Abstract
Purpose: :
To determine the change in ROP in a Level III NICU in which consecutive ROP exams were performed before and after a change in oxygen supplementation practice was implemented.
Methods: :
An IRB approved prospective database recorded the gestational age (GA), birthweight (BW), Stage and Zone of ROP. A retrospective analysis of these characteristics was performed between September 2005 and October 2007. The main outcome measure was prevalence of ROP, Stage and Zone of retinopathy, threshold, and progression to retinal detachment or fold. The first of these two years exams were performed on children with standard oxygen supplementation (saturation target ≥ 95%). The second year exams were performed on infants whose target saturation was 85-92% <34 weeks and 92-97% ≥ 34 weeks. Exams were performed on children between 5-7 weeks of life or any infant less than 1500 grams birthweight or less than 32 weeks gestational age or an unstable clinical course or more than 24 hours of oxygen therapy.
Results: :
A total of 190 consecutive patients were examined between September 2005 and October 2007, of whom 98 infants were examined prior to and 92 infants examined after the change in oxygen standards. Mean GA was identically 28 weeks, and mean BW 1085g for each year. 200 and 155 exams were performed on these patient cohorts, respectively (2.2 exams/pt year 1 and 1.9 exams/pt year 2) . ROP was present in 35% of infants, compared to 13% in the year after the change in oxygen standards; threshold disease decreased from 7% to 1%. There was a decrease in all pathogenic stages of ROP (pre/post oxygen change- Stage 1: 20%/12%; Stage 2: 12%/3%; Stage 3: 10%/ 2%). We also found an increase in Stage 0 (immature vessels) and Zone 3 or fully vascularized retina after the oxygen change was implemented (pre/post oxygen change-24%/43% Stage O; fully vascularized 23%/30% pre/post). The increase in Stage 0 or normal retinal development was matched by a decrease in less mature zones, implying that the retina tended to develop at a quicker rate within the new oxygen parameters (pre/post oxygen change-Zone 1: 5%/2%; Zone 2: 52%/40%; Zone 3: 43%/58%). There were no Stage 4 or 5 eyes.
Conclusions: :
Meticulous control of oxygen with comparatively lower oxygen targets at early gestational age and higher oxygen limits at older gestational decreases the severity and prevalence of ROP.
Keywords: retinopathy of prematurity • oxygen • hypoxia