Outcomes of delivery room resuscitation of bradycardic preterm infants: A retrospective cohort study of randomised trials of high vs low initial oxygen concentration and an individual patient data analysis

Objective: To determine whether hospital mortality (primary outcome) is associated with duration of bradycardia without chest compressions during delivery room (DR) resuscitation in a retrospective cohort study of randomized controlled trials (RCTs) in preterm infants assigned low versus high initial oxygen concentration. Methods: Medline and EMBASE were searched from 01/01/1990 to 12/01/2020. RCTs of low vs high initial oxygen concentration which recorded serial heart rate (HR) and oxygen saturation (SpO₂) during resuscitation of infants <32 weeks gestational age were eligible. Individual patient level data were requested from the authors. Newborns receiving chest compressions in the DR and those with no recorded HR in the first 2 min after birth were excluded. Prolonged bradycardia (PB) was defined as HR < 100 bpm for ≥2 min. Individual patient data analysis and pooled data analysis were conducted. Results: Data were collected from 720 infants in 8 RCTs. Neonates with PB had higher odds of hospital death before [OR 3.8 (95% CI 1.5, 9.3)] and after [OR 1.7 (1.2, 2.5)] adjusting for potential confounders. Bradycardia occurred in 58% infants, while 38% had PB. Infants with bradycardia were more premature and had lower birth weights. The incidence of bradycardia in infants resuscitated with low (≤30%) and high (≥60%) oxygen was similar. Neonates with both, PB and SpO₂ < 80% at 5 min after birth had higher odds of hospital mortality. [OR 18.6 (4.3, 79.7)]. Conclusion: In preterm infants who did not receive chest compressions in the DR, prolonged bradycardia is associated with hospital mortality.