This article includes discussion of extracorporeal membrane oxygenation, extracorporeal life support, and ECMO. The foregoing terms may include synonyms, similar disorders, variations in usage, and abbreviations.
Extracorporeal membrane oxygenation, an advanced life support system, has improved the survival and neurodevelopmental outcome in neonates with respiratory failure due to reversible pulmonary disease. In this article, the author describes the history, criteria, and medical technology involved in extracorporeal membrane oxygenation as well as the outcome of neonates treated with extracorporeal membrane.
• Extracorporeal membrane oxygenation is an effective therapy for hypoxic respiratory failure due to reversible pulmonary disease in neonates.
• It is cost effective therapy with excellent survival rates as well as good long-term outcomes to school age.
• It has been used as an adjunctive therapy for the management of neonates with congenital cardiac defects and for neonates requiring emergency cardiopulmonary support.
Historical note and terminology
Extracorporeal membrane oxygenation is a prime example of cutting-edge technology that has proven its effectiveness in the management of hypoxic respiratory failure in the newborn. Although the acronym “ECMO” indicates only oxygenation, venovenous and venoarterial extracorporeal membrane oxygenation provide oxygenation as well as carbon dioxide removal. Venoarterial extracorporeal membrane oxygenation also provides cardiac support. Therefore, the appropriate terminology would be “extracorporeal life support” (ECLS). However, it will be referred to as extracorporeal membrane oxygenation (ECMO) because of its wide usage and familiarity. The focus will be on ECMO in the neonatal population.
In the past, various investigators have attempted to provide extracorporeal circulation to support patients with cardiorespiratory problems. Gibbon, who began work on extracorporeal circulation in 1937, is considered the father of the cardiopulmonary bypass. Over the next 20 years, the technique was further refined. In the 1950s it was applied mainly to infants and children requiring surgery for congenital heart disease but with poor results. It was not until the mid-1960s that prolonged extracorporeal circulation was attempted in humans, with the first successful report by Hill and colleagues in 1972 (Bartlett 1993). Bartlett is credited with pioneering the technique to successfully provide ECMO support for neonates with hypoxic respiratory failure. In 1976 he reported the first neonatal patient who survived ECMO, named “Esperanza” - meaning “hope” - by the nurses. There are now 223 ECMO centers in the world that contribute ECMO data to the International Registry of Extracorporeal Life Support Organization (ELSO). The Extracorporeal Life Support Organization registry provides ECMO centers each year with the international and center-specific ECMO outcome data for neonatal, pediatric, and adult cases.
In 1975, the National Institutes of Health sponsored a randomized control trial of ECMO versus conventional treatment in the management of adult respiratory distress syndrome. The trial was stopped in 1979 because of a less than 10% survival rate in the treated and control groups (Zapol et al 1979). Study failure has been attributed to various factors such as lack of prior experience with ECMO, a nationwide epidemic of influenza and pneumonia during the study period, and an increase in bleeding complications. Following these discouraging results, more trials in the adult population were discontinued. However, Bartlett, who worked on the technique and its application, successfully reported the use of ECMO in the management of neonatal respiratory failure in 1982.
Bartlett and colleagues reported results of a randomized control trial that showed significantly improved survival with ECMO than with conventional treatment (Bartlett et al 1985). However, the randomization technique was “play the winner" and was not accepted by the scientific community at large. In 1989, O'Rourke and associates reported results of the randomized trial of ECMO versus conventional therapy in neonates with persistent pulmonary hypertension (O'Rourke et al 1989). Overall survival in the ECMO treated group was better than in the conventional therapy group (97% vs. 60%; p<0.05). Results of this trial were not widely accepted due to study design. The third randomized control trial of neonatal ECMO was carried out in the United Kingdom. The mortality was significantly less in patients treated with ECMO versus conventional management (32% vs. 59%; p=0.005) (UK Collaborative Study Group 1996). A 4-year follow-up showed that death or severe disability was less frequent in ECMO versus the conventional treatment group (37% vs. 59%, p=0.004) (Bennett et al 2001).
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