Ad-hoc Assembly of Lean Extracorporeal Membrane Oxygenation Systems for COVID-19

Patrick Hunziker; Urs Zenklusen

The feasibility of ad-hoc integrating Impella blood pumps that are already on-site in many hospitals with standard ECMO gas exchange cartridges, tubes and connectors was tested using different connection techniques. Figure 1 shows the concept, the used parts, assembly process and the results of such lean ad-hoc ECMO systems. Prototype systems were built as a first simplified closed loop with an embedded Impella CP pump only, as a second closed loop setup incorporating a venous suction cannula, a venous return cannula, an oxygenator and in-line Impella pump driven by a standard Impella AIC console (Abiomed, Danvers MA, U.S.A), and a third system additionally containing a second gas exchange module flushed with nitrogen to simulate oxygen extraction in patients. Abiomed Impella CP and Impella 5.0 pumps, and a standard ECMO oxygenator (Hilite 7000, Stolberg, Germany) were used. Key steps are the coaxial introduction of the Impella pump into the tube through a Y tube connector, prevention of recirculation of the pumped blood around the Impella pump head by suited obstruction/constriction of the outer tube, suited tube diameter stepups/stepdowns to minimize flow resistance at pump inlet/outlet and the use of large enough venous drainage cannulas (17-29F; 24-31F dual lumen cannulas) and sufficiently large (17-22F) jugular venous return cannulas. Supplement table 1 is a list of components used and gives detailed tips and tricks for easy assembly.