285 - Cumulative distributions of SpO2/FiO2 ratios in premature infants reveal more hypoxemia among Black infants in the first month after birth.

Sunday, April 30, 2023

3:30 PM – 6:00 PM ET

Poster Number: 285
Publication Number: 285.344

Brynne A. Sullivan, University of Virginia School of Medicine, KESWICK, VA, United States; Zachary A. Vesoulis, Washington University School of Medicine, St. Louis, MO, United States

Presenting Author(s)

Brynne A. Sullivan, MD, MSCR (she/her/hers)

Assistant Professor
University of Virginia School of Medicine
KESWICK, Virginia, United States

Background: Intermittent hypoxemia is common in premature infants with respiratory distress syndrome. The ratio of peripheral oxygen saturation (SpO2) to the fraction of inspired oxygen (S/F ratio) is a tool for non-invasively assessing hypoxemia (low S/F ratio) and lung function. Racial differences in pulse oximeter accuracy and respiratory disease have been identified in studies of premature infants, which may conflict with the common clinical assumption that Black infants have less severe lung disease.

Objective: Determine whether hypoxemia in the first 30 days after birth, measured by the S/F ratio, differs by race in premature infants (gestational age < 32 w).

Design/Methods: We retrospectively studied premature infants admitted to a level IV NICU during 2020-2022 identified as having Black or Non-Black maternal race. To account for prematurity, we matched infants analyzed in each race group for gestational age and excluded any unmatched infants and those admitted for < 12 hours. We calculated S/F ratios using SpO2 and FiO2 values recorded every 15 minutes from admission until 30 days of age in the electronic health record. Where new values were missing, SpO2 and FiO2 values were carried forward for 12 hours. Periods with >12 hours of missing data were removed from analysis. We quantified differences by race in empirical cumulative distributions using the Kolmogorov-Smirnov (K-S) two-sample test. Outcomes of death, chronic lung disease, severe intraventricular hemorrhage (IVH), and treated retinopathy of prematurity (ROP) were compared by race.

Results: We analyzed 290,312 S/F ratios and outcomes for 63 Black and 63 non-Black infants. Gestational age, birthweight, and outcomes were similar between the two groups (Table 1). The S/F ratio curve for Black infants was shifted to the left, indicating overt hypoxemia (low S/F ratio) occurred more often in Black infants compared with non-Black (K-S distance: 0.05; p< 0.01, Figure 1). Examining the cumulative distributions of S/F ratios components by race, we saw a minimal difference in SpO2 values and a right shift in the FiO2 distribution curve for Black infants (K-S distance 0.04, p < 0.01).

Conclusion(s): Using S/F ratios to assess hypoxemia in premature infants in the first 30 days after birth, Black infants had a left shift in S/F ratio and a right shift in the FiO2 distribution, indicating more hypoxemia and greater supplemental oxygen exposure when compared to non-Black infants. Although short-term outcomes were similar between groups, long-term follow-up is needed to assess the potential long-term consequences of hypoxemia.