High blood carbon dioxide variability and adverse outcomes in neonatal hypoxic ischemic encephalopathy

Objective: Hypocarbia during the first 12 h of life is associated with mortality and disability in neonatal hypoxic ischemic encephalopathy (HIE). Notable variation in arterial carbon dioxide tension (PaCO₂) during the first 4 d of life is related to severe intraventricular hemorrhages in preterm infants. We examined the association between PaCO₂ during 72 h of whole-body therapeutic hypothermia for neonatal HIE and 2-year neurodevelopmental outcomes.Methods: A retrospective review of 23 term neonates treated with whole-body hypothermia documented clinical, demographic and arterial blood gas data. Comparisons were made across good and severe neurodevelopmental outcome groups at 2 years of age.Results: Severe neurodevelopmental outcomes were documented in 8 of 23 toddlers. There were no significant differences between outcome groups with regard to the number of patients with hypocarbic means or measurements. There were also no significant differences with mean PaCO₂, PaO₂, pH, time-weighted cumulative hypocarbia, and PaCO₂ range. The severe neurodevelopmental outcomes group had a significantly higher mean PaCO₂ standard deviation (p = 0.04; 95% CI, -5.46 to -0.39).Conclusion: Severe neurodevelopmental outcomes were significantly associated with high PaCO₂ variability over 72 h in whole-body-cooled HIE neonates. Mitigating these fluctuations may be a potential management strategy.