459 Role of oxygen saturation histogram profiles in predicting hypoxemia and hyperoxemia in premature infants

Abstract

<h3>Background</h3> Supplemental oxygen is the commonest ‘drug’ used in the NICU; goals of therapy is to maintain normoxia whilst minimising hyperoxemia and hypoxemia. <h3>Objectives</h3> To determine the percentage of time preterm infants, spend with oxygen saturation (SpO2) &lt;90% and &gt;95%, and to assess whether 4-hour SpO2 histograms are predictive of 24-hour SpO2 histogram profiles. <h3>Methods</h3> This prospective audit reviewed 100 SpO2 histogram profiles for 60 preterm infants (birth gestation between 23+0 and 33+6 weeks) admitted to the NICU, requiring invasive and non-invasive respiratory support, at different points of their neonatal course, between 01/01/2020 to 01/11/2020. Preterm SpO2 target range within this NICU is 90–95%. We collected SpO2 histogram data from bedside Phillips monitors at 5% intervals displaying the percentage of time spent in SpO2 ranges, at 4-, 8-, 12- and 24-hour intervals. <h3>Results</h3> Mean birth gestation was 26.8 ± 2.4 weeks and mean corrected gestational age at the time of the study was 30.4 ± 2.5 weeks. Twenty preterm infants required conventional mechanical ventilation, 28 CPAP, 26 HFNC, 14 low flow oxygen and 12 had no respiratory support at the point of the study. Table 1 shows preterm infants spend substantial amounts of time outside of their SpO2 target range; hyperoxemia was especially marked. Infants &lt;27 weeks versus infants &gt;27 weeks spent more time with SpO2 &lt;90% at 4-, 8-, 12- and 24-hour histogram reviews (p&lt;0.001); there was no significant difference in time spent with SpO2 &gt;95%. Infants &gt;28 days spent significantly more time with SpO2 &lt;90% compared to infants &lt;28 days at 4-, 8-, 12- and 24-hour histogram reviews (p &lt;0.05); there was no significant difference in time spent with SpO2 &gt;95%. Ventilated infants spent significantly more time with SpO2 &lt;90% compared to infants on other modes of respiratory support (p &lt;0.001). There were strong correlations between 4-hour and 24- hour histograms for both hypoxemia and hyperoxemia, with R2 values of 0.7 and 0.8 respectively. <h3>Conclusions</h3> Maintaining normoxia for preterm infants is challenging, with substantial amounts of time spent outside of the SpO2 target range. There is strong correlations between 4-hour and 24-hour histograms, which could help in assessing a preterm infants’ response to changes in respiratory management.