Extracorporeal membrane oxygen (ECMO) has been used for many years in patients 
with life-threatening hypoxaemia and/or hypercarbia. While early trials 
demonstrated that it was associated with poor outcomes and extensive 
haemorrhage, the technique has evolved. It now encompasses new technologies and 
understanding that the lung protective mechanical ventilation it can facilitate 
is inextricably linked to improving outcomes for patients. The positive results 
from the CESAR (Conventional ventilation or ECMO for Severe Adult Respiratory 
failure) study and excellent outcomes in patients who suffered severe influenza 
A (H1N1/09) infection have established ECMO in the care of patients with severe 
acute respiratory distress syndrome. Controversy remains as to at what point in 
the clinical pathway ECMO should be employed; as a rescue therapy or more 
pro-actively to enable and ensure high-quality lung protective mechanical 
ventilation. The primary aims of this article are to discuss: 1) the types of 
extracorporeal support available; 2) the rationale for its use; 3) the 
relationship with lung protective ventilation; and 4) the current evidence for 
its use.