Abstract
Purpose: :
An increasing body of evidence suggests that the hyperoxic environment of the premature infant combined with an immature retina initiate a cascade of events that lead to retinopathy of prematurity (ROP). Early recommendations to limit oxygenation resulted in less ROP but increased medical complications. Fluctuations in oxygenation are also thought to be detrimental to normal vasculogenesis. As such, new policy guidelines have been designed to safely titrate oxygen levels while also minimizing fluctuation. The purpose of this study is to determine whether the revised oxygen guidelines reduces the incidence and/or severity of ROP.
Methods: :
Oximetry alarm limits were lowered to 87-93% for all infants with a birth weight 1500g or less and/or gestational age 32 weeks or less and maintained until oxygen saturations were consistently greater than 93% on room air or the infant developed ROP. For oxygen levels less than 87%, FiO2 was not to be increased by more than 5% increments nor flow increased to more than 100ml/min. The new policy was effective for infants born on or after April 1, 2005. Data was retrospectively collected, and we compared the rate and severity of ROP in the year after the policy change (post-group) to the immediately preceeding year (pre-group). Charts were reviewed with attention to gestational age, birth weight, any ROP, and any intervention. Any ROP was defined as stage 1 disease or greater. Any intervention was defined as laser, cryo, or surgery.
Results: :
The average gestational age was slightly higher in the post-group (28.3 vs. 29.3, p = 0.046). Additionally, the average birth weight was also higher in the post-group (1033g vs. 1239g, p = 0.006). The number of infants with any ROP was 19/37 (51%) in the pre-group and 14/46 (30%) in the post-group (p = 0.05). The number of infants requiring any intervention was 7/37 (19%) in the pre-group and 5/46 (11%) in the post-group (p = 0.31).
Conclusions: :
A change in the oxygen parameters for premature infants at risk of ROP may decrease the incidence and severity of ROP. Our study is limited by sample size and slight differences in the groups at baseline. However, a statistically significant decline in both the rates and severity of ROP was noted following the initiation of new guidelines. Ongoing data collection will allow determination whether the effect of the revised oxygen criteria persists over time. Nevertheless, it is clear that oxygen plays a role in the pathogenesis of ROP, and modulation of ex-utero environmental factors such as oxygen saturation targets may decrease the incidence and severity of ROP.
Keywords: retinopathy of prematurity