Respiratory Targets Associated With Lung Aeration During Delivery Room Resuscitation of Preterm Neonates.

Importance Effective lung aeration is crucial for successful postnatal transition. Goal targets to achieve lung aeration during positive pressure ventilation have not been established for preterm neonates. Objective To identify respiratory parameters associated with successful lung aeration during delivery room resuscitation. Design, Setting, and Participants This multicenter prospective cohort study was conducted from March 2016 to April 2021. The primary population included preterm neonates from 3 centers of 22 weeks to 31 weeks 6 days' gestation with bradycardia who received positive pressure ventilation during resuscitation after birth. An independent population of preterm neonates (24 weeks to 27 weeks 6 days' gestation) in the multicenter Monitoring Neonatal Resuscitation randomized clinical trial served as a confirmatory dataset. Data were analyzed January 2022 to May 2025. Exposures Rolling means of pressure, inspiratory and expiratory tidal volumes (VTE), and mask leak, as measured with a respiratory function monitor (RFM). Counts of spontaneous breaths between inflations and mask removal instances. Main Outcomes and Measures The primary outcome was a sustained increase in heart rate to at least 100 beats per minute, indicating effective lung aeration, within the first 10 minutes of resuscitation. Associations between clinical covariates, respiratory parameters, and heart rate increase were examined using cause-specific Cox proportional hazards regression models. Results There were 132 neonates in the primary dataset (median [IQR] gestation, 26.6 [25.1-29.2] weeks; 67 [50.8%] male) and 115 in the confirmatory dataset (median [IQR] gestation, 26.7 [25.6-27.4] weeks; 65 [56.5%] male). Of 132 primary dataset participants, 125 (94.7%) achieved the primary outcome. Among the measured respiratory parameters, only VTE was associated with an increase in heart rate (adjusted hazard ratio [AHR], 1.10 [95% CI, 1.01-1.20]). The AHR was higher for increases in VTE up to 4 mL/kg (AHR, 1.55 [95% CI, 1.20-2.00]) than for VTEs higher than 4 mL/kg (AHR, 1.04 [95% CI, 0.98-1.10]). These results were consistent with those in the confirmatory dataset: an association for an increase in heart rate with VTE values up to 4 mL/kg (AHR, 1.31 [95% CI, 1.01-1.70]) but not higher than 4 mL/kg (AHR, 1.02 [95% CI, 0.96-1.08]). Other covariates associated with an increase in heart rate included birth weight (per 100 g) (AHR, 1.12 [95% CI, 1.05-1.20]) and mask removal count (AHR, 0.83 [95% CI, 0.70-0.98]). Conclusions and Relevance This cohort study observed in one neonatal population and confirmed in another that a minimum VTE of 4 mL/kg was associated with successful lung aeration as assessed by an increase in heart rate to at least 100 beats per minute during preterm neonate resuscitation. These results may inform future studies to determine the clinical impact of incorporating data-based targets for delivery room resuscitation of preterm neonates.