How does the changing profile of infants referred for ECMO affect the overall respiratory outcome?

Objective: Extracorporeal Membrane Oxygenation (ECMO) has been shown to be effective in full-term neonates with severe but reversible lung disease within the context of randomized controlled trial. Since this trial, ECMO has been open to a wider population of infants in the UK and other treatments have become available. The population referred for ECMO has therefore changed. The aims of this study were (i) to compare respiratory outcomes of infants receiving ECMO in recent years with those from ten years ago, and (ii) to see if respiratory outcome varied with diagnostic group. Methods: All infants referred to a single ECMO centre below the age of 12 months over a 7-year period were eligible. They attended the laboratory one year after ECMO for measurements of lung volume, airways conductance, maximum expiratory flow, and indices of tidal breathing. Results: One hundred and six (77% of those eligible) were tested and results compared with 51 infants referred for ECMO as part of the original UK ECMO trial. The groups were of comparable weight and length. Lung volume was not different but there was a strong trend for the infants seen in more recent years to have better forced expiratory flow and specific airway conductance. Restricting analysis to the major sub-group (Meconium Aspiration) confirmed these findings. When divided into diagnostic subgroups, those infants requiring ECMO for respiratory distress syndrome or who were over 2 weeks when commencing ECMO had a poorer respiratory outcome than others. Conclusions: The respiratory outcome of infants treated beyond the tightly-regulated criteria of the UK trial remains good and even shows a trend towards improvement. Certain subgroups require ECMO for longer and have poorer pulmonary function when followed up. This is important when providing information to parents and may have implications for workload planning of ECMO units and future healthcare provision.