Establishment and Evaluation of a Rat Model of Extracorporeal Membrane Oxygenation (ECMO) Thrombosis Using a 3D-printed Mock Oxygenator

Abstract

Background: Extracorporeal membrane oxygenation (ECMO) research using large animals requires a significant amount of resources, slowing down the development of new means of ECMO anticoagulation. Therefore, this study developed and evaluated a new rat ECMO model using a 3D-printed mock oxygenator.Methods: The circuit consisted of tubing, a 3D-printed mock oxygenator, and a roller pump. The mock oxygenator was designed to simulate the geometry and blood flow patterns of the fiber bundle in full-scale oxygenators but with a low (2.5 mL) priming volume. Rats were placed on arteriovenous ECMO at a 1.9 mL/min flow rate at two different heparin doses (n = 3 each): low (15 IU/kg/h for eight hours) versus high (50 IU/kg/h for one hour followed by 25 IU/kg/h for seven hours). The experiment continued for eight hours or until the mock oxygenator failed. The mock oxygenator was considered to have failed when its blood flow resistance reached three times its baseline resistance.Results: During ECMO, rats maintained near-normal mean arterial pressure and arterial blood gases with minimal hemodilution. The mock oxygenator thrombus weight was significantly different (p < 0.05) between the low (0.02 ± 0.006 g) and high (0.003 ± 0.001 g) heparin delivery groups, and blood flow resistance was also larger in the low anticoagulation group.Conclusions: This model is a simple, inexpensive system for investigating new anticoagulation agents for ECMO and provides low and high levels of anticoagulation that can serve as control groups for future studies.