoagulant should be simple to use and monitor, with a low risk of bleeding problems while keeping anti-thrombotic properties. Anticoagulant medications are currently accessible in a variety of forms, each with its own set of benefits and drawbacks. Heparin, nafamostats, and direct thrombin inhibitors are the three types of anticoagulant medicines now in use.


Unfractionated heparin (UFH) is the most often used anticoagulant during ECLS. It inhibits coagulation enzymes factor Xa and thrombin by binding the enzyme inhibitor antithrombin and boosting its inhibitory potential. Nafamostat mesilate (NM) is a probable UFH substitute. NM is a synthetic serine protease inhibitor that is commonly used as an anticoagulant in hemodialysis patients with a high risk of bleeding. Thrombin, factor Xa, and XIIa, as well as the kallikrein-kinin and complement systems, are all inhibited. Bivalirudin, synthetic hirudin, is a direct thrombin inhibitor peptide that is commonly used as anticoagulation in HITT and heparin-resistant patients. Argatroban is a small molecule direct thrombin inhibitor that can be used instead of UFH in individuals with renal failure and a UFH contraindication.


In a nutshell, by simplifying the circuit, lowering shear stress and stasis, and preserving or increasing usability, the artificial surface area of ECLS devices can be reduced. Heparin-coated ECLS systems were created to lessen the risk of hemorrhage by lowering systemic heparinization. Albumin has been utilized as a coating material since 1980, and it is frequently used when heparin is contraindicated. Phosphorylcholine (PC) is an anti-thrombogenic, protein-resistant, antimicrobial, and anti-fouling substance. Surface endothelialization is a technique for creating an endothelial layer on circuit surface areas by seeding cells onto the surface to achieve total blood-material compatibility. The goal should be to develop biocompatible and biohybrid materials that do not require combined systemic anticoagulation in the future, but intense efforts are still required to fulfill this purpose.


Read more:
Anne Willers, Jutta Arens, Silvia Mariani, Helena Pels, Jos G. Maessen, Tilman M. Hackeng, Roberto Lorusso, Justyna Swol
Membranes (Basel) 2021 Aug; 11(8): 617. Published online 2021 Aug 12. doi: 10.3390/membranes11080617
PMCID: PMC8399034
 

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