Cannulation strategies for extracorporeal membrane oxygenation.

Extracorporeal membrane oxygenation (ECMO) is a type of extracorporeal life support (ECLS) in which the function of the heart and/or lungs is partially or completely replaced by a portable system that provides prolonged support to critically ill patients with respiratory or cardiac failure. There are two major variants of ECMO: veno-venous (VV) ECMO and veno-arterial (VA) ECMO. VV ECMO replaces the function of the lung in which it uses a cannula to remove venous blood and oxygenates it using the extracorporeal system, and returns the blood to the right atrium to be pumped to the body. VA ECMO is slightly different in that it replaces the function of the heart and lungs by returning oxygenated blood to the aorta. As a therapy for respiratory failure, ECMO minimizes hypoxia, diminishes lung stress and strain, and allows lung protective mechanical ventilation. As a support for acute and terminal heart failure, ECMO reduces preload, increases aortic flow, and allows for end-organ perfusion. Due to its physiological support and advantages, it is used for a variety of chronic and acute support purposes such as bridge therapy for heart/lung transplant, durable ventricular assist devices, and intermediate-term mechanical support postoperatively. Our review gives a broad overview of the two main types of ECMO strategies and their clinical indications, cannulation strategies, unique clinical utility, and their limitations.