Presented at the Neonatal Society 2001 Summer Meeting.

McColm J¹, Gellen B¹, Cunningham S³, Wade J¹, Sedowofia K¹, Sharma T², McIntosh N¹, Fleck B²

¹ Child Life & Health, Edinburgh University, Edinburgh, Scotland
² Princess Alexandra Eye Pavilion, Edinburgh, Scotland
³ Royal Hospital for Sick Children, Edinburgh, Scotland

Aim: To investigate clinically relevant oxygen fluctuations combined with hypercarbia on the retinal development of newborn rat pups.

Methods: Transcutaneous oxygen data was recorded every minute for 14 days from a preterm infant who developed severe ROP. This data was translated into a profile of inspired O2 values for the rat (1). Animals were then exposed to either this variable O2 profile (V) or to this variable O2profile with constant 5% carbon dioxide (V/CO2). Controls were raised in room air. After sacrifice, retinal wholemounts were prepared and blood vessels visualised with endothelial cell specific lectin. Digital images were taken using confocal microscopy and analysed using Scion Image.

Results: Values are median (interquartile range).

^ap< 0.05, ^bp<0.01, ^cp<0.001 compared to C; ^dp<0.001 V/CO2 vs V. Statistics were a multilevel analysis. atv = abnormal terminal vessels.*n=16

Conclusion: Variations in oxygen alone induced changes in the developing retinal blood vessels of rats similar to changes seen during human retinopathy (2). However, when this was combined with continuous CO2 these changes were more severe.

References
1. McColm JR,.Cunningham S. J Med Engineer Technol 2000;24:45-52.
2. Cunningham S, McColm JR, Wade J, Sedowofia K, McIntosh N, Fleck B. Invest Ophthalmol Vis Sci 2000;41:4275-80.