Oxygen Saturation in Preterm Infants: Hitting the Target

Laura A. Stokowski, RN, MS


February 06, 2014

In This Article

Study: Time Spent in (and Out of) Oxygen Saturation Targets

A recent prospective observational study examined clinical practice with respect to SpO2 targets in a sample of preterm infants receiving continuous positive airway pressure (CPAP) cared for in 2 NICUs. To better understand SpO2 targeting, Lim and colleagues quantified the proportion of infants who were maintained within SpO2 targets, the frequency of prolonged hyperoxia and hypoxia episodes among these infants, and how often FiO2 adjustments were made in response to these episodes. Of particular interest, they also examined the relationship of these events to certain NICU operational factors -- such as nurse-to-patient ratios, years of nurse experience, and shift -- that might influence how well the targets were met.

The established targets for SpO2 levels in these hospitals were 88%-92%, with alarm limits set at 85%-94% (high limit raised to 100% if the infant was not receiving supplemental oxygen). Twenty-four hour recordings of oxygen saturation, FiO2, and other vital signs were obtained from 45 preterm infants (< 37 weeks') gestation, resulting in 4034 hours of usable data. Data from all infants were pooled for analysis to provide a snapshot of the overall frequency of time spent in hypoxia (SpO2 ≤ 87%), hyperoxia (SpO2 ≥ 93%) and the "normal" (target) range (SpO2 88%-92%) among this sample of preterm infants.


The relative proportion of the recording time that infants spent inside and outside of the SpO2 target range is shown in the Figure.

Figure. Median proportion of time spent in target SpO2 ranges for infants receiving both continuous positive airway pressure and supplemental oxygen.

Infants who were receiving CPAP with supplemental oxygen were in the target SpO2 range only 31% (range, 19%-39%) of the total recording time, and most of the total recording time was spent in the hyperoxia range. Within these periods, there were 48 (range, 6.9-90) episodes/24 hours of severe hyperoxia (SpO2 ≥ 98%), and 9 (range, 1.6-21) episodes/24 hours of severe hypoxia (SpO2 < 80%). Most high SpO2 values were in the mildly hyperoxic range. Prolonged (≥ 30 seconds) episodes of serious hypoxia and hyperoxia (in infants receiving supplemental oxygen) were relatively frequent, occurring more often when nurses were taking care of more than 1 patient.

Of note, babies cared for by nurses with fewer than 5 years of experience spent more time in the targeted SpO2 range than babies cared for by nurses with more experience. Shift (day, evening, or night) had no effect on time spent in the targeted range. Adjustments to FiO2 were made 25 (range, 16-41) times/24 hours, with a lower frequency during the night shift.


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