Choosing the appropriate configuration and cannulation strategies for extracorporeal membrane oxygenation: the potential dynamic process of organ support and importance of hybrid modes

Extracorporeal membrane oxygenation (ECMO) is becoming a common procedure to support patients with severe cardio-circulatory or respiratory failure as well as in case of combined compromise of the two systems. Deciding which ECMO configuration and proceeding with an uneventful implantation, however, may present minor or major shortcomings. Cannulation techniques should be tailored to specific patient conditions to provide sufficient regional and systemic perfusion, both of which must be comprehensively monitored. Changes in the patient's status or suboptimal ECMO-related support, however, may occur and should trigger re-appraisal of the cannulation strategy and circuit configuration. This dynamic management, based around the adequacy of end organ perfusion and patient requirements, may dictate ECMO configuration and cannulation changes. In these circumstances, adjunct of a cannula in the venous or arterial vasculature may represent a mandatory procedure to solve unfavorable hemodynamic status or enhance ECMO efficiency. These type of ECMO configurations, different from basic one, and called hybrid configurations, may represent, therefore, a critical aspect of optimal ECMO management towards optimized and successful temporary support. The aim of this review is to critically appraise and summarize the existing literature on adult ECMO configuration including cannulation strategies and circuit arrangement, and highlighting more complex pattern required in some specific clinical settings.