The Impact of Chorioamnionitis and Early Onset Sepsis on Heart Rate and spo2 in Very Low Birth Weight Infants

Background: Chorioamnionitis and early onset sepsis (EOS) in very low birth weight (VLBW) infants may cause a systemic inflammatory response reflected in patterns of heart rate (HR) and oxygenation measured by pulse oximetry (SpO2). Identification of these patterns might inform decisions about duration of antibiotic therapy after birth.

Methods: We conducted a retrospective study of all inborn VLBW infants admitted to the University of Virginia NICU from 2012-2019 with at least 4 hours of every-2-second HR and SpO2 data available in the first 24h after birth. Placental pathology was reviewed, when available. Hourly HR and SpO2 mean, standard deviation, skewness and kurtosis were calculated for each infant and group means were compared based on histologic chorioamnionitis and EOS category.

Results: Of 397 infants with at least 4h of HR and SpO2 data available, 9 had EOS (2.3%), 83 CS (21%), 195 SRO (49%), 110 no culture (28%). The mean (SD) gestational age for each of the 4 groups was 26.3 (2.1), 26.0 (2.3), 27.4 (2.6), and 30.5 (2.8) weeks, respectively. Placental pathology was available for 98% of cases, and histologic chorioamnionitis was present in 21%. In the 72 hours after birth, mean HR was higher in infants with EOS or clinical sepsis compared to those with sepsis ruled out or no culture obtained. In the 12 hours after birth, HR was higher in infants of mothers with histologic chorioamnionitis. In addition to higher HR, infants with EOS had lower mean SpO2 (Table 1).

Conclusion: Heart rate is higher and SpO2 lower in VLBW infants with culture-proven or clinical EOS. Histologic chorioamnionitis was also associated with higher HR. Future work will adjust for clinical variables and determine whether HR and SpO2 analysis can provide reassurance for reducing antibiotic exposure after birth for VLBW infants.