129 7 AOC for very preterm infants and neurodevelopmental outcome at two years Discussion This is the first study to report data on long-term neurodevelopmental follow-up at two years corrected age in very preterm infants treated with automated oxygen titration as standard of care compared with manual oxygen titration as standard of care. Implementation of automated oxygen titration did not lead to a change in mortality or neurodevelopmental outcome at 2 years. Although earlier studies6-14 demonstrate an increase in time within target range when using automated oxygen titration, we were not able to demonstrate an effect on neurodevelopmental outcome in this large cohort. Todate, there is little data on clinically relevant outcome of infants receiving automated oxygen titration. There is no data available on neurodevelopmental outcome after usage of AOC, and data on follow-up of preterm infants from non-AOC studies are difficult to compare with, because they involved non-standard interventions,23, 24 infants born almost 15 years ago,25, 26 or had a study population that had markedly different characteristics27, 28. The outcomes of both groups in our study are similar to the outcome of a previous cohort study from our centre.26 The reason for fewer readmissions after implementation of automated oxygen titration is not apparent from our data. Rates of BPD, ROP and other morbidity potentially requiring re-hospitalisation are similar, although we did find fewer ventilation days in our previous study for the post-AOC cohort.29 A failure to demonstrate an impact on neurodevelopmental outcome after implementing automated titration can have several causes. In the previous study on achieved target range time in our NICU, we demonstrated that although infants spent more time within target range overall, this was mainly attributed to a reduction in time above the target range. In fact, using the CLiO2 controller led to a 6% increase of time spent under the SpO2 target range (90-95%). This increase was mainly just below (85-90%) target range while still having a similar proportion of hypoxaemia (<80%). If indeed more time spent under the target range is where neurodevelopmental improvement can be gained, the lack of improvement in this area could explain the lack of impact on neurodevelopmental outcome. Furthermore, as reported before it could be that outcome is more largely influenced by the frequency and duration of hypoxia and hypoxic events,30 which were not investigated in our previous study nor in most other automated oxygen controller studies. Also, preterm infants can experience many potentially harmful stimuli and events before being tested at two years of corrected age, in particular during the neonatal phase. Oxygenation deviations during
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