Background and Aims Manual control of oxygen delivery to premature infants is conducted mainly by NICU nurses. This involves F_IO₂ adjustments in order to keep the S_PO₂ within a specific target range (88–92%). Pulse oximeters have alarms set to alert the nurses when S_PO₂ values are outside the range (85–95%). Our aims were to study F_IO₂ alteration in terms of magnitude and time outside target immediately before the F_IO₂ change.

Methods Infants receiving CPAP or ventilation on the Babylog 8000 ventilator (Dec 2010- Apr 2012) were studied. Signals were acquired from oximeters and ventilator using the PowerLab data acquisition system. The 9-minute epoch prior to each F_IO₂ change: F_IO₂ increase (ΔPOS) and F_IO₂ decrease (ΔNEG) were studied.

Results Recordings were obtained from 7 (5 male) infants with mean (± SD) gestation of 26.9 (±1.9) weeks and birthweight 767 (±200) g. 253 F_IO₂ adjustments were recorded (130 ΔPOS and 123 ΔNEG) from 105 hours of total recording time. Mean (range) magnitude of ΔPOS and ΔNEG was 4.6% (0.5–19.5) and 4.5% (0.5–57.0), respectively. Proportion time spent with low alarm in the 9 minutes before ΔPOS was 50.8%, with 28.4% (±20.2) of time in 80–85%, 15.8%(±16.7) in 70–80% band and 6.6%(±11.3) less than 70% saturation. 22.5% of time was spent with high alarm (before ΔNEG) with 4.3% (±8.7) time S_PO₂ exceeding 98% and 7.7% (±11.4) in 96–98% band.

Conclusion Nurses were more likely to tolerate low oxygen saturations than high saturations in preterm infants. Mild desaturation episodes (between 80–85%) were often managed conservatively.