Oxygen saturation guidance in neonatal medicine is complicated by the fact that targets for preterm infants need to be different from those for more mature infants. In the early weeks after birth, avoidance of hyperoxia in preterm infants is important. By the time those same infants are approaching term and beyond, concerns about hyperoxia are diminishing while avoiding the potentially harmful effects of hypoxia on pulmonary hypertension, growth and neurodevelopment are becoming increasingly important.
Interpretation of published data is complicated by variable technical specifications utilised by different oximeters in various studies, especially signal averaging times3. Oximeter settings employed for specific research studies may have been modified for the purposes of clinical trials.
The partial pressure of oxygen (pO2) in arterial blood reflects the molecular concentration of oxygen in tissues and is probably the optimal measure of oxygenation when attempting to reduce the risk of ROP. The flattening of the oxy-haemoglobin dissociation curve at higher saturation values means that pulse oximetry has limitations when detecting hyperoxia. These aspects were taken into account by the committee preparing the National Institute for Health and Care Excellence (NICE) guideline on respiratory care for babies born preterm and agreed that ‘SpO2 should remain the first-line method for continuous monitoring of oxygen saturation levels in preterm babies because of its widespread availability and non-invasive nature.’ They acknowledged that ‘arterial sampling of partial pressure of oxygen remained the ‘gold standard’ but is not always possible and can never be continuous.’4.