**Abstract**

Extracorporeal membrane oxygenation (ECMO) is a special form of organ support for selected cases of cardiovascular and severe respiratory failure. Echocardiography is a diagnostic and monitoring tool widely used in all aspects of ECMO support. The pathophysiology of ECMO, and its distinct effects on cardiorespiratory physiology, requires an echocardiographer with high skills to understand the interaction between the ECMO and the patient. In this chapter, we present the main application of echocardiography in ECMO patients and some general concepts on the ECMO working. ECMO, such as the standard cardiopulmonary bypass employed in cardiac surgery, V-V (veno-venous), can support the insufficient respiratory system by oxygenating and removing carbon dioxide from the blood. VA-ECMO (venous-arterial) can support haemodynamics by providing mechanical circulatory assistance. Today, ECMO can be used as bridge to decision, waiting for the development of the clinical conditions to support with other devices the evolution of cardiorespiratory failure or stop the assistance. Echocardiography (transthoracic (TTE) or transoesophageal (TOE)) can be used primarily to take decisions regarding appropriateness of ECMO support, therefore to control cannula insertion and confirm final position, to modify number and position of the cannulae in case of malfunctioning of these, and, finally, to assess clinical progress and suitability for weaning from ECMO.

**Keywords:** echocardiography, critical care, ARDS, extracorporeal cardiopulmonary resuscitation, thromboembolism, tamponade, hemodynamic monitoring, VV-ECMO, VA-ECMO
