Impact of Respiratory Support Strategies on <scp> CO ₂ </scp> Variability During Therapeutic Hypothermia in Neonates With Asphyxia: Data From the German Hypothermia Registry

ABSTRACT Aim To evaluate associations between respiratory support strategies, partial pressure of carbon dioxide (pCO 2 ) variability and oxygen exposure in neonates with hypoxic–ischaemic encephalopathy (HIE) undergoing therapeutic hypothermia (TH). Methods This retrospective multicentre study used data from the German Hypothermia Registry, including neonates ≥ 36 weeks with moderate‐to‐severe HIE treated with TH between 2022 and 2025. Respiratory support was categorized as continuous positive airway pressure (CPAP) or invasive ventilation. Maximum and minimum pCO 2 and fraction of inspired oxygen (FiO 2 ) were analysed during the first 6 and 72 h of life. Results Among 428 neonates, 99% required respiratory support and 88% received invasive ventilation. Ventilated neonates showed higher maximum pCO 2 levels than CPAP‐supported neonates within the first 6 h (70 vs. 55 mmHg, p = 0.005) and over 72 h (70 vs. 60 mmHg, p &lt; 0.001), while minimum pCO 2 values were lower. Invasive ventilation was also associated with higher FiO 2 requirements and longer oxygen supplementation (4 vs. 1 days, p &lt; 0.001). In neonates with moderate HIE, CPAP was associated with shorter oxygen exposure, earlier oral feeding and reduced hospital stay. Conclusion Respiratory support strategy during TH is associated with distinct patterns of CO 2 and oxygen exposure. CPAP appears feasible in selected neonates with moderate HIE and favourable amplitude‐integrated electroencephalography (aEEG) patterns.