Hylke Salverda

53 3 Comparison of two devices for automated oxygen control in preterm infants Introduction Oxygen therapy for preterm infants with respiratory insufficiency aims to prevent or moderate the effects of hypoxaemia on the central nervous system, lungs, and other organs. Conversely, the immaturity of the premature infant’s lungs, eyes and antioxidant system renders them vulnerable to exposure to supplemental oxygen, and hyperoxaemia has been linked to the development of bronchopulmonary dysplasia (BPD) and retinopathy of prematurity (ROP).1, 2 Mindful of these morbidities, the inhaled fraction of oxygen (FiO2) is titrated manually, based on oxygen saturation (SpO2) readings derived from transcutaneous oximetry. Current guidelines recommend a lower limit for the SpO2 target range (TR) of at least 90% for the preterm infant,3 based on the recent NeOProM metaanalysis of individual patient data from large randomised controlled trials.4 These trials highlighted the potential impact of hypoxaemia and hyperoxaemia on preterm infants, with the lower TR (85-89%) associated with an increased risk of mortality and necrotising enterocolitis (NEC), and the higher TR (91-95%) with an increased rate of ROP. Whilst the need to target an SpO2 range is widely accepted, data from cohort studies and randomised controlled trials point to the difficulty of SpO2 targeting by manual oxygen titration,5-10 with most studies reporting SpO 2 values to be within the TR less than 50% of the time. Although bedside staff adjust the fraction of inspired oxygen (FiO2) relatively frequently to maintain SpO2 within TR, their workload limits time availability and makes it difficult to tailor FiO2 continuously to the infant’s need. This is compounded by the neonatal oxygenation physiology being unstable and nonlinear with significant time delay between FiO2 adjustment and when SpO2 reaches a new stable level.11 Given both the importance and difficulty of SpO2 targeting, automated oxygen control (AOC) is a logical improvement on current practice. In essence, the concept is of an SpO2 input to a device holding a set of computational instructions (an algorithm), which then gives an output, an updated value for FiO2. Studies comparing automated oxygen titration systems with manual titration, conducted over short periods (2-24 hours per epoch), have demonstrated an absolute increase in the proportion of time spent with SpO2 within TR varying between 8% and 31%. 12-23 A single study conducted in our institution has examined the effect of implementation of AOC as standard of care, finding a 14% increase in TR time in the post-implementation cohort, mostly related to a decrease in time above TR.24