Feasibility and Stability of a Long Term “Awake” Extracorporeal Membrane Oxygenation Model in Large Animal

Abstract Background: Extracorporeal membrane oxygenation (ECMO) is rapidly becoming a mainstream technology for lung or heart/lung support especially during the COVID-19 pandemic. “Awake ECMO”is frequently used to indicate an alternative approach of using ECMO without invasive mechanical ventilation, and it has the unique advantages of application. In this study, we explored the feasibility and stability of the establishment method and management strategy of long-term awake ECMO model in healthy sheep. As the sheep are healthy, according to the histopathological analysis , we explored the effect of ECMO circuit itself on organs and tissues. As a preclinical study in large animals, our study aims to provide clues for further research on application expansion, management strategy optimization, pathophysiology exploration, equipment development and subsequent establishment of the disease animal model. Methods: Ten healthy sheep were treated with awake veno-arterial (V-A) or veno-venous (V-V) ECMO for 7 days. They were transferred into the monitoring cages after operation and were ambulatory after anesthesia recovery. ECMO configurations, hemodynamic and hematologic parameters were measured every day. Necropsy was conducted at the endpoint of the experiment to visualize the cannula position in vivo and to examine cannulation related injury and thrombus formation in blood vessels and major organs. Main organs and blood vessels were harvested for pathological investigation. Results: All sheep survived to the end of the experiment (the 7th day). In the whole process of the experiment, the vital signs of which were stable, and no serious bleeding and coagulation events occurred. Hemoglobin concentration and platelet count were in normal reference range, plasma free hemoglobin concentration was maintained at a low level. ECMO flow was stable, and oxygenation performance of oxygenator was satisfied. There was no major adverse pathological injury occurred. Conclusions: Long term awake extracorporeal membrane oxygenation model in large animal is feasible and stable. Perioperative management is the key to the success of this model. As a basic research, it can also provide an alternative strategy for mechanical circulatory support in patients with awake ECMO indications.