Hypocarbia is associated with adverse outcomes in hypoxic ischaemic encephalopathy (HIE)

Area of Science:

• Neonatal Medicine
• Neuroscience
• Pediatric Critical Care

Background:

• Hypoxic-ischaemic encephalopathy (HIE) is a serious condition in newborns following birth asphyxia.
• Early postnatal hypocarbia (low pCO2) is suspected to worsen brain injury in these infants.
• Therapeutic hypothermia is a common treatment for HIE, but its interaction with pCO2 levels requires further investigation.

Purpose of the Study:

• To review studies examining the correlation between pCO2 levels and outcomes in term newborns with moderate/severe HIE.
• To assess the impact of hypocarbia on short-term and long-term outcomes in neonates treated for HIE.

Main Methods:

• A systematic literature search was conducted across major databases (MEDLINE, EMBASE, CINAHL, Web of Science, Cochrane Library).
• Nine relevant studies were identified and included in the review.
• Data on pCO2 monitoring (duration and frequency) and clinical outcomes were extracted and analyzed.

Main Results:

• Seven of the nine studies utilized therapeutic hypothermia.
• pCO2 levels were typically monitored from birth up to 72 hours or the end of hypothermia treatment.
• Eight studies found a significant association between any degree of hypocarbia (moderate, severe, or cumulative) and increased risks of adverse outcomes, including brain injury on MRI, mortality, and neurodevelopmental disability.

Conclusions:

• Hypocarbia in the early postnatal period can lead to adverse short-term and long-term outcomes in neonates with HIE, even with therapeutic hypothermia.
• Close monitoring of pCO2 levels is essential in these vulnerable infants.
• Implementing strategies to maintain normocapnia (normal pCO2) is crucial for improving neurological outcomes in neonates with HIE.