Background Free radical formation and subsequent injury secondary to hyperoxia have been described in premature infants. In vitro models have suggested that hyperoxia may also affect the immune system, but it is not clearly known if this occurs in vivo with clinically relevant consequences.
Objective To determine if avoiding hyperoxia is associated with a lower rate of late bacterial sepsis (LBS) in infants with birth weight # 1,000 grams (ELBW).
Design/Methods Retrospective analysis of a prospectively collected database of all ELBW born at two Emory University perinatal centers from 1/00 through 12/04 who were admitted to the NICU. A change in practice was instituted in January 2003 with the objective of avoiding hyperoxia in preterm infants. Prior to this change, O2 saturation (SpO2) high alarms were set at 100% and low alarms at 92%. The target SpO2 aimed to avoid hyperoxia was 85 to 93%. For the analysis of LBS we included infants who survived > 6 days. Statistics included bivariate analyses and multivariate logistic regression analyzing LBS independently with SpO2 targets between the two periods.
Results Of the 299 ELBW who met enrollment criteria, 124 (43%) were treated with the objective of avoiding hyperoxia. Birth weight (779 6 130 vs 776 6 151; p = .881), gestational age (26.1 6 1.9 vs 26.3 6 2.1; p = .331), and survival (86.7% vs 83.9%; p = .504) were similar between higher and lower saturation periods. The rate of LBS in ELBW (28.2% vs 48.8%; p = .000) was lower in the group avoiding hyperoxia (OR = 0.41 [95% CI = 0.25-0.67]).
Conclusions A practice change with the objective of avoiding hyperoxia was associated with a significant decrease of LBS in ELBW infants. We speculate that unnecessary oxygen exposure may affect the already depressed immune system of ELBW infants.
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