Definition and Overview
Extracorporeal membrane oxygenation is a life-saving procedure used in intensive care medicine to provide both respiratory and cardiac support for patients whose heart and lung functions are compromised. Also known as extracorporeal life support (ECLS), it is typically used on younger patients, but over the last few years, it is also being used for patients suffering from cardiac and respiratory failure.
There are two types of extracorporeal membrane oxygenation—veno-arterial and veno-venous. Both involve the drainage of blood from the veins, which is then oxygenated outside of the patient’s body. The difference between the procedures is the method of returning the oxygenated blood. With veno-arterial, the blood is returned to the arterial system, while with the veno-venous, the blood is returned to the venous system. Also, a veno-venous extracorporeal membrane oxygenation does not provide cardiac support for the patient.
Who Should Undergo and Expected Results
Extracorporeal membrane oxygenation is often used on infants and children with cardiac and respiratory problems, especially those who need a heart-lung bypass support. It can also be offered to patients—even adults—with the following conditions:
- Congenital malformations of the heart
- Severe pneumonia
- MAS, or meconium aspiration syndrome
- Severe air leak problems in the lungs
- CGH, or congenital diaphragmatic hernia
- Severe pulmonary hypertension
- Cardiac arrest
- Hypoxemic respiratory failure
- Refractory cardiogenic shock
- Hypercapnic respiratory failure
The procedure is also recommended for:
- Young patients awaiting a heart or lung transplant who require cardiac and respiratory support before the procedure
- Patients who have undergone a cardiopulmonary bypass during and after cardiac surgery and have not responded well to weaning
Extracorporeal membrane oxygenation can also serve as a bridge to heart transplantation, or during the period where the patient and the medical team are waiting for the placement of a ventricular assist device.
The procedure can help increase the patient’s survival rates, especially in patients with neonatal respiratory failures. For adults with respiratory failure, the procedure provides a 55% survival rate.
How is the procedure performed?
The ECMO machine is the most important component of the procedure. This apparatus has a blood pump connected to raceway tubing, a venous reservoir, a countercurrent heat exchanger, and a membrane oxygenator. The artificial lungs also have a roller pump (for younger patients) or a vortex centrifugal pump. Three types of artificial lungs are used with an ECMO machine, namely hollow-fiber, membrane, and bubble devices. Air bubble detectors are also in place to ensure that there will be no air bubbles in the blood once they are returned to the patient’s body.
The techniques used in this procedure are:
Veno-arterial ECMO - This procedure is often used for neonatal patients. A small incision is made where a cannula is inserted through the patient’s right jugular vein and into the right atrium. The patient’s blood is then drained into a venous reservoir located three to four feet below heart level. The blood is pumped through the oxygenator and then warmed to body temperature before returned to the patient’s body.
Veno-venous ECMO - This technique can be performed on older patients. The surgeon will first make an incision to place a double-lumen cannula into the right jugular vein and the right atrium. The medical team will then initiate the drawing of desaturated blood from the right atrium using the outer cannula. Oxygenated blood will be returned through the inner lumen of the cannula and direct blood across the patient’s tricuspid valve.
Possible Risks and Complications
Patients who are recommended to undergo an ECMO procedure are typically very ill, which means that they are at a higher risk of medical problems in the future. One of the risks is death. Additional risks and complications of an extracorporeal membrane oxygenation include:
- Excessive bleeding
- Formation of blood clots
- Infection in the blood and site of cannula insertion
- Issues with a transfusion
Mechanical issues of the ECMO apparatus—including breakages, stoppage, and obstruction in the interconnected pipes and tubes—can also harm the patient.
Baffes TG, Fridman JL, Bicoff JP, Whitehill JL. Extracorporeal circulation for support of palliative cardiac surgery in infants. Ann Thorac Surg. 1970 Oct. 10(4):354-63.
Smith IJ, Sidebotham DA, McGeorge AD, Dorman EB, Wilsher ML, Kolbe J. Use of extracorporeal membrane oxygenation during resection of tracheal papillomatosis. Anesthesiology. 2009 Feb. 110(2):427-9.