By Aaron Dix

Extracorporeal Membrane Oxygenation (ECMO) started in the 1970s as a way of supporting the heart and lung functions of neonates and young pediatric patients. Original ECMO devices were as large as a vehicle and difficult to operate.

Over the past several years technological advances have allowed ECMO machines to become smaller, about the size of a large cardiac monitor weighing just over 25 pounds, and even portable enough to fit in most ambulances. As the size of the ECMO machine has shrunk, the role of ECMO has expanded rapidly.

Patients are now routinely transferred to medical facilities for ECMO initiation or between facilities with ECMO already in place. Most recently, emergency department resuscitationists have begun to use ECMO for the treatment of refractory cardiac arrest. In France, mobile ECMO teams respond to out-of-hospital cardiac arrests; in San Diego, California, certain cardiac arrest patients are transported with ongoing resuscitation for rapid implantation of ECMO which is known as ECPR.

As ECMO becomes more common, paramedics must become familiar with the fundamentals of this procedure. Here are five things to know about ECMO:

1. Temporary circulatory and respiratory support

ECMO provides temporary support of heart and/or lung function to allow the organs to recover after severe injury from conditions such as Acute Respiratory Distress Syndrome (ARDS), pulmonary ebolism, and heart failure. Traditional heart-lung bypass is performed in an operating room during open heart surgery. Patients under general anesthesia have catheters placed directly into the great vessels of their heart, bypassing both the lung and the heart. This allows for appropriate oxygenation and circulation while the heart is stopped.

ECMO differs from traditional heart-lung bypass in a few significant areas. ECMO catheters can be placed in the emergency department, ICU, or even the patient's home or office as is currently being done in Paris. Instead of catheters being placed directly into the great vessels of the heart, ECMO catheters are inserted into large veins in the neck or leg and can be placed on patients who remain conscious.

2. Oxygenation and carbon-dioxide removal

The ECMO machine syphons blood from either the internal jugular or the common femoral vein. The blood is then oxygenated and carbon dioxide removed. In most cases, the oxygenated blood is warmed to 37 C and pumped back into the body either veno-venously or veno-arterially.

3. Types of ECMO

Veno-venous ECMO is used to support respiratory conditions; the patient's heart function remains undisturbed by the procedure. Blood is reintroduced through another venous catheter into a different large vein, typically the femoral vein or internal carotid vein. The oxygenated blood then goes through the normal circulatory process. In this method the patient’s normal hemostatic actions remain intact.

Veno-arterial ECMO is used when the patient’s cardiac output is absent or insufficient to support life. Oxygenated blood is delivered directly into a large artery, typically the right carotid common artery or the iliac artery, bypassing the heart completely.

4. Improved outcomes for refractory cardiac arrest

The SAVE-J Trial done in Japan, as well as studies from San Diego and Australia, have demonstrated significant positive outcomes for patients with refractory cardiac arrest who received ECMO. These patients with prolonged own time would typically have resuscitative measures ceased and death certain. However, patients with a relatively short down time, 45 minutes from collapse to initiation of ECMO, can survive with quality neurological outcomes when ECMO is initiated in conjunction with therapeutic hypothermia. Cardiac arrest protocols in the future may call for patients who meet certain criteria to be placed on a mechanical CPR device for transport to the hospital for initiation of ECMO prior to ROSC.

5. Medics support ECMO teams

Paramedics will not be initiating ECMO in the field. Physicians will either respond to conduct the procedure, as is the case in Paris, or the patient transported to the emergency department like San Diego. In that same vein, paramedics should be transporting patients on ECMO with a specialty hospital ECMO team. However, paramedics are prehospital clinicians, not drivers. Medics must understand the basic principles of ECMO to assist in the delivery and monitoring of this life-sustaining technique.

Learn more about ECMO from these resources:

About the author

Aaron Dix is the operations director for the Greenville Healthcare Simulation Center. He has a MBA in health care management, is a nationally certified EMS educator, and has 20 years of EMS experience. Previously he was the training coordinator for the largest and busiest EMS system in South Carolina, managing the education of over 500 EMTs, paramedics and firefighters. In addition to his duties at the simulation center, he remains a practicing paramedic with Anderson County EMS, Clear Spring Fire Rescue, and is an active member of the Emergency Medical Services for Children Advisory Council in South Carolina.