ECMO: where to from here

Extracorporeal support of ARDS was first applied in 1972. The first randomized trial ever performed in ALI/ARDS showed that patients treated with extracorporeal support or with conventional ventilation had similar mortality, equal to about 90%. In the 1980s, our center introduced extracorporeal CO2 removal in ARDS, aiming at lung rest with a suggestion of benefit. A randomized study performed in 1994 did not show any survival benefit with extracorporeal CO2 removal support. The results of this trial may have been significantly influenced by bleeding complications in patients undergoing extracorporeal CO2 removal. Despite the discouraging results, in Europe few centers continued to use veno-venous extracorporeal support as a last resource in selected series of patients. In the United States, Bartlett et al. continued to provide extracorporeal support associated to mechanical ventilation with less strict entry criteria and with encouraging results. The interest on ECMO renewed after the publication of CESAR trial in 2009, which showed clear benefits on outcome when severely hypoxemic patients were treated with in an expert high case volume center (with ECMO capability) when compared to non-specialized hospitals. The rebirth of the technique, however, was due to its use as a rescue therapy during H1N1 flu epidemics in Australia and New Zealand during in severely hypoxemic patients untreatable with conventional methods. The approach vas veno-venous with high blood flows. This report showed a survival rate higher than 70% and an impressive number of centers in Europe, United States, South America, Canada and Asia started to use ECMO in patients severely hypoxemic patients which does not receive benefits from maximal mechanical ventilation. Survival rate range was comprised between 56 and 79%. The impressive diffusion of ECMO led to the great improvement of this technology, and there are increasing numbers of reports describing simple forms of extracorporeal support, primarily aiming at CO2 removal. The actual indications for ECMO depend on the patient’s need and the physician’s request. The choice of the technique may vary from low flow bypass with CO2 removal to high flow ECMO with total oxygenation support. If the aim is the treatment of life threatening hypoxemia, the clear cut indication is high flow veno-venous ECMO. If the patient, however, presents severe cardiac failure, veno-arterial ECMO must be used.