Oxygen monitoring in preterm babies: too high, too low?

Maternal and fetal arterial and venous oxygen saturation and partial pressure in late pregnancy.¹⁵

Oxygen saturation monitoring policies in the UK. Results from a telephone survey of 100 units with three or more intensive care cots caring for babies of less than 28 weeks’ gestation in 2001. High (A) and low (B) oximeter alarm settings.¹⁸

Relationship between the limits within which oxygen saturation was allowed to vary and the proportion of 1 year survivors so nursed who later developed severe (grade 3+) retinopathy of prematurity: a comparison of four policies. Staff aimed to keep saturation in the upper half of the permitted range.²⁰ (Reproduced from ref. 20 with permission from BMJ Publishing Group.)

Length of time that babies of 24–27 weeks’ gestation were ventilated in 1995–96 (when the upper and lower oximeter alarms were set at 98% and 88%, respectively) and in 1998–2000 (when the alarms were set at 93% and 75%).¹⁸

Relationship between fractional oxygen saturation measured with a pulse oximeter and arterial partial pressure in mmHg and kPa. The dashed line marks the transcutaneous PO₂ above which there was an increased risk of retinopathy in the study reported by Flynn in 1992.¹⁴ The bars in (B) show the range within which 95% of all measures of partial pressure varied when the oximeter read 90%, 92%, 94%, 96% and 98% in the study reported by Brockway and Hay in 1998.²⁸ Note that pulse oximeters calibrated to display functional saturation produce readings about 2% higher than those reflecting fractional saturation. (Reproduced from Neonatal Formulary 3, p. 171, , 2002, with permission from BMJ Books.)