Introduction
Extra Corporeal Membrane Oxygenation (ECMO) is a form of mechanical circulatory support and extracorporeal life support system that provides cardiopulmonary support in patients with cardiac and/or pulmonary failure that is refractory to conventional medical management1,2. It is utilised to provide oxygenation, remove carbon dioxide and provide perfusion support via a circuit consisting of arterial and/or venous cannulae, connecting tubing, a blood pump and a gas exchange device. ECMO is broadly divided into two types: veno-arterial ECMO (VA-ECMO) and veno-venous-ECMO (VV-ECMO), which differ not only in their configurations and functions, but also their indications. VV-ECMO is indicated for pulmonary failure due to any cause or following lung transplantation due to primary graft failure whilst VA-ECMO is indicated for severe refractory cardiac failure due to any cause or for post-cardiotomy cardiogenic shock (PCCS) due to failure to wean from cardiopulmonary bypass (CPB).
Institution of ECMO should only be on a temporary basis as a bridge to recovery, meaning until organ recovery occurs at which point ECMO can be removed1. ECMO may also be utilised as a bridge to destination therapy, meaning it may be used until implantation of a permanent ventricular assist device (VAD) or as a bridge to transplant therapy for use until organ transplantation is carried out. It is not useful in cases where pathology is not thought to be reversible and end organ functional recovery likely.
Whilst ECMO is a supportive therapy rather than a disease modifying treatment, it has been demonstrated to improve patient outcomes. The patient outcomes associated with the use of ECMO are dependent on the indication and the patient population it is utilised in with the survival to discharge rates for its use in acute respiratory failure being reported as ranging from 59% to 73%3. Survival to discharge for ECMO for cardiac support has been reported to be between 43% and 53%. Survival to discharge for ECMO indicated for cardiopulmonary resuscitation has been reported as ranging from 29% to 42%. In cardiac surgery patients specifically, various studies have demonstrated the survival benefit associated with institution of VA-ECMO in patients with PCCS which would otherwise be fatal4-13.