ECMO – Long term follow-up

Abstract

Since ECMO was first introduced in the late 1970s for the treatment of acute hypoxic respiratory failure (AHRF) in children, it has been used in over 25,000 patients worldwide. Data from the Extracorporeal Life Support Organization (ELSO) shows that ECMO has been used in over 20,000 neonates with an overall survival of 80%. Despite this impressive record, less is known about the long term morbidity associated with what is the ultimate means of technological support. In neonatal respiratory failure, the main area of concern is neurological morbidity which is likely to be multifactorial in aetiology. Factors that may influencethis morbidity are the degree of hypoxaemia prior to cannulation, the use of hyperventilation to treat PPHN, the cannulation and ligation of the carotid artery and the internal jugular vein, the use of systemic heparinization in the near-term or pre-term infant and the duration of ECMO support. Outside of the central nervous system, major factors that determine long term pulmonary morbidity are pre-existing pulmonary morbidity (BPD) and the pulmonary vascular disease and pulmonary hypoplasia that is seen in congenital diaphragmatic hernia. This latter category of patient seems to be particularly problematic, firstly because the overall survivor rate is lower than other forms of neonatal respiratory failure (60% survival vs. 80% survival) and the incidence of significant neurological disability also seems higher. A recent retrorospective review from ECMO centres in the United Kingdom showed that in 73 patients with CDH treated with ECMO there were 27 survivors to one year of age, but 13 of these had long term respiratory morbidity, while 7 had neurodevelopmental problems. However, when evaluating data like this, one has to try and separate the morbidity associated with the use of ECMO versus the morbidity inherent with acute hypoxic respiratory failure in the newborn. The best data that we have in order to help separate these two issues is the long term outcome from the UK randomised controlled trial of neonatal ECMO. The end point for this study wasoutcome at one yearof age and subsequent evaluation. Patients randomized to receive ECMO had better overall outcomes at the one year mark and the four year survival data was published in the Lancet in 2004. This showed that 50% of the ECMO long term survivors had no disability while only 37% of those treated in the conventional arm were normal (Table 1). This landmark study has established the superiority of ECMO over conventional therapy for infants with severe AHRF. With further technological advances such as the use of heparin bonded circuits, repair of the neck vessels at the time of decannulation and the decreased use of hyperventilation to treat PPHN, there is an expectation that this neurological morbidity will fall substantially in the future. Long term outcome in older children with AHRF is