A pulsatile pneumatically driven neonatal extracorporeal membrane oxygenation system using neck vessel cannulas tested with neonatal mock circulation

In posthypoxic circulatory failure, pulsatility of flow generated by mechan ical support devices significantly influences outcome. Pneumatically driven assist devices can create highly pulsatile flow, but need large graft cann ulas implanted by thoracotomy in children and neonates. Emergency applicati on is therefore hindered. We conducted an in vitro study using neonatal moc k circulation (NMC) to test whether an extracorporeal membrane oxygenation (ECMO) system driven by a commercially available pneumatic assist device al so can be operated through commonly used neonatal neck vessel cannulas. Usi ng the pneumatically operated Medos ventricular assist device (VAD) 10 ml v entricle along with the Jostra M8/HEC40 oxygenator/heat exchanger, a neonat al ECMO system was assembled and connected to the NMC by means of commercia lly available neonatal neck Vessel cannulas. Effective ECMO flow, combined circulation flow, and circulation pressures were measured during various wo rking settings (ventricle driving pressures [systolic/diastolic (mbar)]: lo w: +100/-25, moderate: +200/-50, high: +300/-99) and loading conditions (de vice working against 0, 50, and 100% native circulation flow). Additionally , maximum possible ECMO flow through Various sizes of neonatal ECMO cannula s and resulting pressure gradients were assessed. High pressure settings we re necessary to achieve 100 ml/kg/min pulsatile circulation flow in case of zero native circulation. With residual 30% native circulation flow, 100 ml /kg/min pulsatile circulation flow could be established by moderate pressur e settings. Low preload or high systemic vascular resistance reduced ECMO f low markedly. We concluded that in the described setting a pneumatically dr iven neonatal ECMO system could be operated even through commonly used neon atal neck vessel cannulas. It was necessary to accept partial emptying of t he artificial ventricle and tapering of driving pressures with increasing n ative circulation.