Figure 1  (A) The relationship between fractional oxygen saturation measured with a pulse oximeter and arterial partial pressure of oxygen (pO₂) in mm Hg and kPa. (B) The bars show the range within which 95% of all measures of pO₂ varied when the oximeter read 90%, 92%, 94%, 96% and 98% in the study reported by Brockway and Hay14. The dashed lines in A and B mark the transcutaenous pO₂ above which there was an increased risk of retinopathy in the study reported by Flynn in 1992.11 Reproduced with permission from Neonatal Formulary.15