S(pO2) Histograms in Preterm Infants: A Helpful Tool for Neonatologists?

In recent years, oxygen targeting has become a relevant topic in neonatal intensive care medicine.1 Despite large SpO2 targeting trials including numerous subjects and the available results of a meta-analysis of these data,2,3 there is still an ongoing debate on the optimum SpO2 target range in preterm infants. Both conditions, hyperoxia as well as hypoxia, frequently occur in extremely low birthweight infants4 and may contribute to the development of retinopathy of prematurity,5 bronchopulmonary dysplasia,6 and impaired neurodevelopmental outcome7 in this population. In addition, the duration and severity of hypoxemic episodes during the neonatal period might be associated with late death or neurological impairment at 18 months corrected age.8 It has been shown that some preterm infants only spend about half of the time within a specific SpO2 target range. 9 This might be a crucial point in the ongoing discussion about the optimum saturation ranges in preterm infants. Pulse oximetry monitoring without frequent surveillance of the obtained data (ie, percentage of time in target saturation range, detection of prolonged hypoxemic/hyperoxemic episodes) may diminish the possible benefits of oxygen targeting. How can we reach the target, if the target is out of sight? Standard monitoring in the neonatal intensive care unit includes SpO2 monitoring, and target oxygen saturation ranges are usually well defined, whereas the documentation of these data differs from unit to unit. Hand-transcribed SpO2 documentation is still a widespread practice in neonatal intensive care units despite the evidence that this may underestimate SpO2 fluctuations. 10 Therefore, regular visualization and comparison of SpO2 data over time seems to be a promising approach to guide therapeutic interventions (eg, adjustment of respiratory support, faster adjustment of FIO2, and/or adapting methylxanthine treatment) and may improve neonatal outcome. In the current issue of RESPIRATORY CARE, Viscardi et al11 used SpO2 histograms, provided by pulse oximetry, to visualize the percentage of time infants spent within specific oxygen saturation ranges. This approach may help to predict failure to wean from noninvasive respiratory support in preterm neonates. The authors were able to show that infants who spent 15% of time with SpO2 86% in the