ECMO circuit monitoring: detecting oxygenator complications

Extracorporeal membrane oxygenation or ECMO in short, is an external circuit that acts as a heart-lung machine or life support system. This treatment is administered to critically ill patients that need cardiac and/or respiratory support. Typically, when on ECMO, the patient’s blood is drawn out using a centrifugal pump and pushed through a membrane oxygenator where the blood is oxygenated before being sent back to the patient. The porous membrane oxygenator which is designed to reduce blood velocity and maximize the surface area available for gas transfer, inevitably becomes a region prone to the build-up of blood clots with prolonged treatment. Clotting of blood within the oxygenator, blocks gas transfer fibers and obstructs the flow of blood. This increase in resistance to blood flow and drop in oxygenation of blood leads to oxygenator failure and an increased chance of mortality. In this study we show the use of blood flow monitoring in the shunt tube of the ECMO circuit as a potential marker to monitor for oxygenator obstruction. Blood flow monitoring can be done continuously and with no contact of blood using ultrasound flow meters available in hospitals and clinics, which could help in an efficient and automated method to evaluate ECMO circuits for building clots / obstructions in the oxygenator. The efficiency and feasibility of using blood flow monitoring was evaluated both experimentally and computationally for different configurations of ECMO. Furthermore, the impact of hemodynamic parameters on ECMO was evaluated.