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.