EXTRACORPOREAL MEMBRANE OXYGENATION

Extracorporeal Membrane Oxygenation

Extracorporeal Membrane Oxygenation

Introduction

ECMO is temporary support of heart and lung function by partial cardiopulmonary bypass (up to 75% of cardiac output). It is used for patients who have reversible cardiopulmonary failure from pulmonary, cardiac or other disease.

The term extracorporeal membrane oxygenation (ECMO) was initially used to describe long-term extracorporeal support that focused on the function of oxygenation. Subsequently, in some patients, the emphasis shifted to carbon dioxide removal and the term extracorporeal carbon dioxide removal was coined. Extracorporeal support was later used for postoperative support in patients following cardiac surgery. Other variations of its capabilities have been tested and used over the last few years, making it an important tool in the armamentarium of life and organ support measures for clinicians. With all of these uses for extracorporeal circuitry, a new term, extracorporeal life support (ECLS), has come into vogue to describe this technology(Suchyta 2003).The differences between ECMO and cardiopulmonary bypass are as follows:

ECMO is frequently instituted using only cervical cannulation, which can be performed under local anesthesia. Standard cardiopulmonary bypass is usually instituted by transthoracic cannulation under general anesthesia.

Unlike standard cardiopulmonary bypass, which is used for short-term support measured in hours, ECMO is used for longer-term support ranging from 3-10 days.

The purpose of ECMO is to allow time for intrinsic recovery of the lungs and heart; a standard cardiopulmonary bypass provides support during various types of cardiac surgical procedures(Murray 2004).

A diagram of extracorporeal membrane oxygenation is shown below.

Extracorporeal membrane oxygenation (ECMO) system.

History of extracorporeal membrane oxygenation

In May 1953, Gibbon used artificial oxygenation and perfusion support for the first successful open heart operation.1 In 1954, Lillehei developed the cross-circulation technique by using slightly anesthetized adult volunteers as live cardiopulmonary bypass apparatuses during the repair of certain congenital cardiac disorders.2 In 1955, at the Mayo Clinic, Kirklin et al improved on Gibbon's device and successfully repaired an atrial septal defect(Morris 2001).

In 1965, Rashkind and coworkers were the first to use a bubble oxygenator as support in a neonate dying of respiratory failure.4 In 1969, Dorson and colleagues reported the use of a membrane oxygenator for cardiopulmonary bypass in infants.

In 1970, Baffes et al reported the successful use of extracorporeal membrane oxygenation (ECMO) as support in infants with congenital heart defects who were undergoing cardiac surgery.6 In 1975, Bartlett et al were the first to successfully use ECMO in neonates with severe respiratory distress

PHYSIOLOGY

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