107 6 The effect of AOC on clinical outcomes in preterm infants: a pre- and post- study Introduction Preterm infants born under 30 weeks of gestation spend a long period in the neonatal intensive care unit (NICU), where they experience considerable morbidities during and after their admittance.1 Often they receive respiratory support which includes supplemental oxygen, administered with the aim of keeping oxygen saturation (SpO2) within a prescribed target range (TR) and preventing hypoxia and hyperoxia. Both frequent and prolonged SpO2 deviations have been associated with mortality and prematurity-related morbidities, including retinopathy of prematurity (ROP), periventricular leukomalacia (PVL), necrotising enterocolitis (NEC), bronchopulmonary dysplasia (BPD) and neuro-developmental impairment.2-5 Titrating the fraction of inspired oxygen (FiO2) to keep SpO2 within the TR has proved challenging. Several studies have reported on the difficulty of SpO2 targeting when FiO2 is titrated manually, reflected in a proportion of SpO2 TR time of around 50% or less. Lack of knowledge and a high workload for the caregivers were described as important factors for low compliance.6-10 Continuous oxygen titration by an automated oxygen control (AOC) device aims to circumvent these problems and improve SpO2 targeting whilst reducing the bedside workload. During AOC, signals from a pulse oximeter are continuously input to a computer algorithm which determines what adjustments to FiO2 are necessary based on the oxygenation feedback. 11 The changes to FiO2 are actuated automatically within a ventilator or other respiratory support device. Studies investigating the effect of AOC on oxygen saturation over 24 hour periods have demonstrated a beneficial effect, with infants spending more time within TR, accompanied by a decrease of severe hypoxia and hyperoxia.12-19 AOC was implemented as standard care in the Neonatal Intensive Care Unit (NICU) of the Leiden University Medical Center (LUMC) in August 2015. We recently reported the effect of this implementation on oxygen saturation in preterm infants during admission.20 Infants spent more time within TR and less time with SpO 2 >95%, but there was a lesser effect on duration of SpO2 <80%. Thus far, none of the studies comparing manual oxygen control with AOC have reported the effect on clinical outcomes. We therefore aimed to assess the effect of implementation of AOC as standard care on outcomes in preterm infants during their hospital admission.