Extracorporeal Membrane Oxygenation (ECMO), Extracorporeal Life Support (ECLS) and Cardiopulmonary Support (CPS) are acronyms that all refer to the establishment of cardiopulmonary bypass using portable mechanical circulatory support systems.
Extracorporeal Cardiopulmonary Resuscitation (ECPR) is the initiation of bypass during resuscitation of the arresting patient.
These systems are highly portable, as large as a small appliance on wheels to as small as a cardiac transport monitor (Maquet Cardiohelp™), and can quickly be brought to the arresting patient in almost any setting, including the operating rooom, ICU, Emergency Department, or even the prehospital arena.
ECPR is performed by the resuscitationist via percutaneous vascular access during traditional CPR. In other words, one doctor is “running the code” and another doctor is accessing the femoral vessels. Rarely, femoral vessel cutdown is necessary. We recently published a study (Bellezzo, et al) showing that Emergency Physicians can successfully perform ECPR, but the procedure can be done by any resuscitationist with training in advanced vascular access.
ECMO can provide both cardiac and respiratory support to patients whose heart or lungs are so damaged that they cannot perform their function. This is a temporizing measure to allow the time to address the problem that caused the arrest. There are several indications for ECMO but a classic example is the the patient with massive MI and refractory ventricular fibrillation. In this example ECMO would provide the circulatory support necessary to buy enough time to get the patient to the coronary cath lab.
The two most common types of ECMO are veno-arterial ECMO (VA-ECMO) and veno-venous ECMO (VV-ECMO). In both forms, blood is drained from the venous systems using large percutaneous cannulas where oxygen is added and carbon dioxide is removed. In VA-ECMO this blood is returned to the arterial system and in VV-ECMO the blood is returned to the venous system.
VV-ECMO is typically used for pure respiratory support. The classic example here is the patient with status asthmaticus who is failing mechanical ventilatory support.
Blood is drained from the body via a cannula in the common femoral vein and returned to the venous system via the femoral vein, or internal jugular vein. Alternatively, a dual lumen cannula is inserted in the internal jugular vein and blood is drained from the inferior and superior vena cavae and returned at the right atrial inlet. While placement of the dual lumen cannula should be done under visualization (ie fluoroscopy), individual cannulas can be placed “blind.”
For more information, take a look at our page that walks you through the initiation of VV-ECMO .
VA-ECMO is the configuration that is typically done in the ED setting. ECPR is VA-ECMO. A venous cannula is placed in the common femoral vein (drainage) and an arterial cannula is placed in the femoral artery (infusion). Ideally, the tip of the venous cannula is draining blood from the right atrial inlet, while the tip of the arterial cannula delivers blood to the iliac artery just below the renal arteries. Establishment of the circuit is therefore retrograde.