Hylke Salverda

145 8 Clinical outcomes comparison of two different AOCs Discussion In this observational study infants in the OxyGenie group had less morbidity. Fewer infants needed laser coagulation for retinopathy of prematurity in the OxyGenie cohort when compared to the CLiO2 cohort. On average, administered supplemental oxygen was of a modest proportion in both groups and with the exception of a shorter duration of continuous positive airway pressure and invasive mechanical ventilation, the durations on other modes of respiratory support were not significantly different. Infants in the OxyGenie cohort had a significantly shorter duration of stay in the NICU. Other short-term clinical outcomes were not significantly different between groups. In a prior study we reported on the effect of AOC on clinical outcome during standard of care for preterm infants in which the AOC cohort consisted almost entirely of infants treated with the CLiO2 algorithm. 23 In this larger cohort around 6% of infants needed laser coagulation for ROP, similar to what is previously reported (5.9%) in a cohort of over 154.000 very preterm infants. Contrary to our results, a recent study in the Netherlands reported an increase in treatment for ROP in the more recent epoch.24 The prevalence was 2.3% in the most recent epoch, however the upper gestational age criterion was higher (i.e. 32 weeks).1 These figures of prevalence, combined with the relatively modest cohort size, may be indicative that the prevalence of laser coagulation for retinopathy of prematurity in the CLiO2 group may be an overestimation. Nevertheless, the occurrence of laser coagulation in the Oxygenie group was much lower than our prevalence during manual treatment. A reduction in ROP when using OxyGenie could be plausible. In a randomised crossover trial comparing OxyGenie to CLiO2 we reported significantly less time above target range, tighter target range adherence (i.e. less fluctuation of oxygenation) and less frequent and shorter episodes of both hypoxaemia and hyperoxaemia while using OxyGenie.25 Hypoxaemia, hyperoxaemia, and fluctuation of oxygenation have all been associated with an increased rate of ROP.11, 12, 26 Early after preterm birth, a varying oxygenation of the retina might lead to decreased retinal vascular growth and blood vessel loss, leaving the retina more susceptible to damage due to hypoxia. In a later phase, this increases the risk of uncontrolled neovascularisation and retinal detachment.27 Although our randomised trial was limited to 48 hours per studied infant, there is no reason why those results cannot be generalised largely to the rest of the admission, as the postnatal age at study was variable. We did not have data on cardiotonic medication, the other risk factors (postnatal steroids, sepsis, NEC and mechanical ventilation > 3 days) were not different between cohorts.