Oxygen Therapy in Preterm Infants: Hitting the Target

The appropriate use of oxygen in the preterm infant has been the source of concern and study for more than half a century.1 Oxygen therapy has been causally linked to adverse neonatal outcomes including retinopathy of prematurity and chronic lung disease.2,3 Lowering oxygen saturation targets in preterm infants in the first few weeks of life has been shown to reduce the incidence of certain complications3; however, prolonged periods of hypoxemia may result in poor growth, cardiopulmonary complications of chronic lung disease, neurodevelopmental disabilities, or increased mortalities. In this issue of Pediatrics, Hagadorn et al4 present their study of intensive care teams’ ability to maintain saturations within limits established in their units. The study elucidates the many complexities of oxygen targeting in preterm infants.Although maintaining ranges of hemoglobin oxygen saturation in the vulnerable preterm population in the proximity of 85% to 90% is gaining increasing acceptance, marked variability in opinion exists. Center protocols studied by Hagadorn et al4 differed in terms of both targets and ranges, and the optimal guideline needs to be determined. The exact limits of such targets are probably less important than avoiding saturations ≥95%. In addition, the Hagadorn et al data demonstrate marked instability of the preterm population with fluctuations in saturations on both sides of the target, displaying the daunting challenge of caring for these tiny infants. However, remarkably, this study also documents the inability of the health care teams at 14 esteemed intensive care nurseries globally to maintain saturations within the target range on these infants even half of the time. Although the authors comment that the compliance necessary to achieve the benefits of a targeted saturation range is unknown, it is hard to believe that falling out of the range half of the time is adequate. This is not a new finding. Horbar et al5 demonstrated similar deviations in time spent at various oxygen tensions using the transcutaneous monitor in 1980. However, the use of pulse oximetry as the surrogate indicator for oxygen tension adds an additional source for error because investigators have demonstrated poor correlation of saturation and oxygen tension at saturations >92%, even when technical problems with saturation monitors such as motion artifact and poor perfusion are minimized.6How are we to move forward with targeted oxygen saturations in preterm infants? First, it needs to be recognized that appropriate oxygen levels are a multifactorial issue, and the solutions require a multidisciplinary approach. Oxygen delivery with minimal toxicity is the goal, and anyone deciding on targets for oxygen therapy needs to consider oxygen delivery to tissue, which means attention to adequate blood pressure maintenance and transfusion practices in addition to hemoglobin saturation. Research is ongoing in these areas. However, maintaining saturations within a targeted range may require a new approach with an elaborate educational program including “buy in” from the entire health care team and even the patient’s guardians. This requires changing the mind-set of team members who need to understand that high saturations are not better. Accepting wider ranges of targets to decrease incessant alarms, the use of improved saturation monitors, and applying performance-improvement principles to this process are important adjuncts to success. Providers need to understand that cumulative oxygen saturations over time represent a bell-shaped curve, and the role of the health care team is to minimize the tails in both directions. Another approach may be to use new technologies to help us control oxygen delivery7,8 and to better understand the mechanisms behind fluctuations in hemoglobin saturations, which may help us to proactively address the issue.9 But, understanding the pathophysiology may not immediately lead to effective treatments, and commercially available oxygen controllers for preterm neonates, while showing some improvement in achieving targets, have been difficult to develop.A learning from the study by Hagadorn et al4 is that infants born at <28 weeks’ gestation experience fluctuations in oxygen saturations to the degree that is not generally acknowledged, and these fluctuations are not well controlled by the current bedside staff even when strict targets and ranges with alarms are in place. Reducing these fluctuations may require bedside personnel with specific training and time dedicated to refining care. We then might be able to hit the targets more often than we miss them and enhance outcomes.