Objective To explore the contribution of nurse oxygen adjustment behaviours to the stability of oxygenation in preterm infants, by controlling for infants’ intrinsic instability.

Methods Oxygen adjustment behaviours of 24 trained neonatal nurses while caring for 13 ventilated infants during 133 nursing shifts were studied. Average time per shift that each individual infant spent with saturation (SpO₂) >94% in supplemental oxygen (hyperoxic), the variability (SD) of SpO₂ and time spent with SpO₂ <86% were calculated. The oxygen adjustment behaviours of the nurses who for ⩾50% of their shifts the infant in their care was more unstable by these measures than the average for that infant, were compared with the behaviours of the remaining nurses. Behaviours compared were mean number FiO₂ increases, mean size FiO₂ increase, mean FiO₂ variability, mean FiO₂ and mean SpO₂ maintained. Independent samples t-tests were used for comparisons.

Results Nurses whose babies spent more time hyperoxic than average (24% vs 14%) made larger increases in FiO₂, (9.9% vs 7.6%, p = 0.02) but not more frequent increases. Nurses whose babies showed greater than average variability in SpO₂ increased the FiO₂ more frequently (28 vs 21 times per shift, p = 0.03) but not in larger steps. Nurses whose babies spent most time with SpO₂ <86% (16% vs 10%) also made more frequent (29 vs 20 times per shift, p = 0.003) but not larger increases in FiO₂.

Conclusion After controlling for the intrinsic instability of the infant we found that larger and more frequent changes in FiO₂ contribute to instability of oxygenation.